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.

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.

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).

scholarly journals Influence of the pre-treatment of nanofibers obtained from mushrooms on the mechanical properties of the paper

Polimery ◽  
2021 ◽  
Vol 66 (9) ◽  
pp. 466-471
Author(s):  
Mizan Izzati Mat Zin ◽  
Muhammad Azammuddin Suratem ◽  
Wan Mohd Fazli Wan Nawawi
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Treatment Process ◽  
Crystal Formation ◽  
Ice Crystal ◽  
Elongation At Break ◽  
Fiber Modification ◽  
Commercial Species ◽  
Oyster Mushrooms ◽  
Pre Treatment

The influence of the pre-treatment process (freezing, drying) on the tensile properties of chitin paper obtained from nanofibers of three commercial species of fungi: oyster mushrooms (P. ostreatus), enoki (F. velutipes) and shiitake (L. edodes) was investigated. The chitin nanofibers were extracted by a mild alkaline process. The highest tensile strength was observed for paper obtained from fresh mushrooms fibers, which may result from the lack of the chitin fiber modification. Freezing and drying processes have been found to reduce the strength of the paper, possibly due to ice crystal formation and the keratinization effect of the nanofibers, respectively. The paper obtained from enoki fungus nanofibers was characterized by the highest tensile strength, which may be due to the very long fiber. However, in terms of elongation at break, the best results were obtained with oyster mushrooms nanofibers, probably due to the relatively shorter chitin fiber. The long enoki nanofibers can therefore be used as a good reinforcement of the paper.

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.

scholarly journals Freezing of tissue-limits for the autoradiographic localization of diffusible substances.

1979 ◽  
Vol 27 (11) ◽  
pp. 1520-1523 ◽  
Author(s):  
P M Frederik ◽  
W M Busing
Keyword(s):  
Surface Layer ◽  
Electron Microscope ◽  
Crystal Growth ◽  
Freeze Drying ◽  
Crystal Size ◽  
Ice Crystals ◽  
Ice Crystal ◽  
Thin Sections ◽  
Freeze Dried ◽  
Freeze Etching

Frozen thin sections and sections from freeze-dried and embedded tissue are used for the autoradiographic localization of diffusible substances at the electron microscope level. The presence of ice crystals in such sections may limit the autoradiographic resolution. Ice crystals are formed during freezing and may grow during subsequent processing of tissue. The contribution of ice crystal growth to the final image was estimated by measuring the distribution of the ice crystal sizes in freeze-etch replicas and in sections from freeze-dried and embedded tissues. A surface layer (10-15 mu) without visible ice crystals was present in both preparations. Beneath this surface layer the diameter of ice crystals increased towards the interior with the same relationship between crystal size and distance from the surface in the freeze-etch preparation as in the freeze-dry preparation. Ice crystal growth occurring during a much longer time during freeze-drying compared to freeze-etching does not significantly contribute to the final image in the electron microscope. The formation of ice crystals during freezing determines to a large extent the image (and therefore the autoradiographic resolution) of freeze-dry preparations and this probably holds also for thin cryosections of which examples are given.

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.

An Aldehyde/Hydrazide Polymerization Technique for Biological SEM Specimen Preparation

1981 ◽  
Vol 39 ◽  
pp. 644-645
Author(s):  
W. T. Gunning ◽  
R. E. Crang
Keyword(s):  
Electron Microscopy ◽  
Freeze Drying ◽  
Water Soluble ◽  
Specimen Preparation ◽  
Crystal Formation ◽  
Ice Crystal ◽  
Polymer Medium ◽  
Low Contrast ◽  
Transmission Electron ◽  
Limited Application

Two water-soluble embedding techniques for transmission electron microscopy (TEM) utilizing the polymerization of glutaraldehyde were proposed in the early 1970's. Pease and Peterson introduced a glutaraldehyde-urea polymer medium and Heckman and Barrnett proposed a glutaraldehyde-carbohydrazide (GACH) medium. Both permitted the retention of lipids in tissues without the harsh extraction of cellular constituents by fixatives, organic dehydrators and embedding agents. These techniques were of limited application and yielded low contrast or negative-stained images in the TEM. This technique has not been previously considered as potentially useful for scanning electron microscopy (SEM) due to the covering and obliterating of surface morphology. Virtually all SEM techniques for biological and specimen preparation, aside from freeze-drying, replace or extract most of the native elemental compositions of cells and tissues. Freezing and freeze-drying techniques are cumbersome, time-consuming, may require elaborate equipment and can induce artifacts due to ice crystal formation. We propose a new approach of SEM sample preparation using modifications of the GACH technique employed in TEM.

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.

Influence of Thickness on Ice Crystal Formation in Strawberry during Freeze-drying

2010 ◽  
Vol 10 (21) ◽  
pp. 2741-2744 ◽  
Author(s):  
M.Z. Nurzahida ◽  
A.M. Mimi Sakin ◽  
Jaafar Abdullah
Keyword(s):  
Freeze Drying ◽  
Crystal Formation ◽  
Ice Crystal ◽  
Ice Crystal Formation
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