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1.
Neural Regen Res ; 17(1): 130-136, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34100448

RESUMO

Our previous study showed that cell cycle exit and neuronal differentiation 1 (CEND1) may participate in neural stem cell cycle exit and oriented differentiation. However, whether CEND1-transfected neural stem cells can improve the prognosis of traumatic brain injury remained unclear. In this study, we performed quantitative proteomic analysis and found that after traumatic brain injury, CEND1 expression was downregulated in mouse brain tissue. Three days after traumatic brain injury, we transplanted CEND1-transfected neural stem cells into the area surrounding the injury site. We found that at 5 weeks after traumatic brain injury, transplantation of CEND1-transfected neural stem cells markedly alleviated brain atrophy and greatly improved neurological function. In vivo and in vitro results indicate that CEND1 overexpression inhibited the proliferation of neural stem cells, but significantly promoted their neuronal differentiation. Additionally, CEND1 overexpression reduced protein levels of Notch1 and cyclin D1, but increased levels of p21 in CEND1-transfected neural stem cells. Treatment with CEND1-transfected neural stem cells was superior to similar treatment without CEND1 transfection. These findings suggest that transplantation of CEND1-transfected neural stem cells is a promising cell therapy for traumatic brain injury. This study was approved by the Animal Ethics Committee of the School of Biomedical Engineering of Shanghai Jiao Tong University, China (approval No. 2016034) on November 25, 2016.

2.
Int J Biol Macromol ; 130: 307-314, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30825564

RESUMO

A comparison of the anti-tumor activity of CMPS-II and CBPS-II polysaccharides, respectively is obtained from the fermented mycelium and cultivated fruiting bodies of Cordyceps militaris. This in vitro anti-tumor activity is investigated using an MTT assay, immunofluorescence staining, a Western Blot assay, a qRT-PCR assay, and Annexin V-FITC/PI double staining. The experimental results indicate that the inhibition rate of CMPS-II on H1299 tumor cells is higher than that of CBPS-II. With a concentration of 500 µâ€¯g/mL, the inhibition rate of CMPS-II and CBPS-II were 54.55% and 34.80%, respectively. Both CMPS-II and CBPS-II can increase the protein and mRNA expression level of cell apoptosis factors Caspase-3, Caspase-9, and p53, while reducing the protein and mRNA expression levels of proliferating cell nuclear antigen (PCNA), to induce tumor cells apoptosis. The induction effect of CMPS-II was stronger than CBPS-II. These results suggest that CMPS-II is superior to CBPS-II regarding the inhibition of H1299 lung cancer cells. Furthermore, CMPS-II is a potentially useful substitution for CBPS-II in the treatment of lung cancer and provides new insights into the mechanism of its anti-tumor activity.


Assuntos
Antineoplásicos/farmacologia , Cordyceps/metabolismo , Fermentação , Carpóforos/metabolismo , Polissacarídeos Fúngicos/farmacologia , Micélio/metabolismo , Antineoplásicos/metabolismo , Apoptose/efeitos dos fármacos , Caspase 3/genética , Caspase 3/metabolismo , Caspase 9/genética , Caspase 9/metabolismo , Linhagem Celular Tumoral , Polissacarídeos Fúngicos/biossíntese , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Antígeno Nuclear de Célula em Proliferação/genética , Antígeno Nuclear de Célula em Proliferação/metabolismo , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo
3.
RSC Adv ; 9(32): 18205-18216, 2019 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-35515207

RESUMO

This study investigates the effect of fermentation conditions on the structure and anti-tumor activity of intracellular polysaccharides (IPS) of Cordyceps gunnii (C. gunnii) in submerged fermentation. The environmental and nutritional conditions are determined in a shaker flask by a single factor test. The inhibition of IPS on S180 cells was as an optimization index. The results show that the optimal fermentation conditions of C. gunnii are an initial pH value of 6, a temperature of 25 °C, a rotation speed of 150 rpm, 4% glucose, and 1.0% peptone. Under these conditions, the macro molecular weight (M w) polysaccharide content and anti-tumor activity of IPS are significantly higher than that in the basal culture medium. GC, HPGPC, periodate oxidation-Smith degradation, NMR, and FT-IR determine the structural characteristics of CPS-JC and CPS-YH (pure IPS cultured in basal culture medium and optimal culture medium, respectively). The results indicate that CPS-JC is mainly composed of α-d-glucans, whereas CPS-YH primarily contain α-d-glucans with a trace amount of ß-d-glucans.

4.
J Neurotrauma ; 36(8): 1279-1290, 2019 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-30351220

RESUMO

Transient receptor potential vanilloid 1 (TRPV1) is expressed widely in the central nervous system and is activated by various stimuli. Inhibiting TRPV1 has neuroprotective effects in cerebral ischemia. The role of inhibiting TRPV1 to maintain blood-brain barrier (BBB) integrity after traumatic brain injury (TBI) remains unclear, however. Therefore, we investigated the effects of capsazepine-mediated TRPV1 inhibition on the BBB in a mouse model of TBI. Adult male C57BL/6 mice underwent controlled cortical impact injury and received capsazepine (1 µmol/kg body weight, twice daily, intraperitoneally) until sacrifice. Further, mouse brain microvascular endothelial (bEnd.3) cells were cultured and underwent biaxial stretch injury to investigate the mechanisms underlying the protective effects of capsazepine. The TRPV1 expression was upregulated in the pericontusional area after TBI, peaking at 24 h post-TBI. Capsazepine-treated mice demonstrated decreased brain edema (p = 0.010), Evans Blue extravasation (p = 0.001), tissue hemoglobin levels (p = 0.002), and loss of tight junction proteins (p = 0.016 ZO-1 expression; p = 0.013 occludin expression) after TBI compared with the vehicle-treated group. Capsazepine significantly alleviated early-stage apoptosis by attenuating activation of JNK, P38, and caspase-3, resulting in a protective effect on the level of ZO-1 in bEnd.3 cells after stretch injury. We conclude that the expression of TRPV1 is upregulated after TBI, and inhibition of TRPV1 attenuated disruption of the BBB in a mouse model of TBI, at least partly, through its antiapoptotic effects on brain endothelial cells. Blocking TRPV1 may be a promising pharmacotherapeutic intervention to protect against BBB disruption after TBI.


Assuntos
Barreira Hematoencefálica/patologia , Lesões Encefálicas Traumáticas/patologia , Células Endoteliais/metabolismo , Canais de Cátion TRPV/antagonistas & inibidores , Animais , Apoptose/efeitos dos fármacos , Barreira Hematoencefálica/efeitos dos fármacos , Lesões Encefálicas Traumáticas/metabolismo , Capsaicina/análogos & derivados , Capsaicina/farmacologia , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL
5.
World Neurosurg ; 122: 48-52, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30347301

RESUMO

BACKGROUND: Gliomas are usually located in the supratentorial region and are extremely rare at the cerebellopontine angle (CPA). Consequently, gliomas in the CPA are easy to misdiagnose preoperatively. CASE DESCRIPTION: This paper presents a 55-year-old man with an extraaxial CPA glioblastoma arising from the proximal portion of cranial nerve (CN) VIII. Preoperative imaging findings suggested an acoustic neuroma. The tumor was removed subtotally, and it was completely separated from the brainstem and cerebellum. The histopathologic examination showed a glioblastoma. CONCLUSIONS: To our knowledge, this case is the second report of a true primary extraaxial CPA glioblastoma. Therefore glioma should be considered in the differential diagnosis of CPA masses with atypical imaging features, although they are extremely rare.


Assuntos
Neoplasias Cerebelares/diagnóstico , Neoplasias Cerebelares/cirurgia , Ângulo Cerebelopontino , Glioblastoma/diagnóstico , Glioblastoma/cirurgia , Neoplasias Cerebelares/patologia , Diagnóstico Diferencial , Evolução Fatal , Glioblastoma/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Neuroma Acústico/diagnóstico , Pneumonia Aspirativa
6.
Neuroscience ; 392: 180-189, 2018 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-30278249

RESUMO

This study aims to investigate the value of diffusion kurtosis imaging (DKI) in assessing microstructural changes associated with cognitive impairment in chronic traumatic brain injury (TBI). At 7 months, six TBI rats and six control rats underwent Morris water maze (MWM) tests, followed by DKI examinations. DKI parameters were measured in bilateral cortex, hippocampus, and callosum. Brain immunohistochemistry (IHC) analysis of neuron [neuron-specific nuclear protein (NeuN)], astroglia [glial fibrillary acidic protein (GFAP)], microglia [ionized calcium binding adaptor molecule 1 (Iba-1)], and myelin [myelin basic protein (MBP)] was performed in the same area as DKI parameter. The DKI parameters, IHC results, and MWM results were compared between TBI and control groups. Correlation analysis was performed to analyze the relationship between DKI parameters and IHC and MWM results. TBI group had worse performance in MWM test. DKI showed higher mean diffusion (MD) in all ipsilateral regions of interest (ROIs), and lower mean kurtosis (MK) in ipsilateral cortex and callosum in TBI group (P < 0.05). TBI group also showed lower IHC staining of NeuN, and higher staining of Iba-1 and MBP in all ipsilateral ROIs (P < 0.05). Further correlational study showed a positive relationship between MK and NeuN, MD and MBP in ipsilateral cortex, and a negative relationship between MK and Iba-1, MBP in ipsilateral cortex and hippocampus (P < 0.05). The MK in ipsilateral cortex and hippocampus were also correlated with MWM test results (P < 0.05). Our study suggests that DKI could be used to assess the microstructural changes associated with cognitive impairment in chronic TBI.


Assuntos
Lesões Encefálicas Traumáticas/patologia , Encéfalo/patologia , Disfunção Cognitiva/patologia , Imagem de Difusão por Ressonância Magnética/métodos , Animais , Encéfalo/diagnóstico por imagem , Lesões Encefálicas Traumáticas/complicações , Lesões Encefálicas Traumáticas/diagnóstico por imagem , Doença Crônica , Disfunção Cognitiva/diagnóstico por imagem , Disfunção Cognitiva/etiologia , Masculino , Aprendizagem em Labirinto , Microglia/patologia , Neurônios/patologia , Ratos Sprague-Dawley
7.
J Neurotrauma ; 35(23): 2850-2860, 2018 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-29860924

RESUMO

Adjudin, a small molecular compound that is used as a male contraceptive, has been reported to play a neuroprotective role in an ischemic stroke injury model. However, its effect on traumatic brain injury (TBI) has not been assessed. Hence, we investigated the effects of adjudin on cerebral edema using a mouse model of TBI and explored the underlying mechanisms. Adult male C57BL/6 mice received controlled cortical impact (CCI) injury, then an injection of adjudin (50 mg/kg). The mice were euthanized 3 days post-CCI injury, and samples were collected for further analysis. Cultured primary mouse astrocytes were used for in vitro experiments. Adjudin treatment significantly attenuated cerebral edema on Day 3 and improved neurobehavioral outcomes on Days 3, 7, and 14 after CCI injury, compared with the vehicle group. Additionally, the evaluation of Evans blue extravasation and expression of tight junction proteins demonstrated remarkable effects of adjudin on blood-brain barrier protection. Further, adjudin treatment significantly decreased the gene and protein expression of aquaporin 4 in post-injury mice and inhibited progression of neuroinflammation in both mice and cultured astrocytes. The Western blot results of the peritraumatic protein samples demonstrated that adjudin significantly blocked the phosphorylation of IKKα, IκBα/ß, and NF-κB p65, which resulted in a reduction of NF-κB p65 nuclear translocation. In conclusion, adjudin attenuated the development of TBI-induced cerebral edema at least partly via anti-inflammatory effects and inhibition of the NF-κB pathway. These findings suggest that adjudin is a potential therapeutic intervention preventing the development of cerebral edema after TBI.


Assuntos
Edema Encefálico/etiologia , Lesões Encefálicas Traumáticas/complicações , Hidrazinas/farmacologia , Indazóis/farmacologia , Fármacos Neuroprotetores/farmacologia , Recuperação de Função Fisiológica/efeitos dos fármacos , Animais , Barreira Hematoencefálica/efeitos dos fármacos , Edema Encefálico/patologia , Lesões Encefálicas Traumáticas/patologia , Lesões Encefálicas Traumáticas/fisiopatologia , Modelos Animais de Doenças , Masculino , Camundongos , Camundongos Endogâmicos C57BL
8.
Acta Pharmacol Sin ; 38(11): 1445-1455, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28770828

RESUMO

Sesamin, a major lignan of sesame oil, was reported to have neuroprotective effects in several brain injury models. However, its protective action in maintaining blood-brain barrier (BBB) integrity has not been studied. In this study we investigated the effects of sesamin on the BBB in a mouse model of traumatic brain injury (TBI) and explored the underlying mechanisms. Adult male C57BL/6 mice were subjected to a controlled cortical impact (CCI) injury and then received sesamin (30 mg·kg-1·d-1, ip). The mice were euthanized on the 1st and 3rd days after CCI injury and samples were collected for analysis. Sesamin treatment significantly attenuated CCI-induced brain edema on the 1st and 3rd days after the injury, evidenced by the decreases in water content, tissue hemoglobin levels, Evans blue extravasation and AQP4 expression levels in the ipsilateral cortical tissue compared with the vehicle-treated group. Furthermore, sesamin treatment significantly alleviated CCI-induced loss of the tight junction proteins ZO-1 and occludin in the brain tissues. The neuroprotective mechanisms of sesamin were further explored in cultured mouse brain microvascular bEnd.3 cells subjected to biaxial stretch injury (SI). Pretreatment with sesamin (50 µmol/L) significantly alleviated SI-induced loss of ZO-1 in bEnd.3 cells. Furthermore, we revealed that pretreatment with sesamin significantly attenuated SI-induced oxidative stress and early-stage apoptosis in bEnd.3 cells by decreasing the activation of ERK, p-38 and caspase-3. In conclusion, sesamin alleviates BBB disruption at least partly through its anti-oxidative and anti-apoptotic effects on endothelial cells in CCI injury. These findings suggest that sesamin may be a promising potential therapeutic intervention for preventing disruption of the BBB after TBI.


Assuntos
Barreira Hematoencefálica/efeitos dos fármacos , Lesões Encefálicas Traumáticas/tratamento farmacológico , Permeabilidade Capilar/efeitos dos fármacos , Dioxóis/farmacologia , Lignanas/farmacologia , Fármacos Neuroprotetores/farmacologia , Animais , Apoptose/efeitos dos fármacos , Aquaporina 4/metabolismo , Barreira Hematoencefálica/metabolismo , Barreira Hematoencefálica/patologia , Edema Encefálico/metabolismo , Edema Encefálico/patologia , Edema Encefálico/prevenção & controle , Lesões Encefálicas Traumáticas/metabolismo , Lesões Encefálicas Traumáticas/patologia , Caspase 3/metabolismo , Linhagem Celular , Modelos Animais de Doenças , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/metabolismo , Células Endoteliais/patologia , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Ocludina/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Fatores de Tempo , Proteína da Zônula de Oclusão-1/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno
9.
J Neurotrauma ; 34(4): 925-933, 2017 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-27297934

RESUMO

Glibenclamide is a hypoglycemic drug that is widely used for the treatment of diabetes mellitus type 2 (DM II), but it also plays a protective role following injury to the central nervous system (CNS). However, the precise mechanisms underlying its neuroprotective actions remain to be elucidated. Therefore, the present study evaluated the effects of glibenclamide on the blood-brain barrier (BBB) in a mouse model of traumatic brain injury (TBI). In the present study, 86 adult male C57BL/6 mice were exposed to a controlled cortical impact (CCI) injury and then received glibenclamide (10 µg) for 3 days. Tight junction (TJ) protein levels, BBB permeability, and tissue hemoglobin levels were evaluated following the CCI injury. Additionally, a biaxial stretch injury was applied to cell cultures of bEnd.3 cells using the Cell Injury Controller II system to explore the mechanisms by which glibenclamide inhibits apoptosis-signaling pathways. Compared with the control group, glibenclamide-treated mice exhibited decreases in brain water content (p < 0.05), tissue hemoglobin levels (p < 0.05), and Evans Blue extravasation (p < 0.01) after the CCI injury. Glibenclamide primarily attenuated apoptosis via the JNK/c-jun signaling pathway and resulted in an elevation of stretch injury-induced ZO-1 expression in bEnd.3 cells (p < 0.01).Glibenclamide downregulated the activity of the JNK/c-jun apoptosis-signaling pathway which, in turn, decreased apoptosis in endothelial cells (ECs). This may have prevented the disruption of the BBB in a mouse model of TBI.


Assuntos
Apoptose/efeitos dos fármacos , Barreira Hematoencefálica/efeitos dos fármacos , Lesões Encefálicas Traumáticas/tratamento farmacológico , Glibureto/farmacologia , Fármacos Neuroprotetores/farmacologia , Transdução de Sinais/efeitos dos fármacos , Animais , Barreira Hematoencefálica/fisiopatologia , Lesões Encefálicas Traumáticas/fisiopatologia , Modelos Animais de Doenças , Glibureto/administração & dosagem , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fármacos Neuroprotetores/administração & dosagem
10.
Appl Biochem Biotechnol ; 177(6): 1229-40, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26299378

RESUMO

High-fructose corn syrup (HFCS) is an agro-source product and has been the most commonly used substitute for sugar as sweetener in food industry due to its low price and high solution property. In this study, the F55 HFCS, rich in fructose and glucose, was first tested for biomass and docosahexaenoic acid productions as a mixed carbon source by a newly isolated Aurantiochytrium sp.YLH70. After the compositions of the HFCS media were optimized, the results showed that the HFCS with additions of metal ion and vitamin at low concentrations was suitable for biomass and docosahexaenoic acid productions and the metal ion and sea salt had the most significant effects on biomass production. During the 5-l fed-batch fermentation, total HFCS containing 180 g l(-1) reducing sugar was consumed and yields of biomass, lipid, and DHA could reach 78.5, 51, and 20.1 g l(-1), respectively, at 114 h. Meanwhile, the daily productivity and the reducing sugar conversion yield for docosahexaenoic acid were up to 4.23 g l(-1)day(-1) and 0.11 g g(-1). The fatty acid profile of Aurantiochytrium sp.YLH70 showed that 46.4% of total fatty acid was docosahexaenoic acid, suggesting that Aurantiochytrium sp.YLH70 was a promising DHA producer.


Assuntos
Biomassa , Ácidos Docosa-Hexaenoicos/biossíntese , Xarope de Milho Rico em Frutose/química , Estramenópilas/crescimento & desenvolvimento , Estramenópilas/isolamento & purificação
11.
Dalton Trans ; 41(43): 13280-3, 2012 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-23032371

RESUMO

A distinct way to target long-lasting phosphors (LLPs) is disclosed. This new material is a metal-organic framework featuring a 1D zig-zag chain and 3D hydrogen bonded PtS net with three-fold interpenetration. It exhibits persistent luminescence lasting about 1 s which can be traced by the naked eye. The green persistent luminescence is exclusively due to emission from multiple triplet excited states. In this way, LLP can be easily achieved by using a simple hydrothermal synthesis without any codopant that in nature is responsible for well-known inorganic LLPs.

12.
Chem Commun (Camb) ; 48(5): 759-61, 2012 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-22134331

RESUMO

A nanoscale aluminium-based metal organic framework (NMOF) with high thermal stability has been synthesized, which shows high H(2) and CO(2) uptake capacities and an excellent selectivity for CO(2) over N(2) and O(2).

13.
Guang Pu Xue Yu Guang Pu Fen Xi ; 30(1): 26-9, 2010 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-20302073

RESUMO

The present paper mainly reports a new method to synthesize long afterglow photoluminescent material BaAl2O4:Eu2+, Dy3+. Al(NO3)3.9H2O, Ba(NO3)2, urea, RE(NO3) 3(RE==Eu, Dy) were employed as raw materials, the admixture of H2O/n-butanol and H2O/n-butanol/SBS were used as medium, then BaAl2O4:Eu2+, Dy3+ phosphor was achieved by calcining the precursor, which was synthesized by hydrothermal method, at 130 degrees C under reduction atmosphere. The TEM and SEM were used to analyse the morphology and BaAl2O4:Eu2+, Dy3+ synthesized by annealing at 1300 degrees C are all nanorods. The excitation and emission spectra of the phosphor indicated that all of them are broad band, and the main emission peak is around 498 nm, which is due to 5d-->4f transition of Eu2+. The state-solid synthesis of the long afterglow phosphor BaAl2O4:Eu2+, Dy3+ generally requires a high calcination temperature, so the products are easily agglomerated, and in this paper the hydrothermal solvothermal synthesis was used, so the synthesized products calcined at 130 degrees degrees C still present well-dispersed rod structure, need not milling, and display well luminescence performance. The authors compared the two different conditions of experiment, and found that under the condition without surfactant the authors can still get well-dispersed rod structure of BaAl2O4:Eu2+, Dy3+. The method is hopeful to be used in synthesizing other alkali-earth aluminate and silicate and other luminescent materials.

14.
Sci Technol Adv Mater ; 11(3): 035002, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27877339

RESUMO

A phosphorescent material in the form of Y2O2S:Eu3+, Mg2+, Ti4+ hollow microspheres was prepared by homogeneous precipitation using monodispersed carbon spheres as hard templates. Y2O3:Eu3+ hollow microspheres were first synthesized to serve as the precursor. Y2O2S:Eu3+, Mg2+, Ti4+ powders were obtained by calcinating the precursor in a CS2 atmosphere. The crystal structure, morphology and optical properties of the composites were characterized. X-ray diffraction measurements confirmed the purity of the Y2O2S phase. Electron microscopy observations revealed that the Y2O2S:Eu3+, Mg2+, Ti4+ particles inherited the hollow spherical shape from the precursor after being calcined in a CS2 atmosphere and that they had a diameter of 350-450 nm and a wall thickness of about 50-80 nm. After ultraviolet radiation at 265 or 325 nm for 5 min, the particles emitted strong red long-lifetime phosphorescence originating from Eu3+ ions. This phosphorescence is associated with the trapping of charge carriers by Ti4+ and Mg2+ ions.

15.
Sci Technol Adv Mater ; 10(4): 045002, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27877302

RESUMO

An environment-friendly hydrothermal method was used to prepare TiO2@C core-shell composite using TiO2 as core and sucrose as carbon source. TiO2@C served as a support for the immobilization of Ag by impregnation in silver nitrate aqueous solution. The chemical structures and morphologies of TiO2@C and TiO2@C/Ag composite were characterized by x-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, energy dispersive x-ray spectroscopy and Brunauer-Emmett-Teller (BET) analysis. The antibacterial properties of the TiO2@C/Ag core-shell composite against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were examined by the viable cell counting method. The results indicate that silver supported on the surface of TiO2@C shows excellent antibacterial activity.

16.
Guang Pu Xue Yu Guang Pu Fen Xi ; 28(5): 1023-5, 2008 May.
Artigo em Chinês | MEDLINE | ID: mdl-18720793

RESUMO

The present reports a hydrothermal process to synthesize the precursor of Eu(3+)-doped LaPO4 nanoparticles with PEG2000 used as additive. SEM shows that the nanoparticles are similar to spheres. The Eu(3+-)doped LaPO4 phosphor was characterized by powder X-ray diffractometer. According to our measurements with XRD, the products belong to monoclinic monazite type, and the samples were well crystallized after sintering at 700 degrees C for 2 h. The effects of synthesis condition, sintering temperature and time on the luminescence of the samples were investigated. The luminescence data indicated that the optimum condition for synthesizing the precursor was at 180 degrees C for 14 h, and the optimum condition for heat-treatment of the precursor was at 850 degrees C for 1 hour. The effects of different contents of Eu3+ on the luminescence of LaPO4 : EuO3+ nanoparticles were also investigated, and the results showed that the luminescence intensity was enhanced with the slight increase in the Eu3+ content, and the optimum Eu(3+)-doping concentration was 4% (mole fraction).

17.
Guang Pu Xue Yu Guang Pu Fen Xi ; 27(2): 232-5, 2007 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-17514943

RESUMO

Green-emitting LaF3:Ce, Tb phosphor nanoparticles were synthesized by a simple hydrothermal method and characterized by XRD, TEM and fluorescence spectra. The prepared samples had a hexagonal shape, fine size (30 nm), and high brightness under ultraviolet, and the structure of LaF3 remained unchanged after being doped with Ce3+ and Tb3+ ions. The blue Ce3+ emission centered at 261 nm is efficiently quenched in the samples of LaF3:Ce, Tb, in which the dominant emission is in the green at 544 nm, originating from the doped Tb3+ ions' transition of (5)D4 to (7)F5. Excitation spectra of the LaF3:Ce, Tb, observed at 544 nm, consist of both contributions from Ce3+ and Tb3+ ions. There is energy transfer of Ce3+ --> Tb3+ in this system. The energy transfer mechanism was discussed. Above all, the phosphor nanoparticles have high photoluminescence intensity even without any calcination, about twice that of bulk materials prepared by high temperature solid synthesis, and the intensity is also stronger than calcined phosphor nanoparticles.

18.
Artigo em Inglês | MEDLINE | ID: mdl-16815080

RESUMO

LaF3:Eu3+ nanoparticles were prepared by a simple hydrothermal process at low temperature and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and fluorescence spectrum. Well-dispersed nanoparticles with an average size of 30 nm and a hexagonal shape were obtained. The influences of reaction temperature and time on the preparation and luminescence of LaF3:Eu3+ nanoparticles were investigated. Luminescent quenching occurred at a much higher concentration ( approximately 25mol%) and stronger luminescent intensity than in bulk LaF3:Eu3+. Fluorescence intensity of the LaF3:Eu3+ nanoparticles varied remarkably with calcination temperatures. It was found that samples without any further calcinations can emit quite strong fluorescence.


Assuntos
Európio/química , Fluoretos/química , Lantânio/química , Nanopartículas/química , Temperatura Alta , Luminescência , Microscopia Eletrônica de Transmissão , Tamanho da Partícula , Difração de Raios X
19.
Guang Pu Xue Yu Guang Pu Fen Xi ; 24(11): 1302-5, 2004 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-15762461

RESUMO

The concentration dependence of luminescence under different excitations in Y2O2S:Sm3+ phosphor has been studied. The optimum activator concentration was found to be a function of the number of excited activator ions as well as the excitation wavelength. The concentration dependence curve of Y2O2S:Sm3+ phosphor under 413 nm excitation was different from the curve obtained with 263 nm excitation. For excitation radiation having longer wavelength (413 nm), the concentration quenching of Y2O2S:Sm3+ phosphor occurred at about 2%, which is ten times the result with shorter wavelength (263 nm) excitation (-0.2%). Fitting the concentration dependence curve and the result shows that the cross-relaxation caused by the dipole-quadrupole interaction of neighboring Sm3+ ions results in the concentration quenching.

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