Fractal dimension determination of sol–gel powders using transmission electron microscopy images

Dobrescu, Gianina; Crışan, Maria; Zaharescu, Maria; Ionescu, N. I.

doi:10.1016/j.matchemphys.2004.05.034

Cited by 7 publications

(6 citation statements)

References 30 publications

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“…; Dobrescu et al. ). Therefore, our data suggest fractality of mineralized bone matrix, albeit limited to the investigated range of spatial frequencies at nano‐scale due to the complex hierarchical organization of bone (Currey, ).…”

Section: Discussionmentioning

confidence: 98%

Age‐dependence of power spectral density and fractal dimension of bone mineralized matrix in atomic force microscope topography images: potential correlates of bone tissue age and bone fragility in female femoral neck trabeculae

2012

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There is an increasing interest in bone nano-structure, the ultimate goal being to reveal the basis of agerelated bone fragility. In this study, power spectral density (PSD) data and fractal dimensions of the mineralized bone matrix were extracted from atomic force microscope topography images of the femoral neck trabeculae. The aim was to evaluate age-dependent differences in the mineralized matrix of human bone and to consider whether these advanced nano-descriptors might be linked to decreased bone remodeling observed by some authors and age-related decline in bone mechanical competence. The investigated bone specimens belonged to a group of young adult women (n = 5, age: 20-40 years) and a group of elderly women (n = 5, age: 70-95 years) without bone diseases. PSD graphs showed the roughness density distribution in relation to spatial frequency. In all cases, there was a fairly linear decrease in magnitude of the power spectra with increasing spatial frequencies. The PSD slope was steeper in elderly individuals (À2.374 vs. À2.066), suggesting the dominance of larger surface morphological features. Fractal dimension of the mineralized bone matrix showed a significant negative trend with advanced age, declining from 2.467 in young individuals to 2.313 in the elderly (r = 0.65, P = 0.04). Higher fractal dimension in young women reflects domination of smaller mineral grains, which is compatible with the more freshly remodeled structure. In contrast, the surface patterns in elderly individuals were indicative of older tissue age. Lower roughness and reduced structural complexity (decreased fractal dimension) of the interfibrillar bone matrix in the elderly suggest a decline in bone toughness, which explains why aged bone is more brittle and prone to fractures.

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Section: Discussionmentioning

confidence: 98%

Age‐dependence of power spectral density and fractal dimension of bone mineralized matrix in atomic force microscope topography images: potential correlates of bone tissue age and bone fragility in female femoral neck trabeculae

2012

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“…The confidential intervals were estimated so that the mean of our experimental d f values could be compared with that derived from numerically computed d f s (Wilkinson and Willemsem, 1983 ; Meakin and Djordjevi, 1985 ; Tolman and Meakin, 1989 ; Dobrescu et al, 2004 ; Table 1 ). The interval estimation reflects the degree of uncertainty in the derived mean.…”

Section: Methodsmentioning

confidence: 99%

“…Self-organizing molecules, such as titanium dioxide, and sol–gel powders, etc., are readily seen under TEM. We applied this method to determine the d f of the intracellular environment using the procedure described by Dobrescu et al ( 2004 ).…”

Section: Introductionmentioning

confidence: 99%

Physiological environment induces quick response – slow exhaustion reactions

Hiroi

Lu²,

Iba

et al. 2011

Front. Physio.

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In vivo environments are highly crowded and inhomogeneous, which may affect reaction processes in cells. In this study we examined the effects of intracellular crowding and an inhomogeneity on the behavior of in vivo reactions by calculating the spectral dimension (ds), which can be translated into the reaction rate function. We compared estimates of anomaly parameters obtained from fluorescence correlation spectroscopy (FCS) data with fractal dimensions derived from transmission electron microscopy (TEM) image analysis. FCS analysis indicated that the anomalous property was linked to physiological structure. Subsequent TEM analysis provided an in vivo illustration; soluble molecules likely percolate between intracellular clusters, which are constructed in a self-organizing manner. We estimated a cytoplasmic spectral dimension ds to be 1.39 ± 0.084. This result suggests that in vivo reactions initially run faster than the same reactions in a homogeneous space; this conclusion is consistent with the anomalous character indicated by FCS analysis. We further showed that these results were compatible with our Monte-Carlo simulation in which the anomalous behavior of mobile molecules correlates with the intracellular environment, leading to description as a percolation cluster, as demonstrated using TEM analysis. We confirmed by the simulation that the above-mentioned in vivo like properties are different from those of homogeneously concentrated environments. Additionally, simulation results indicated that crowding level of an environment might affect diffusion rate of reactant. Such knowledge of the spatial information enables us to construct realistic models for in vivo diffusion and reaction systems.

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“…The most attractive process for the synthesis of TiO 2 nanoparticles is the solgel method [7][8][9][10][11][12][13][14][15][16][17][18][19]. This process involves the hydrolysis and polycondensation of a metal alkoxide Ti(OR) 4 (R=alkyl groups) precursor and subsequent formation of a gel, which after heat treatment results in a three dimensional crystalline network of linked TiO 6 octahedra [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterisation of clay-supported titania photocatalysts

Daniel

Frost

Zhu

2007

Journal of Colloid and Interface Science

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This study examines the use of laponite, a synthetic smectite, which forms exfoliated silicate layers when dispersed in water, as an inorganic support for titania nanocrystals. Titania nanocrystals are prepared prior to addition to the clay dispersion, by a sol-gel synthesis incorporating a microwave hydrothermal step. The characteristics of the resultant structure such as titania phase, crystallite size and particulate size are examined via X-Ray Diffraction (XRD), Transmission Electron Spectroscopy (TEM) and Infrared Spectroscopy.

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Fractal dimension determination of sol–gel powders using transmission electron microscopy images

Cited by 7 publications

References 30 publications

Age‐dependence of power spectral density and fractal dimension of bone mineralized matrix in atomic force microscope topography images: potential correlates of bone tissue age and bone fragility in female femoral neck trabeculae

Age‐dependence of power spectral density and fractal dimension of bone mineralized matrix in atomic force microscope topography images: potential correlates of bone tissue age and bone fragility in female femoral neck trabeculae

Physiological environment induces quick response – slow exhaustion reactions

Synthesis and characterisation of clay-supported titania photocatalysts

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