Effects of Magnetic Field on the Phase Change Cells and the Formation of Ice Crystals in Biomaterials: Carrot Case

2017 ◽  
Vol 9 (3) ◽  
Author(s):  
Bin Liu ◽  
Jianfei Song ◽  
Zhaodn Yao ◽  
Rachid Bennacer
Keyword(s):  
Magnetic Field ◽  
Phase Transformation ◽  
Phase Change ◽  
Fruits And Vegetables ◽  
Membrane Damage ◽  
Optical Microscope ◽  
Ice Crystals ◽  
Control Panel ◽  
Crystal Formation ◽  
Ice Crystal

In order to explore the effect of direct current (DC) and alternating current (AC) magnetic field (MF) on the biological (fruits and vegetables) phase transformation and ice crystal formation, we used carrot strips (0.5 × 0.5 × 1 cm3) and put them at low temperature control panel. The samples were frozen under AC and DC MF of 50 Hz with different intensities, i.e., 0, 0.46, 0.9, 1.8, 3.6, and 7.2 mT. The ice crystals formation during the process of cell freezing was observed and recorded using the optical microscope, and the beginning and ending time of the phase transformation with the corresponding temperatures were determined. The results show that the DC and AC MF situations compared to non-MF can decrease ice crystal volume and be more flocculent. The changes will reduce the cell membrane damage rate. The increase of magnetic field intensity delays the phase change time and leads to a shorter phase transition duration, a reduction in the cells’s lowest noncrystallization temperature is also observed. Such changes in thermal dynamic process and size elementary freezing (rapid formation of small ice crystals) reduce the damage to the quality of fruits and vegetables.

Effects of magnetic field on freezing characters of carrot, potato and broccoli

2021 ◽  
Vol 93 (1) ◽  
pp. 10201
Author(s):  
Aiqiang Chen ◽  
Yue Liu ◽  
Georges El Achkar ◽  
Erlong Li ◽  
Qifen Zou ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Cell Morphology ◽  
Fruits And Vegetables ◽  
Transition Process ◽  
Freezing Process ◽  
Crystal Formation ◽  
Ice Crystal ◽  
Temperature Changes ◽  
Phase Transition Process

In order to study the effects of magnetic field on the freezing characteristics of fruits and vegetables, carrot, potato and broccoli were frozen without and with a magnetic field of intensities 4.6 Gs, 9.2 Gs, 18 Gs and 36 Gs, while recording the temperature changes. The microstructure and temperature change of carrot during freezing were analyzed in detail. The results show that the magnetic field has effects on the freezing process of carrot strips, characterized by a reduction of the phase transition time and a characteristic diversity of the ice crystal formation zone. Crystallization characteristics are similar in the samples without and with a magnetic field of low intensities (4.6 Gs and 9.2 Gs), which show as a non-homogeneous phase transition process in the carrot sample, and the tissue changed showing a sunken, cell morphology variation and increased intercellular space. The freezing is almost homogeneous under a magnetic field of intensities 18 Gs and 36 Gs, then results in a slightly change of cell morphology. In addition, the effects of magnetic field on fruits and vegetables are varying with their species.

The “KIMWIPE” Effect in Ultra-Thin Cryosections

1985 ◽  
Vol 43 ◽  
pp. 458-459
Author(s):  
I. Taylor ◽  
P. Ingram ◽  
J.R. Sommer
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Muscle Fibers ◽  
Ice Crystals ◽  
Crystal Formation ◽  
Ice Crystal ◽  
Thin Sections ◽  
Skeletal Muscle Fibers ◽  
Freeze Dried ◽  
Ice Crystal Formation

In studying quick-frozen single intact skeletal muscle fibers for structural and microchemical alterations that occur milliseconds, and fractions thereof, after electrical stimulation, we have developed a method to compare, directly, ice crystal formation in freeze-substituted thin sections adjacent to all, and beneath the last, freeze-dried cryosections. We have observed images in the cryosections that to our knowledge have not been published heretofore (Figs.1-4). The main features are that isolated, sometimes large regions of the sections appear hazy and have much less contrast than adjacent regions. Sometimes within the hazy regions there are smaller areas that appear crinkled and have much more contrast. We have also observed that while the hazy areas remain still, the regions of higher contrast visibly contract in the beam, often causing tears in the sections that are clearly not caused by ice crystals (Fig.3, arrows).

Magnetically Assembling Nanoscale Metal Network Into Phase Change Material—Percolation Threshold Reduction in Paraffin Using Magnetically Assembly of Nanowires

2014 ◽  
Vol 5 (3) ◽  
Author(s):  
Junwei Su ◽  
Iman Mirzaee ◽  
Fan Gao ◽  
Xiao Liu ◽  
Majid Charmchi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Percolation Threshold ◽  
Phase Change Materials ◽  
Optical Microscope ◽  
Nickel Particles ◽  
Solid Foundation ◽  
Energy Storage Applications

A high throughput manufacturing process to magnetically assembling nanowire (NW) network into paraffin was developed for enhancing conductivity in phase change materials (PCMs) used in energy storage applications. The prefabricated nickel NWs were dispersed in melted paraffin followed by magnetic alignment under a strong magnetic field. Measuring electrical conductivity of the nanocomposite, as well as observing cross section of the sample slice under an optical microscope characterized the alignment of NWs. As a comparison, nickel particles (NPs) based paraffin nanocomposites were also fabricated, and its electrical conductivity with and without applied magnetic field were measured. The effects of aspect ratio of fillers (particles and NWs) and volume concentration on percolation threshold were studied both experimentally and theoretically. It was found that the NW based paraffin nanocomposite has much lower percolation threshold compared to that of particle based paraffin composite. Furthermore, the alignment of particles and NWs under magnetic field significantly reduces the threshold of percolation. This work provides solid foundation for the development of a manufacturing technology for high thermal conductivity PCMs for thermal energy storage applications.

Physical Preservation Methods for Biological Material

1972 ◽  
Vol 30 ◽  
pp. 134-135
Author(s):  
Stanley Bullivant
Keyword(s):  
Freeze Drying ◽  
Freeze Substitution ◽  
Ice Crystals ◽  
Crystal Formation ◽  
Glycerol Solution ◽  
Ice Crystal ◽  
Glutaraldehyde Fixation ◽  
Preservation Methods ◽  
Glycerol Treatment ◽  
Pre Treatment

This review will be limited to physical preservation methods involving freezing, and will include discussion of freeze-drying, freeze-substitution, ultracryomicrotomy and freezeetching. Pre-treatment and freezing steps can be considered as common to all techniques.The most common pre-treatment is soaking in a cold 20% glycerol solution to provide protection against ice crystal formation. Glutaraldehyde fixation is often used before freezing. With special freezing techniques no pretreatment may be necessary.Freezing should be so rapid that it does not produce ice crystals larger than 2nm. in diameter. Following glycerol treatment, immersion in Freon 12 at its melting point of -155 C is adequate. Freezing in boiling liquid nitrogen is not usually satisfactory.

scholarly journals Implementation of a comprehensive ice crystal formation parameterization for cirrus and mixed-phase clouds in the EMAC model (based on MESSy 2.53)

2018 ◽  
Vol 11 (10) ◽  
pp. 4021-4041 ◽  
Author(s):  
Sara Bacer ◽  
Sylvia C. Sullivan ◽  
Vlassis A. Karydis ◽  
Donifan Barahona ◽  
Martina Krämer ◽  
...  
Keyword(s):  
Climate Model ◽  
Ice Nucleation ◽  
Cirrus Clouds ◽  
Mixed Phase ◽  
Ice Crystals ◽  
Dust Particles ◽  
Crystal Formation ◽  
Ice Crystal ◽  
Upper Troposphere ◽  
Mixed Phase Clouds

Abstract. A comprehensive ice nucleation parameterization has been implemented in the global chemistry-climate model EMAC to improve the representation of ice crystal number concentrations (ICNCs). The parameterization of Barahona and Nenes (2009, hereafter BN09) allows for the treatment of ice nucleation taking into account the competition for water vapour between homogeneous and heterogeneous nucleation in cirrus clouds. Furthermore, the influence of chemically heterogeneous, polydisperse aerosols is considered by applying one of the multiple ice nucleating particle parameterizations which are included in BN09 to compute the heterogeneously formed ice crystals. BN09 has been modified in order to consider the pre-existing ice crystal effect and implemented to operate both in the cirrus and in the mixed-phase regimes. Compared to the standard EMAC parameterizations, BN09 produces fewer ice crystals in the upper troposphere but higher ICNCs in the middle troposphere, especially in the Northern Hemisphere where ice nucleating mineral dust particles are relatively abundant. Overall, ICNCs agree well with the observations, especially in cold cirrus clouds (at temperatures below 205 K), although they are underestimated between 200 and 220 K. As BN09 takes into account processes which were previously neglected by the standard version of the model, it is recommended for future EMAC simulations.

The effects of vitrification on oocyte quality

2021 ◽  
Author(s):  
Ching-Chien Chang ◽  
Daniel B Shapiro ◽  
Zsolt Peter Nagy
Keyword(s):  
Phase Transitions ◽  
Osmotic Stress ◽  
Negative Impact ◽  
Oocyte Quality ◽  
Ice Crystals ◽  
Crystal Formation ◽  
Ice Crystal ◽  
Cooling Process ◽  
Developmental Potential ◽  
Intracellular Ice

Abstract Vitrification, is an ultra-rapid, manual cooling process that produces glass-like (ice crystal free) solidification. Water is prevented from forming intercellular and intracellular ice crystals during cooling as a result of oocyte dehydration and the use of highly concentrated cryoprotectant. Though oocytes can be cryopreserved without ice crystal formation through vitrification, it is still not clear whether the process of vitrification causes any negative impact (temperature change/chilling effect, osmotic stress, cryoprotectant toxicity, and/or phase transitions) on oocyte quality that translate to diminished embryo developmental potential or subsequent clinical outcomes. In this review, we attempt to assess the technique’s potential effects and the consequence of these effects on outcomes.

scholarly journals Implementation of a comprehensive ice crystal formation parameterization for cirrus and mixed-phase clouds into the EMAC model (based on MESSy 2.53)

2018 ◽  
Author(s):  
Sara Bacer ◽  
Sylvia C. Sullivan ◽  
Vlassis A. Karydis ◽  
Donifan Barahona ◽  
Martina Krämer ◽  
...  
Keyword(s):  
Climate Model ◽  
Ice Nucleation ◽  
Mixed Phase ◽  
Ice Crystals ◽  
Dust Particles ◽  
Crystal Formation ◽  
Ice Crystal ◽  
Data Set ◽  
Particle Spectra ◽  
Mixed Phase Clouds

Abstract. A comprehensive ice nucleation parameterization has been implemented in the global chemistry-climate model EMAC to realistically represent ice crystal number concentrations. The parameterization of Barahona and Nenes (2009, hereafter BN09) allows the treatment of ice nucleation, taking into account the competition for water vapour between homogeneous and heterogeneous nucleation and pre-existing ice crystals in cold clouds. Furthermore, the influence of chemically-heterogeneous, polydisperse aerosols is considered via multiple ice nucleating particle spectra, which are included in the parameterization to compute the heterogeneously formed ice crystals. BN09 has been implemented to operate both in the cirrus and in the mixed-phase regimes. Compared to the standard EMAC results, BN09 produces fewer ice crystals in the upper troposphere but higher ice crystal number concentrations in the middle troposphere, especially in the Northern Hemisphere where ice nucleating mineral dust particles are relatively abundant. The comparison with a climatological data set of aircraft measurements shows that BN09 used in the cirrus regime improves the model results and, therefore, is recommended for future EMAC simulations.

scholarly journals Effects of Immersion Freezing on Ice Crystal Formation and the Protein Properties of Snakehead (Channa argus)

Foods ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 411
Author(s):  
Shulai Liu ◽  
Xiaohong Zeng ◽  
Zhenyu Zhang ◽  
Guanyu Long ◽  
Fei Lyu ◽  
...  
Keyword(s):  
Food Preservation ◽  
Ice Crystals ◽  
Random Coil ◽  
Maximum Temperature ◽  
Crystal Formation ◽  
Ice Crystal ◽  
Protein Properties ◽  
Immersion Freezing ◽  
Ft Ir ◽  
Ice Crystal Formation

This study aimed to evaluate the effect of immersion freezing (IF) at different temperatures on ice crystal formation and protein properties in fish muscle. Snakehead blocks were frozen by IF at −20, −30, and −40 °C, and conventional air freezing (AF) at −20 °C. The size of ice crystals in the frozen samples was evaluated using Image J software. Changes in protein properties were analyzed by Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). Snakehead blocks frozen using IF contained smaller ice crystals and better microstructures, especially at lower temperatures. The mean cross-sectional areas of ice crystals formed in the frozen samples were 308.8, 142.4, and 86.5 μm2 for IF treatments at −20, −30, and −40 °C, respectively, and 939.6 μm2 for the AF treatment. The FT-IR results show that protein aggregation in the frozen fish blocks was manifested by a decrease in α-helices connected to the increased random coil fraction. The DSC results show that samples prepared by IF had a higher denaturation enthalpy (∆H) and denaturation maximum temperature (Tmax) than those prepared by AF. These results confirm that IF generated a larger number of smaller ice crystals, which is conducive to food preservation.

Magnetically Assembling Nanoscale Metal Network Into Phase Change Material

2014 ◽  
Author(s):  
Junwei Su ◽  
Xiao Liu ◽  
Iman Mirzaee ◽  
Fan Gao ◽  
Majid Charmchi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electrical Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Percolation Threshold ◽  
Phase Change Materials ◽  
Optical Microscope ◽  
Nickel Particles ◽  
Solid Foundation ◽  
Energy Storage Applications

A high throughput manufacturing process to magnetically assembling nanowire (NW) network into paraffin was developed for enhancing conductivity in phase change materials (PCMs) used in energy storage applications. The prefabricated nickel nanowires were dispersed in melted paraffin followed by magnetic alignment under a strong magnetic field. Measuring electrical conductivity of the nanocomposites, as well as observing cross-section of the sample slice under an optical microscope characterized the alignment of nanowires. As a comparison, nickel particles (NPs) based paraffin nanocomposites were also fabricated and its electrical conductivity with and without applied magnetic field were measured. The effects of aspect ratio of fillers (particles and nanowires) and volume concentration on percolation threshold were studied both experimentally and theoretically. It was found that the nanowire based paraffin nanocomposite has much lower percolation threshold compared to that of particle based paraffin composite. Furthermore, the alignment of particles and nanowires under magnetic field significantly reduce the threshold of percolation. This work provides solid foundation for the development of a manufacturing technology for high thermal conductivity phase change materials (PCM) for thermal energy storage applications.

High-pressure freezing and freeze substitution of plant tissue

1992 ◽  
Vol 50 (1) ◽  
pp. 748-749
Author(s):  
William P. Sharp ◽  
Robert W. Roberson
Keyword(s):  
High Pressure ◽  
Cell Structure ◽  
Leaf Tissue ◽  
Freeze Substitution ◽  
Crystal Formation ◽  
Ice Crystal ◽  
High Pressure Freezing ◽  
Cell Components ◽  
Cold Metal ◽  
Brome Grass

The aim of ultrastructural investigation is to analyze cell architecture and relate a functional role(s) to cell components. It is known that aqueous chemical fixation requires seconds to minutes to penetrate and stabilize cell structure which may result in structural artifacts. The use of ultralow temperatures to fix and prepare specimens, however, leads to a much improved preservation of the cell’s living state. A critical limitation of conventional cryofixation methods (i.e., propane-jet freezing, cold-metal slamming, plunge-freezing) is that only a 10 to 40 μm thick surface layer of cells can be frozen without distorting ice crystal formation. This problem can be allayed by freezing samples under about 2100 bar of hydrostatic pressure which suppresses the formation of ice nuclei and their rate of growth. Thus, 0.6 mm thick samples with a total volume of 1 mm3 can be frozen without ice crystal damage. The purpose of this study is to describe the cellular details and identify potential artifacts in root tissue of barley (Hordeum vulgari L.) and leaf tissue of brome grass (Bromus mollis L.) fixed and prepared by high-pressure freezing (HPF) and freeze substitution (FS) techniques.

Sign in / Sign up

Export Citation Format

Share Document