Search results

1 – 10 of over 5000
Article
Publication date: 1 March 2006

Ker Chin Ang, Kah Fai Leong, Chee Kai Chua and Margam Chandrasekaran

The purpose of this paper is to investigate the mechanical properties and porosity relationships in fused deposition modelling (FDM) fabricated porous structures.

4832

Abstract

Purpose

The purpose of this paper is to investigate the mechanical properties and porosity relationships in fused deposition modelling (FDM) fabricated porous structures.

Design/methodology/approach

Porous structures of numerous build architectures aimed at tissue engineering (TE) application were fabricated using the FDM. The employment of FDM to fabricate these non‐random constructs offers many advantages over conventional scaffold fabrication techniques as patient specific scaffolds with well‐defined architectures and controllable pore sizes can be fabricated accurately and rapidly. There exist several FDM parameters that one needs to specify during the scaffold fabrication process. These parameters, which can be interdependent and exhibit varying effects on scaffold properties, were identified and examined using the design of experiment (DOE) approach. Essentially, the effects of five FDM process parameters, namely air gap, raster width, build orientation, build layer and build profile, on the porosity and mechanical properties of acrylonitrile‐butadienene‐styrene (ABS) scaffold structures with three‐dimensional interconnectivity were investigated in two designed experiments. Statistical analyses of the data were performed and the respective factors that have significant influence on the porosity and mechanical properties of the scaffolds were identified. The relationship between scaffold's mechanical properties and porosity was thereafter established empirically.

Findings

Models of TE scaffolds of numerous build architectures were successfully fabricated using different parameter settings on the FDM. The DOE approach determined air gap and raster width as the most significant parameters in affecting the porosity and mechanical properties of the ABS scaffold structures. The relationship between scaffolds' mechanical properties and porosity was determined to be logarithmic, with the best mechanical properties observed in scaffolds of low porosity.

Originality/value

The paper highlights how the application FDM to tissue scaffold application can overcome most of the limitations encountered in the conventional techniques.

Details

Rapid Prototyping Journal, vol. 12 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

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…

3580

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: 20 January 2020

Li Wu, Xinxin Li, Tianmin Guan, Yong Chen and Chunwei Qi

The 3 D bioprinting technology is used to prepare the tissue engineering scaffold with precise structures for the cell proliferation and differentiation.

Abstract

Purpose

The 3 D bioprinting technology is used to prepare the tissue engineering scaffold with precise structures for the cell proliferation and differentiation.

Design/methodology/approach

According to the characteristics of the ideal tissue engineering scaffold, the microstructural design of the tissue engineering scaffold is carried out. The bioprinter is used to fabricate the tissue engineering scaffold with different structures and spacing sizes. Finally, the scaffold with good connectivity is achieved and used to cell PC12 culture.

Findings

The results show that the pore structure with the line spacing of 1 mm was the best for cell culture, and the survival rate of the inoculated cells PC12 is as high as 90%. The influence of the pore shape on the cell survival is not evidence.

Originality/value

This study shows that tissue engineering scaffolds prepared by 3 D bioprinting have graded structure for three-dimensional cell culture, which lays the foundation for the later detection of drug resistance.

Details

Rapid Prototyping Journal, vol. 26 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

Abstract

Purpose

To advance the learning of professional practices in teacher education and medical education, this conceptual paper aims to introduce the idea of representational scaffolding for digital simulations in higher education.

Design/methodology/approach

This study outlines the ideas of core practices in two important fields of higher education, namely, teacher and medical education. To facilitate future professionals’ learning of relevant practices, using digital simulations for the approximation of practice offers multiple options for selecting and adjusting representations of practice situations. Adjusting the demands of the learning task in simulations by selecting and modifying representations of practice to match relevant learner characteristics can be characterized as representational scaffolding. Building on research on problem-solving and scientific reasoning, this article identifies leverage points for employing representational scaffolding.

Findings

The four suggested sets of representational scaffolds that target relevant features of practice situations in simulations are: informational complexity, typicality, required agency and situation dynamics. Representational scaffolds might be implemented in a strategy for approximating practice that involves the media design, sequencing and adaptation of representational scaffolding.

Originality/value

The outlined conceptualization of representational scaffolding can systematize the design and adaptation of digital simulations in higher education and might contribute to the advancement of future professionals’ learning to further engage in professional practices. This conceptual paper offers a necessary foundation and terminology for approaching related future research.

Book part
Publication date: 26 August 2019

Janet S. Gaffney and Rebecca Jesson

Purpose – The purpose of this chapter is to understand how children expand independence within instructional interactions with their teachers. To do so, the authors…

Abstract

Purpose – The purpose of this chapter is to understand how children expand independence within instructional interactions with their teachers. To do so, the authors re-examine how scaffolding is understood and applied.

Approach – First, the authors consult websites and literature used by teachers and academics to examine how the notion of scaffolding is employed and explained. The authors analyze the roles, the intentions, the means, and the timing of scaffolding as used in popular literature to explain and support instruction. The authors then entertain a conceptual shift: What would the scaffolding process look like if learning were conceived as agentive? With this in mind, the authors interrogate descriptions of the tenets and functions of scaffolding to consider the process in relief.

Findings – The authors track the consequences of the inversion of scaffolding onto the understandings of the gradual release of responsibility (GRR) model. Scaffolding is understood as sitting within a GRR model, wherein the learner gradually releases responsibility to a teacher at the point of need. Intersubjectivity remains a basis for the model. A Window for Examining Teaching–Learning Interactions is offered as a frame with which to analyze the theories of both the child and the teacher apparent within scaffolding interactions. An accurate teacher’s theory of the child’s current and changing theories is required for teaching to be honed to invite children to efficiently access personal and contextual resources and to seek assistance when needed within engaging tasks with scope.

Practical Implications – When children are positioned as initiators of their learning, they are able to use their vast repertoire of knowledge of the world, language/s and literacies, and familial, cultural, and community ways of knowing to create, interpret, and engage in tasks. In this agentive view, children are positioned as holding full responsibility at the onset of any task and gradually releasing their responsibility to access support, when needed. Within tasks that are sufficiently wide for engagement at varied entry points, learners are the catalyst of the functions that were formerly initiated by teachers. Teachers invite children to access personal and contextual resources and to seek assistance, as needed, through additional external, contextual resources. This inverted model of scaffolding, that is child-directed rather than teacher-initiated, requires teachers to go beyond theories of teaching and learning and develop a theory of an individual child.

Details

The Gradual Release of Responsibility in Literacy Research and Practice
Type: Book
ISBN: 978-1-78769-447-7

Keywords

Article
Publication date: 19 April 2022

Md Abdullah Al Mamun

This study aims to present a scaffolding framework incorporating sophisticated technology that can inform instructional design to support student inquiry learning in the…

Abstract

Purpose

This study aims to present a scaffolding framework incorporating sophisticated technology that can inform instructional design to support student inquiry learning in the self-regulated online environment.

Design/methodology/approach

The classic predict, observe and explain (POE) framework has been extended through the incorporation of an additional evaluate (E) phase into the model to enhance the self-regulated online learning environment. The extended POEE scaffolding approach, in this study, has been conceptualized as an implicit guide to support the process of guided inquiry for learning particular science concepts. Digital tools were sourced and integrated into this design framework to substitute for the support typically offered by teachers and peers in classrooms.

Findings

The findings suggest that the POEE pedagogical design facilitated the inquiry process through promoting self-regulation and engaged exploration. It also promoted positive emotions in students towards the scaffolded learning modules.

Originality/value

Integrating technologies that benefit students differentially in educational settings remains a considerable challenge. More specifically, in science education, an appropriate inquiry learning context that allows access to well informed pedagogical design is imperative. The application of this inquiry-based scaffolding framework can inform educators in the process of creating their own instructional designs and contexts to provide more effective guided learning.

Article
Publication date: 8 June 2022

Mohit Kumar, Shubham Shankar Mohol and Varun Sharma

This paper aims to develop a computational approach to analyze the mechanical behavior, perfusion bioreactor test and degradation of the designed scaffolds. Five types of…

196

Abstract

Purpose

This paper aims to develop a computational approach to analyze the mechanical behavior, perfusion bioreactor test and degradation of the designed scaffolds. Five types of pore architecture scaffolds have been made using a computer-aided designed tool and fabricated through fused deposition modeling.

Design/methodology/approach

Compressive structural analysis has been performed using the finite element method to forecast the mechanical performance of the scaffolds. Also, the experimental study was done to validate the simulation outcomes. A computational fluid dynamic analysis was performed to ascertain the fluid pressure distribution, velocity profile, wall shear stress, strain rate and permeability of scaffolds. The interconnected pore architecture of the scaffolds plays a crucial role in enhancing the mechanical properties and fluid flow characteristics.

Findings

The scaffolds with continuous vertical support columns resulted in better strength because they provide better ways to transfer the load. The pore architecture of the scaffold plays a significant role in the path of fluid flow. Scaffolds with regular interconnected pore architecture showed better accessibility of the fluid. The degradation analysis showed that the degradation rate is dependent on the architecture of the scaffolds because of different surface area to volume ratios.

Originality/value

The simulation results provide a straightforward prediction of the scaffold suitability in terms of mechanical strength, perfusion and degradation behavior.

Graphical abstract

Details

Rapid Prototyping Journal, vol. 28 no. 10
Type: Research Article
ISSN: 1355-2546

Keywords

Open Access
Article
Publication date: 12 October 2021

AbdulLateef Olanrewaju, Jack Son Khor and Christopher Nigel Preece

Statistics show that the construction sector has the second-highest number of accident cases in Malaysia. A total of 100, 000 construction workers suffer from work-related…

2078

Abstract

Purpose

Statistics show that the construction sector has the second-highest number of accident cases in Malaysia. A total of 100, 000 construction workers suffer from work-related bad health each year. Scaffolding accidents are the second cause of accidents on construction sites. Therefore, this present research provided answers to the following questions: (1) what are the causes of scaffolding accidents and (2) what are the possible measures to reduce scaffolding accidents?

Design/methodology/approach

The research developed a questionnaire instrument that included 24 causes of scaffolding accidents and 21 remedial actions. The research was based on a cross-sectional survey questionnaire administered to 129 members of construction organizations.

Findings

Data revealed that scaffolding-related cases caused a total of 70% of the deaths/injuries on sites. Furthermore, scaffolding accidents were mainly caused by a lack of guard rails on scaffoldings, poor inspections, improper assembly, a poor safety culture, poor attitudes towards safety, poor footing of scaffoldings and unsecured planking. To reduce scaffolding accidents, there must be a lifeline on scaffolding, proper guardrails and proper assembling of scaffoldings, and preventing access to incomplete or defective scaffoldings. The 24 causes are structured into six factors through factor analysis and the 21 remedial actions into six factors.

Originality/value

This research serves as the first attempt to conduct broad research on the causes and remedial actions concerning scaffolding accidents on construction sites in Malaysia. Theoretically, the research has provided fresh insights into the impact of scaffolding accidents.

Details

Frontiers in Engineering and Built Environment, vol. 2 no. 1
Type: Research Article
ISSN: 2634-2499

Keywords

Abstract

Purpose

Additive manufacturing (AM) or solid freeform fabrication (SFF) technique is extensively used to produce intrinsic 3D structures with high accuracy. Its significant contributions in the field of tissue engineering (TE) have significantly increased in the recent years. TE is used to regenerate or repair impaired tissues which are caused by trauma, disease and injury in human body. There are a number of novel materials such as polymers, ceramics and composites, which possess immense potential for production of scaffolds. However, the major challenge is in developing those bioactive and patient-specific scaffolds, which have a required controlled design like pore architecture with good interconnectivity, optimized porosity and microstructure. Such design not only supports cell proliferation but also promotes good adhesion and differentiation. However, the traditional techniques fail to fulfill all the required specific properties in tissue scaffold. The purpose of this study is to report the review on AM techniques for the fabrication of TE scaffolds.

Design/methodology/approach

The present review paper provides a detailed analysis of the widely used AM techniques to construct tissue scaffolds using stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM), binder jetting (BJ) and advanced or hybrid additive manufacturing methods.

Findings

Subsequently, this study also focuses on understanding the concepts of TE scaffolds and their characteristics, working principle of scaffolds fabrication process. Besides this, mechanical properties, characteristics of microstructure, in vitro and in vivo analysis of the fabricated scaffolds have also been discussed in detail.

Originality/value

The review paper highlights the way forward in the area of additive manufacturing applications in TE field by following a systematic review methodology.

Details

Rapid Prototyping Journal, vol. 27 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 23 October 2021

Fangfang Sun, Tianze Wang and Yong Yang

Rapid prototyping (RP) technology is widely used in many fields in recent years. Bone tissue engineering (TE) is an interdisciplinary field involving life sciences…

Abstract

Purpose

Rapid prototyping (RP) technology is widely used in many fields in recent years. Bone tissue engineering (TE) is an interdisciplinary field involving life sciences, engineering and materials science. Hydroxyapatite (HAp) are similar to natural bone and it has been extensively studied due to its excellent biocompatibility and osteoconductivity. This paper aims to review nanoscaled HAp-based scaffolds with high porosity fabricated by various RP methods for bone regeneration.

Design/methodology/approach

The review focused on the fabrication methods of HAp composite scaffolds through RP techniques. The paper summarized the evaluation of these scaffolds on the basis of their biocompatibility and biodegradability through in vitro and in vivo tests. Finally, a summary and perspectives on this active area of research are provided.

Findings

HAp composite scaffold fabricated by RP methods has been widely used in bone TE and it has been deeply studied by researchers during the past two decades. However, its brittleness and difficulty in processing have largely limited its wide application in TE. Therefore, the formability of HAp combined with biocompatible organic materials and fabrication techniques could be effectively enhanced, and it can be used in bone TE applications finally.

Originality/value

This review paper presented a comprehensive study of the various types of HAp composite scaffold fabricated by RP technologies and introduced their potential application in bone TE, as well as future roadmap and perspective.

Details

Rapid Prototyping Journal, vol. 28 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

1 – 10 of over 5000