Effect of preparation conditions on the porous properties of coprecipitated Al2O3–SiO2 xerogels synthesized from aluminium nitrate nonahydrate and tetraethylorthosilicate

The relative effectiveness of deferoxamine (DFO), 1,2-dimethyl-1,3-hydroxypyrid-4-one (L1), and citric and succinic acids in mobilizing and promoting excretion of aluminium (Al) were compared in female uraemic rats which had previously received aluminium nitrate nonahydrate i.p. in a daily dose of 45 mg kg-1 for 3 weeks (5 days/week). Chelators were administered s.c. at doses equal to one-eighth of their respective LD50 for five days. L1 was also given p.o. in doses of 200 mg kg-1 day-1. Total urines were collected 24 h after each chelator administration. Total urinary Al excreted over the 5-day period, expressed as mg kg-1, were: controls, 3.4; DFO-treated, 4.5 (P<0.05); citric acid-treated, 3.7; and succinic acid-treated, 2.7. Although the daily amounts of Al excreted into urine by L1-treated rats were significantly higher ( P<0.001) than those of the controls, most animals died during the period of treatment. Measurements of Al in selected tissues 24 h after the last administration of each chelator revealed that none of the compounds significantly altered the Al concentration in bone, kidney, and brain, whereas only DFO and succinic acid significantly reduced the levels of Al in spleen. Moreover, L1 (given s.c. or p.o.) and citric acid treatment led to a significant reduction in the liver Al burden. These results indicate the need for further investigations to determine the toxicity and the therapeutical safety margins of L1.

Download Full-text

Surface Acidity and Hydrophilicity of Coprecipitated Al2O3–SiO2 Xerogels Prepared from Aluminium Nitrate Nonahydrate and Tetraethylorthosilicate

Journal of Colloid and Interface Science ◽

10.1006/jcis.1999.6461 ◽

1999 ◽

Vol 219 (1) ◽

pp. 195-200 ◽

Cited By ~ 16

Author(s):

Kiyoshi Okada ◽

Takahiro Tomita ◽

Yoshikazu Kameshima ◽

Atsuo Yasumori ◽

Kenneth J.D. MacKenzie

Keyword(s):

Surface Acidity ◽

Aluminium Nitrate ◽

Nitrate Nonahydrate ◽

Aluminium Nitrate Nonahydrate

Download Full-text

Aluminium Nitrate Nonahydrate (Al(NO3)3⋅9 H2O): An Efficient Oxidant Catalyst for the One-Pot Synthesis of Biginelli Compounds from Benzyl Alcohols

Helvetica Chimica Acta ◽

10.1002/hlca.201100242 ◽

2012 ◽

Vol 95 (1) ◽

pp. 115-119 ◽

Cited By ~ 7

Author(s):

Eskandar Kolvari ◽

Mohammad Ali Zolfigol ◽

Maryam Mirzaeean

Keyword(s):

Aluminium Nitrate ◽

One Pot ◽

Benzyl Alcohols ◽

One Pot Synthesis ◽

Biginelli Compounds ◽

Nitrate Nonahydrate ◽

The One ◽

Aluminium Nitrate Nonahydrate

Download Full-text

Synthesis of highly porous Al2O3-YAG composite ceramics

Science of Sintering ◽

10.2298/sos1603303e ◽

2016 ◽

Vol 48 (3) ◽

pp. 303-315

Author(s):

Adela Egelja ◽

Jelena Majstorovic ◽

Nikola Vukovic ◽

Miroslav Stankovic ◽

Dusan Bucevac

Keyword(s):

Sintering Temperature ◽

Water Solution ◽

Nitrate Hexahydrate ◽

Yttrium Nitrate ◽

Aluminium Nitrate ◽

Composite Ceramics ◽

X Ray ◽

Highly Porous ◽

Yttrium Nitrate Hexahydrate ◽

Aluminium Nitrate Nonahydrate

Al2O3-YAG composite was obtained by sintering of porous Al2O3 preforms infiltrated with water solution of aluminium nitrate nonahydrate, Al(NO3)3?9H2O and yttrium nitrate hexahydrate, Y(NO3)3?6H2O. Al2O3 preforms with porosity varying from 26 to 50% were obtained after sintering at temperature ranging from 1100 to 1500?C. Sintering of the infiltrated Al2O3 preforms led to formation of YAG particles due to reaction between Y2O3 and Al2O3 at high temperature. It was found that variation of porosity of alumina preforms and sintering temperature is an effective way to fabricate Al2O3-YAG composite with an unusual combination of properties. Open porosity was in the range 15-35%, specific surface was 0.6-6.1 m2/g, pore size was 150-900 nm whereas compressive strength was from 50 to 250 MPa. The effect of sintering temperature on YAG formation and phase composition were investigated using X-ray diffractometry whereas microstructure of the composite was analysed by scanning electron microscopy.

Download Full-text

Interpretation of irradiation-induced changes in electron diffractograms and images of extinction contours at low temperatures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100111458 ◽

1984 ◽

Vol 42 ◽

pp. 268-269

Author(s):

E. Knapek ◽

H. Formanek ◽

G. Lefranc ◽

I. Dietrich

Keyword(s):

Low Temperatures ◽

Carbon Films ◽

Organic Crystals ◽

Wide Spread ◽

Lens System ◽

Preparation Conditions ◽

Thin Carbon ◽

Electron Diffractograms ◽

Diffraction Patterns ◽

Induced Changes

A few years ago results on cryoprotection of L-valine were reported, where the values of the critical fluence De i.e, the electron exposure which decreases the intensity of the diffraction reflections by a factor e, amounted to the order of 2000 + 1000 e/nm2. In the meantime a discrepancy arose, since several groups published De values between 100 e/nm2 and 1200 e/nm2 /1 - 4/. This disagreement and particularly the wide spread of the results induced us to investigate more thoroughly the behaviour of organic crystals at very low temperatures during electron irradiation.For this purpose large L-valine crystals with homogenuous thickness were deposited on holey carbon films, thin carbon films or Au-coated holey carbon films. These specimens were cooled down to nearly liquid helium temperature in an electron microscope with a superconducting lens system and irradiated with 200 keU-electrons. The progress of radiation damage under different preparation conditions has been observed with series of electron diffraction patterns and direct images of extinction contours.

Download Full-text

The 3-Dimensional Molecular Structure of the Actin Filament Revisited

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100119223 ◽

1985 ◽

Vol 43 ◽

pp. 480-481

Author(s):

U. Aebi ◽

R. Millonig ◽

H. Salvo

Keyword(s):

Actin Filament ◽

Supramolecular Assembly ◽

Specimen Preparation ◽

X Ray Diffraction ◽

Single Filament ◽

X Ray ◽

3 Dimensional ◽

Filament Diameter ◽

Preparation Conditions ◽

Apparent Diameter

To date, most 3-D reconstructions of undecorated actin filaments have been obtained from actin filament paracrystal data (for refs, see 1,2). However, due to the fact that (a) the paracrystals may be several filament layers thick, and (b) adjacent filaments may sustantially interdigitate, these reconstructions may be subject to significant artifacts. None of these reconstructions has permitted unambiguous tracing or orientation of the actin subunits within the filament. Furthermore, measured values for the maximal filament diameter both determined by EM and by X-ray diffraction analysis, vary between 6 and 10 nm. Obviously, the apparent diameter of the actin filament revealed in the EM will critically depend on specimen preparation, since it is a rather flexible supramolecular assembly which can easily be bent or distorted. To resolve some of these ambiguities, we have explored specimen preparation conditions which may preserve single filaments sufficiently straight and helically ordered to be suitable for single filament 3-D reconstructions, possibly revealing molecular detail.

Download Full-text

Structures of chemically stabilized ceramics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100150459 ◽

1993 ◽

Vol 51 ◽

pp. 924-925

Author(s):

Pratibha L. Gai ◽

M. A. Saltzberg ◽

L.G. Hanna ◽

S.C. Winchester

Keyword(s):

High Temperature ◽

Calcium Nitrate ◽

Nitrate Hexahydrate ◽

Chemical Route ◽

Cubic Form ◽

Tetragonal Form ◽

Wet Chemical ◽

Wet Chemical Route ◽

Final Composition ◽

Aluminium Nitrate Nonahydrate

Silica based ceramics are some of the most fundamental in crystal chemistry. The cristobalite form of silica has two modifications, α (low temperature, tetragonal form) and β (high temperature, cubic form). This paper describes our structural studies of unusual chemically stabilized cristobalite (CSC) material, a room temperature silica-based ceramic containing small amounts of dopants, prepared by a wet chemical route. It displays many of the structural charatcteristics of the high temperature β-cristobalite (∼270°C), but does not undergo phase inversion to α-cristobalite upon cooling. The Structure of α-cristobalite is well established, but that of β is not yet fully understood.Compositions with varying Ca/Al ratio and substitutions in cristobalite were prepared in the series, CaO:Al2O3:SiO2 : 3-x: x : 40, with x= 0-3. For CSC, a clear sol was prepared from Du Pont colloidal silica, Ludox AS-40®, aluminium nitrate nonahydrate, and calcium nitrate hexahydrate in proportions to form a final composition 1:2:40 composition.

Download Full-text