scholarly journals Ice Formation from a Supercooled State and Water Transport through Ionomers during PEFC Cold Startup

2021 ◽  
Author(s):  
Yutaka Tabe ◽  
Naoyuki Wakatake ◽  
Yuta Ishima ◽  
Takemi Chikahisa
Keyword(s):  
Water Transport ◽  
Ice Formation ◽  
Supercooled State

Water Transport in Ionomer and Ice Formation during Cold Startup with Supercooled State in PEFC

2016 ◽  
Vol 75 (14) ◽  
pp. 623-630 ◽  
Author(s):  
N. Wakatake ◽  
Y. Tabe ◽  
T. Chikahisa
Keyword(s):  
Water Transport ◽  
Ice Formation ◽  
Supercooled State

On the Possible Application of a Microscale Thermocouple to Measure Intercellular Ice Formation in Cells Embedded in an Extracellular Matrix

2004 ◽  
Author(s):  
Deepak Kandra ◽  
Ram V. Devireddy
Keyword(s):  
Extracellular Matrix ◽  
Water Transport ◽  
Ice Formation ◽  
Scanning Calorimetry ◽  
Microscopy Technique ◽  
Intracellular Ice ◽  
Tissue Systems ◽  
Low Temperature Microscopy ◽  
Microfabrication Techniques ◽  
In Cells

To optimize a freezing protocol for tissue systems, knowledge of intercellular ice formation and water transport is essential. Water transport during freezing can be measured using low temperature microscopy technique [1] and/or by differential scanning calorimetry method [2]. To study the formation of intracellular ice in cells embedded in an extracellular matrix we propose to design and develop an array of microscale thermocouples using microfabrication techniques [3]. The microfabricated thermocouples will be required to accurately measure the small temperature fluctuations in an embedded cell due to the formation of intracellular ice.

Measurement of Intracellular Ice Formation and Water Transport During Freezing of Human Dermal Fibroblasts Using Differential Scanning Calorimetry

2011 ◽  
Author(s):  
Shoji Mori ◽  
Jeunghwan Choi ◽  
John Bischof
Keyword(s):  
Differential Scanning Calorimetry ◽  
Water Transport ◽  
Cell Damage ◽  
Dermal Fibroblasts ◽  
Spherical Cell ◽  
Ice Formation ◽  
Scanning Calorimetry ◽  
Cell Systems ◽  
Intracellular Ice Formation ◽  
Intracellular Ice

In cryopreservation protocols maximum survivability is achieved when cooling occurs slowly enough to avoid Intracellular ice formation (IIF) yet fast enough to avoid solute effects injury (1). IIF plays a significant role in cell damage during cryopreservation. IIF has been extensively studied using cryomicroscopy. This technique is a useful tool to understand the dynamic processes during cooling, i.e. volume change of cells and IIF occurrence associated with temperature. However it has some limitations in being applied to biological systems. The central assumption in cryomicroscopy is that the projected two-dimensional area of the cell can be extrapolated to a spherical three-dimensional volume. While reasonable for spherical cell systems, this assumption is inappropriate for obtaining quantitative volumetric information in nonspherical cell systems. Differential scanning calorimetry (DSC), however, can be applied to nonspherical cell systems. Thus, DSC exotherms during freezing needed to be compared with cryomicroscopy observations in simple spherical cell systems. Several studies related to IIF using DSC havebeen reported (2)–(5). Most of them, however, discussed only IIF peaks and/or Extracellular ice formation (EIF). In order to predict the optimum cooling rate from DSC results, it is important to quantify not only IIF and EIF but also water transport (WT) during cooling at various cooling rates.

Water-transport and intracellular ice formation of human adipose-derived stem cells during freezing

2020 ◽  
Vol 93 ◽  
pp. 102689
Author(s):  
Zifei Li ◽  
Lingxiao Shen ◽  
Yu Huang ◽  
Xingxue Xiang ◽  
Gang Zhao ◽  
...  
Keyword(s):  
Stem Cells ◽  
Water Transport ◽  
Ice Formation ◽  
Adipose Derived Stem Cells ◽  
Intracellular Ice Formation ◽  
Intracellular Ice

scholarly journals Microscopic Observations of Freezing Phenomena in PEM Fuel Cell at Cold Starts

2011 ◽  
Author(s):  
Takemi Chikahisa
Keyword(s):  
Water Transport ◽  
Porous Layer ◽  
High Current Density ◽  
Transport Phenomena ◽  
Catalyst Layer ◽  
Optical Microscope ◽  
Gas Diffusion ◽  
Ice Formation ◽  
Micro Channels ◽  
Cold Starts

In Polymer electrolyte membrane fuel cells (PEMFCs), the generated water transfers from the catalyst layer to the gas channel through micro channels of different scales in a two phase flow. It is important to know details of the water transport phenomena to realize better cell performance, as the water causes flooding in the high current density conditions and start up problem under freezing temperatures. The keynote speech presents specifics of the ice formation characteristics in the catalyst layer and in the gas diffusion layer (GDL) with photos taken with an optical microscope and a CRYO-SEM. The observation results show that cold starts at −10°C results in ice formation at the interface between the catalyst layer and the micro porous layer (MPL) of GDL, at −20°C most of the ice is formed in the catalyst layer. Water transport phenomena through the micro porous layer and GDL are also a matter of interest, because the role of the MPL is not well understood from the water management angle. The speech will discuss the difference in the water distribution at the interface between the catalyst layer and the GDL arising from the presence of such a micro porous layer.

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