89 research outputs found
Monitoring of wild pseudomonas biofilm strain conditions using statistical characterization of scanning electron microscopy images
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.The present paper proposes a novel method of quantification of the variation in biofilm architecture, in correlation with the alteration of growth conditions that include variations of the substrate and conditioning layer. The polymeric biomaterials serving as substrates are widely used in implants and indwelling medical devices, while the plasma proteins serve as the conditioning layer. The present method uses descriptive statistics of field emission scanning electron microscopy (FESEM) images of biofilms obtained during a variety of growth conditions. We aim to explore here the texture and fractal analysis techniques, to identify the most discriminatory features which are capable of predicting the difference in biofilm growth conditions. We initially extract some statistical features of biofilm images on bare polymer surfaces, followed by those on the same substrates adsorbed with two different types of plasma proteins, viz., bovine serum albumin (BSA) and fibronectin (FN), for two different adsorption times. The present analysis has the potential to act as a futuristic technology for developing a computerized monitoring system in hospitals with automated image analysis and feature extraction, which may be used to predict the growth profile of an emerging biofilm on surgical implants or similar medical applications.SDS acknowledges the funding from the Department of Science and Technology (DST), Govt. of
India through the Women’s Scientist Scheme – A, project no. LS-466/WOS A/2012-2013
Fractal analysis of AFM images of worn-out contact lens inner surface
Interesovanje za tehnologiju površina biomaterijala podstaklo je istraživanje unutrašnje površine gas-propusnih kontaktnih sočiva, uz korišćenje skenirajućeg mikroskopa za snimanje. Topografski i fazni snimci su prikupljeni radi ispitivanja površinske hrapavosti i svojstava nakon produženog perioda nošenja kontaktnog sočiva. Analiza se zasniva na fraktalnom pristupu primenjenom u Matlab okruženju za analizu slike. Fraktalna dimenzija određena 'metodom nebodera', je korišćena za identifikaciju i dodatno pojašnjenje funkcionalnog ponašanja površine. Autori su želeli da istaknu da je vreme nošenja gas- propusnih sočiva komercijalna kategorija u pogledu učestalosti zamene sočiva i da samo značajne promene svojstava površine čine zamenu neophodnom.The interest in biomaterials surface technology has led to an investigation of rigid gas permeable contact lens inner surface using scanning probe microscopy for measurement. Topography and phase images were recorded in order to investigate surface roughness and properties after an extended period of contact lens wearing. Analysis is based on fractal approach incorporated with MatLab software for image processing. The fractal dimension, calculated by skyscrapers method, is used for surface identification and subsequently for surface behavior explanation. The authors' aim is to point out that time is merely a commercial category for rigid gas permeable contact lens replacement and that only significant changes in surface properties render such replacement necessary
Fractal analysis of AFM images of worn-out contact lens inner surface
Interesovanje za tehnologiju površina biomaterijala podstaklo je istraživanje unutrašnje površine gas-propusnih kontaktnih sočiva, uz korišćenje skenirajućeg mikroskopa za snimanje. Topografski i fazni snimci su prikupljeni radi ispitivanja površinske hrapavosti i svojstava nakon produženog perioda nošenja kontaktnog sočiva. Analiza se zasniva na fraktalnom pristupu primenjenom u Matlab okruženju za analizu slike. Fraktalna dimenzija određena 'metodom nebodera', je korišćena za identifikaciju i dodatno pojašnjenje funkcionalnog ponašanja površine. Autori su želeli da istaknu da je vreme nošenja gas- propusnih sočiva komercijalna kategorija u pogledu učestalosti zamene sočiva i da samo značajne promene svojstava površine čine zamenu neophodnom.The interest in biomaterials surface technology has led to an investigation of rigid gas permeable contact lens inner surface using scanning probe microscopy for measurement. Topography and phase images were recorded in order to investigate surface roughness and properties after an extended period of contact lens wearing. Analysis is based on fractal approach incorporated with MatLab software for image processing. The fractal dimension, calculated by skyscrapers method, is used for surface identification and subsequently for surface behavior explanation. The authors' aim is to point out that time is merely a commercial category for rigid gas permeable contact lens replacement and that only significant changes in surface properties render such replacement necessary
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TISMorph: A tool to quantify texture, irregularity and spreading of single cells
A number of recent studies have shown that cell shape and cytoskeletal texture can be used as sensitive readouts of the physiological state of the cell. However, utilization of this information requires the development of quantitative measures that can describe relevant aspects of cell shape. In this paper we develop a toolbox, TISMorph, that calculates a set of quantitative measures to address this need. Some of the measures introduced here have been used previously, while others are new and have desirable properties for shape and texture quantification of cells. These measures, broadly classifiable into the categories of textural, irregularity and spreading measures, are tested by using them to discriminate between osteosarcoma cell lines treated with different cytoskeletal drugs. We find that even though specific classification tasks often rely on a few measures, these are not the same between all classification tasks, thus requiring the use of the entire suite of measures for classification and discrimination. We provide detailed descriptions of the measures, as well as the TISMorph package to implement them. Quantitative morphological measures that capture different aspects of cell morphology will help enhance large-scale image-based quantitative analysis, which is emerging as a new field of biological data.National Science Foundation [PHY-1151454]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
Quantifying the pattern of microbial cell dispersion, density and clustering on surfaces of differing chemistries and topographies using multifractal analysis
The effects of surface topography on bacterial distribution across a surface are of extreme importance when designing novel, hygienic or antimicrobial surface coatings. The majority of methods that are deployed to describe the pattern of cell dispersion, density and clustering across surfaces are currently qualitative. This paper presents a novel application of multifractal analysis to quantitatively measure these factors using medically relevant microorganisms (Staphylococcus aureus or Staphylococcus epidermidis). Surfaces (medical grade 316 stainless steel) and coatings (Ti–ZrN, Ti–ZrN/6.0%Ag, Ti–ZrN/15.6%Ag, TiZrN/24.7%Ag) were used in microbiological retention assays. Results demonstrated that S. aureus displayed a more heterogeneous cell dispersion (∆αAS < 1) whilst the dispersion of S. epidermidis was more symmetric and homogeneous (∆αAS ≥ 1). Further, although the surface topography and chemistry had an effect on cell dispersion, density and clustering, the type of bonding that occurred at the surface interface was also important. Both types of cells were influenced by both surface topographical and chemical effects; however, S. aureus was influenced marginally more by surface chemistry whilst S. epidermidis cells was influenced marginally more by surface topography. Thus, this effect was bacterially species specific. The results demonstrate that multifractal analysis is a method that can be used to quantitatively analyse the cell dispersion, density and clustering of retained microorganisms on surfaces. Using quantitative descriptors has the potential to aid the understanding the effect of surface properties on the production of hygienic and antimicrobial coatings
Applied Fracture Mechanics
The book "Applied Fracture Mechanics" presents a collection of articles on application of fracture mechanics methods to materials science, medicine, and engineering. In thirteen chapters, a wide range of topics is discussed, including strength of biological tissues, safety of nuclear reactor components, fatigue effects in pipelines, environmental effects on fracture among others. In addition, the book presents mathematical and computational methods underlying the fracture mechanics applications, and also developments in statistical modeling of fatigue. The work presented in this book will be useful, effective, and beneficial to mechanical engineers, civil engineers, and material scientists from industry, research, and education
Caractérisation de la surface d'implants de titane et de cobalt-chrome par la dimension fractale et l'influence de la topographie sur les interactions interfaciales
Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal
Electrochemical method for the determination of arsenic 'in the field' using screen-printed grid electrodes
This project describes development and problem solving efforts to realise a viable
portable sensor for arsenic, applicable to drinking water. The work is the first
dedicated effort towards this goal, after the preliminary investigations previously
conducted at Cranfield University (Cooper, 2004 and Noh, 2005). Using polymeric
gold ink BQ331 (DuPont Microcircuit Materials, Bristol, UK) as working electrode
on screen printed strips, the electrochemical procedure was studied. Due to the wealth
of research on electrochemical and non electrochemical methods for arsenic
determination, this project attempts to capitalise on the unique advantages of the
screen-printed gold surface.
In particular, the issues surrounding the performance of the sensor were evaluated by
electrochemical and spectroscopic means (including infrared, nuclear magnetic
resonance and X-ray photoelectron spectroscopy). A number of custom screen printed
electrodes were prepared in house comparing sensor performance on compositional
factors. An interference coming from silver interaction with chloride in the reference
electrode was identified. As such, the design of the sensor needs to change to include
either an immobilising layer, such as Nafion, over the silver, or to omit screen-printed
silver altogether. The Nafion was presumed to work by excluding (or at least much
reducing) the passage of negatively charged chloride ions to the silver surface
preventing formation of soluble silver chloride complexes.
The design of the sensor was considered in light of performance and sensitivity. The
screen-printed electrodes were cut to facilitate a microband design lending favourable
diffusive to capacitive current characteristics. With this design, As(III) detection was
demonstrated comfortably at 5 ppb (in a copper tolerant 4 M HCl electrolyte) without
electrode need for additional preparation procedures. This is below the World Health
Organisation (WHO) guideline and United States Environmental Protection Agency
(USEPA) regulation level of 10 ppb in drinking water. The electrode materials are
already mass manufacturable at an estimated cost less than £ 0.5 per electrode. Themicroband design could, in principle, be applied to mercury and other metal ions. The
procedure for As(V) either with chemical or electrochemical reduction and
determination still needs to be assessed. However, the presented electrode system
offers a viable alternative to the colorimetric test kits presently employed around the
world for arsenic in drinking water.
Also, the Nicholson Method (Nicholson, 1965a), used for characterising electron
transfer kinetics at electrode surfaces, was extended for application to rough surfaces
using a fractal parameter introduced by Nyikos and Pajkossy (1988). This work
includes mathematical derivation and numerical evaluation and gives a number of
predictions for electrochemical behaviour. These predictions could not be tested
experimentally, as yet, since the physical conditions must be carefully controlled
Fractal analyses of some natural systems
Fractal dimensions are estimated by the box-counting method for real world data sets and for mathematical models of three natural systems. 1 he natural systems are nearshore sea wave profiles, the topography of Shei-pa National Park in Taiwan, and the normalised difference vegetation index (NDV1) image of a fresh fern. I he mathematical models which represent the natural systems utilise multi-frequency sinusoids for the sea waves, a synthetic digital elevation model constructed by the mid-point displacement method for the topography and the Iterated Function System (IFS) codes for the fern leaf. The results show that similar fractal dimensions are obtained for discrete sub-sections of the real and synthetic one-dimensional wave data, whilst different fractal dimensions are obtained for discrete sections of the real and synthetic topographical and fern data. The similarities and differences are interpreted in the context of system evolution which was introduced by Mandelbrot (1977). Finally, the results for the fern images show that use of fractal dimensions can successfully separate void and filled elements of the two-dimensional series
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