Temperature Lag Effect Research Articles

Daily Radial Growth of Oak in Relation to Maximum and Minimum Temperature

1. The relations between daily radial growth and maximum and minimum temperature of the day of growth measurement, 1 day before growth measurement, and 2 days before growth measurement were studied during the 1960 growing season for northern pin oak (Quercus ellipsoidalis Hill) growing on Plain-field sand in central Wisconsin. Correlation coefficients were obtained between growth and maximum and minimum temperature for (a) a 98-day period from June 8 to September 13; (b) a 70-day period from June 8 to August 16; (c) seven 2-week periods from June 8 to September 13; and, (d) four 3-week periods from June 8 to August 30. 2. Daily radial increment was significantly correlated with maximum and minimum temperature. The closeness of correlation varied during the growing season, with a general tendency to decline in the latter part. Earlier in the season, based on 3-week analyses, a closer relationship was indicated between growth and minimum temperature than between growth and maximum temperature. In late summer correlations between growth and temperature were not significant. 3. Correlations generally were better between growth and temperature of the day of growth measurement than between growth and temperature of the day before growth measurement. The possibility of a 1-day lag effect of temperature on growth was indicated, however, as was the absence of a 2-day effect. Possible physiological implications of the lag effect of temperature on growth are discussed. 4. Marked response of trees to even small amounts of intermittent precipitation during the growing season complicates evaluation of temperature-growth relations. Radial increase following a rain consists of a cambial growth component and increase resulting from stem rehydration. The hydration component often is greater than cambial growth.

An Improved Thunberg Technique for Bacterial Oxidations

Although more accurate methods of measuring redox potentials in connection with bacterial oxidations are now available,1,2 the Thunberg technique,3 which has been extended by Quastel4,5 and others, will no doubt continue to find wide application. It is especially useful where a large number of determinations are to be made, because of its greater simplicity and less time-consuming nature than the electrometric methods. At the same time, however, there are important sources of error. The purpose of this paper is to describe an improved method which either totally eliminates or greatly reduces the errors associated with the Thunberg technique as it has generally been used.In a recent critical study, Yudkin6,7 points out 6 factors which may interact to alter the reduction time of methylene blue by bacteria, when the suspension is evacuated and placed in a water bath. These are: (1) the temperature lag effect, (2) presence of residual oxygen, (3) gradual poisoning of the enzyme by methylene blue, (4) affinity...

Heat Transfer in the Vulcanization of Rubber

Abstract Temperature lag in the heating of rubber articles is found to cause marked non-uniformity of cure in the product. The theory of “unsteady state” heat flow is discussed, and a method described for analyzing data on temperatures in rubber being heated. From data on the temperatures at different times during the heating process and on the relation between the rate of cure and the temperature, it is shown how the resulting curing effect at different points in a solid rubber object may be calculated. A new water cure process for tires is described which is very effective in reducing the non-uniformity of cure caused by the temperature lag effect, and at the same time appreciably reduces the necessary curing time.

Heat Transfer in the Vulcanization of Rubber1

Abstract Temperature lag in the heating of rubber articles is found to cause marked non-uniformity of cure in the product. The theory of “unsteady state” heat flow is discussed, and a method described for analyzing data on temperatures in rubber being heated. From data on the temperatures at different times during the heating process and on the relation between the rate of cure and the temperature, it is shown how the resulting curing effect at different points in a solid rubber object may be calculated. A new water cure process for tires is described which is very effective in reducing the non-uniformity of cure caused by the temperature lag effect, and at the same time appreciably reduces the necessary curing time.