scholarly journals The flow in metals under large constant stresses

1914 ◽  
Vol 90 (619) ◽  
pp. 329-342 ◽  
Keyword(s):  
High Temperature ◽  
Viscous Flow ◽  
Low Temperatures ◽  
Effect Of Temperature ◽  
Initial Part ◽  
Time Curve ◽  
Permanent Set ◽  
Pure Metals ◽  
Metallic Wires

§1. The object of this research was to examine the general laws of flow in metallic wires when extended in the region of large permanent set by stresses kept constant throughout the flow. Previously I have investigated in detail the flow for one metal, lead, and put forward some empirical laws; it was desired to see if these laws could be extended to other metals, and especially to investigate the effect of temperature on the nature of the flow. For lead, rise of temperature causes a very rapid increase in the rate of the viscous part of the flow ( loc. cit. ); hence it seemed likely that at very low temperatures the viscous part of the flow would case altogether, although large permanent extensions might be obtainable, and thus lead might behave in this respect as iron behaves at atmospheric temperatures. Similarly iron at a high temperature might behave like lead at atmospheric temperatures. It was also desired to see if very pure metals behaved in the same way as commercial metals, for it has been supposed that the nonviscous character of the initial part of the extension-time curve is due to impurities. Further, the properties of the viscous flow itself were to be investigated in greater detail. Investigation on these points are described in this paper; a summary of the results will be found in §10. Incidentally, in the case of alloys, a type of flow not hitherto observed has been found.

scholarly journals The effect of temperature on the activity of radium and transformation products

1907 ◽  
Vol 78 (526) ◽  
pp. 494-500
Keyword(s):  
High Temperature ◽  
Low Temperatures ◽  
Glass Tube ◽  
Transformation Products ◽  
Effect Of Temperature ◽  
Active Matter ◽  
Apparent Increase ◽  
Positive Results ◽  
Very High ◽  
Active Substances

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.

scholarly journals XI. Bakerian lecture.―The effect of temperature and pressure on the thermal conductivities of solids.—Part II. The effects of low temperatures on the thermal and electrical conductivities of certain approximately pure metals and alloys

1908 ◽  
Vol 208 (427-440) ◽  
pp. 381-443 ◽  
Keyword(s):  
Low Temperatures ◽  
Metals And Alloys ◽  
Effect Of Temperature ◽  
The Third ◽  
Electrical Conductivities ◽  
Pure Metals ◽  
Temperature And Pressure ◽  
Thermal Part ◽  
Thermal Conductivities

During the last fifty years a considerable amount of attention has been bestowed on the question of the variations of the thermal and electrical conductivities of metals with the temperature, hut the results obtained by different observers, especially of thermal conductivities, differed so widely from each other that the answer to the thermal part of the question long remained doubtful. In recent years, however, there has been an accumulation of evidence in favour of a slight decrease of thermal con­ductivity with increase of temperature from 0°C. to 100°C. in the case of most of the metals. The experiments of Lorenz, and more especially the careful work of Jager and Diesselhorst have contributed greatly to this result. In both these cases the experiments were limited to the range of temperature between 0°C. and 100°C., and it seemed advisable, in view of the importance of both questions in the electronic theories of conduction of heat and electricity in metals, to extend the range over which the theories could be tested, particularly in the direction of low temperatures, where the experiments of Dewar and Fleming had already furnished information as to the electrical conductivities. The present paper contains an account of the measurements of the thermal and electrical conductivities carried out for this purpose, and the results obtained. The first section deals with measurements of the thermal, the second with measurements of the electrical, conductivities of certain metals and alloys, and the third section compares the results with the electronic theories.

Textures in Extruded Uranium

1959 ◽  
Vol 3 ◽  
pp. 315-330
Author(s):  
R. B. Russell
Keyword(s):  
High Temperature ◽  
Low Temperatures ◽  
Reduction Ratio ◽  
Extrusion Temperature ◽  
Effect Of Temperature ◽  
Gamma Phase ◽  
Axial Texture ◽  
Pole Figures ◽  
Ram Speed ◽  
Reduction In Area

AbstractBy means of cristallographie (inverse) pole figures for extruded uranium rods and tubes, the effect of extrusion variables on the texture can be examined. The principal variables are: prior texture, billet and liner temperatures, reduction in area, and ram speed. The final texture can be deeply affected by the prior texture, since two extrusions made under the same conditions but with different prior textures can be markedly different.In general, an increase in extrusion temperature has an effect similar to an increase in reduction ratio. Ram speed has no important effect between 13 and 100 in./min except that a slow ram speed allows more time for recrystallization to occur.The effect of temperature on texture is the development of a strong 110 axial texture for relatively high temperature (above about 525°C), a strong 010 axial texture for relatively low temperatures (below 400°C), and a mixture of 110 and 010 axial textures at intermediate temperatures, although these textures may be somewhat complicated by 130 axial recrystallization textures.The variation of axial texture along the extrusion length and parallel to the radius of extruded tubes may be large.A 900°C gamma-phase extrusion is shown to have a mild 100, 010, 021, 001 texture.

scholarly journals The modification effect of temperature on the relationship between air pollutants and daily incidence of influenza in Ningbo, China

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Rui Zhang ◽  
Yujie Meng ◽  
Hejia Song ◽  
Ran Niu ◽  
Yu Wang ◽  
...  
Keyword(s):  
Air Pollution ◽  
High Temperature ◽  
Air Pollutants ◽  
Meteorological Data ◽  
Effect Of Temperature ◽  
Distributed Lag ◽  
Modification Effect ◽  
Incidence Risk ◽  
The Impact ◽  
The Relationship

Abstract Background Although exposure to air pollution has been linked to many health issues, few studies have quantified the modification effect of temperature on the relationship between air pollutants and daily incidence of influenza in Ningbo, China. Methods The data of daily incidence of influenza and the relevant meteorological data and air pollution data in Ningbo from 2014 to 2017 were retrieved. Low, medium and high temperature layers were stratified by the daily mean temperature with 25th and 75th percentiles. The potential modification effect of temperature on the relationship between air pollutants and daily incidence of influenza in Ningbo was investigated through analyzing the effects of air pollutants stratified by temperature stratum using distributed lag non-linear model (DLNM). Stratified analysis by sex and age were also conducted. Results Overall, a 10 μg/m3 increment of O3, PM2.5, PM10 and NO2 could increase the incidence risk of influenza with the cumulative relative risk of 1.028 (95% CI 1.007, 1.050), 1.061 (95% CI 1.004, 1.122), 1.043 (95% CI 1.003, 1.085), and 1.118 (95% CI 1.028, 1.216), respectively. Male and aged 7–17 years were more sensitive to air pollutants. Through the temperature stratification analysis, we found that temperature could modify the impacts of air pollution on daily incidence of influenza with high temperature exacerbating the impact of air pollutants. At high temperature layer, male and the groups aged 0–6 years and 18–64 years were more sensitive to air pollution. Conclusion Temperature modified the relationship between air pollution and daily incidence of influenza and high temperature would exacerbate the effects of air pollutants in Ningbo.

scholarly journals Potential for the Postharvest Biological Control of Phthorimaea operculella (Lepidoptera, Gelechiidae) by Blattisocius tarsalis (Mesostigmata, Blattisociidae)

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 288
Author(s):  
Jorge Gavara ◽  
Ana Piedra-Buena ◽  
Estrella Hernandez-Suarez ◽  
Manuel Gamez ◽  
Tomas Cabello ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Storage Conditions ◽  
Control Agent ◽  
Phthorimaea Operculella ◽  
Effect Of Temperature ◽  
Potato Storage ◽  
Release Rates ◽  
Blattisocius Tarsalis ◽  
Predatory Capacity ◽  
Pest Density

Phthorimaea operculella is one of the most important pests causing damage to stored potatoes. In this work, the effect of temperature (at 10, 20 and 30 °C) on the predation of pest eggs by Blattisocius tarsalis was studied in the laboratory. In addition, the effect of three predatory release rates on two pest densities was studied under microcosm conditions. The results showed that B. tarsalis maintains its predatory capacity at low temperatures (10 °C), obtaining an efficiency of 49.66 ± 5.06% compared to the control. In turn, at 20 °C, a maximum efficacy of 78.17 ± 4.77% was achieved, very similar to that presented at 30 °C (75.57 ± 4.34%). Under microcosm conditions and at low pest density (10 eggs/container), the mortality due to the mite was 96.97 ± 3.03%, 81.82 ± 8.84%, and 84.85 ± 8.30%, respectively, for the three predatory release rates (5, 10 or 20 mites/container). At the high infestation level, the pest control ranged from 61.54 ± 9.21% to 92.31 ± 2.74%, depending on the predatory release rate. The results obtained show that B. tarsalis could be a relevant control agent against P. operculella under non-refrigerated potato storage conditions, as well as in the first stages of their storage under refrigerated conditions.

Effect of temperature on the microbial ecology of a hydrocarbon-contaminated Antarctic soil: Implications for high temperature remediation

2008 ◽  
Vol 53 (1) ◽  
pp. 115-129 ◽  
Author(s):  
Susan H. Ferguson ◽  
Shane M. Powell ◽  
Ian Snape ◽  
John A.E. Gibson ◽  
Peter D. Franzmann
Keyword(s):  
High Temperature ◽  
Microbial Ecology ◽  
Effect Of Temperature ◽  
Antarctic Soil

Carbon Nanotubes Grown on Metallic Wires by Cold Plasma Technique

2002 ◽  
Vol 737 ◽  
Author(s):  
D. Sarangi ◽  
A. Karimi
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Growth Conditions ◽  
Effect Of Temperature ◽  
Rutherford Back Scattering ◽  
Novel Approach ◽  
Transmission Electron ◽  
Back Scattering ◽  
Metallic Wires ◽  
Metal Wires

ABSTRACTCarbon nanotubes on metallic wires may be act as electrode for the field emission (FE) luminescent devices. Growing nanotubes on metallic wires with controlled density, length and alignment are challenging issues for this kind of devices. We, in the present investigation grow carbon nanotubes directly on the metal wires by a powerful but simple technique. A novel approach has been proposed to align nanotubes during growth. Methane, acetylene and dimethylamine have been used as source gases. With the same growth conditions (viz. pressure, growth temperature and plasma) methane does not produce any nanotube but nanotubes grown with dimethylamine show shorter length and radius than acetylene. The effect of temperature to control the radius, time to control the density, plasma conditions to align the nanotubes has been focused. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Rutherford Back Scattering (RBS) are used to characterize the nanotubes.

ALPHA DECAY AND FISSION OF ALIGNED NUCLEI

1960 ◽  
Vol 38 (2) ◽  
pp. 290-314 ◽  
Author(s):  
N. R. Steenberg ◽  
R. C. Sharma
Keyword(s):  
Angular Distribution ◽  
High Temperature ◽  
Experimental Work ◽  
Low Temperatures ◽  
Alpha Decay ◽  
Alpha Particles ◽  
Nuclear Shape ◽  
Fission Fragments ◽  
Partial Waves ◽  
High Temperature Approximation

The theory of the angular distribution of alpha particles and of fission fragments from nuclei aligned at low temperatures is presented. Very explicit results are obtained in the high temperature approximation. These are directly dependent upon the branching which takes place to the various allowed partial waves. This branching is influenced by the nuclear shape, but it is shown that for this problem the effect of penetrating a spheroidal barrier is not critical. An application is made to the experimental work so far available and the result is reasonably satisfactory.

The Influence of Growth Temperature on Oxygen Concentration in GaN Buffer Layer

2008 ◽  
Vol 1068 ◽  
Author(s):  
Ewa Dumiszewska ◽  
Wlodek Strupinski ◽  
Piotr Caban ◽  
Marek Wesolowski ◽  
Dariusz Lenkiewicz ◽  
...  
Keyword(s):  
High Temperature ◽  
Buffer Layer ◽  
Oxygen Concentration ◽  
Growth Temperature ◽  
Low Temperatures ◽  
Buffer Layers ◽  
Crystalline Quality ◽  
Temperature Growth ◽  
Gan Buffer Layer

ABSTRACTThe influence of growth temperature on oxygen incorporation into GaN epitaxial layers was studied. GaN layers deposited at low temperatures were characterized by much higher oxygen concentration than those deposited at high temperature typically used for epitaxial growth. GaN buffer layers (HT GaN) about 1 μm thick were deposited on GaN nucleation layers (NL) with various thicknesses. The influence of NL thickness on crystalline quality and oxygen concentration of HT GaN layers were studied using RBS and SIMS. With increasing thickness of NL the crystalline quality of GaN buffer layers deteriorates and the oxygen concentration increases. It was observed that oxygen atoms incorporated at low temperature in NL diffuse into GaN buffer layer during high temperature growth as a consequence GaN NL is the source for unintentional oxygen doping.

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