Freezing Rate Research Articles

Quantitative characterisation of last stage solidification in nickel base superalloy using enthalpy based method

An enthalpy based method was used to determine the solidification characteristics in the Ni base superalloy IN713LC with the emphasis on the late stages of solidification. Solidification commences with freezing of γ-solid, which is followed by precipitation of carbides (MC) and subsequent divorced growth of MC and γ until solidification terminates. During solidification enthalpy change was measured using differential thermal analysis and latent heat was calculated using a multicomponent thermodynamic software database. The measured enthalpy and calculated latent heat were then used to determine liquid fraction evolution and local freezing rate. A quantitative comparison of calculated fraction liquid evolution and local freezing rate with those determined using equilibrium and Scheil approximations was carried out. The comparison reveals that the present method offers a more accurate approach for characterising the late stages of solidification than the equilibrium and Scheil models.

Effects of different freezing parameters on the morphology and viability of preantral follicles after cryopreservation of doe rabbit ovarian tissue

To compare the effects of dimethyl sulfoxide (DMSO), 1,2-propanediol (PROH), sucrose, trehalose, concentration of cryoprotectants, equilibration method, and postseeding freezing rate on doe rabbit ovarian tissue preservation after freezing, using fractional experimental design. Experimental prospective study. Research institute in veterinary and agronomic colleges. Californian doe rabbits. Ovarian cortices were prepared from ovaries collected in slaughterhouse. Fractional experimental design was used to evaluate simultaneously five chemophysical factors influencing the cryopreservation of ovarian tissue. Follicle viability by Live/Dead viability/cytotoxicity kit and histologic evaluation of the ovarian tissue. Experimental design suggests that equilibration method and cryoprotectant concentration have no effect on the proportion of normal follicles. Penetrating and nonpenetrating cryoprotectants seems to influence the preservation of the follicles with advantage for PROH and trehalose. The follicular preservation seems to be highly influenced by the postseeding freezing rate. Freezing rate of 0.3 degrees C/min seems to be less deleterious than 2 degrees C/min. Morphologic preservation ratio reaches 85% using PROH and trehalose. Cryopreservation of doe rabbit ovarian tissue using conventional cryoprotectant and 0.3 degrees C/min as freezing rate seems to be a promising technique and could be used as a model for women.

Controlling the freezing process: A robotic device for rapidly freezing biological tissues with millisecond time resolution

A robotic cryogenic device was developed which allows freezing of thick biological tissues with millisecond time resolution. The device consists of two horizontally oriented hammers (pre-cooled with liquid N 2) driven by two linear servo-motors. The tissue sample is bathed in Ringers contained in a chamber which drops rapidly out of the way just as the hammers approach. A third linear motor is vertically oriented, and permits the rapidly dropping chamber to smoothly decelerate. All movements were performed by the three motors and four solenoids controlled by a PC. Mechanical adjustments, that change the size of the gap between the hammers at the end position, permit the final thickness of the frozen tissue to be varied. Here we show that the freezing time increased with the square of the final thickness of the frozen bundle. However, when bundles of different original thicknesses (up to at least 1 mm) were compressed to the same final thickness (e.g., 0.2 mm), they exhibited nearly equal freezing times. Hence, by being able to adjust the final thickness of the frozen bundles, the device not only speeds the rate of freezing, but standardizes the freezing time for different diameter samples. This permits the use of freezing for accurate determination of the kinetics of cellular processes in biological tissue.

Mobility improvement by detached solidification of CZT crystals

The mobility of undoped CdZnTe (CZT) crystals grown by vertical Bridgman method is improved by growing crystals without wall contact. Among the different factors playing an important role for appearance of detached growth, we have chosen the freezing rate as an effective factor for investigation with other factors were held constant. After growing a set of samples we have measured the dislocation densities for the grown samples by Warren–Averbach method. Unique results were obtained when we compared the dislocation densities and mobility, together with the freezing rate. This work and the included relations are published for the first time.

Physical characterization of air inclusions in river ice

The physical characteristics of air inclusions embedded in the ice covers of the Saint Francois River (Quebec, Canada) and the Athabasca River (Alberta, Canada) are studied because of the importance of such inclusions to the analysis and interpretation of Synthetic Aperture Radar satellite images used to characterize river ice. Studies of ice cores sampled from these two rivers show that the concentration of air inclusions in the ice cover is highly dependent on both the ice type as well as the rate of freezing. When this rate is slow, the ice cover will have few air inclusions. However, when it is rapid and sustained in duration, the amount and cross sectional diameter of these inclusions increase. Air inclusions in the snow ice were found to be spherical and ranging in size from just a few millimetres up to about a centimetre. Generally, air inclusions formed in the sampled columnar ice were sparse and either spherical or tubular in shape. Air inclusions in the frazil ice were found to present a different structure from those formed in the other ice types. In most cases, their shape were irregular and their distribution was inhomogeneous. The study of these inclusions under a microscope showed them to have angular boundaries with a whitish appearance. These results will be valuable to the development of radar backscatter analysis algorithms for river ice characterization.

Application of the SAFES (systematic approach to food engineering systems) methodology to strawberry freezing process

SAFES methodology has been applied in strawberry freezing process using data from references. Three cases of freezing have been studied. All of them start from the refrigerated temperature ( T c) and there is a first stage of cooling until the initial freezing temperature ( T m) is reached. However, the changes of components depend on the temperature reached and the rate of freezing. Case 1 studies the decrease of temperature from T m until the first layers of cells reach −18 °C, since this is the typical storage temperature in consumer’s freezer. In case 2, strawberries are frozen at the maximally cryoconcentrated temperature ( T m ′ ) of the matrix and then down to −100 °C. In case 3, a deep freezing process decreases the temperature of strawberries down to −196 °C. The last two cases are below the temperature of glass transition of strawberry (−51.3 °C) and therefore they have higher stability than in case 1. By means of this methodology it is possible to follow and predict the critical points (appearance or disappearance of components or phases) of the process to prevent quality loss. Components, phases and aggregation systems can also be analysed. Moreover, transport phenomena, chemical reaction and transition can actually be described. It has been demonstrated that SAFES methodology can describe the behaviour of strawberry freezing by using composition data, state diagrams and thermodynamic parameters. Nevertheless, to get better results more information about kinetic data related to freezing process would be required.

94 CRYOPRESERVATION OF HONEY BEE SPERMATOZOA

Our project investigated a new method for the cryopreservation of honey bee (Apis mellifera) sperm cells (SC). Few methods have been developed and none achieve normal sex ratios in progeny. Recently, honey bee colonies have been decimated by colony collapse disorder and infestation by varroa bee mites. A bank of preserved SC might enable the creation of a seed stock for restoration of genetic diversity through AI (Cobey 1983 Am. Bee J. 123, 389–395). We investigated two freezing rates using two diluents and their effect on post-thaw survival of the SC. The slower freezing rate was chosen from a report with the highest success to date (Harbo 1983 Ann. Entomol. Soc. Am. 76, 890–891). The rapid freezing rate was a method developed by us. We reasoned that the small volumes of ejaculate made it potentially suitable for vitrification. The SC were frozen either in 40% Harbo's DMSO diluent containing 25% DMSO, 25% egg yolk, 50% buffer (1.1% NaH2PO4�H2O (w/v) and 0.845% Na2HPO4�2H2O (w/v)), and 60% semen; or in 50% glycerol-based diluent containing 9% glycerol, 24% egg yolk, 67% buffer (5.9% Tris (w/v), 0.8% glucose (w/v), and 3.2% citric acid (w/v)), and 50% semen. Ejaculates were collected by applying bilateral pressure to the abdomens of the drones causing endophallus eversion. About 1 µL (8 � 106 SC) of ejaculate was drawn into siliconized 50-µL capillary tubes fitted to a Hamilton threaded-plunger syringe preloaded with Fluorinert (Sigma, St. Louis, MO, USA). Micro-glass cryostraws (µC) were constructed by pulling Pasteur pipettes to a 230-µm internal diameter and keeping what was the tip end of the pipette as the large end of the µC. The large end was fitted with Silastic tubing to act as a bulb for drawing and expelling fluid. Three µC per treatment were filled with 5 µL of diluted ejaculate and sealed with Critoseal. The µC were inserted into 500-µL Cassou straws (IMV Technologies, L'Aigle, France), immersed in a water bath, and cooled from 21�C to 5�C over 2 h. A Freeze Control� programmable cryochamber (CryoLogic Pty. Ltd., Mulgrave, Victoria, Australia) was used to cool samples slowly from 5�C to –40�C at 3�C min–1. At –40�C, the cryostraws were plunged into liquid N2 (LN2). Rapid freezing was done by plunging µC into a LN2 vortex, created using a magnetic stir bar. The µC were reinserted into the Cassou straws, while still under LN2, for storage in an LN2 tank. The µC were thawed by removal from the Cassou straws and immediate immersion in a 35�C H2O bath. Survival rates were evaluated using a dual fluorescent staining system (Molecular Probes, Eugene, OR, USA) and fluorescent microscopy. The largest portion of live staining cells (93.18%) were treated with DMSO diluent using the rapid freezing. The remaining treatments ranked as follows: slow freezing with DMSO (78.84%), rapid freezing with glycerol (38.9%), and slow freezing with glycerol (26%). All treatments differed significantly (P < 0.01). Other studies state that queens inseminated with greater than 50% viable SC have a good probability of producing normally throughout a season. Therefore, our technique of rapid freezing in DMSO diluent might be useful to apiculturists.

Storage of hemopoietic stem cells

Background:Autologous, and in some cases allogeneic, hemopoietic stem cells (HSC) are stored for varying periods of time prior to infusion. For periods of greater than 48 h, storage requires cryopreservation. It is essential to optimize cell storage and ensure the quality of the product for subsequent reinfusion.Methods:A number of important variables may affect the subsequent quality of infused HSC and therapeutic cells (TC). This review discusses these and also reviews the regulatory framework that now aims to ensure the quality of stem cells and TC for transplantation.Results:Important variables included cell concentration, temperature, interval from collection to cryopreservation, manipulations performed. They also included rate of freezing and whether controlled-rate freezing was employed. Parameters studied were type of cryoprotectant utilized [dimethyl sulphoxide (DMSO) is most commonly used, sometimes in combination with hydroxyethyl starch (HES)]; and storage conditions. It is also important to assess the quality of stored stem cells. Measurements employed included the total cell count (TNC), mononuclear cell count (MNC), CD34+ cells and colony-forming units - granulocyte macrophage (CFU-GM). Of these, TNC and CD34+ are the most useful. However, the best measure of the quality of stored stem cells is their subsequent engraftment. The quality systems used in stem cell laboratories are described in the guidance of the Joint Accreditation Committee of ISCT (Europe) and the EBMT (JACIE) and the EU Directive on Tissues and Cells plus its supporting commission directives. Inspections of facilities are carried out by the appropriate national agencies and JACIE.Conclusion:For high-quality storage of HSC and TC, processing facilities should use validated procedures that take into account critical variables. The quality of all products must be assessed before and after storage.

Freezing characteristics of acrylamide-based aqueous solution used for the preparation of supermacroporous cryogels via cryo-copolymerization

Solvent freezing crystallization is a crucial step to the satisfactory formation of homogenous and interconnected supermacropores within cryogels during the preparation of supermacroporous cryogel beds via cryo-copolymerization. In this work, the freezing characteristics of an aqueous solution system containing acrylamide (AAm), N ′ , N ′ -methylene-bis-acrylamide (MBAAm) and allyl glycidyl ether (AGE) for the production of polyacrylamide-based cryogels were investigated experimentally under various cooling conditions. Freezing curves of solution of AAm + AGE + MBAAm under various concentrations were measured to determine the corresponding values of freezing point temperature T mc and the actual initial solvent crystallization temperature T c . The effects of freezing rate and monomer concentration on T c and T mc were addressed. The results showed that the freezing rate had a limited effect on T mc when the freezing rate was very low under the present work. At the same time, T c changed randomly in a certain range with monomer concentration and freezing rate, while T mc decreased with the increase of monomer concentration under freezing condition at a constant freezing rate. Based on these results, the in-column freezing behaviors of 7% (w/w) aqueous solution of AAm + AGE + MBAAm reactive system initiated by ammonium persulfate (APS) and N, N, N ′ , N ′ -tetramethylethylenediamine (TEMED) under different freezing-temperature variation conditions were measured to reveal the actual solvent crystallization processes occurring within the column during the cryo-copolymerization. The properties of these cryogels were also measured and discussed.

Viabilidad de espermatozoides criopreservados de macha Mesodesma donacium (Mollusca, Bivalvia)

The viability of the surf clam spermatozoa was evaluated using the percentage of fertilization obtained with cryopreserved spermatozoa and different protocols. In total, 42 protocols combined three types of cryoprotectants (DMSO, Methanol, and Prophylen-glycol) at three different concentrations (0.5 M, 1.0 M, and 1.5 M), four freezing rates (-5, -10, -15, and -206oC·min -1 ), and two thawing rates (slow: 72oC·min -1 and fast: 312oC·min -1 ). The best sperm motility was obtained with DMSO frozen at -15oC·min -1 and with a slow thawing rate. The best fertilization percentages were obtained with DMSO frozen at -15oC·min -1 but with a fast thawing rate.

P-223: Use of two-cell stage mouse embryo as a model for comparison of vitrification in super-cooled liquid nitrogen with ultra-rapid freezing and slow-controlled rate freezing

To better understand the effect of different cooling rate in 2-cell mouse embryo cryopreservation, the vitrification in super-cooled liquid nitrogen (nitrogen slush) was compared with ultra-rapid freezing and slow controlled-rate freezing. The mouse embryo development post-thaw was followed. Laboratory experimental study. Six-eight week old female mice CD-1 (ICR) underwent superovulation with intraperitoneal administration of 5 IU of pregnant mare serum gonadotropin followed by 5 IU of human chorionic gonadotropin (hCG) 48 h later. Females were mated with mature males. Females with a vaginal plug were killed 40 hours after hCG receiving. Two-cell embryos were isolated from oviducts. The embryos were washed and incubated in 50 μl droplets of culture medium (global medium, Vitrolife®) under mineral oil (Medicult, Denmark). The embryos were allocated randomly to four groups. Embryos in group 1 (n = 245) were cryopreserved by exposure to vitrification solution for 2.5 min, then transfer to aluminium foil spoon before plunging into nitrogen slush (-210 °C, cooling rate 40,000 °C/min of 1 μl sample). In group 2 (n = 242), embryos were plunged with aluminum foil spoon in liquid nitrogen (-196 °C, cooling rate 2,500 °C/s) after equilibration in ultra-rapid freezing solution for 2.5 min. For slow freezing (group 3, n = 243), embryos were cryopreserved by programmable freezing (Planer Kryo10/1.7 freezer, cooling rate 250 °C/s) in conventional straw. Non-frozen embryos (group 4, n = 245) were control. Frozen embryos were thawed after preserve in close containers under liquid nitrogen for 2 weeks. They were then cultured in groups of 10-15 embryos in 25 μl drops of global monoculture medium under oil at 37 °C in an atmosphere of humidified 5% CO2, 5% O2, 20% N2. The numbers of survived embryos, further cleavage embryos, hatching blastocyst formation were assessed after immediate thawing, 24, 48 and 72 hours of culture. Fisher’s exact and χ2-tests were used for data analysis. Statistical tests were considered significant at the p < 0.05. Vitrification in nitrogen slush was significantly achieved in higher embryo survival rate (234/245; 96.73% vs 233/242; 96.28%, 166/243; 68.31% in group 2, 3, respectively), further cleavage rate (133/245; 54.29% vs 123/242; 50.83%, 62/243; 25.51% in group 2, 3) and hatching blastocyst formation rate (79/245; 32.24% vs 47/242; 19.42%, 39/243; 16.05%, in group 2, 3) compared with that of ultra-rapid and slow freezing group. Controls had higher further cleavage rate (166/245; 67.76%) and hatching blastocyst formation rate (101/245; 41.22%) than embryos that underwent freezing/thawing. Vitrification in nitrogen slush was demonstrated in effect of higher cooling rate to better improve in embryo cryopreservation. The use of mouse embryos as a model for cleavage human embryo freezing was approved.

Effect of pretreatments and freezing rate on the firmness of potato tissue after a freeze–thaw cycle

SummaryThe texture of potato tissue after a freeze–thaw process using different freezing rates and different pretreatments was analysed, in order to select the best strategy for optimum preservation of the textural characteristics of pre‐frozen potato. Ten blanching conditions were tested and a two‐step blanching process with calcium chloride (0.07 g mL−1) proved the most effective in protecting the tissue after a freeze–thaw process (maximum load force around 10–55% of the raw tissue, depending on potato batch, for air‐blast freezing and 20–60% for immersion freezing). Vacuum impregnation at 100 and 400 mbar, even when followed by different pre‐drying treatments to remove excess water, was very detrimental to resistance to a freeze–thaw process (maximum load force below 10% of the raw tissue for air‐blast freezing and below 20% for immersion freezing). Microstructure analysis confirmed better tissue integrity retention with ethyleneglycol immersion freezing instead of air‐freezing. Differences were found between batches with a 6‐month difference in storage time, indicating that the fresher batch was more suitable for freezing.

Corn Seed Germination and Vigor Following Freezing during Seed Development

The potential for an early autumn frost to reduce corn (Zea mays L.) seed quality is a concern for seed producers. This study evaluated the effect of freezing rate, freezing temperature (−6, −11°C) and duration (4, 6 h), ear attachment, and endosperm composition on seed germination and vigor (accelerated aging [AA] and cold test) during seed development and maturation of six corn hybrids in 1998, 1999, and 2000. Severe reductions in seed germination and vigor occurred for the most immature seeds frozen at &gt;400 g kg−1 seed moisture content (SMC). The effect was reduced as seed developed for all hybrids resulting in a linear increase in germination and vigor to maximum levels at ≤300 g kg−1 seed moisture, which was slightly after physiological maturity (PM, maximum dry seed weight). The effect of freezing on seed germination and vigor was the same when (i) ears were frozen attached or detached from the plant; (ii) ears were exposed to different freezing rates; or (iii) seeds with sugary and starchy endosperm were frozen. The degree of freezing injury at a given temperature and duration of freezing was similar across four F1 hybrids, but seed from one F2 hybrid was injured slightly less at a given moisture content. Thus, the stage of seed development must be considered by seed companies before making harvesting decisions when facing a potential predicted freezing event. Our results suggest that a seed producer will have higher germination and vigor if they harvest immature seeds (≤400 g kg−1 SMC) before the freezing event instead of after they are exposed to freezing temperatures.

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing.

Cryopreservation of the Endangered Mahseer (Tor khudree) Spermatozoa: Effect of Dimethyl Sulfoxide, Freezing, Activating Media, and Cryostorage on Post-Thaw Spermatozoa Motility and Fertility

The present study was conducted with the goal of evaluating the viability of spermatozoa of the Deccan mahseer (Tor khudree, Cyprinidae) cryopreserved using different strategies. Immotile spermatozoa pooled from 2–4 males were diluted with modified fish Ringer's solution (pH: 7.48) and protected with dimethyl sulfoxide (Me2SO) at 5%, 10%, and 15% and subjected to different equilibration periods. Diluted samples (1:10) were drawn into 500 µL plastic straws and frozen at a distance of 5 cm from the level of liquid nitrogen (LN2) and preserved for 385 days in LN2. Me2SO at 10% resulted in higher post-thaw spermatozoa motility rate (46.7%) than 5% or 15% (up to 33.3%) after 385 days of cryopreservation. Of the different equilibration periods, 20–40 min generally produced higher motility (%) rates than 0, 10, 50, 60, 70, 80, or 90 min. The highest post-thaw motility of spermatozoa was obtained when they were frozen at 2 cm (−120.3°C) above the level of LN2 and the optimum freezing rate was found to be 14.5 ± 0...

Freeze Concentration of Equal Molarity Solutions with Ultrasonic Irradiation Under Constant Freezing Rate: Effect of Solute

The performance of freeze concentration at constant freezing rate (40 mm h–1) with/ without ultrasonic irradiation was examined using three one-component solutions containing only one solute (ionic or molecular concentration: 0.03 mol L–1) and a three-component solution containing three solutes (each component concentration: 0.01 molL–1). Without ultrasonic irradiation the solutes are hardly concentrated at this freezing rate. On the other hand, with ultrasonic irradiation, the concentration efficiency increases with increasing intensity of ultrasonic irradiation. The solutes of smaller molecular weight are concentrated more effectively than solutes of larger molecular weight, regardless of the intensity of ultrasonic irradiation. This corresponds well to the magnitude of the diffusion coefficient of each solute. The difference between the concentration efficiencies of each solute in the three-component solution is smaller than that between the concentration efficiencies in the one-component solution, but the order of the values of the efficiencies is the same.

Critical freezing rate in freeze drying nanocrystal dispersions

Recent advances in nanoparticle technologies have significantly enhanced the oral and parenteral delivery of poorly water-soluble active pharmaceutical ingredients (APIs). However, reports have been limited on the various drying procedures to convert a liquid nanocrystal dispersions into solid dosage forms. The solid dosage form should consist of nanocrystals that can readily reconstitute into their original size upon dissolution in water. Herein, the freeze drying process of nanocrystal dispersions was examined at varying freezing rates (speed of freezing interface). As freezing rate decreases, more particle–particle aggregation developed. A critical freezing rate, below which the dried nanocrystals cannot be re-dispersed, was identified based on the plot of the particle size of reconstituted nanocrystals versus freezing rate. Freeze drying at a freezing rate near the critical value produces dry powders of bimodal particle size distribution after re-dispersion. In addition, API concentration was found to significantly affect the critical freezing rate and therefore the re-dispersibility of dry powders. The concept of critical freezing rate is critical for the development of solid dosage forms of liquid nanocrystal dispersions.

Beneficial Effects of Freezing Rate Determined by Indirect Thermophysical Calculation on Cell Viability in Cryopreserved Tissues

Many types of mammalian cells, such as sperm, blood, embryos, etc., have been successfully cryopreserved for the last few decades, while no optimal method for the cryopreservation of mammalian tissues or organs has been established, showing a poor survival after thawing with a low recovery of function. In this study, the freezing rate was determined by indirect thermodynamic calculation, and its potential effect on the cryoprotection of human saphenous veins and tissue-engineered bones was investigated. The vein segments were frozen according to the calculated freezing rate, using rate-controlled freezing devices, with a freezing solution composed of 10% dimethylsulphoxide and 20% fetal bovine serum in RPMI 1640 media. The efficacy of indirect calculation was assessed by the cell viability measured using fluorescence double-staining methods. The results indicated that the freezing rate determined by indirect calculation significantly (P < 0.05) maintained the post-thaw cellular viability of the blood vessel, particularly in terms of the endothelial cells. However, it exerted relatively less protective effect on the osteoblastic cell-cultured scaffolds. These results suggest that freezing-induced injuries may occur in tissues, and the freezing rate determined by indirect thermophysical calculation can be used for the optimization of tissue cryopreservation by minimizing the injuries.

Can a Rapider Freezing Rate Maintain Chicken Breast Quality?

Can a Rapider Freezing Rate Maintain Chicken Breast Quality?

An analytical study on the thermal effects of cryosurgery on selective cell destruction

The aim of cryosurgery is to kill cells within a closely defined region maintained at a predetermined low temperature. To effectively kill cells, it is important to be able to predict and control the cooling rate over some critical range of temperatures and freezing states in order to regulate the spatial extent of injury during any freeze–thaw protocol. The objective of manipulating the freezing parameters is to maximize the destruction of cancer cells within a defined spatial domain while minimizing cryoinjury to the surrounding healthy tissue. An analytical model has been developed to study the rate of cell destruction within a liver tumor undergoing a freeze–thaw cryosurgical process. Temperature transients in the tumor undergoing cryosurgery have been quantitatively investigated. The simulation is based on solving the transient bioheat equation using the finite volume scheme for a single or multiple-probe geometry. Simulated results show good agreement with experimental data obtained from in vivo clinical study. The calibrated model has been employed to study the effects of different freezing rates, freeze–thaw cycle(s), and multi-probe freezing on cell damage in a liver tumor. The effectiveness of each treatment protocol is estimated by generating the cell survival–volume signature and comparing the percentage of cell damaged within the ice-ball. Results from the model show that employing freeze–thaw cycles has the potential to enhance cell destruction within the cancerous tissue. Results from this study provide the basis for designing an optimized cryosurgical protocol which incorporates thermal effects and the extent of cell destruction within tumors.