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1.
Cancer Cell Int ; 24(1): 201, 2024 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-38844922

RESUMO

BACKGROUND: Colorectal cancer (CRC) has the third highest incidence and second mortality rate of malignant tumors globally, highlighting the urgency to explore the mechanisms underlying CRC progression for refined treatment of this patient population. METHODS: R Studio was used for data sorting and analysis. Cell apoptosis and cell cycle detection were performed by flow cytometry. Quantitative real-time PCR (qRT-PCR) was used to explore mRNA expression levels. Western blotting was used to explore protein expression levels. CCK8, EdU, and colony formation assays were performed to explore the proliferation capacity of CRC cells. Transwell invasion and migration assays, along with the wound healing assay, were used to explore the invasive and migratory abilities of CRC cells. Subcutaneous Xenograft Assay was utilized to evaluate the tumorigenic capacity of CRC cells in vivo. RESULTS: SULF1 was highly expressed in CRC samples and cell lines. The knockdown of SULF1 inhibited the proliferation, invasion, and migration of CRC and increased the rate of cell apoptosis. Meanwhile, we demonstrated that SULF1 could negatively regulate ARSH through the FAK/PI3K/AKT/mTOR pathway. CONCLUSION: We demonstrated that SULF1 could promote CRC progression by regulating ARSH. The SULF1/ARSH/FAK/PI3K/AKT/mTOR signaling pathway represents a promising target for the treatment of this patient population. Colorectal cancer (CRC) has the third highest incidence and second mortality rate of malignant tumors globally. Sulfatase 1 (SULF1) belongs to the sulfatase family, The function of SULF1 in CRC remains elusive. Our study demonstrated that the knockdown of SULF1 could inhibit the proliferation, invasion, and migration of CRC. Meanwhile, our findings indicated that SULF1 could interact with Arylsulfatase Family Member H (ARSH) to regulate the proliferation, invasion, and migration of CRC via the FAK/PI3K/AKT/mTOR signaling pathway. Taken together, our findings suggest that SULF1 might be a new therapeutic target in CRC.

2.
Cancer Sci ; 113(9): 2962-2973, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35289035

RESUMO

The high prevalence of oral squamous cell carcinoma (OSCC) in South Asia is associated with habitual areca nut chewing. Arecoline, a primary active carcinogen within areca nut extract, is known to promote OSCC pathological development. Dysregulation of N6-methyladenosine (m6A) modification has begun to emerge as a significant contributor to cancer development and progression. However, the biological effects and molecular mechanisms of m6A modification in arecoline-promoted OSCC malignance remain elusive. We reveal that chronic arecoline exposure substantially induces upregulation of fat mass and obesity-associated protein (FTO), MYC, and programmed cell death-ligand 1 (PD-L1) in OSCC cells. Moreover, upregulation of PD-L1 is observed in OSCC cell lines and tissues and is associated with areca nut chewing in OSCC patients. We also demonstrate that arecoline-induced FTO promotes the stability and expression levels of PD-L1 transcripts through mediating m6A modification and MYC activity, respectively. PD-L1 upregulation confers superior cell proliferation, migration, and resistance to T-cell killing to OSCC cells. Blockage of PD-L1 by administration of anti-PD-L1 antibody shrinks tumor size and improves mouse survival by elevating T-cell-mediated tumor cell killing. Therefore, targeting PD-L1 might be a potential therapeutic strategy for treating PD-L1-positive OSCC patients, especially those with habitual areca nut chewing.


Assuntos
Carcinoma de Células Escamosas , Neoplasias de Cabeça e Pescoço , Neoplasias Bucais , Animais , Apoptose , Areca/efeitos adversos , Areca/metabolismo , Arecolina/farmacologia , Carcinoma de Células Escamosas/patologia , Imunidade , Ligantes , Camundongos , Neoplasias Bucais/patologia , Obesidade/complicações , Carcinoma de Células Escamosas de Cabeça e Pescoço
3.
Blood Purif ; 42(1): 3-8, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26905433

RESUMO

OBJECTIVE: The study aimed to study the safety and efficacy of 1.25 mmol/l calcium dialysate on maintenance hemodialysis (MHD) in elderly patients who suffered from secondary hypoparathyroidism. METHODS: Eighty-two elderly patients (ages ≥65) who had been in MHD with dialysate calcium at 1.5 mmol/l over 6 months and had 2 consecutive serum intact parathyroid hormone (iPTH) measurements at level below 100 pg/ml were selected and randomized into 2 groups: treatment group (41 patients, with dialysate calcium at 1.25 mmol/l) and control group (41 patients, still with dialysate calcium at 1.5 mmol/l). Both groups were studied for the duration of 12 months. The changes of serum iPTH, calcium, phosphorus, calcium and phosphorus product and other indicators as well as related adverse reactions were recorded at the following time points: before the study and 1, 3, 6 and 12 months into the study. In addition, the intimal media thickness (IMT) of carotid artery and abdominal aorta calcification score (AACS) were measured in the 0, 6 and 12 months during the study. RESULTS: (1) In the treatment group, the levels of serum corrected calcium, phosphorus and calcium-phosphate product began to decline after 1 month and exhibited further decrease 3 months later. Serum iPTH level increased significantly after 1 month into the study and the trend continued. The above markers stabilized after month 6. Compared with pre-study markers, the changes of the above markers were significant after study (p < 0.05). (2) The average IMT and AACS were evidently decreased during the 6 and 12 months of study in the treatment group. There was statistical significance (p < 0.05) when compared with the above indexes of the pre-study and the control group. (3) In the control group, there were no significant differences in above laboratory markers over the 12-month study period. (4) There was no significant difference in the adverse events observed between the 2 groups. CONCLUSION: Safety of low calcium dialysate (dialysate calcium 1.25 mmol/l) in elderly MHD patients with iPTH <100 pg/ml is good, as well as improving carotid IMT, resistance index and AACS as indexes of vascular calcification in the small study group and warrants further investigation.


Assuntos
Cálcio/farmacologia , Soluções para Diálise/química , Hipoparatireoidismo/etiologia , Idoso , Idoso de 80 Anos ou mais , Cálcio/sangue , Artérias Carótidas/patologia , Estudos de Casos e Controles , Soluções para Diálise/farmacologia , Humanos , Estudos Longitudinais , Hormônio Paratireóideo/sangue , Segurança do Paciente , Fósforo/sangue , Diálise Renal/efeitos adversos , Diálise Renal/métodos , Resultado do Tratamento , Calcificação Vascular/etiologia
4.
Phys Chem Chem Phys ; 16(16): 7538-47, 2014 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-24632683

RESUMO

The effects of the surface atomic and electronic structures, oxygen defects, and hydration on CO2 adsorption on ZnGa2O4(100), (110), and (111) surfaces were studied using density functional theory (DFT) slab calculations. For the perfect (100) surface, the most stable adsorption state involved the Zn-O-Ga bridge site, with an adsorption energy of 0.16 eV. In the case of the (110) and (111) surfaces, the strongest binding occurred on the Zn-O bridge sites, with much lower adsorption energies of -0.22 eV and -0.35 eV, respectively. In addition, the perfect surfaces showed CO2 activation ability, but dissociation adsorption could not proceed. The oxygen vacancies on these three surfaces (1) made the metal sites beside them carry less positive charge and further reduced the adsorption energies on these metal sites, and (2) created efficient adsorption sites that allowed even dissociative adsorption. The most favorable molecular and dissociative adsorption states both involved the O3c vacancy site of the (100) surface, and these two processes were spontaneous with adsorption energies of 0.74 eV and 0.80 eV, respectively. When H2O molecules are present on the perfect and defective surfaces, the generation of hydrogen bonds between H2O and CO2 would slightly enhance the stability of adsorption (except for that on the surface), making them energetically favorable. However, the co-adsorption of H2O could also increase the energy barriers for the decomposition reactions on the defective surfaces, making them kinetically unfavorable. Furthermore, the oxygen vacancy defects showed good activity for H2O adsorption and decomposition, as well. Thus, when both H2O and CO2 were present in the adsorption system, H2O would compete with CO2 for the oxygen vacancy sites and further decrease the amount of CO2 adsorption and decomposition. These findings have important implications for the decomposition of CO2 on the ZnGa2O4 surfaces and can provide theoretical guidance for chemists to efficiently synthesize ZnGa2O4 catalysts.

5.
Int Immunopharmacol ; 134: 112172, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38703566

RESUMO

BACKGROUND: The clinical significance and comprehensive characteristics of chemokines and chemokine receptors in colorectal cancer (CRC) have not been previously reported. Our study aims to investigate the expression profiles of chemokines and chemokine receptors, as well as establish subtypes in CRC. METHODS: 1009 CRC samples were enrolled in our study. Consensus unsupervised clustering analysis was conducted to establish subtypes, and a risk score model was developed using univariate Cox regression and least absolute shrinkage and selection operator (LASSO) analyses. 36 pairs of tissue specimens of CRC patients and two CRC cell lines were used to validate the subtypes and risk score in vitro. Quantitative real-time PCR and western blotting were employed to validate mRNA and protein expression levels, respectively. Flow cytometry was utilized for analyzing cell apoptosis, while cell viability assay and EdU assay were conducted to assess cell proliferation ability. RESULTS: The Cluster B group shares similarities with the low-risk group in terms of exhibiting a higher level of immune cell infiltration and belonging to hot tumor. Patients CRC in the Cluster B group demonstrate a more favorable prognosis and exhibit better response to immunotherapy and chemotherapy. On the other hand, the Cluster A group resembles the high-risk group as it displays lower levels of immune cell infiltration, indicating a cold tumor phenotype. CRC patients in the Cluster A group have poorer prognoses and show less therapeutic efficacy towards immunotherapy and chemotherapy. Furthermore, we utilized a total of 36 pairs of tissue samples obtained from patients with CRC, along with two CRC cell lines for validation in vitro. This comprehensive approach further enhances the scientific validity and reliability of the identified subtypes and risk score in their ability to predict prognosis, response to immunotherapy, and response to chemotherapy among CRC patients. CONCLUSION: We first established robust prognostic subtypes based on chemokines and chemokine receptors, which could potentially serve as a novel biomarker for guiding individualized treatment in patients with CRC undergoing immunotherapy and chemotherapy.


Assuntos
Quimiocinas , Neoplasias Colorretais , Imunoterapia , Receptores de Quimiocinas , Humanos , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/imunologia , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/terapia , Imunoterapia/métodos , Prognóstico , Feminino , Masculino , Quimiocinas/metabolismo , Quimiocinas/genética , Receptores de Quimiocinas/metabolismo , Receptores de Quimiocinas/genética , Pessoa de Meia-Idade , Biomarcadores Tumorais/metabolismo , Linhagem Celular Tumoral , Idoso , Regulação Neoplásica da Expressão Gênica , Antineoplásicos/uso terapêutico , Antineoplásicos/farmacologia , Proliferação de Células/efeitos dos fármacos , Apoptose/efeitos dos fármacos
6.
Sci Rep ; 13(1): 21358, 2023 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-38049474

RESUMO

The clinical significance and comprehensive characteristics of chemokines and chemokine receptors in female patients with advanced colorectal adenocarcinoma have not ever been reported. Our study explored the expression profiles of chemokines and chemokine receptors and constructed a chemokine- and chemokine receptor-based signature in female patients with advanced colorectal adenocarcinoma. Four independent cohorts containing 1335 patients were enrolled in our study. Univariate Cox regression and least absolute shrinkage and selection operator (LASSO) analyses were performed to construct the signature. CIBERSORT was used to evaluate the landscape of immune cell infiltration. Thirty-two pairs of tissue specimens of female advanced colorectal cancer (CRC) patients and two CRC cell lines were used to validate the signature in vitro. Quantitative real-time PCR and western blotting were performed to validate the mRNA and protein expression levels of signature genes. EdU and colony formation assays were performed to examine proliferative ability. Transwell and wound healing assays were used to evaluate cell invasion and migration capacity. During the signature construction and validation process, we found that the signature was more applicable to female patients with advanced colorectal adenocarcinoma. Hence, the subsequent study mainly focused on the particular subgroup. Enrichment analyses revealed that the signature was closely related to immunity. The landscape of immune cell infiltration presented that the signature was significantly associated with T cells CD8 and neutrophils. Gene set enrichment analysis (GSEA) confirmed that the high-risk group was chiefly enriched in the tumor-promoting related pathways and biological processes, whereas the low-risk group was mainly enriched in anti-tumor immune response pathways and biological processes. The signature was closely correlated with CTLA4, PDL1, PDL2, TMB, MSI, and TIDE, indicating that our signature could serve as a robust biomarker for immunotherapy and chemotherapy response. ROC curves verified that our signature had more robust prognostic power than all immune checkpoints and immunotherapy-related biomarkers. Finally, we used 32 pairs of tissue specimens and 2 CRC cell lines to validate our signature in vitro. We first provided a robust prognostic chemokine- and chemokine receptor-based signature, which could serve as a novel biomarker for immunotherapy and chemotherapy response to guide individualized treatment for female patients with advanced colorectal adenocarcinoma.


Assuntos
Adenocarcinoma , Neoplasias Colorretais , Humanos , Feminino , Adenocarcinoma/genética , Adenocarcinoma/terapia , Neoplasias Colorretais/genética , Neoplasias Colorretais/terapia , Imunoterapia , Quimiocinas/genética , Receptores de Quimiocinas , Prognóstico
7.
Langmuir ; 28(13): 5882-91, 2012 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-22401140

RESUMO

The interaction between implanted La, substitutional N, and an oxygen vacancy at TiO(2) anatase (101) surface has been investigated by means of first-principles density function theory calculations to investigate the origin of enhanced visible-light photocatalytic activity of La/N-codoped anatase observed in experiments. Our calculations suggest that both the adsorptive and substitutional La-doped TiO(2) anatase (101) surfaces are probably defective configurations in experiments. The h-Cave-adsorbed La doping decreases the formation energy for the substitutional N implantation and vice versa, while the charge compensation effects do not take effect between the adsorptive La and substitutional N dopants, resulting in some partially occupied states in the band gap acting as traps of the photoexcited electrons. The Ti(5c)-substituted La doping decreases the energy required for the substitutional N implantation, and the substitutional La and N codoping promotes the formation of an oxygen vacancy, which migrates from the O(sb-3c) site at the inner layer toward the surface O(b) site. For the substitutional La/N-codoped (Ti(5c)_O(3c-down)) surface, the charge compensation between the substitutional La and substitutional N leads to the formation of two isolated occupied N(s)-O π* impurity levels in the gap, while the excitation energy from the higher impurity level to the CBM decreases by about 0.89 eV. After further considering an oxygen vacancy on the Ti(5c)_O(3c-down) surface, the two electrons on the double donor levels (O(b) vacancy) passivate the same amount of holes on the acceptor levels (substitutional La and N), forming the acceptor-donor-acceptor compensation pair, which provides a reasonable mechanism for the enhanced visible-light photocatalytic activity of La/N codoped TiO(2) anatase. This knowledge may aid the further design and construction of new effective visible-light photocatalysts.

8.
Inorg Chem ; 51(12): 6762-70, 2012 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-22667686

RESUMO

In general, the presence of shared edges of polyhedra for high-valence low-coordinated small cations is rarely seen except under extreme conditions such as high pressure. However, the ambient-pressure synthesis of KZnB(3)O(6) built of edge-sharing BO(4) tetrahedra is contrary to this. By investigating the molecular dynamics, lattice dynamics, and electronic properties via density functional theory, we studied the origin of the phase stability of the edge-sharing (es) and "corner-sharing (cs)" KZnB(3)O(6). Lattice dynamics results show that there are no phonon anomalies that could lead to the instability of es-KZnB(3)O(6), which is consistent with molecular dynamics analysis. For "cs-KZnB(3)O(6)", a soft mode at the G point in the phonon dispersion is identified that reflects the dynamic instability with respect to small distortions. Eigenvector analysis of the soft mode of "cs-KZnB(3)O(6)" indicates that the instability comes from the linkage of ZnO(5) polyhedra rather than BO(x) polyhedra. Electronic property calculation indicates that the edge-sharing BO(4) polyhedra connected by the longest B-O σ bonds provide a solid framework for es-KZnB(3)O(6). In the case of "cs-KZnB(3)O(6)", the overlong Zn-O bond possesses the smallest covalent nature and the least orbital overlap among the bonds in a ZnO(5) polyhedron, and these two features of the electronic structure reduce the stability of "cs-KZnB(3)O(6)" compared to es-KZnB(3)O(6). The electronic property calculation further confirms the results obtained from lattice dynamics analysis.

9.
Phys Chem Chem Phys ; 13(4): 1379-85, 2011 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-21103578

RESUMO

We have employed DFT calculations to carry out an accurate analysis of the effect of N- and NH-doping on the visible photocatalytic activity in the cubic In(2)O(3). In the substitutional N-doped In(2)O(3), the 2p impurity states of N induce a red shift in the optical absorption, while in the interstitial N-doping the red shift is dominantly caused by the localized π antibonding states of NO. When a H atom is accompanied by a N impurity in the lattice, the H atom acts as a charge donor and compensates the hole state created by N-doping, thus the energy level of the impurity states is reduced. As a result, the mixing of impurity states and the valence band is enhanced. At the same nitrogen dopant concentration, NH-codoping yields a larger band gap narrowing, especially for the interstitial NH-codoping. The theoretical calculations presented in this work explain well the previous experimental results of the enhanced visible photocatalytic activity in NH-codoped cubic In(2)O(3).

10.
Cancer Med ; 10(18): 6402-6415, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34378866

RESUMO

Arecoline, a major alkaloid within areca nut extract, is recognized as the primary active carcinogen promoting oral squamous cell carcinoma (OSCC) pathological development. Dysregulation of N6-methyladenosine (m6A) methyltransferase components (e.g., Fat mass and obesity-associated protein [FTO] and methyltransferase-like 3 [METTL3]) are closely associated with multiple cancer progression, including oral cancer. However, the biological function role of FTO in arecoline-induced oral cancer is largely unknown. We identified that FTO was significantly upregulated in OSCC tissues from patients with areca nut chewing habits and chronic arecoline-treated OSCC cell lines. Depletion of FTO attenuated the arecoline-promoted stemness, chemoresistance, and oncogenicity of OSCC cells. Finally, we revealed that FTO was negatively regulated by a transcription factor forkhead box protein A2 (FOXA2) in OSCC cells. This study, for the first time, demonstrated that FTO plays an oncogenic role in arecoline-induced OSCC progression. Thus, developing new therapeutic agents targeting FTO may serve as a promising method to treatment OSCC patients, especially those with areca nut chewing habits.


Assuntos
Dioxigenase FTO Dependente de alfa-Cetoglutarato/genética , Arecolina/efeitos adversos , Fator 3-beta Nuclear de Hepatócito/metabolismo , Neoplasias Bucais/genética , Carcinoma de Células Escamosas de Cabeça e Pescoço/genética , Dioxigenase FTO Dependente de alfa-Cetoglutarato/metabolismo , Areca/efeitos adversos , Areca/química , Carcinogênese/induzido quimicamente , Carcinogênese/genética , Carcinogênese/patologia , Estudos de Casos e Controles , Linhagem Celular Tumoral , Cisplatino/farmacologia , Cisplatino/uso terapêutico , Resistencia a Medicamentos Antineoplásicos/genética , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Técnicas de Silenciamento de Genes , Humanos , Metiltransferases/metabolismo , Mucosa Bucal/efeitos dos fármacos , Mucosa Bucal/patologia , Neoplasias Bucais/induzido quimicamente , Neoplasias Bucais/tratamento farmacológico , Neoplasias Bucais/patologia , Nozes/efeitos adversos , Nozes/química , Carcinoma de Células Escamosas de Cabeça e Pescoço/induzido quimicamente , Carcinoma de Células Escamosas de Cabeça e Pescoço/tratamento farmacológico , Carcinoma de Células Escamosas de Cabeça e Pescoço/patologia , Regulação para Cima
11.
Inorg Chem ; 49(15): 6917-24, 2010 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-20583801

RESUMO

First-principles calculations of the electronic, optical properties and lattice dynamics of tantalum oxynitride are performed with the density functional theory plane-wave pseudopotential method. The analysis of the electronic structure shows a covalent nature in Ta-N bonds and Ta-O bonds. The hybridization of anion 2p and Ta 5d states results in enhanced dispersion of the valence band, raising the top of the valence band and leading to the visible-light response in TaON. It has a high dielectric constant, and the anisotropy is displayed obviously in the lower energy region. Our calculation indicated that TaON has excellent dielectric properties along [010] direction. Various optical properties, including the reflectivity, absorption coefficient, refractive index, and the energy-loss spectrum are derived from the complex dielectric function. We also present phonon dispersion relation, zone-center optical mode frequency, density of phonon states, and some thermodynamic properties. The experimental IR modes (B(u) at 808 cm(-1) and A(u) at 863 cm(-1)) are reproduced well and assigned to a combination of stretching and bending vibrations for the Ta-N bond and Ta-O bond. The thermodynamic properties of TaON, such as heat capacity and Debye temperature, which were important parameters for the measurement of crystal physical properties, were first given for reference. Our investigations provide useful information for the potential application of this material.

12.
J Phys Chem A ; 114(2): 1052-9, 2010 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-19957984

RESUMO

We present a detailed investigation on the optical properties, including dielectric function, reflectivity, absorption, refractive index, and electron energy-loss spectrum, of the high-pressure phase SnO(2) in the rutile, pyrite, fluorite, and cotunnite structures by using the density functional theory (DFT) plane-wave pseudopotential method. The results indicate that with the increasing of pressure the band gaps become larger, the density of states are broader, so the curves of optical properties have a little blue shift. Except that the fluorite phase has some metallic properties, the other three phases exhibit excellent dielectric behavior. Interestingly, the fluorite and cotunnite SnO(2) phases always have some special characteristics, such as higher plasma frequency, which need further fundamental and application research.

13.
Artigo em Inglês | MEDLINE | ID: mdl-32988808

RESUMO

OBJECTIVE: Overproduction of reactive oxygen species (ROS) has been implicated in inflammatory activities and tumorigenesis in oral submucous fibrosis (OSF). Nuclear receptor coactivator 7 (NCOA7) is capable of regulating cellular responses to ROS. The aim of this study was to investigate the expression of NCOA7 in endothelial cells and the role of NCOA7 in areca nut-induced endothelial-to-mesenchymal transition (EndMT). STUDY DESIGN: Immunohistochemistry and immunofluorescence were used to detect the expression of NCOA7 in endothelia. Human umbilical vein endothelial cells (HUVECs) were treated with various dosages of arecoline (0, 5, 10, 20 µg/mL); then NCOA7 expression, the correlation of NCOA7 with EndMT, and the potential signaling were analyzed by using small interfering RNA (siRNA) transfection, reverse transcription polymerase chain reaction, Western blotting, and flow cytometry. RESULTS: NCOA7 was significantly elevated in OSF tissues, as detected with immunohistochemistry and immunofluorescence. After arecoline treatment, NCOA7 expression and EndMT were induced in HUVECs. Transfection of HUVECs with si-NCOA7, which reduced 73% of NCOA7 expression, aggravated the arecoline-induced EndMT process. Inhibition of ROS markedly, but not completely, reverses this arecoline-induced EndMT in si-NCOA7 cells. CONCLUSIONS: This study highlights NCOA7 as a potential target for therapeutic intervention to mediate EndMT via ROS species production.


Assuntos
Arecolina , Fibrose Oral Submucosa , Células Cultivadas , Células Endoteliais , Transição Epitelial-Mesenquimal , Humanos , Coativadores de Receptor Nuclear , Estresse Oxidativo
14.
RSC Adv ; 10(37): 21754-21759, 2020 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-35516613

RESUMO

The trigonal lithium niobate crystal (LiNbO3, LN) is a multi-functional material that possesses excellent nonlinear optical, pyroelectric and piezoelectric properties. In this work, the irradiation damage mechanism and stability of the electro-elastic properties of LN crystals irradiated with different doses (1013-1016 ions per cm2) of 6 MeV Xe23+ ions were evaluated for potential piezoelectric applications under irradiation conditions below 650 °C. The vacancy formation energies for Li, O, and Nb atoms are much lower than the irradiation energy of 6 MeV, with the lowest vacancy formation energy being obtained for Li, so that a high concentration of vacancies will be generated in LN upon irradiation. The vacancies narrow the band gap and decrease the electrical resistivity after irradiation. In contrast to the electrical resistivity, the relative dielectric permittivity of the LN crystal was found to increase with increasing irradiation dose, due to the weakened chemical bonds and distorted crystal structure, as confirmed by X-ray photoelectron spectroscopy. Despite the irradiation, the effective piezoelectric coefficients of bulk LN crystal remain nearly unchanged, indicating the favorable properties of LN for use under irradiation conditions at temperatures up to 650 °C.

15.
ACS Appl Mater Interfaces ; 12(1): 1306-1314, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31823598

RESUMO

High-quality monocrystalline graphene has gained considerable attention in fundamental physics, materials science, and nanoelectronics. However, the performance of the graphene obtained by chemical synthesis methods is currently significantly restricted by the crystal quality. Herein, a seeding chemical vapor deposition (SCVD) method is designed to cultivate high-quality monocrystalline graphene on a Cu(111) substrate with hexagonal boron nitride (h-BN) as the seed crystal. Combining the experimental and theoretical research, the nucleation behavior of the growth-induced graphene on the h-BN seed crystal is investigated, and the induced growth mechanism on the Cu(111) substrate is studied. The results show that the h-BN seed crystal can dramatically reduce the adsorption energy of active carbon atoms and the energy barrier for C-C aggregation at the BN/Cu(111) step, thus promoting graphene growth around the h-BN seed. Large monocrystalline graphene domains are obtained by the proposed SCVD method. Further study shows that the growth-induced graphene has good crystal quality and could maintain high structural integrity. This new strategy can be applied for growing high-quality graphene and other two-dimensional materials.

17.
ACS Appl Mater Interfaces ; 10(49): 43156-43165, 2018 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-30396269

RESUMO

It is well-known that reducing the nucleation density is an effective way to enhance the growth quality of graphene. In this work, we explore the mechanism of graphene nucleation and growth around CuO defects on a Cu(111) substrate by using density functional theory combined with the nudged elastic band method. The defect formation mechanism at the initial nucleation stage is also studied. Our calculation results of the C adsorption energy and the reaction barrier of C-C dimer formation illustrate that the initial nucleation of graphene could be promoted by artificially introducing CuO defects on a Cu(111) surface and the nucleation on the clean Cu(111) substrate could thus be suppressed. These conclusions have been verified by graphene growth experiments using a chemical vapor deposition method. Further studies showed that graphene grown around CuO "seed crystals" could maintain its structural integrity without significantly producing defective carbon rings. This work provides a fundamental understanding and theoretical guidance for the controllable preparation of large-dimension and high-quality graphene by artificially introducing CuO seeds.

18.
Opt Express ; 13(10): 3883-9, 2005 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-19495296

RESUMO

The absorption spectra of the 0.5at.% and 1at.% Co: LaMgAl11O19 (LaMg1-xCoxAl11O19, x=0.005 and 0.01, abbreviated as Co:LMA) crystals were measured at room temperature, and the results show that the Co: LMA crystals have two absorption bands, and the absorption band located at 1030-1660 nm can be used for a passive saturable absorber Q switch of 1.3-1.6mum laser. The passive pulsed laser output of LD-end-pumped Nd:GdVO4 1.34mum laser was demonstrated for the first time by using the 0.5 at.% Co:LMA crystal as a saturable absorber Q switch. The maximum average output power of 500 mW was obtained under the pumping power of 25 W. The shortest pulse width, the largest pulse energy and the highest peak power were obtained to be 160 ns, 25.5muJ and 150 W, respectively.

19.
J Phys Condens Matter ; 23(22): 225401, 2011 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-21572224

RESUMO

Li(2)CdGeS(4) and Li(2)CdSnS(4) are novel quaternary diamond-like semiconductors (DLSs) which have been synthesized recently. We present first-principles calculations of their electronic, optical and lattice dynamic properties with the plane-wave pseudopotential method. We have found an indirect band gap of 2.78 eV for Li(2)CdGeS(4) and a direct band gap of 2.50 eV for Li(2)CdSnS(4). The serious stretching vibrations of the Ge/Sn-S and Li-S bonds may enhance their phonon energies, and cause them to exhibit high heat capacities and Debye temperatures, which are promising for nonlinear optical applications. Compared with Cu-based DLSs, Li plays a key role in enlarging the band gaps and increasing the lattice phonon energies, which would increase the thermal conductivity accompanied by an increase of the optical damage threshold.

20.
Zhonghua Er Ke Za Zhi ; 43(11): 863-5, 2005 Nov.
Artigo em Zh | MEDLINE | ID: mdl-16316539

RESUMO

OBJECTIVE: To study the clinical features of juvenile primary fibromyalgia syndrome (FMS) and to evaluate outcome after treatment. METHODS: Six patients with juvenile primary FMS were registered in department of rheumatology and their clinical data were assessed, including degree of pain (visual analog scale, VAS), fatigue, depression, anxiety, sleep disturbances, arthrodynia, subjective joint swelling, abdominal pain, irritable bowel symptoms, urinary urgency, dysmenorrhea, morning stiffness, paresthesias, illness changes with weather, feeling worse with exercise, laboratory examination and outcome of treatment. RESULTS: Abdominal pain was the first symptom in 5 of the cases with juvenile primary FMS, diffuse aching and left knee pain were the first symptoms in one patient. All the 6 patients were misdiagnosed prior to their rheumatological evaluation. Diffuse aching, fatigue, sleep disturbances, illness changes with weather and feeling worse with exercise existed in all the 6 patients (100%), the mean pain score was 8.8 and the mean initial tender points (TP) count was 13.7. Arthrodynia, subjective joint swelling, abdominal pain, irritable bowel symptoms and urinary urgency existed in 5 of the 6 patients (83%). Dysmenorrhea existed in 4 (67%), depression in 3 (50%), morning stiffness in 2 (33%), paresthesias in 2 (33%) and anxiety in 2 (33%), respectively. The results of laboratory examination were normal and the outcomes of treatment were good. CONCLUSION: Juvenile primary FMS may not be a rare disease and the clinicians should pay more attention to it for avoiding misdiagnosis.


Assuntos
Fibromialgia/diagnóstico , Fibromialgia/patologia , Adolescente , Criança , Feminino , Humanos , Masculino , Resultado do Tratamento
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