scholarly journals Morphological Characterization of Nanofibers: Methods and Application in Practice

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Jakub Širc ◽  
Radka Hobzová ◽  
Nina Kostina ◽  
Marcela Munzarová ◽  
Martina Juklíčková ◽  
...  
Keyword(s):  
Specific Surface ◽  
Mercury Porosimetry ◽  
Three Dimensional ◽  
Nitrogen Adsorption ◽  
Morphological Characterization ◽  
Biologically Active ◽  
Porous Scaffolds ◽  
Electrospinning Technique ◽  
Pore Size Distributions

Biomedical applications such as wound dressing for skin regeneration, stem cell transplantation, or drug delivery require special demands on the three-dimensional porous scaffolds. Besides the biocompatibility and mechanical properties, the morphology is the most important attribute of the scaffold. Specific surface area, volume, and size of the pores have considerable effect on cell adhesion, growth, and proliferation. In the case of incorporated biologically active substances, their release is also influenced by the internal structure of nanofibers. Although many scientific papers are focused on the preparation of nanofibers and evaluation of biological tests, the morphological characterization was described just briefly as service methods. The aim of this paper is to summarize the methods applicable for morphological characterization of nanofibers and supplement it by the results of our research. Needleless electrospinning technique was used to prepare nanofibers from polylactide, poly(ε-caprolactone), gelatin, and polyamide. Scanning electron microscopy was used to evaluate the fiber diameters and to reveal eventual artifacts in the nanofibrous structure. Nitrogen adsorption/desorption measurements were employed to measure the specific surface areas. Mercury porosimetry was used to determine total porosities and compare pore size distributions of the prepared samples.

Morphological Characterization of 3D Porous Scaffolds Based on Portland Cement

2008 ◽  
Vol 396-398 ◽  
pp. 687-690 ◽  
Author(s):  
Alexandra A.P. Mansur ◽  
Herman S. Mansur
Keyword(s):  
Portland Cement ◽  
Three Dimensional ◽  
Morphological Characteristics ◽  
Bone Substitutes ◽  
Morphological Characterization ◽  
Porous Scaffolds ◽  
Air Voids ◽  
Total Immersion ◽  
Potential Use

There is a constant need for bone substitutes. This work was focused on evaluating morphological characteristics of new bioceramic three-dimensional scaffold for bone tissue engineering based on Portland cement with air-voids introduced by outgassing reaction product from lime and aluminum powder. Pores morphology was observed using scanning electron microscopy (SEM). Bulk density, apparent density, and apparent porosity were measured by Archimedes method. Water absorption by total immersion and by capillarity was also investigated. The results have indicated that cement based scaffolds exhibit a hierarchical structure with interconnected macropores and a micropores framework that indicate potential use of the developed porous materials as bone substitutes.

Characterization of photosystem II with the atomic-force microscope

1992 ◽  
Vol 50 (2) ◽  
pp. 1146-1147
Author(s):  
Kathleen M. Marr ◽  
Mary K. Lyon
Keyword(s):  
Photosystem Ii ◽  
Atomic Force Microscope ◽  
Three Dimensional ◽  
Biologically Active ◽  
Atomic Force ◽  
Freeze Etching ◽  
Image Averaging ◽  
Oxygen Evolving ◽  
Averaging Techniques

Photosystem II (PSII) is different from all other reaction centers in that it splits water to evolve oxygen and hydrogen ions. This unique ability to evolve oxygen is partly due to three oxygen evolving polypeptides (OEPs) associated with the PSII complex. Freeze etching on grana derived insideout membranes revealed that the OEPs contribute to the observed tetrameric nature of the PSIl particle; when the OEPs are removed, a distinct dimer emerges. Thus, the surface of the PSII complex changes dramatically upon removal of these polypeptides. The atomic force microscope (AFM) is ideal for examining surface topography. The instrument provides a topographical view of individual PSII complexes, giving relatively high resolution three-dimensional information without image averaging techniques. In addition, the use of a fluid cell allows a biologically active sample to be maintained under fully hydrated and physiologically buffered conditions. The OEPs associated with PSII may be sequentially removed, thereby changing the surface of the complex by one polypeptide at a time.

Cementitious Sealing Material: 3D Digital Image Based Characterization of Pore Size Distribution and Modeling of Transport Properties

2013 ◽  
Author(s):  
Neven Ukrainczyk ◽  
Eduardus A. B. Koenders ◽  
Klaas van Breugel
Keyword(s):  
Pore Size ◽  
Transport Properties ◽  
Digital Image ◽  
Oil And Gas ◽  
Transport Model ◽  
Medial Axis ◽  
Three Dimensional ◽  
Cementitious Materials ◽  
Pore Size Distributions

Exhausted oil and gas reservoirs are one of the most potential storage facilities to sequestrate the worlds CO2. These reservoirs are sealed with cementitious materials, that should have a long time performance. Therefore, this paper emphasizes the characterization of the evolving capillary pore network and transport properties of the cementitious microstructure used to seal the wellbore. The Hymostruc numerical model is employed to simulate the development of an evolving virtual microstructure of cementitious materials. The simulated 3D microstructures were then digitized to form a matrix of cubic voxels. The pore-size distributions of the obtained virtual microstructures were calculated using a combination of three-dimensional digital image processing algorithms: 1) distance transform and 2) medial axis thinning algorithm to obtain a 3D skeleton of the pore structure. Transport properties of the simulated microstructures are analyzed employing a finite difference 3D transport model. The modeling results are compared with available literature results.

scholarly journals Kinetic study of CO2 reaction with CaO by a modified random pore model

2016 ◽  
Vol 18 (1) ◽  
pp. 93-98 ◽  
Author(s):  
S.M.M. Nouri ◽  
H. Ale Ebrahim
Keyword(s):  
Mercury Porosimetry ◽  
Nitrogen Adsorption ◽  
Intrinsic Rate ◽  
Product Layer ◽  
Carbonation Reaction ◽  
Pore Model ◽  
Partial Pressures ◽  
Pore Size Distributions ◽  
Kinetics Of ◽  
Random Pore Model

Abstract In this work, a modified random pore model was developed to study the kinetics of the carbonation reaction of CaO. Pore size distributions of the CaO pellets were measured by nitrogen adsorption and mercury porosimetry methods. The experiments were carried out in a thermogravimeter at different isothermal temperatures and CO2 partial pressures. A fractional concentration dependency function showed the best accuracy for predicting the intrinsic rate of reaction. The activation energy was determined as 11 kcal/mole between 550–700°C. The effect of product layer formation was also taken into account by using the variable product layer diffusivity. Also, the model was successfully predicted the natural lime carbonation reaction data extracted from the literature.

scholarly journals Textural properties of synthetic clay-ferrihydrite associations

Clay Minerals ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 395-407 ◽  
Author(s):  
R. Celis ◽  
J. Cornejo ◽  
M. C. Hermosin
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Mercury Porosimetry ◽  
Textural Properties ◽  
Nitrogen Adsorption ◽  
Fractal Approach ◽  
Adsorption Data ◽  
Synthetic Clay ◽  
Nitrogen Adsorption Data

AbstractKaolinite-ferrihydrite and montmorillonite-ferrihydrite associations were prepared following a procedure based on the Russell method for the synthesis of ferrihydrite and the texture of the clay-ferrihydrite complexes was studied using different techniques. The textural properties of kaolinite were little affected by the Fe association, showing only a slight increase in the specific surface area measured by nitrogen adsorption and a decrease in the largest pores (>10 µm), as measured by mercury porosimetry. In contrast, the nitrogen specific surface area of the montmorillonite complexes was much higher than that of the clay without Fe and the pore structure depended on the amounts of Fe in the complexes. Application of the fractal approach to nitrogen adsorption data indicated that the surface roughness (microporosity) was greater for the complexes prepared from diluted Fe(III) solutions, in agreement with the information obtained from classical interpretation of the adsorption isotherms (shape of the isotherms and t-plots).

Hydroxyapatite/Biopolymers Composite Scaffolds for Bone Tissue Engineering

2011 ◽  
Vol 493-494 ◽  
pp. 826-831
Author(s):  
A.C.B.M. Fook ◽  
Thiago Bizerra Fideles ◽  
R.C. Barbosa ◽  
G.T.F.S. Furtado ◽  
G.Y.H. Sampaio ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Bone Tissue Engineering ◽  
Bone Tissue ◽  
Freeze Drying ◽  
Three Dimensional ◽  
Porous Scaffolds ◽  
X Ray Diffraction ◽  
X Ray ◽  
Interconnected Pores

The application of a hybrid composite consisting of biopolymer and calcium phosphate, similar morphology and properties of natural bone, may be a way to solve the problem of the fragility of ceramics without reducing its mechanical properties, retaining the properties of biocompatibility and high bioactivity. This work aims at the preparation and characterization of three-dimensional scaffolds composite HA / biopolymers (chitosan and gelatin). The freeze-drying technique was employed in this study to obtain these frameworks and partial results showed the effectiveness of this method. This involved the study of structural, chemical and morphological frameworks, in order to direct the research suggested the application. The X Ray Diffraction (XRD) and infrared spectroscopy and Fourier transform (FTIR) results confirmed the formation of hydroxyapatite (HA) phase and the presence of characteristic bands of HA and biopolymers in all compositions. The microstructure of the scaffolds study conducted by Scanning Electron Microscopy (SEM) revealed the formation of longitudinally oriented microchannels with interconnected pores. In all compositions the porous scaffolds showed varying sizes and mostly larger than 100μm, and is therefore considered materials with potential for application in bone tissue engineering.

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