Search results

1 – 10 of over 13000
Article
Publication date: 1 February 2004

F. Wang, L. Shor, A. Darling, S. Khalil, W. Sun, S. Güçeri and A. Lau

Successes in scaffold guided tissue engineering require scaffolds to have specific macroscopic geometries and internal architectures to provide the needed biological and

3572

Abstract

Successes in scaffold guided tissue engineering require scaffolds to have specific macroscopic geometries and internal architectures to provide the needed biological and biophysical functions. Freeform fabrication provides an effective process tool to manufacture many advanced scaffolds with designed properties. This paper reports our recent study on using a novel precision extruding deposition (PED) process technique to directly fabricate cellular poly‐ε_rm;‐caprolactone (PCL) scaffolds. Scaffolds with a controlled pore size of 250 μm and designed structural orientations were fabricated.

Details

Rapid Prototyping Journal, vol. 10 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 11 March 2014

T. Patrício, M. Domingos, A. Gloria, U. D'Amora, J.F. Coelho and P.J. Bártolo

The main purpose of this research work is to study the effect of poly lactic acid (PLA) addition into poly (e-caprolactone) (PCL) matrices, as well the influence of the…

2154

Abstract

Purpose

The main purpose of this research work is to study the effect of poly lactic acid (PLA) addition into poly (e-caprolactone) (PCL) matrices, as well the influence of the mixing process on the morphological, thermal, chemical, mechanical and biological performance of the 3D constructs produced with a novel biomanufacturing device (BioCell Printing).

Design/methodology/approach

Two mixing processes are used to prepare PCL/PLA blends, namely melt blending and solvent casting. PCL and PCL/PLA scaffolds are produced via BioCell Printing using a 300-μm nozzle, 0/90° lay down pattern and 350-μm pore size. Several techniques such as scanning electron microscopy (SEM), simultaneous thermal analyzer (STA), nuclear magnetic resonance (NMR), static compression analysis and Alamar BlueTM are used to evaluate scaffold's morphological, thermal, chemical, mechanical and biological properties.

Findings

Results show that the addition of PLA to PCL scaffolds strongly improves the biomechanical performance of the constructs. Additionally, polymer blends obtained by solvent casting present better mechanical and biological properties, compared to blends prepared by melt blending.

Originality/value

This paper undertakes a detailed study on the effect of the mixing process on the biomechanical properties of PCL/PLA scaffolds. Results will enable to prepare customized PCL/PLA scaffolds for tissue engineering applications with improved biological and mechanical properties, compared to PCL scaffolds alone. Additionally, the accuracy and reproducibility of by the BioCell Printing enables to modulate the micro/macro architecture of the scaffolds enhancing tissue regeneration.

Details

Rapid Prototyping Journal, vol. 20 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 1 August 2003

R. Contro and P. Vena

This paper aims at showing that the finite element method is the most important numerical tool to analyse bio‐solids or bio‐fluids because of the constitutive complexity…

1197

Abstract

This paper aims at showing that the finite element method is the most important numerical tool to analyse bio‐solids or bio‐fluids because of the constitutive complexity and unusual clinical input data and requirements involved. These features are absolutely mandatory and modify the mentality of an expert of FEM when he wants to contribute really to the progress of medical practice in their several forms, from biological basis to the surgical assistance. In this context, a clear view of the hierarchic importance of the phenomena involved is necessary to reply correctly to medical operators and to choose the right level of scale. While a scholarly culture of FEM and relative developments have to appeal the attention of biomedical engineers, at the same time their attention mainly is focused on the problem to solve, which must be validated clinically and experimentally. So while convergence remain a typical goal of the analyst, accuracy must be compared with the medical sensitivity. To do this, some physical conditions, less important in other application fields, as the boundary conditions, must be modelled in order to avoid that any model refinement gives unappreciable precision while tends to disregard what a clinician or a surgeon is able to understand and to use in the context of his professional practice. Setting up correct boundary conditions is an emblematic topic because it concerns a typical approach of computational methods applied to biomedical engineering which must consider two separate scale into analysis or a design approach. When a district of the body is to be analysed, the main goal should be to define correctly the subdomain that the district represents with respect to the whole and then to analyse other subdomains inside, at a level more and more micro, as into a system of Chinese boxes. When a medical device is to be designed a systemic view must be acquired. In this paper, we will start from this underlying feature concerning just FEM applications of a knee design carried out by the research staff of the Laboratory of Biological Structure Mechanics. Then other uses of FEM will be described as analysis fragments through problems studied by the authors and referenced in bibliography.

Details

Engineering Computations, vol. 20 no. 5/6
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 November 2003

Muhsi Yang, Tsai‐Chi Robert Kuo and Roseanne Murphy Jones

Recently, researchers have explored the medical applications of umbilical cord blood (UCB) to treat certain types of cancer and other disorders. UCB is a hematopoietic…

1931

Abstract

Recently, researchers have explored the medical applications of umbilical cord blood (UCB) to treat certain types of cancer and other disorders. UCB is a hematopoietic tissue that contains a motherlode of cells, and creates the blood cells that carry oxygen, fight infections, and form clots at the sites of injuries. The use of UCB involves fewer ethical and legal problems than other stem cell technology. UCB banking not only involves the creation of a UCB storage bank, but is also a serial process that includes collecting UCB, extracting stem cells from UCB, storing these stem cells in liquid nitrogen at –385°F, and defrosting them if required by their owner. UCB banking service is thus a form of biological insurance, where the reward is an increased chance of good health rather than monetary compensation. Many people have begun to consider the need for public and private UCB banks to preserve cord blood donations. The main purpose of this research is to develop the UCB consumers’ behavior based on the consumer buying behavior model. It clarifies the opinions of Taiwan people about UCB banking, identifies the main factors motivating people to store UCB, and provides the marketing strategies for the UCB banking service.

Details

International Journal of Health Care Quality Assurance, vol. 16 no. 6
Type: Research Article
ISSN: 0952-6862

Keywords

Article
Publication date: 4 September 2017

Ismahen Essaidi, Ahmed Snoussi, Hayet Ben Haj Koubaier, Hervé Casabianca and Nabiha Bouzouita

The paper aims to analyse the effect of acid hydrolysis on the chemical composition and the biological activities of Rubia tinctorum collected from the south of Tunisia…

Abstract

Purpose

The paper aims to analyse the effect of acid hydrolysis on the chemical composition and the biological activities of Rubia tinctorum collected from the south of Tunisia. It proposes to clarify the relationship between alizarin content and the antioxidant and antimicrobial activities of Rubia extract.

Design/methodology/approach

The paper opted for analytical tools (HPLC) and the in-vitro study of biological activities, namely, the antioxidant activity which is evaluated using the radical scavenging assay (ABTS) and ferric reducing power assay (FRAP); the antimicrobial activity is tested using the wells agar diffusion method.

Findings

The paper provides information about the positive effect of acid hydrolysis, namely, the enhancement of alizarin content in the extract which has increased its antioxidant and antimicrobial activities.

Originality/value

This paper fulfils an identified need to study the relationship between the chemical composition, biological activities and colour enhancement.

Details

Pigment & Resin Technology, vol. 46 no. 5
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 7 March 2008

Benjamin T. Schmidt, Joseph M. Feduska, Ashley M. Witt and Bridget M. Deasy

The purpose of this paper is to focus on the advantages of a robotic time‐lapsed microscopic imaging system for tracking stem cells in in vitro biological assays which…

Abstract

Purpose

The purpose of this paper is to focus on the advantages of a robotic time‐lapsed microscopic imaging system for tracking stem cells in in vitro biological assays which measure stem cell activities.

Design/methodology/approach

The unique aspects of the system include robotic movement of stem cell culture flasks which enables selection of a large number of regions of interest for data collection. Numerous locations of a cell culture flask can be explored and selected for time‐lapsed analysis. The system includes an environmentally controlled chamber to maintain experimental conditions including temperature, gas levels, and humidity, such that stem cells can be tracked by visible and epifluorescence imaging over extended periods of time.

Findings

This is an extremely unique system for both individual cell tracking and cell population tracking in real‐time with high‐throughput experimental capability. In comparison to a conventional manual cell culture and assay approach, this system provides stem cell biologists with the ability to quantify numerous and unique temporal changes in stem cell populations, this drastically reduces man‐hours, consumes fewer laboratory resources and provides standardization to biological assays.

Research limitations/implications

Fundamental basic biology questions can be addressed using this approach.

Practical implications

Stem cells are often available only in small numbers – due both to their inherent low frequency in the post‐natal tissue as compared to somatic cells, and their slow growth rates. The unique capabilities of this robotic cell culture system allow for the study of cell populations which are few in number.

Originality/value

The robotic time‐lapsed imaging system is a novel approach to stem cell research.

Details

Industrial Robot: An International Journal, vol. 35 no. 2
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 1 March 2006

H.Y. Moustafa

To prepare bioactive polymeric materials by grafting methods and characterisation of the biological activity of such materials.

Abstract

Purpose

To prepare bioactive polymeric materials by grafting methods and characterisation of the biological activity of such materials.

Design/methodology/approach

New bioactive polysaccharides were prepared by grafting of acrylonitrile onto water soluble starch and the resulted material was reacted with bioactive heterocyclic rings, converting to N‐halamine biocidal polymers by chlorination and to polyquats by converting it to quaternary ammonium salts using hydrochloric acid. The biological activity of the materials prepared against gram positive and gram negative bacteria was studied by three methods.

Findings

Most of the bioactive materials prepared showed high disinfecting power against bacteria.

Research limitations/implications

The bioactive materials were prepared by grafting of acrylonitrile onto starch and then reacting the resultant material with sulphadiazine. Many other heterocyclic rings that contain tertiary nitrogen atoms or amide group can also be used.

Practical implications

The new bioactive materials prepared can be used in disinfection of drinking water, swimming pools, etc.

Originality/value

The materials prepared and the use of such materials for disinfection were novel.

Details

Pigment & Resin Technology, vol. 35 no. 2
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 2 January 2009

K.A. Spanos, A. Feest and P.V. Petrakis

This paper aims to present a general analysis and overview of forest biodiversity, emphasising the three main components (structure, composition, function) related to…

Abstract

Purpose

This paper aims to present a general analysis and overview of forest biodiversity, emphasising the three main components (structure, composition, function) related to biodiversity. Following this theoretical consideration of forest biodiversity the current proposal of the European Environment Agency for biodiversity indicators is presented as a table with the application to forests identified and the direct/indirect nature of the indicator also indicated.

Design/methodology/approach

The biodiversity of forests is determined by a number of overall large‐scale factors that intimately affect the individual components of biodiversity. A more specific and direct measurement of forest biodiversity is presented with data assessed by the Fungib programme to provide a set of biodiversity indices that can be used to: create biodiversity baselines; compare sites; and follow biodiversity changes through time, all with the possibility of determining significance of change statistically. An example of data derived from a macrofungal survey is presented as an example of how this methodology can be adapted to many groups of organisms. Finally, a further example of using biodiversity quality data to understand changes in biodiversity is presented comparing butterfly biodiversity quality with nitrogen deposition.

Findings

This paper shows how an example of function (nitrogen deposition) has affected an element of composition (butterfly biodiversity). This has been made possible by the use of a rational sampling methodology (TRIM) used over a number of years. This metadata analysis of butterfly survey data shows clearly that changes in the butterfly biodiversity quality would have been missed if the normal approach of equating biodiversity with species richness had been adopted. In this example nitrogen‐sensitive species loss was compensated by nitrophilic species gain.

Originality/value

Such a methodology, therefore, has much to recommend it and it has been shown to be applicable to a wide range of organisms from bryophytes to beetles. For forest biodiversity monitoring the adoption of this kind of rationale will hopefully yield far greater information to the scientific community and policy makers for little extra effort.

Details

Management of Environmental Quality: An International Journal, vol. 20 no. 1
Type: Research Article
ISSN: 1477-7835

Keywords

Article
Publication date: 3 May 2013

Markus Kraiger and Bernhard Schnizer

The purpose of this paper is to present new expressions in Cartesian coordinates for the potential and magnetic field of prolate and oblate spheroids with arbitrary…

Abstract

Purpose

The purpose of this paper is to present new expressions in Cartesian coordinates for the potential and magnetic field of prolate and oblate spheroids with arbitrary direction of the symmetry axis in a homogeneous field.

Design/methodology/approach

The potentials found in prolate or oblate spheroidal coordinates are transformed to Cartesian coordinates. These results are represented in such a form that they depend only on expressions, which are invariant under rotations around the symmetry axis. Thus, it is easy to change to arbitrary directions of both the symmetry axis and of that of the primary field. The gradients of the potentials are calculated and transformed exactly to the simplest form possible.

Findings

The paper presents simple expressions for the magnetic perturbations due to homogeneous prolate or oblate spheroids in a homogeneous magnetic field.

Research limitations/implications

Results are exact for single non‐ferromagnetic spheroids in a homogeneous field.

Practical implications

Superposition of these perturbations presupposes small values of the magnetic susceptibilities of both the spheroids and their environment as in biological tissues.

Originality/value

The paper presents novel formulas for fields of homogeneous spheroids in a homogeneous magnetic field which are very useful for modelling biological tissues in studies of magnetic resonance imaging and magnetic resonance spectroscopy.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 32 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 August 2004

A.M. El‐Masry, H.Y. Moustafa, A.I. Ahmed and A.F. Shaaban

New N‐halamine polymeric compounds were prepared by reacting cyanuric acid and polyacrylonitrile. Grafting of acrylonitrile monomer onto cotton linters was carried out and

Abstract

New N‐halamine polymeric compounds were prepared by reacting cyanuric acid and polyacrylonitrile. Grafting of acrylonitrile monomer onto cotton linters was carried out and the product was reacted with cyanuric acid and finally was chlorinated. Cyanoethylation of polyvinyl alcohol was performed using acrylonitrile monomer to give polyvinylcyanoethyl ether, which, in turn, was reacted with cyanuric acid. The biological activity of the various chlorinated compounds obtained was examined against Gram (+) and Gram (−) bacteria using columns and dishes methods. A high disinfecting power of the chlorinated compounds obtained was observed. Thus, the bacteria was deactivated after the first cycle without contact with the product. All of the compounds prepared were insoluble in water and most of inorganic solvents. These compounds were also found to be very stable and did not decompose to give any toxic compounds. Thus, the chlorinated compounds prepared had no harmful effects on humans.

Details

Pigment & Resin Technology, vol. 33 no. 4
Type: Research Article
ISSN: 0369-9420

Keywords

1 – 10 of over 13000