scholarly journals Characterisation of Ex Vivo Liver Thermal Properties for Electromagnetic-Based Hyperthermic Therapies

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 3004 ◽  
Author(s):  
Nuno P. Silva ◽  
Anna Bottiglieri ◽  
Raquel C. Conceição ◽  
Martin O’Halloran ◽  
Laura Farina
Keyword(s):  
Thermal Properties ◽  
Ex Vivo ◽  
Tissue Perfusion ◽  
Heating Process ◽  
Volumetric Heat Capacity ◽  
Accurate Knowledge ◽  
Different Temperatures ◽  
Treatment Plans ◽  
Specific Tissue ◽  
Tissue Target

Electromagnetic-based hyperthermic therapies induce a controlled increase of temperature in a specific tissue target in order to increase the tissue perfusion or metabolism, or even to induce cell necrosis. These therapies require accurate knowledge of dielectric and thermal properties to optimise treatment plans. While dielectric properties have been well investigated, only a few studies have been conducted with the aim of understanding the changes of thermal properties as a function of temperature; i.e., thermal conductivity, volumetric heat capacity and thermal diffusivity. In this study, we experimentally investigate the thermal properties of ex vivo ovine liver in the hyperthermic temperature range, from 25 °C to 97 °C. A significant increase in thermal properties is observed only above 90 °C. An analytical model is developed to model the thermal properties as a function of temperature. Thermal properties are also investigated during the natural cooling of the heated tissue. A reversible phenomenon of the thermal properties is observed; during the cooling, thermal properties followed the same behaviour observed in the heating process. Additionally, tissue density and water content are evaluated at different temperatures. Density does not change with temperature; mass and volume losses change proportionally due to water vaporisation. A 30% water loss was observed above 90 °C.

scholarly journals Testing a Gypsum Composite Based on Raw Gypsum with a Direct Admixture of Paraffin and Polymer to Improve Thermal Properties

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3241
Author(s):  
Krzysztof Powała ◽  
Andrzej Obraniak ◽  
Dariusz Heim
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Properties ◽  
Phase Change ◽  
Large Scale ◽  
Building Materials ◽  
Residential Buildings ◽  
Energy Performance ◽  
Polymer Content ◽  
Volumetric Heat Capacity

The implemented new legal regulations regarding thermal comfort, the energy performance of residential buildings, and proecological requirements require the design of new building materials, the use of which will improve the thermal efficiency of newly built and renovated buildings. Therefore, many companies producing building materials strive to improve the properties of their products by reducing the weight of the materials, increasing their mechanical properties, and improving their insulating properties. Currently, there are solutions in phase-change materials (PCM) production technology, such as microencapsulation, but its application on a large scale is extremely costly. This paper presents a solution to the abovementioned problem through the creation and testing of a composite, i.e., a new mixture of gypsum, paraffin, and polymer, which can be used in the production of plasterboard. The presented solution uses a material (PCM) which improves the thermal properties of the composite by taking advantage of the phase-change phenomenon. The study analyzes the influence of polymer content in the total mass of a composite in relation to its thermal conductivity, volumetric heat capacity, and diffusivity. Based on the results contained in this article, the best solution appears to be a mixture with 0.1% polymer content. It is definitely visible in the tests which use drying, hardening time, and paraffin absorption. It differs slightly from the best result in the thermal conductivity test, while it is comparable in terms of volumetric heat capacity and differs slightly from the best result in the thermal diffusivity test.

The Study of Thermal Properties and Micro Structures of YSZ

2007 ◽  
Author(s):  
S. M. Guo ◽  
M. B. Silva ◽  
Patrick F. Mensah ◽  
Nalini Uppu
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Gas Turbine ◽  
Bond Coat ◽  
Sintering Temperature ◽  
Heating Process ◽  
Thermal Barrier ◽  
Inlet Temperature ◽  
Low Thermal Conductivity ◽  
Gas Tight

Thermal barrier coatings (TBCs) are used in gas turbine engines to achieve a better efficiency by allowing increased turbine inlet temperature and decreasing the amount of cooling air used. Plasma spraying is one of the most reliable methods to produce TBCs, which are generally comprised of a top coating of ceramic and a bond-coat of metal. Usually, the top coating is Yttria-Stabilized-Zirconia (YSZ), providing the thermal barrier effect. The bond-coat is typically a layer of M-Cr-Al-Y (where “M” stands for “metal”), employed to improve the attachment between the ceramic top-coat and the substrate. Due to the extreme temperature gradient presented in the plasma jet and the wide particle size distribution, during the coating process, injected ceramic powders may experience a significantly different heating process. Different heating history, coupled with the substrate preheating temperature, may affect the thermal properties of the YSZ layers. In this paper, four sets of mol 8% YSZ disks are fabricated under controlled temperatures of 1100°C, 1200°C, 1400°C and 1600°C. Subsequently the thermal properties and the microstructures of these YSZ disks are studied. The results indicate a strong microstructure change at a temperature slightly below 1400°C. For a high sintering temperature, a dense YSZ layer can be formed, which is good for gas tight operation; At low sintering temperature, say 1200°C, a porous YSZ layer is formed, which has the advantage of low thermal conductivity. For gas turbine TBC applications, a robust low thermal conductivity YSZ layer is desirable, while for Solid Oxide Fuel Cells, a gas-tight YSZ film must be formed. This study offers a general guideline on how to prepare YSZ layers, mainly by controlling the heating process, to form microstructures with desired properties.

scholarly journals Heterogeneity of blood flow: impact of age on muscle specific tissue perfusion during exercise

2014 ◽  
Vol 592 (8) ◽  
pp. 1729-1730 ◽  
Author(s):  
Joel D. Trinity ◽  
Gwenael Layec ◽  
Joshua F. Lee
Keyword(s):  
Blood Flow ◽  
Tissue Perfusion ◽  
Specific Tissue

scholarly journals Comparison of Burn Depth at Different Temperatures on Ex Vivo Human Skin with Standardized Model and Comparison of the Results with Rat Contact Burn Model

2018 ◽  
Vol 5 (2) ◽  
pp. 88-91
Author(s):  
Mehmet Surhan Arda ◽  
Nilsun Kuas ◽  
Erdem Söztutar ◽  
Atacan Emre Koçman ◽  
Hüseyin İlhan
Keyword(s):  
Human Skin ◽  
Ex Vivo ◽  
Different Temperatures ◽  
Comparison Of The Results ◽  
Burn Depth

Transient Thermal Analysis of an Anisotropic Conductive Film Package Assembly Process

2000 ◽  
Author(s):  
Victor Adrian Chiriac ◽  
Tien-Yu Tom Lee
Keyword(s):  
Temperature Drop ◽  
Thermal Response ◽  
Heating Process ◽  
Assembly Process ◽  
Anisotropic Conductive Film ◽  
Conductive Film ◽  
Different Temperatures ◽  
Computational Fluid Dynamics Cfd ◽  
Nozzle Head ◽  
Transient Thermal

Abstract Transient thermal simulation was performed to analyze thermal response of the assembly process for a package using Anisotropic Conductive Film (ACF). Two assembly processes were modeled: a simplified process where the package was fixed at two different temperatures during assembly, and a detailed process where the package experienced a ramping heating process, followed by a constant temperature curing process. A 3D conjugate Computational Fluid Dynamics (CFD) study was first conducted, followed by a 3D conduction-only analysis due to the minimal effect of convection and radiation. Results from the detailed process modeling indicated that during the initial ramping, within 0.02 second, the die and nozzle head experienced a small temperature drop due to the cooling effect of the ACF material and substrate. The ACF material also displayed a steep increase in temperature after contacting the die, followed by a short decay, then ramped up again. At the end of the 10-second ramping process, the ACF reached a temperature of almost 203°C, while the die was at 206°C. During the 5 seconds of curing, all parts reached steady state in less than 2 seconds.

Vessel-Sealing Capability of Novel Microwave Sealer: Experimental Study in Animal Models

2020 ◽  
pp. 155335062093786
Author(s):  
Khiem Tran Dang ◽  
Shigeyuki Naka ◽  
Atsushi Yamada ◽  
Ken-ichi Mukaisho ◽  
Tohru Tani
Keyword(s):  
Thermal Damage ◽  
Ex Vivo ◽  
Vessel Diameter ◽  
Heating Process ◽  
Damage Evaluation ◽  
Vessel Sealing ◽  
Surgical Devices ◽  
Harmonic Focus ◽  
Thermal Spread

Background. Ultrasonically activated dissectors (UADs) and radiofrequency-based devices have been considered excellent surgical devices because of their reliability and flexibility. Meanwhile, microwave-based devices have demonstrated potential with their unique heating mechanism. This study aims to compare the sealing function of a newly invented forceps-like microwave sealer (MS) with that of currently available UADs. Materials and Methods. MS and 2 examples of UADs (Harmonic Focus+ [HF+] and Sonicision [SNC]) were employed to perform mesenterectomies (in vivo) and sealing sizable vessels (ex vivo). Vessel diameter, seal time, burst pressure (BP), sealing completion, and instrument sticking were recorded. The samples underwent histological investigation for thermal damage evaluation. Results. During mesenterectomies, MS required 3 seconds and 30 W to secure a complete seal. The BP achieved by the MS seal was higher than that of HF+ and SNC on arteries (851 ± 203.7 vs 682.4 ± 287.3, P < .05; vs 833.1 ± 251.2 mmHg, P = .4523, respectively) but was not statistically different on veins (324.9 ± 203.5 vs 460.1 ± 320.3 vs 508.3 ± 350.7 mmHg, P = .215). In all trials, MS caused less sticking but exhibited similar heat-induced alterations to UADs. MS’s thermal spread was not statistically more extended than that of UADs on either arteries or veins. Conclusions. MS was capable of not only sealing tiny vessels but also achieving high-pressure endurance on sizable vessels. Its forceful grasping and synchronous heating process helped create solid stumps with an acceptable thermal spread.

scholarly journals Techniques for Thermal Conductivity Measurements in Antarctica

1982 ◽  
Vol 3 ◽  
pp. 96-102 ◽  
Author(s):  
Richard E. Ewing ◽  
Richard S. Falk ◽  
John F. Bolzan ◽  
Ian M. Whillans
Keyword(s):  
Thermal Properties ◽  
Mathematical Problem ◽  
Numerical Procedure ◽  
Measurement Procedure ◽  
Physical Experiment ◽  
Insufficient Data ◽  
Conductivity Measurements ◽  
Numerical Techniques ◽  
Accurate Knowledge ◽  
Well Posed

An accurate knowledge of the thermal properties of firn and ice within a glacier is essential for any reliable mathematical model of heat transfer. This paper considers the problem of determining the thermal properties of firn at Dome C, Antarctica, for use in such a model.First, the difficulties in accurately determining thermal properties are discussed. Then a physical experiment which can be performed under field conditions, but which will yield a well-posed mathematical problem for determining the unknown properties, is presented. Next, two different numerical techniques for solving the mathematical problem are discussed. Finally, some numerical approximations and error estimates are presented for the results of applying our numerical procedure to data from Dome C. Although insufficient data were obtained to test our methods fully, we have established a measurement procedure and a method of analysis which appear to be promising.

High Temperature Properties of CoFe/CoNi and Fe/CoNi Biphase Microwires

2015 ◽  
Vol 233-234 ◽  
pp. 265-268 ◽  
Author(s):  
Irene Iglesias ◽  
Rhimou El Kammouni ◽  
Kseniay Chichay ◽  
Manuel Vazquez ◽  
Valeria Rodionova
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Single Phase ◽  
Amorphous Structure ◽  
Magnetic Behaviour ◽  
Heating Process ◽  
Saturation Magnetostriction ◽  
Magnetostriction Constant ◽  
Different Temperatures ◽  
Drawing Technique

The objective of this work has been to analyze the high-temperature behavior of magnetically single-and biphase microwires because of its interest from fundamental and applications viewpoints. Two alloy compositions with amorphous structure covered by glass have been prepared as magnetically single phase microwires by quenching & drawing technique: CoFe-based with near zero saturation magnetostriction constant and Fe-based with positive saturation magnetostriction constant. The same wires were used as the core for magnetically biphase microwires. Second CoNi phase was deposited by electroplating. Magnitudes as saturation magnetization and hysteresis parameters are determined in the temperature range from room temperature up to 1200 K. We proceed to a comparative analysis of their magnetic behaviour at different temperatures as well as after cooling down to room temperature. Information on the Curie temperature of different phases and on the influence of heating process on the magnetic properties is thus derived.

Pulsed Heat Shocks to Enhance Collagen Production of Human Dermal Fibroblasts in Ex-Vivo Skin

2010 ◽  
Author(s):  
S. D. Dams ◽  
M. de Liefde ◽  
A. M. Nuijs ◽  
C. W. J. Oomens ◽  
F. P. T. Baaijens
Keyword(s):  
Ex Vivo ◽  
Contemporary Literature ◽  
Collagen Matrix ◽  
Dermal Fibroblasts ◽  
Human Dermal Fibroblasts ◽  
Procollagen Type ◽  
Different Temperatures ◽  
Heat Shocks ◽  
Ablative Techniques ◽  
Type 3

Well-known characteristics of aging skin are the development of fine lines and wrinkles, but also changes in skin tone, skin texture, thickness and moisture content [1, 2]. Rejuvenation of the skin aims at reversing the signs of aging and can be established in the epidermis as well as in the dermis. Aged dermis for that matter has a degenerated collagen matrix. To regenerate this matrix, fibroblasts need to be stimulated into synthesizing new collagen. Among the rejuvenation methods used the non-ablative techniques are gaining popularity. These methods produce dermal remodeling without obvious epidermal injury using a thermal approach. The generation of heat would cause collagen injury and contraction followed by collagen synthesis [2, 3]. However, little research on physiological evidence can be found in contemporary literature. In this study, the effects of heat shocks of different temperatures on the expression of procollagen type 1and type 3 of human dermal fibroblasts in ex-vivo skin are investigated.

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