Initial Freeze Research Articles

Finite Element Analysis of Cold Embedments in Fresh Concrete

Analytical and finite element analyses are used in parametric studies to determine if ice forms in freshly placed concrete along embedments initially at subfreezing temperatures. The ice thicknesses and time frozen are also investigated. A nomograph that relates the initial bar temperature, bar size, freeze depth, and time frozen is presented. This nomograph is a convenient construction reference. Current codified precautions are evaluated for effectiveness. Possible adverse effects as well as remedies are discussed. The need for follow‐up testing is elaborated on.

Calorimetric analysis of antifreeze glycoproteins of the polar fish, Dissostichus mawsoni

Solutions of antifreeze glycoproteins 1 through 5 and 8 were analyzed for activity by differential scanning calorimetry. With a scan rate of 1 degree C min-1, antifreeze glycoproteins 1-5 (20 mg/ml) revealed antifreeze activity with a delay in the freeze exotherm during cooling in the presence of ice. Antifreeze glycoprotein 8 (60 mg/ml), however, did not reveal antifreeze activity. When a 0.1 degree C min-1 scan rate was used, glycoproteins 1-5 again yielded a delay in the freeze onset, but the exotherm consisted of multiple events. At the slower scan glycoprotein 8 revealed an initial freeze followed by multiple exothermic events resembling those of glycoproteins 1-5. Thermograms exhibiting antifreeze activity had an initial shoulder in the exotherm direction upon cooling followed by a delay before the exotherm. The shoulders were correlated with c-axis ice growth observed in visual methods. The glycoprotein antifreezes had a linear increase in activity with decreased ice content.

Apparent Nucleation and Freezing in Various Parts of Young Citrus Trees during Controlled Freezes

One- to 4-year-old sweet orange trees, Citrus sinensis (L.) Osbeck cv. Valencia on rough lemon (C. jambhiri Lush.) rootstock, were used in a series of tests on the depth and stability of supercooling in various parts of greenhouse-grown trees held in pots during controlled freezes. Thermocouples were attached to flowers, fruit, leaves, and wood. Supercooling levels were inconsistent, ranging from – 3C to – 7C. Nucleation was spontaneous and well defined by sharp exotherms. Rapid progression of crystallization (≈ 60 cm·min–1) indicated no major obstacles to ice propagation throughout the tree above soil level. The site of initial freezing was variable, with a tendency for trees to freeze from the base of the stem toward the top. The location of tissue damage did not necessarily correspond to the location of initial freeze event. Freezing in the wood often preceded freezing of flowers.

An improved method for preparing refrozen rethawed human lymphocytes on plates for microcytotoxicity studies

This report describes simplified methods for the initial freezing and thawing of human lymphocytes and the subsequent use of these cells after refreezing on cytotoxicity plates, storage, and a second thaw. The proposed initial freeze method eliminates some technical inconveniences required previously such as chilling of cells prior to addition of DMSO, preparing cryoprotective mixtures just prior to freezing, controlled rate of freezing and thawing and the washing of cells after thawing. However, pH of the media, blood freshness, type of storage tube used, and constant storage temperature were found to be very important to maintain good cell viability. Most lymphocytes maintain an average viability of 85 to 95% for at least a year when prepared according to the present freezing and thawing technique. When panels of lymphocytes are prepared for refrozen rethawed cytotoxicity test plates, the thaw time between freezes must be brief. Production of test plates on ice, however, was not found to be necessary. As the period of storage of refrozen cells on plates increases, viability of the cells after a second thaw decreases and treatment with DNase to enzymatically remove the dead cells is useful. With this procedure, refrozen rethawed lymphocytes up to a year old can be prepared on microcytotoxicity test plates with average viabilities of 90 ± 1%.

The Effectiveness of Phase II Price Controls

Phase II of the Economic Stabilization Program lasted from November 1971, when it replaced the initial freeze, until January 1973, when the less stringent controls of Phase III were initiated. It is widely thought that controls during Phase II succeeded in holding down wages and prices. The alleged success of Phase II controls and the rapid price rises during Phase III led to frequent demands for a return to the “good old days” of Phase II. The apparent success of Phase II controls contrasted with the failure of most past price control programs.

Results in labyrinthine cryosurgery monitored by evoked response.

AbstractCryosurgery is one conservative approach for Ménière's disease designed to control vertigo without adversely affecting the hearing in most cases. Report is made of 47 consecutive cases of cryosurgery. All patients were unresponsive to medical therapy. During the surgical procedure, the hearing is monitored at 2,000 cycles per second, and the vestibular function is monitored by evoked response to a loud click stimuli. Initial testing for threshold at 2,000 cycles and to a click stimulus is done by the evoked response. An initial freeze at —160°C. for two minutes is done, and the vestibular and auditory function is retested. A repeat freeze is completed unless there is a definite hearing change or the vestibular recording changes as evinced by the evoked response. If necessary, a third freeze is done, depending upon vestibular and auditory threshold changes. By this method a significant improvement of vertiginous symptoms resulted in 76 to 80 percent of the patients. The results of postoperative electronystagmography suggest an increase in unilateral weakness, but all cases showed a caloric response. In general, the hearing postoperatively continued to fluctuate as before surgery, accompanied by tinnitus, fullness, and recruitment. Morbidity in the way of hearing loss and temporary facial paralysis occurs in approximately 10 percent of the patients treated in this manner. Until a more knowledgeable approach to Ménière's disease is forthcoming, cryosurgery to the lateral semicircular canal still holds a position in the armamentarium for the treatment of patients who have incapacitating vertigo.