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ABSTRACT: Morphological evolution from SnO2 quantum dots (QDs) to quantum chains (QCs) confined in channels of mesoporous silica (MS) has been studied systematically in this work by varying the nuclei quantity deposited on the channels’ inner surface under hydrothermal conditions. Decreasing the MS amounts could influence the nuclei quantity and the subsequent crystal growth as well as the assembly process to form QCs by oriented attachment inside the channels. It is interesting to find that the evolution of SnO2 QDs→QCs systems would induce the variation of strain type tolerated, simultaneously, from tensile to compressive strain, and also exhibit morphology-dependent photoluminescence properties.
10/2011;
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ABSTRACT: A one-pot solvothermal approach has been developed for the synthesis of single-crystal anatase TiO2 nanospindles. The introduction of adscititious water in nonaqueous reaction mixture is critical for the spindle formation by allowing for a slow growth rate of TiO2 to facilitate the shape control of TiO2 nanospindles. Arising from the prominent light scattering effect, the fabricated dye sensitized solar cells with the TiO2 nanospindles as light scattering layer show a 27% increment of energy conversion efficiency compared to that of P25 single layer film.
07/2011;
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ABSTRACT: Premixed atmospheric flat flame deposition is a large-scale composite fabrication method that combined the advantages of flame synthesis and thermal evaporation. The technology has been successfully developed to sythesize SnO2 nanowires. The results showed that the as-prepared SnO2 nanowires with special tips are uniform single crystals, growing along [001] direction. Meanwhile, the growth mechanism of the present novel structure, which is a combination of both a vapor-solid (VS) growth mechanism and a particle formation mechanism in a flame without any catalyst, is also proposed. Furthermore, the optical property is investigated by photoluminescence (PL) spectroscopy, indicating that such SnO2 nanowires exhibit a much stronger emission peak at 620 nm. More importantly, this approach also provides a new pathway for sequentially engineering one-dimensional nanomaterials.
04/2011;
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ABSTRACT: Well-crystalline SnO2 nanorods were first synthesized via a continuous and scalable iron-assisted flame approach with production rate up to 50 g/h in laboratory-scale. The as-prepared SnO2 nanorods with uniform length up to 200 nm and diameter around 20 nm are smooth and single crystal rutile structures, growing along the [001] direction. Iron dopant is incorporated into the SnO2 lattice and selectively effects a specific SnO2 crystal plane, promoting the further crystal oriented growth into nanorods. Meanwhile, the photoluminescence (PL) spectrum of such SnO2 nanorods exhibits a broad, stronger orange-emission peak around 620 nm, suggesting potential applications in optoelectronics. It is noteworthy that this dopant-assisted flame approach provides a new strategy for sequentially engineering one-dimensional nanomaterials.
03/2010;
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ABSTRACT: Ball-in-shell structured TiO2 nanospheres were successfully made by flame synthesisa single-step, continuous, and scalable process. The morphology and structure were systematically characterized by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, scanning electron microscopy, and N2 sorption. TiO2 nanostructures with good crystalline nature and thermal stability were formed by feeding a titanium tetrachloride and alcohol vapor mixture to a facile diffusion flame. The resultant ball-in-shell spheres were composed of nanocrystallites, with shell thickness and void space width of 30−50 nm and 10−30 nm, respectively. The formation mechanism of ball-in-shell spheres was investigated, depending on the competition between the chemical reaction rate and diffusion rate during the flame process. Furthermore, UV−vis characterization indicates that this structure endows the spheres with higher light absorbance, which may be favorable to design and prepare novel materials with enhanced photocatalytic activities.
12/2008;
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ABSTRACT: An improved process for the preparation of SrAl2O4:Eu,Dy phosphors was developed by introducing a precalcination process for the precursor synthesized via the coprecipitation method. The structural and initial photoluminescent characteristics of these SrAl2O4:Eu,Dy phosphors were investigated using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), electron paramagnetic resonance (EPR), Fourier transform infrared spectroscopy (FT-IR), and photoluminescence spectroscopy (PL). The experimental results revealed that the precalcination process could facilitate the doped boron’s effect as a flux along with the formation of more oxygen vacancies around Eu2+ ions, which resulted in the remarkable increase of the initial photoluminescent intensity of the samples. When the doping concentration of boron was 30%, the obtained SrAl2O4:Eu,Dy sample possessed a photoluminescent intensity two times higher than that of the sample prepared without the precalcination process. The boron doping also induced the appearance of Sr4Al14O25 phase in the sample and an obvious blue shift of the emission band can be observed. Due to the promising initial photoluminescent properties, the as-prepared SrAl2O4:Eu,Dy samples show potential display applications in particular areas.
07/2008;
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ABSTRACT: To investigate the characteristics of endothelial cells derived from human cavernous hemangioma in morphology, phenotypes and functions.
Endothelial cells were isolated from human hepatic cavernous hemangioma. The morphological, and phenotypical and functional features of these cells were analyzed by transmission electron microscopy, fluorescence-activated cell sorter, RT-PCR, zymography, and confocal microscopy. Human liver sinusoidal endothelial cells (LSEC) were used as control.
As compared with the LSEC, abnormally expanded endoplasmic reticulums and similarly arranged cytoplasmic vacuoles were found in the endothelial cells derived from hepatic cavernous hemangioma (HCHEC) by transmission electron microscopy. Flow cytometry showed that expression of alphavbeta3 was significantly increased in the HCHEC. The mRNA of vascular endothelial cell growth factor and angiopoietin 1 were more abundant in HCHEC than that in LSEC. Functional analysis indicated that the HCHEC exhibited strong activated angiogenesis capacity and formed abnormal capillary-like structures. HCHEC produced more pro-matrix metalloproteinase 2 (MMP-2) and the activated MMP-2 form as compared with the LSEC. Confocal microscopy revealed that MMP-2 was concentrated in those cytoplasmic granules of the HCHEC and was consistent with the distribution of the expanded endoplasmic reticulums.
The endothelial cells derived from human cavernous hemangioma differ from the normal endothelial cells in morphology, phenotypes and functions.
Zhonghua yi xue za zhi 12/2007; 87(43):3051-5.
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ABSTRACT: A simple and effective method for the preparation of hollow alumina nanospheres was established via a high-speed jet flame combustion process. The morphology and structure of the hollow nanospheres were investigated using TEM, HRTEM, SEM, FTIR, XRD, BET, etc. A vapors mixture of C2H5OH and AlCl3 was exhausted at high speed into a flame reactor at 150 m/s and condensed into mesoscale droplets due to the Joule-Thomson cooling effect and the entrainment of cool gases into the expanding high-speed jet. The hollow alumina nanospheres were formed after the hydrolysis of AlCl3 in the H2/air flame at about 1200 °C. The hollow alumina nanosphere was composed of nanocrystallites about 5 nm and the shell thickness was 10−30 nm. The formation mechanism of the hollow alumina nanospheres was investigated, conforming to the one-droplet-to-one-particle theory.
10/2007;
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ABSTRACT: To investigate the phenotypic and functional characteristics of human adrenal microvascular endothelial cells (AdrEC).
AdrEC were isolated and purified from a sample of human adrenal tissue by sub-cell clone method. The cells identified by flow cytometry for classical endothelial markers von Willebrand factor (vWF) and CD31, uptake of Dil-labeled acetylated low density lipoprotein (Dil-Ac-LDL), as well as phenotypes. The cell fenestrations were checked by scanning electron microscopy. The expressions of endogenous vascular endothelial growth factor (VEGF) mRNA and protein were detected by reverse transcription-polymerase chain reaction (RT-PCR) and immunocytochemistry. The glucocorticoid-induced cytotoxicities in different organs-derived microvascular endothelial cells were compared.
Human AdrEC expressed those classical endothelial markers such as vWF, CD31, and uptake of Dil-Ac-LDL. The phenotypic analysis indicated that alpha-1 proteinase inhibitor, tumor necrosis factor receptor p55, and intercellular adhesion molecule-1 were expressed in human AdrEC. Scanning electron microscopy demonstrated that there were many microvilli and fenestrations on cellular surface. RT-PCR and immunocytochemistry showed that there was expression of endogenous VEGF in AdrEC. In response to glucocorticoid-induced cytotoxicity, microvascular endothelial cells (MVEC) derived from human brain were highly susceptible, MVEC derived from human lung and human liver sinusoidal endothelial cells were sub-sensitive, while AdrEC were highly resistant.
Human AdrEC are specially differentiated and have characteristics that are different from other organ-derived MVEC in phenotypes and functions.
Zhongguo yi xue ke xue yuan xue bao. Acta Academiae Medicinae Sinicae 09/2006; 28(4):502-6.
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ABSTRACT: The pathogenesis of cavernous hemangiomas is largely unknown, and it is speculated that abnormal vasculogenesis and angiogenesis may be involved. In this study, the characteristics of cavernous hemangioma endothelial cells (CHECs) derived from the human liver were analyzed in terms of morphology, phenotype and function and compared with human liver sinusoidal endothelial cells (LSECs).
By transmission electron microscopy, abnormally expanded endoplasmic reticulum (ER) and similarly arranged cytoplasmic vacuoles were only found in CHECs. Phenotypic analysis showed that the expression of alphavbeta3 was significantly increased in CHECs. mRNA expression of vascular endothelial growth factor A, and angiopoietins 1 and 2 was significantly increased in CHECs compared to LSECs. The functional analysis indicated that CHECs released more vascular endothelial growth factor A, produced significantly more pro-matrix metalloproteinase 2 (pro-MMP2) and activated MMP2, and exhibited higher procoagulant and fibrinolytic activities compared with LSECs. Confocal microscopy revealed that MMP2 was concentrated in some cytoplasmic granules of CHECs and was consistent with the distribution of expanded ER. CHECs exhibited more activated angiogenesis capacity and formed abnormal capillary-like structures in vitro.
These results suggested that endothelial cells (ECs) derived from human cavernous hemangiomas differ from normal ECs in morphology, phenotype and function.
Journal of Vascular Research 02/2006; 43(6):522-32. · 2.65 Impact Factor
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ABSTRACT: To investigate the effect of alpha-1 antitrypsin on ischemia-reperfusion injury of human liver sinusoidal endothelial cells (LSECs).
LSECs were cultured and put into 4 degrees C refrigerator for 12 hours and then into 37 degrees C culture box with 95% O(2) and 5% CO(2) for 2 - 6 hours to establish an experimental hypoxia-reoxygenation injury model. The LSECs were inoculated in 24-pit culture plate and L-NAME, NO inhibitor, SNAP, a NO supplier, BB3103, a matrix metalloproteinase (MMP) inhibitor, or alpha-1 antitrypsin of different concentrations were added. The LSECs were put into 4 degrees C refrigerator for 12 hours and then into 37 degrees C culture box with 5% CO(2) for 2 - 6 hours. The supernatant was collected to detect the production of nitric oxide (NO) and activity of MMPs. LSECs were cultured under conditions of presence or absence of alpha-1 antitrypsin and normal temperature and oxygen concentration, low-temperature and hypoxia, and low temperature and hypoxia -reoxygenation respectively. Then the supernatant was collected to detect the activities of MMP-2 and MMP-9 with zymography and the production of NO with determination of nitrite concentration and expression of eNOS and iNOS by immunohistochemistry.
Immunohistochemistry showed that LSECs were alpha-1 trypsin positive, RT-PCR showed LSECs did not express alpha-1 trypsin mRNA. TUNEL staining showed that hypothermia for 12 hours caused apoptosis of LSECs, apoptosis of LSECs was more obvious after hypothermia and hypoxia-reoxygenation; however, with the presence of alpha-1 trypsin apoptosis of LSECs was significantly decreased after hypothermia and hypoxia-reoxygenation. Hypoxia-reoxygenation induced apoptosis was significantly decreased by L-NAME and BB3103 and increased by SNAP. significantly decreased the apoptosis Zymography showed a significant increase of MMP production, in the forms of proMMP-2 and proMMP-9, in LSECs, paralleling with the number of apoptotic LSECs; and alpha-1 trypsin significantly inhibited the MMP activity during hypothermia and hypoxia-reoxygenation dose-dependently. Paralleling with the number of apoptotic LSECs, the expression of iNOS and eNOS, especially the former, was significantly increased after hypothermia and hypoxia-reoxygenation. L-NAME significantly decreased and SNAP significantly increased the production of NO during hypothermia and hypoxia-reoxygenation. The NOS expression and NO production of LSECs during hypothermia and hypoxia-reoxygenation were inhibit by alpha-1 trypsin dose-dependently.
alpha-1 antitrypsin protects LSEC from apoptosis during hypothermia and hypoxia-reoxygenation injury by decreasing NO production and inhibiting MMP activity.
Zhonghua yi xue za zhi 02/2005; 85(2):106-10.
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ABSTRACT: Magnetic iron/silica core/shell nanostructures were prepared by reducing the initially formed α-Fe2O3/SiO2 composites prepared via a sonication-assisted Stöber process. Monodisperse α-Fe2O3 nanocrystals were prepared by a simple solution method using PEG as a surfactant. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, (high-resolution) transmission electron microscopy ((HR)TEM), scanning electron microscopy (SEM) and magnetic hysteresis loops. After the reduction process, the silica coating can protect the Fe core from oxidation effectively. And the formed Fe/SiO2 nanostructures show better magnetic behavior, which is promising in targeted drug delivery systems.
Journal of Alloys and Compounds.
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ABSTRACT: Core/shell TiO2/SiO2 nanoparticles have been synthesized successfully by a facile flame method. The structural and optical properties of these TiO2/SiO2 particles are investigated using the X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared, and photoluminescence spectroscopy. Both anatase and rutile phase TiO2 can be found in the products. With addition of SiO2 into the matrix, the transformation from anatase to rutile has been hindered due to the surface modification of SiO2. The luminescence has been enhanced remarkably with the addition of SiO2, and the effect of the SiO2 layer on the optical properties is also discussed.
Journal of Alloys and Compounds 432. · 2.29 Impact Factor
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Particuology. 9(6):632-636.
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ABSTRACT: MgO:Dy3+ and Li-doped MgO:Dy3+ nanocrystals have been synthesized via a facile combustion method. The prepared MgO samples were characterized by X-ray diffraction, transmission electron microscopy, UV diffuse reflectance and photoluminescence spectroscopy. The crystallinity of MgO nanocrystals becomes better after Li addition, resulting in the enhancement of luminescent intensity of the characteristic emission of Dy3+ ions. This material is promising for applications in display technologies.
Journal of Alloys and Compounds.
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ABSTRACT: A series of Y2O3:Eu3+ samples with interesting three-dimensional (3D) microarchitectures were synthesized through a facile hydrothermal method in the presence of hexamethylenetetramine (HMT) followed by a subsequent heat treatment. The as-formed precursor via the hydrothermal process could transform to cubic Y2O3 with the same morphology after annealing at 500 °C for 2 h. The Y2O3 microstructures, with an average diameter about 10–20 μm, were composed of nanolamellas with thickness of about 50 nm. Besides a probable self-assembly mechanism, the Ostwald Ripening process was proposed to explain the formation of the architectures on the basis of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. The as-synthesized lamella-composed Y2O3:Eu3+ samples showed a strong red emission corresponding to 5D0→7F2 transition (612 nm), suggesting promising applications in optoelectronics.
Physica E: Low-dimensional Systems and Nanostructures.
