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1 – 10 of over 1000
Article
Publication date: 7 March 2016

Anup Paul, Arunn Narasimhan and Sarit Kumar Das

The large blood vessels (LBV) would act as a heat sink and hence play a significant role during photo-thermal therapy. Gold nanoshell was considered as a high-heat absorbing agent

Abstract

Purpose

The large blood vessels (LBV) would act as a heat sink and hence play a significant role during photo-thermal therapy. Gold nanoshell was considered as a high-heat absorbing agent in photo-thermal heating to reduce the cooling effect of LBV. The heat sink effect of LBV results in insignificant irreversible tissue thermal damage. The paper aims to discuss these issues.

Design/methodology/approach

In this paper, the thermal history of tissue embedded with LBV during photo-thermal heating were calculated using finite element-based simulation technique. A volumetric laser source term based on modified Beer-Lambert law was introduced to model laser heating. The numerically predicted temperature drop was validated against that of previously performed experiments by the authors on tissue mimic embedded with simulated blood vessels. In the later part of the study, Arrhenius equation was coupled with the energy equation to investigate and report the irreversible thermal damage to the bio-tissues.

Findings

The results obtained conclude that tissue with different orientation of blood vessels results in different thermal response at the tissue surface. Gold nanoshells were introduced into the laser irradiated tissue to overcome the cooling effect of LBV during plasmonic photo-thermal heating. The effect of size and concentration of nanoparticles on tissue heating were analyzed. The predicted damage parameter was much lower in case of tissue embedded with blood vessel than that predicted in case of bare tissue, which results in incomplete tissue necrosis. Finally, the effects of laser specification, blood vessel specification and blood perfusion on the tissue thermal damage were examined.

Originality/value

The conjugate energy equations in conjunction with Arrhenius equation were solved numerically to predict the tissue irreversible damage embedded with LBV.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 26 no. 2
Type: Research Article
ISSN: 0961-5539

Keywords

Content available
Article
Publication date: 1 June 1998

103

Abstract

Details

Aircraft Engineering and Aerospace Technology, vol. 70 no. 3
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 1 November 2011

R.S. Sudheesh and N. Siva Prasad

The purpose of this paper is to study the effect of trailing liquid nitrogen (LN2) heat sink on arc welding of mild steel plates. The effect on temperature field, stress and…

Abstract

Purpose

The purpose of this paper is to study the effect of trailing liquid nitrogen (LN2) heat sink on arc welding of mild steel plates. The effect on temperature field, stress and distortions are studied using experimental and numerical methods.

Design/methodology/approach

The methodology consists of experimental and numerical methods. The temperature measured at a point near the arc is used to estimate the cooling capacity of the heat sink using inverse heat transfer (IHT) method. The estimated cooling flux is applied to the finite element model to study the stress and distortions using LN2 heat sink. The stresses are measured using X‐ray diffraction technique and the distortions using dial gauges.

Findings

IHT method has been employed in estimating the cooling capacity of the LN2 jet. This has been applied to welding to study the effect on weld induced stresses and distortions. The method can be extended to calculate the heat removal rate in various manufacturing processes where cooling is employed.

Research limitations/implications

The lack of temperature dependent material properties resulted in deviation of stresses between analytical results and experiment values.

Originality/value

IHT method developed for heat removal capacity of trailing heat sink is a contribution. The estimated heat flux shows good agreement in analytical and experimental temperature values. These temperatures have been extended to calculate stresses and out of plane distortions in welding and there is a reasonable agreement between finite element analysis and experimental results.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 21 no. 8
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 7 September 2012

Song Hee Koo, Kyungmin Park, Hyunmin Hwang, Youngjae Yoo, Jong Hun Han, Kwonwoo Shin and Jeong Ho Cho

The purpose of this paper is to develop environmentally stable near‐infrared (NIR)‐absorbing windows by blending an NIR‐absorbing dye and a thermally‐crosslinkable polymer.

Abstract

Purpose

The purpose of this paper is to develop environmentally stable near‐infrared (NIR)‐absorbing windows by blending an NIR‐absorbing dye and a thermally‐crosslinkable polymer.

Design/methodology/approach

To enhance the environmental stability of the NIR‐absorbing window, a poly(vinyl phenol‐co‐methyl methacrylate) (poly(VP‐co‐MMA)) prepolymer and a poly(melamine‐co‐formaldehyde) (PMF) cross‐linking agent were mixed, and thermal crosslinking was performed under mild conditions (100°C).

Findings

The resistance of the crosslinked hybrid films to heat, humidity, and ultraviolet radiation damage improved dramatically relative to the pristine NIR‐absorbing dye. The improved environmental stability of the crosslinked NIR hybrid film resulted from the reduced free volume and restrictions in the molecular thermal dynamic motions of the polymer due to the presence of the crosslinked network surrounding the NIR‐absorbing dye molecules.

Originality/value

The methods provided a novel, simple, and practical solution to improving environmentally stability of NIR‐absorbing window.

Details

Pigment & Resin Technology, vol. 41 no. 5
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 14 November 2008

George K. Stylios

Examines the fourteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects…

1246

Abstract

Examines the fourteenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.

Details

International Journal of Clothing Science and Technology, vol. 20 no. 6
Type: Research Article
ISSN: 0955-6222

Keywords

Article
Publication date: 1 June 2022

Sandeep Singh, Shashi Kant Sharma and M. Abdul Akbar

The purpose of this work is to improve the air entrainment capacity of a concrete by using fine mineral admixtures such as fly ash (FA) and silica fume (SF) as cement substitute…

Abstract

Purpose

The purpose of this work is to improve the air entrainment capacity of a concrete by using fine mineral admixtures such as fly ash (FA) and silica fume (SF) as cement substitute, and coal bottom ash (CBA) as fine aggregate substitute. Air entrainment capacity has been studied indirectly as a measure of heat resistance of concrete. Literature has suggested that mineral admixtures improve the air absorption in the paste component of the concrete, on the one hand, whereas they perform pore and grain size refinement, on the other, thereby reducing the air entrainment. CBA, which being porous, creates the possibility of air adsorption by the aggregate component. Therefore, the study finds out whether a double benefit of adding both of these materials will be achieved, or CBA will try to improve the deficiency in the air entrainment created by the mineral admixtures.

Design/methodology/approach

Air-entrained concrete (AEC) mixes were constituted in three groups. First group represents mixes with natural fine aggregates only, and second with 25% fine aggregates substituted by CBA. Progressively, the third group has 50% fine aggregates substituted with CBA. In all the three groups, cement was substituted with FA and SF @ 0%, 20% and 40%, and 0%, 5% and 10%, respectively, thereby creating four binary and four ternary mixes corresponding to each group. Compressive and flexural strength tests were conducted at 28 days on the concrete mixes pre and post high-temperature heat treatment, i.e. 100°C, 200°C and 400°C, respectively. This study also examines the microstructure characteristics of AEC after 14 days of curing via X-ray diffraction. Sorptivity test was also conducted to estimate the capillary and air-entrained voids in concrete.

Findings

It was found that a concrete mix containing 20% FA and 10% SF along with 50% CBA could give similar post-heated strength to a normal (without mineral admixtures) AEC. In AECs where only CBA is present and cement paste is not substituted, both of the pre- and post-heated strengths of concrete reduce. Also, some mixtures containing large amounts of mineral admixtures in concrete with nil CBA show a high reduction in post-heated strength though they show good pre-heated strength. Therefore, mineral admixtures and CBA complement each other in improving the post-heated strength. Air pore structure found from sorptivity test also verifies these results.

Originality/value

AEC is very helpful for insulation of buildings during summer season by absorbing heat waves. AEC containing FA and CBA reduces carbon footprint because of substitution of cement and it also helps to conserve natural resources by the use of CBA in place of fine aggregates.

Details

Journal of Engineering, Design and Technology , vol. 21 no. 2
Type: Research Article
ISSN: 1726-0531

Keywords

Article
Publication date: 1 October 2000

Radosllaw Werner, Andrzej Krysztafkiewicz and Teofil Jesionowski

Studies on the surface modification of sodium‐aluminium silicate P‐820 using silane coupling agents are described. The best modifiers were selected, which induced a change of the…

Abstract

Studies on the surface modification of sodium‐aluminium silicate P‐820 using silane coupling agents are described. The best modifiers were selected, which induced a change of the silicate surface from hydrophilic to hydrophobic. Physicochemical analyses of the modified silicate were performed. The methods of evaluating silicate surface modification degree were presented. The degree of hydrophobization of silicate surface was determined by a calorimetric method. Near infra‐red spectroscopy (NIR) was used to determine the degree of condensation of the silicate surface silanol groups. Studies on morphology and microstructure using transmission electron microscopy (TEM) were performed. Attempts were made to apply the unmodified and modified sodium‐aluminium silicate P‐820 as filler and pigment in silicate and dispersion paints.

Details

Pigment & Resin Technology, vol. 29 no. 5
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 27 July 2018

Taiwo S. Yusuf and Basant K. Jha

The purpose of this paper is to present a semi-analytical solution for time-dependent natural convection flow with heat generation/absorption in an annulus partially filled with…

Abstract

Purpose

The purpose of this paper is to present a semi-analytical solution for time-dependent natural convection flow with heat generation/absorption in an annulus partially filled with porous material.

Design/methodology/approach

The governing partial differential equations are transformed into the ordinary differential equations using the Laplace transform technique. The exact solution obtained is inverted from the Laplace domain to time domain using the Riemann-sum approximation approach. Justification of the Riemann-sum approximation approach is achieved by comparing the values obtained with those of the implicit finite difference method at both the transient state and the steady state at large time.

Findings

If is found that the peak axial velocity always occur in the clear fluid region. In addition, there is an indication that heat generating fluid is desirable for optimum mass flux in the annular gap most importantly when the convection current is enhanced by constant heat flux.

Originality/value

In view of the amount of works done on natural convection with internal heat generation/absorption, it becomes interesting to investigate the influence of this essential activity on natural convection flow in a vertical cylinder partially filled with porous material where the outer surface of the inner cylinder is either heated isothermally or with constant heat flux.

Details

Multidiscipline Modeling in Materials and Structures, vol. 14 no. 5
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 5 October 2010

Florencia Edith Wiria, Kah Fai Leong and Chee Kai Chua

Tissue engineering (TE) involves biological, medical and engineering expertise and a current engineering challenge is to provide good TE scaffolds. These highly porous 3D…

1811

Abstract

Purpose

Tissue engineering (TE) involves biological, medical and engineering expertise and a current engineering challenge is to provide good TE scaffolds. These highly porous 3D scaffolds primarily serve as temporal holding devices for cells that facilitate structural and functional tissue unit formation of the newly transplanted cells. One method used successfully to produce scaffolds is that of rapid prototyping. Selective laser sintering (SLS) is one such versatile method that is able to process many types of polymeric materials and good stability of its products. The purpose of this paper is to present modeling of the heat transfer process, to understand the sintering phenomena that are experienced by powder particles in the SLS powder bed during the sintering process. With the understanding of sintering process obtained through the theoretical modeling, experimental process of biomaterials in SLS could be directed towards the appropriate sintering window, so as not to cause unintentional degradation to the biomaterials.

Design/methodology/approach

SLS uses a laser as a heat source to sinter parts. A theoretical study based on heat transfer phenomena during SLS process was carried out. The study identified the significant biomaterial and laser beam properties that were critical to the sintering result. The material properties were thermal conductivity, thermal diffusivity, surface reflectivity and absorption coefficient.

Findings

The influential laser beam properties were laser power and scan speed, which were machine parameters that can be controlled by users. The identification of the important parameters has ensured that favorable sintering conditions can be achieved.

Research limitations/implications

The selection of biopolymer influences the manner in which energy is absorbed by the powder bed during the SLS process. In this paper, the modeling and investigative work was validated by poly(vinyl alcohol) which is a biomaterial that has been used for many biomedical and pharmaceutical purposes.

Practical implications

The paper can be the foundation for extension to other types of biomaterials including biopolymers, bioceramics and biocomposites.

Originality/value

The formulation of the theory for heat transfer phenomena during the SLS process is of significant value to any studies in using SLS for biomedical applications.

Details

Rapid Prototyping Journal, vol. 16 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 1 December 2004

George K. Stylios

Examines the tenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects…

3517

Abstract

Examines the tenth published year of the ITCRR. Runs the whole gamut of textile innovation, research and testing, some of which investigates hitherto untouched aspects. Subjects discussed include cotton fabric processing, asbestos substitutes, textile adjuncts to cardiovascular surgery, wet textile processes, hand evaluation, nanotechnology, thermoplastic composites, robotic ironing, protective clothing (agricultural and industrial), ecological aspects of fibre properties – to name but a few! There would appear to be no limit to the future potential for textile applications.

Details

International Journal of Clothing Science and Technology, vol. 16 no. 6
Type: Research Article
ISSN: 0955-6222

Keywords

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