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 20,729 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We demonstrate a one-pot hydrothermal cohydrolysis-carbonization process using glucose and iron nitrate as starting materials for the fabrication of carbonaceous spheres embedded with iron oxide nanoparticles. It is verified by TEM, (57)Fe Mossbauer, and Fe K-edge XAS that iron oxide nanoparticles are highly dispersed in the carbonaceous spheres, leading to a unique microstructure. A formation mechanism is also proposed. This route is also applicable to a range of other naturally occurring saccharides and metal nitrates. A catalytic study revealed the remarkable stability and selectivity of the reduced Fe(x)O(y)@C spheres in the Fischer-Tropsch synthesis, which clearly exemplifies the promising application of such materials.
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PMID:Fe(x)O(y)@C spheres as an excellent catalyst for Fischer-Tropsch synthesis. 2002 26

Silver nanoparticles doped on titanium oxide (TiO(2)) were produced by laser-liquid interaction of silver nitrate (AgNO(3)) in isopropanol. Characteristics of Ag/TiO(2) (Ag doped TiO(2)) nanoparticles produced by the methods presented in this article were investigated by XRD, TEM, SEM, EDX, and UV-Vis. From the UV-Vis measurements, the absorption of visible light of the Ag/TiO(2) photocatalysts was improved (additional absorption at longer wavelength in visible light region) obviously. The photocatalytic efficiency of Ag/TiO(2) was tested by the degradation of methylene blue (MB) in aqueous solution. A maximum of 82.3% MB degradation is achieved by 2.0 wt% Ag/TiO(2) photocatalyst under 2 h illumination with a halogen lamp.
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PMID:Laser-induced silver nanoparticles on titanium oxide for photocatalytic degradation of methylene blue. 2008 59

The emission behavior of polyatomic ions in the ionization source of thermal ionization mass spectrometry (TIMS) was investigated. The results suggest that the presence of a graphite promoter plays a key role for the formation and stable emission of polyatomic ions, such as M(2)X(+), M(2)BO(2)(+), Cs(2)NO(2)(+), and Cs(2)CNO(+). Our data further implied that the intensity of M(2)X(+) and M(2)BO(2)(+) increases and the emission temperature decreases with increasing cationic and anionic radius. During the boron isotopic measurement using the Cs(2)BO(2)(+)-graphite-PTIMS method, the isobaric interference ion Cs(2)CNO(+) cannot be transformed from nitrate or organic compounds containing an amide group but can be induced by the existence of trace amounts of boron because of its special electron-deficiency property (B(3+)). Characterization on the planar crystalline structure of various graphite samples with SEM, TEM, and Raman spectroscopy confirmed the relationship of the emission capacity of polyatomic ions and the crystal microstructure of graphite and provides direct evidence that graphite with a perfect parallel and equidistant layer orientation shows a beneficial effect on the emission of polyatomic ions in TIMS. The mechanism study on the formation of polyatomic ions opens the possibility to establish high precision methods for isotopic composition analysis of more nonmetal elements with the TIMS technique.
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PMID:Effect of microstructure of graphite on the nonreductive thermal ion emission in thermal ionization mass spectrometry. 2011

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.
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PMID:[Synthesis and properties of nanorod-long afterglow BaAl2O4:Eu2+, Dy3+ phosphor]. 2030 73

This work represents a new method to synthesis of ZnO and/or Zn nanoparticles by means of microwave plasma whose electrons are the reducing agents. Glass quadratic slides sized 2.5 x 2.5 cm were coated by ZnO and/or Zn particles whose sizes ranged from a few micrometers to approximately 20 nm. The size of the particles can be controlled by the type of the precursor and its concentration. In the current paper, the mechanism of the reactions of ZnO and/or Zn formation was proposed. Longer plasma irradiation and lower precursor concentration favor the fabrication of metallic Zn nanoparticles. The nature of the precursor's ion (acetate, nitrate, or chloride) is also of importance in determining the composition of the product. The glass slides coated by ZnO and/or Zn nanoparticles were characterized by HR-SEM, HR-TEM, AFM, XRD, ESR, contact angle and diffuse reflectance spectroscopy (DRS).
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PMID:Synthesis of ZnO and Zn nanoparticles in microwave plasma and their deposition on glass slides. 2033 10

Well-dispersed barium borate nanorods with uniform diameters were synthesized successfully, using Na2B4O7 x 10H2O and Ba(NO3)2 as raw materials and oleic acid as a modifying agent. Oleic acid was used to modify the surface property of nanorods prepared from the precipitation reaction. TEM images confirmed that the synthesized sample presented nanorod morphology with a length of about 200-400 nm and an average diameter of 20 nm. Moreover, the photoluminescence properties of both pure and modified BaB2O4 nanorods were tested. After the surfaces of the nanorods were modified with oleic acid, the visible light emission of the sample centered at 380 and 400 nm became more intensive. It was discussed that the enhancement of the luminescence intensity was attributed to the formation of surface BaB2O4/oleic acid complexes.
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PMID:Synthesis and enhanced photoluminescence of surface-modified barium borate nanorods. 2035 42

Silver-polyphenylsilane nanocomposites have been effectively prepared by the dehydrocoupling reaction of phenylsilane (PS, PhSiH3) to polyphenylsilane (PPS, [PhSiH]n) in the presence of silver nitrate. The one-step reduction of Ag(+1) nitrate to stable Ag(0) nanoparticles is mediated by PS, resulting in the formation of Ag-PPS composites. The Ag-PPS nanocomposites were characterized by various analytical techniques such as XRD, TEM, FE-SEM, and solid-state UV-vis. TEM and FE-SEM data clearly show that the silver nanoparticles with the size of < 20 nm are well dispersed throughout the PPS matrix in the nanocomposites. XRD patterns are consistent with those for fcc crystalline silver. The size of silver nanoparticles increased with increasing the relative molar concentration of silver salts added. It was found that in the absence of PS, most of the silver nanoparticles undergo macroscopic precipitation by aggregation, indicating that PPS is essential to stabilize the silver nanoparticles by the complexation of Si-H to the silver metal centers.
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PMID:Efficient preparation and characterization of silver-polyphenylsilane nanocomposites. 2035 29

We present a systematic study of the self-assembly of wormlike micelles (WLMs) comprised of cetyltrimethylammonium bromide (CTAB) and sodium nitrate (NaNO(3)) in aqueous solution as a function of CTAB concentration, NaNO(3) concentration, and temperature throughout the dilute and semi-dilute regions of the phase diagram where linear micelles are observed. Combining measurements using isothermal titration calorimetry, rheometry, flow-birefringence, cryo-transmission electron microscopy (cryo-TEM), and small angle neutron scattering (SANS) enables complete characterization of the structure, thermodynamics, and rheology of CTAB/NaNO(3) micelles. The addition of NaNO(3) is found to increase the micellization enthalpy as well as the micellar scission energy, resulting in the elongation and growth of WLMs. We find quantitative agreement between the scission energy determined from rheology and the enthalpy of micellization determined from ITC, as well as for contour lengths extracted from rheology and SANS. At fixed molar ratio of NaNO(3) and CTAB, the solution rheology exhibits scaling consistent with dilute, semi-dilute overlapping, and semi-dilute entangled regimes typically found in polymer solutions, as confirmed by cryo-TEM and SANS. The transition between these scaling regimes coincides with the structural transitions identified by SANS. The results validate the relationship between structural parameters and rheological behavior underlying theories for ionic WLMs.
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PMID:A systematic study of equilibrium structure, thermodynamics, and rheology of aqueous CTAB/NaNO(3) wormlike micelles. 2054 Dec 17

A fungal strain, KSU-09, isolated from the roots of date palm (Phoenix dactylifera), was identified as Amylomyces rouxii based on sequence analysis of the internal transcribed spacer (ITS) region of its rRNA genes. Mycelia-free water extracts obtained from mycelium suspended in water for 72h facilitated the production of stable, predominantly monodispersed and spherical silver nanoparticles (AgNPs) in the size range of 5-27nm upon addition of 1mM silver nitrate, as determined by the XRD, AFM and TEM. The AgNPs exhibited antimicrobial activity against Shigella dysenteriae type I, Staphylococcus aureus, Citrobacter sp., Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Candida albicans and Fusarium oxysporum. Thus, the strain KSU-09 could be used for simple, non-hazardous and efficient synthesis of antimicrobial AgNPs.
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PMID:Production of antimicrobial silver nanoparticles in water extracts of the fungus Amylomyces rouxii strain KSU-09. 2061 41

Abstract: Recently, silver nanoparticles have generated enough interest due to their immense usage. Until now chemical synthesis has been a fast method to produce nanoparticles, but the release of environmental pollutants has raised caution. So a more subtle biochemical approach is in research. Three microorganisms, Aspergillus flavus, Phoma exigua and Bacillus megaterium, were selected to reduce silver nitrate to silver nanoparticles in aqueous form. All three microorganisms showed varying reducing capacity, of which Phoma exigua showed the highest, when their biomass was incubated in silver nitrate for 48 hours. The nanoparticles showed all the optical and physical properties, which were analyzed by measuring the surface plasmon resonance and TEM. It was also observed that the fungal species have varied growth in silver nitrate and can be used to produce silver nanoparticles, directly incubating the inocula of fungus in the media containing silver nitrate. On comparing all the characteristics and results produced, Aspergillus flavus was found to be the most effective microorganism, which can convert the silver nitrate to silver nanoparticles in aqueous condition. The bacterial species showed no growth with incubation with silver nitrate.
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PMID:Bioconversion of silver salt into silver nanoparticles using different microorganisms. 2067 Jan 8


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