scholarly journals The effect of temperature upon radioactive disintegration

Within the last few years the influence of high temperature on the activity of radium emanation, of the active deposit, and of radium C has been examined in detail by several authors. The conclusions arrived at have been conflicting, some workers affirming a positive effect of tem­perature, others denying it. This lack of agreement is due, however, to a difference in the method of measurement of the active matter under investigation. Those workers who measured the activity by γ-rays are all agreed that temperature has no effect whatever, while those who measured by β-rays found always an effect of some kind, in many cases of considerable magnitude, and often, indeed, of a very surprising nature. While, however, the fact that there is a β-ray effect is admitted by all, there is still a lack of agreement between the results of the experiments of different workers, and even of different experiments of the same worker, which is hardly to be expected if the effects were due to a definite change in the properties of the disintegrating atoms at high temperatures. In view, therefore, of the uncertainty which has arisen on a point of such great theoretical importance, a systematic investigation was necessary to obtain definite results, whether positive or negative. This the author, at the request of prof. Rutherford, has carried out.

2021 ◽  
Author(s):  
Esra Guneri ◽  
Yeliz Yukselen Aksoy

Abstract Thermal changes affect the engineering behavior of surrounding soils at energy geostructures. For that reason, there is a need for durable soils which are not affected from high temperatures or thermal cycles. Such kind of soil mixtures can be developed by adding temperature resistant materials such as perlite to the sand-bentonite mixtures. In this study, 10% and 20% perlite additives were added to 10% and 20% sand-bentonite mixtures, in order to develop the durable soil mixture under high temperatures. Direct shear and hydraulic conductivity tests were performed under room temperature and high temperature. The results of the experiments showed that the perlite additive reduced the unit weight of the sand-bentonite mixtures and had a positive effect on the shear strength of 20B-80S mixtures both under room and high temperature. The perlite addition increased the angle of internal friction of sand-bentonite mixtures under room and high temperature especially for 20B-80S mixtures. The hydraulic conductivity (k) values of both mixtures increased with increasing temperature. As a results of thermal cycles, it was seen that the samples cannot turn back to their initial k values.


A large number of investigators have attempted to alter the activity of various radio-active substances by subjecting them to very high and also to very low temperatures. Among all these attempts only two, as far as the writer is aware, have apparently given positive results. Curie and Danne found that the rate of transformation of the active deposit from radium was apparently permanently increased after it had been subjected to temperatures above 800°C. The writer repeated these experiments, and showed that this apparent increase was due to the volatilisation of radium B. By having the active deposit sealed in a glass tube when heated, it was shown conclusively that the rate of transformation had not been permanently altered by temperature up to 1100° C. In both the above experiments the rate of transformation was determined in the cold after the active matter had been removed from the furnace, and no attempt was made to detect any change in the activity of the active deposit while it was actually at a high temperature.


Forests ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 300 ◽  
Author(s):  
Congcong Guo ◽  
Yongbao Shen ◽  
Fenghou Shi

Pinus bungeana Zucc. ex Endl. is an endemic conifer tree species in China with high ornamental value. In order to investigate favorable conditions for seed germination and explore the germination inhibition mechanism of this species at high temperatures, the effects of temperature, light, and storage on the mean germination time (MGT), speed of germination (SG), and total germination percentage (TGP) are evaluated here. Seeds that have either been kept still or entered into a state of dormancy at high temperature are assessed here by a recovery experiment. Furthermore, the contribution of covering layers on thermo-inhibition is analyzed here, including the way they work. This has been realized by the structural observation and via the determination of the abscisic acid (ABA) content. The results show that seeds germinate to a high percentage (approximately 90%) at temperatures of 15 or 20 °C, with or without light, whereas higher temperatures of 25 or 30 °C impeded radicle protrusion and resulted in the germination percentage decreasing sharply (within 5%). Inhibition at high temperatures was thoroughly reversed (bringing about approximately 80% germination) by placing the ungerminated seeds in favorable temperatures and incubating them for an additional 30 days. Dry cold storage did little to reduce the temperature request for germination. Embryo coverings, especially the nucellar membrane, and ABA levels both had a dominant role in seed germination regulation in response to temperature. Under favorable temperature conditions, the levels of ABA significantly decreased. Germination occurred when the levels dropped to a threshold of 15 ng/g (FW (Fresh Weight)). Incubation at a high temperature (25 °C) greatly increased ABA levels and caused the inhibition of radicle protrusion.


Author(s):  
S Singh ◽  
P. K. Singh ◽  
S. K. Pathak

In the present study, we derived new relationship and expression for temperature dependence of thermal pressure for NaCl crystal. A mostly elastic property of solid depends on the strength of inter atomic forces of solids. The present work approach has been developed on the temperature dependence of thermal pressure for NaCl crystal at atmospheric pressure and volume expansion ratio at high temperature. So far our work has been concerted on thermal pressure is dependent of temperature and diverges it’s linearly in high temperature volume expansion ratio through effect of temperature. A close data and Gruneisen parameter is found to be in close agreement with investigational and theoretical shows the standing of present study.


1996 ◽  
Vol 121 (5) ◽  
pp. 920-926 ◽  
Author(s):  
James E. Faust ◽  
Royal D. Heins

The effect of temperature on axillary bud and lateral shoot development of poinsettia (Euphorbia pulcherrima Willd.) `Eckespoint Lilo' and `Eckespoint Red Sails' was examined. Rooted `Eckespoint Lilo' cuttings were transplanted and placed into growth chambers maintained at 21, 24, 27, or 30 °C for 2 weeks before apex removal. The percentage of nodes developing lateral shoots after apex removal was 68%, 69%, 73%, or 76% at 21, 24, 27, or 30 °C, respectively. Cuttings were removed from the lateral shoots, rooted, and placed into a 21 °C greenhouse, and the apices were removed. The percentage of nodes developing into lateral shoots on cuttings taken from plants held at 21, 24, 27, and 30 °C were 74%, 65%, 66%, and 21%, respectively. Of the cuttings in the 30 °C treatment, 83% of the nodes not producing a lateral shoot had poorly developed axillary buds or no visible axillary bud development. Visual rating of axillary bud viability decreased from 100% to 0% when `Eckespoint Red Sails' plants were transferred from a 21 °C greenhouse to a greenhouse maintained at 27 °C night temperature and 30 °C for 3 hours followed by 33 °C for 10 hours and 30 °C for 3 hours during the 16-hour day. Transfer from the high-temperature greenhouse to a 21 °C greenhouse increased axillary bud viability from 0% to 95%. Axillary buds of leaves not yet unfolded were sensitive to high temperatures, whereas those of unfolded leaves (i.e., fully developed correlatively inhibited buds) were not. Sixteen consecutive days in the high-temperature treatment were required for axillary bud development of `Eckespoint Red Sails' to be inhibited.


In a previous paper* it has been shown that the activity of radium emanation sealed in a quartz tube is temporarily changed by subjecting it for a short time to temperatures between 1000° C. and 1200° C. From the results obtained it seemed probable that this change was not due to any alteration of the emanation itself, but rather to a change of activity of one of the more quickly decaying products of the emanation with which it is in equilibrium. It seemed, however, desirable to put the matter beyond doubt, and, at the suggestion of Professor J. J. Thomson, we have measured the rate of decay of the emanation when kept at a temperature of 1100° C. The experiments indicate that the rate of decay of the emanation is the same under these conditions as at ordinary temperatures, the activity falling to half its original value in 3·88 days. This value is intermediate between that obtained by Curie† (3·99 days) and that given by Rutherford and Soddy‡ (3·71 days). The method of measurement was the same as that employed in the previous research, § and a diagram of the apparatus used is reproduced (fig. 1). In the present experiments, however, greater care was taken to eliminate errors due to any change of sensitiveness of the electrometer which might have occurred during the 10 days over which the observations extended. For this purpose the ionisation produced in the air contained in a cylindrical vessel by the rays (β and γ) coming from the quartz tube containing the emanation was compared with that produced between two parallel plates by a constant quantity of uranium. Assuming that the radiation from the latter remained constant, it was possible to allow for any slight change of sensitiveness of the electrometer.


Horticulturae ◽  
2021 ◽  
Vol 7 (11) ◽  
pp. 484
Author(s):  
Samia Samad ◽  
Denis Butare ◽  
Salla Marttila ◽  
Anita Sønsteby ◽  
Sammar Khalil

The growing interest in using everbearing (EB) strawberry cultivars to extend the cultivation period has faced some challenges. These include poor runner production due to its perpetual flowering nature; irregular flowering behavior and extended periods of high temperature have caused floral inhibition and reduced yield. As flowering is an interplay between temperature and photoperiod, it is important to investigate the effects of this interaction on the cultivation. Therefore, this study used meristem dissection as a tool to study the effect of temperature and photoperiod on meristem development. Tray plants of two EB strawberry cultivars ‘Florentina’ and ‘Favori’ were grown at 20 °C, 25 °C, and 30 °C under short day (SD) conditions, and subsequently at 20 °C under long day (LD) conditions. The meristem development was analysed every 6 weeks for a 15-week period in SD and for 14 weeks in LD conditions using meristem dissection. The plants showed similar flowering patterns to previously studied everbearing cultivars, which was qualitative LD plants at high temperatures and quantitative LD plants at lower temperatures. Our results show that meristem dissection can be used to determine the temperature and photoperiodic effect on meristem development, and for the occurrence of cropping peaks, and can therefore be used to decide the environmental input and to evaluate yield potential.


2003 ◽  
Vol 762 ◽  
Author(s):  
A. Gordijn ◽  
J.K. Rath ◽  
R.E.I. Schropp

AbstractDue to the high temperatures used for high deposition rate microcrystalline (μc-Si:H) and polycrystalline silicon, there is a need for compact and temperature-stable doped layers. In this study we report on films grown by the layer-by-layer method (LbL) using VHF PECVD. Growth of an amorphous silicon layer is alternated by a hydrogen plasma treatment. In LbL, the surface reactions are separated time-wise from the nucleation in the bulk. We observed that it is possible to incorporate dopant atoms in the layer, without disturbing the nucleation. Even at high substrate temperatures (up to 400°C) doped layers can be made microcrystalline. At these temperatures, in the continuous wave case, crystallinity is hindered, which is generally attributed to the out-diffusion of hydrogen from the surface and the presence of impurities (dopants).We observe that the parameter window for the treatment time for p-layers is smaller compared to n-layers. Moreover we observe that for high temperatures, the nucleation of p-layers is more adversely affected than for n-layers. Thin, doped layers have been structurally, optically and electrically characterized. The best n-layer made at 400°C, with a thickness of only 31 nm, had an activation energy of 0.056 eV and a dark conductivity of 2.7 S/cm, while the best p-layer made at 350°C, with a thickness of 29 nm, had an activation energy of 0.11 V and a dark conductivity of 0.1 S/cm. The suitability of these high temperature n-layers has been demonstrated in an n-i-p microcrystalline silicon solar cell with an unoptimized μc-Si:H i-layer deposited at 250°C and without buffer. The Voc of the cell is 0.48 V and the fill factor is 70 %.


Alloy Digest ◽  
1995 ◽  
Vol 44 (3) ◽  

Abstract NICROFER 5520 Co is a nickel-chromium-cobalt-molybdenum alloy with excellent strength and creep properties up to high temperatures. Due to its balanced chemical composition the alloy shows outstanding resistance to high temperature corrosion in the form of oxidation and carburization. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: Ni-480. Producer or source: VDM Technologies Corporation.


Alloy Digest ◽  
1994 ◽  
Vol 43 (7) ◽  

Abstract Carlson Alloy C601 is characterized by high tensile, yield and creep-rupture strengths for high temperature service. The alloy is not embrittled by extended exposure to high temperatures and has excellent resistance to stress-corrosion cracking, to carburizing, nitriding and sulfur containing environments. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on forming, heat treating, machining, and joining. Filing Code: Ni-458. Producer or source: G.O. Carlson Inc.


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