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ABSTRACT: Submicron BiFeO3 powders were successfully synthesized via a simple hydrothermal process with the assistance of mineralizer (NaOH) at 150–190°C,
using FeCl3 and Bi(NO3)3⋅5H2O as reactants. The effects of mineralizer concentration, reaction temperature and time on the phase evolution and crystal
morphology of the resulting samples were investigated. X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetry
and differential scanning calorimetry (TG-DSC), and vibrating sample magnetometry (VSM) were used to characterize the as-synthesized
samples. The experimental results revealed that a pure BiFeO3 phase could be formed at a temperature ranging from 170 to 190°C for 4–20h in the presence of 0.03–0.12M NaOH. It was found
that the mineralizer concentration, reaction temperature and time played a key role in controlling the growing speed of nuclei
and formation of BiFeO3 crystallites. The possible formation mechanisms of submicron BiFeO3 powders with different morphologies were presented. The magnetization of BiFeO3 powders showed a weak ferromagnetic behavior at room temperature.
Applied Physics A 05/2012; 103(2):511-516. · 1.63 Impact Factor
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Seying Dai,
Zhangwei Shen,
Zhenqiu Zha,
Ruixue Leng,
Weizi Qin,
Chao Wang,
Lili Chen,
Min Tian,
Zhangjun Huang,
Guimei Chen,
Han Cen,
Lei Xue, Juan Wang,
Yousheng Lu,
Biwu Cao,
Dongqing Ye
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ABSTRACT: This study aimed at understanding the HIV prevalence, distribution of HIV risk factors and whether the HIV has spread from high-risk groups to the general population in the Yanyuan and Muli counties, Liangshan Prefecture, Sichuan Province, China. A multistage probability method was used to select a representative sample of villages in each county, with stratification by risk employed in the sampling for the Yanyuan county. A real-name registration and confidential method were adopted to collect the information of the participants. Blood specimens were tested for HIV, syphilis, and hepatitis C virus. A total of 4,950 subjects participated in the study. Of the participants aged ≥ 15 years, 0.12% self-reported being drug users and 40% were injection drug users; 0.46% had multiple sex partners and the condom use rate was only 26.3% during the last sexual intercourse. HIV, syphilis, and HCV prevalence of Yanyuan county were 0.06% (95% CI: 0-0.142), 0.06% (95% CI: 0-0.142), and 0.15% (95% CI: 0.020-0.280), respectively. HCV prevalence of Muli county was 0.06% (95% CI: 0-0.191), and none was found to be HIV or syphilis positive. Therefore, the rate of HIV infection in Yanyuan and Muli counties is at a low level currently. The Yanyuan county HIV infection rate is similar to the average rate in all of China, and the Muli county rate is below China's average. The HIV epidemic has not spread from high-risk groups to the general population in these two counties.
Journal of Medical Virology 01/2012; 84(1):1-5. · 2.82 Impact Factor
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ABSTRACT: The aim of this study was to investigate the serum RANTES (regulated on activation, normal T-cell expressed and secreted) level in patients with systemic lupus erythematosus (SLE), and the associations with disease activity and clinical laboratory indexes. Twenty-seven SLE patients and 27 normal controls were enrolled in this study. Serum RANTES was measured by enzyme-linked immunosorbent assay (ELISA). The clinical and laboratory parameters of the patients were also recorded. Results showed that serum RANTES level was significantly elevated in SLE patients when compared with normal controls. Serum RANTES level was correlated with C3, ANA, anti-dsDNA antibodies, anti-Sm antibodies, and anti-SSB antibodies. Nevertheless, no association of serum RANTES level with SLEDAI was found. Taken together, serum RANTES level was significantly higher in SLE patients, suggesting that RANTES might be involved in the pathogenesis of SLE.
Rheumatology International 01/2011; 32(5):1231-3. · 1.88 Impact Factor
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ABSTRACT: The present research reports fabrication of nano-and submicrometer-sized BiFeO 3 (BFO) powders from bismuth nitrate and iron chloride by a simple hydrothermal method at 180°C for 16 h in the presence of various MOH mineralizers (M = K + , Na + and Li +). The final products were characterized by X-ray powder diffraction (XRD) and high-resolution transmission electron microscope (HR-TEM). Alkaline mineralizers introduced at suitable concentration have been found to play the key role in the formation of BFO crystallites with certain morphologies and sizes due to cationic radii of minera-lizers during the hydrothermal process. A nucleation and crystal growth mechanisms are proposed for the formation of BFO crystallites in the size range of nano and submicrometer.
Ceramics Silikaty 01/2009; 53:113-117. · 0.38 Impact Factor
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ABSTRACT: SnS2 microspheres composed of submicron-sized flakes were successfully prepared via a simple surfactant-free hydrothermal reaction route at 240 °C for 12 h, using SnCl4 and Na2S as reactants. The powders were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The X-ray diffraction pattern confirmed that the SnS2 microspheres had a single-phase hexagonal structure. The SEM micrographs indicated that these microspheres with the size of ∼30 μm in diameter were mainly constructed by self-assembly of submicron-sized SnS2 flakes. The effect of reaction temperature and the amount of mineralizer (urea) on the formation of SnS2 microspheres under hydrothermal conditions were investigated and a possible formation mechanism was preliminarily presented.
Journal of Alloys and Compounds 490. · 2.29 Impact Factor
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ABSTRACT: In this study, the effects of different organic additives on the formation of europium-doped yttrium orthovanadate (YVO4:Eu3+) microspheres under hydrothermal conditions were investigated. The organic additives employed were sodium dodecyl sulfate (SDS) as an ionic surfactant, polyvinylpyrrolidone (PVP) and ethylene glycol (EG) as nonionic surfactants, disodium ethylenediaminetetraacetic acid (Na2EDTA) as an organic salt, and acetone as an organic solvent. The as-synthesized samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectroscopy. The experimental results demonstrated that the organic additives in the hydrothermal system played an important role in the formation of YVO4:Eu3+ powders with different morphologies and sizes, as follows: ellipsoids (SDS) → irregular microspheres (acetone) → inhomogeneous microspheres (EG) → uniform microspheres with the diameter of 4–5 μm (PVP) → uniform microspheres with the diameter of 1–3 μm (Na2EDTA). The luminescence properties were greatly affected by the morphologies and sizes of the as-synthesized samples. The highest emission intensity was observed in the sample hydrothermally synthesized with Na2EDTA due to the formation of uniform microspheres with less aggregation.Graphical abstract
Solid State Sciences. 13(7):1401-1406.
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ABSTRACT: Nano- and micro-scaled Eu-doped yttrium orthovanadate (YVO4:Eu3+) powders had been fabricated via disodium ethylenediamine tetraacetate (Na2EDTA)-assisted morphology controllable hydrothermal method in a wide pH range at 180 °C for 24 h. The as-synthesized samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence spectroscopy (PL). The results showed that the pH value of the synthesis solution played a key role in the formation of the final products with different morphologies, including ball-like micro-spheres, micro-spheres composed of submicron cubes and flower-like structures containing nano-plates. The photoluminescence measurement revealed that the luminescent properties of the samples were changed by varying their morphologies. The significant ball-like micro-spheres of YVO4:Eu3+ particles had been synthesized, and the luminescence intensity of them is the strongest one among all products.
Materials Science and Engineering: B.
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ABSTRACT: Spherical YVO4:Eu3+ microstructures were hydrothermally synthesized by the reaction of NH4VO3, Y2O3, and Eu2O3 at 180 °C for 24 h with the assistance of polyvinylpyrrolidone (PVP) as a surfactant. The resulting products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectroscopy. The experimental results showed that ball-like YVO4:Eu3+ microspheres with a diameter of about 4–5 μm, corresponding to the SEM observations, formed at 180 °C for 24 h using 0.2 g PVP with the molecular weight of 20,000 g mol−1. The amount of PVP and the reaction time of hydrothermal processing were found to play a key role in the formation of YVO4:Eu3+ microspheres. It has been observed that the relative luminescence intensities of the as-synthesized samples increased with increasing hydrothermal reaction times due mainly to the increase of crystallinity.
Materials Chemistry and Physics.
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ABSTRACT: Two kinds of boron-doped goethites were synthesized, one was called ad-B-goethite prepared by reacting the original goethite with borax solution and the other called oc-B-goethite prepared in the presence of boric acid solution. The goethites were characterized by IR and XRD. The IR bands of FeOHFe in-plane bending and free OH of the boron-doped goethites were weak compared with the original goethite. The IR bands of bending modes of trigonal and tetrahedral B were found in ad-B-goethite (420 cm− 1) and oc-B-goethite (527 cm− 1 and 476 cm− 1). These results suggest that some hydroxyl groups were replaced by the introduced boron. Analysis of XRD patterns indicated ad-B-goethite remained the characteristic of α-FeOOH, while oc-B-goethite did not. The specific surface areas of these goethites using BET method were 108 m2/g, 89 m2/g and 120 m2/g for the original goethite, ad-B-goethite and oc-B-goethite, respectively. The relatively large surface area of oc-B-goethite indicated the likelihood of higher activity than the original goethite, which was supported by evidence of the higher Mn2+ adsorption ability of oc-B-goethite. The amount of adsorbed Mn2+ increased with pH by the geothites and the order of Mn2+ adsorption capability was oc-B-goethite > ad-B-goethite > the original goethite. It was suggested that boron in soils not only serves as a plant nutrient, but can also decreases the Mn2+ toxicity through the function of enhancing Mn2+ adsorption in acidic soils.
Applied Clay Science 38:43-50. · 2.47 Impact Factor
