Theoretical Considerations on the Thermal Expansion of Copper‐Invar‐Copper Metalcore Boards for Surface Mounting Technology

The study of the coefficients of thermal expansion of substances has in the past, for the most part, been confined to direct measurement by optical methods. At the present time X-rays are being used for determining the expansion of the atomic lattice as distinct from the specimen block. A question has arisen as to tire relation between the coefficient of expansion as measured visually and that measured by X-rays. From theoretical considerations Zwicky* has predicted that the two are not identical. X -ray measurements on the thermal expansion of single crystals of bismuth by Goetz and Hergenrothers have shown that there is a difference between the values obtained by the two methods of measurement. On the other hand Y. Tu finds no evidence in his experiments on rock salt of the secondary structure described by Zwicky. The question to be answered is thus one of great importance. the present paper gives evidence to shown that for silver and quarts there is no difference between the coefficients of expansion as measured by X-rays and those from optical measurements. The work described in this paper was carried out to measure the thermal expansion of quartz by X-rays and by comparing the results with those from optical measurements to test the validity of the assumption, made in previous papers, that the coefficient of thermal expansion of silver is the same whether measured by X-rays or optical methods.

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Microstructural and Microchemical Characterization of Nickel Sulfide Inclusions in Plate Glass

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100089123 ◽

1991 ◽

Vol 49 ◽

pp. 962-963

Author(s):

J. Cooper ◽

O. Popoola ◽

W. M. Kriven

Keyword(s):

Thermal Expansion ◽

Phase Transformation ◽

Glass Matrix ◽

Nickel Sulfide ◽

Plate Glass ◽

Thermal Expansion Mismatch ◽

Volume Increase ◽

Β Phase ◽

Microchemical Characterization

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.

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The Biological Clock and Sleep in the Elderly

Zeitschrift für Gerontopsychologie & -psychiatrie ◽

10.1024/1011-6877.19.1.45 ◽

2006 ◽

Vol 19 (1) ◽

pp. 45-51 ◽

Cited By ~ 1

Author(s):

Myriam Juda ◽

Mirjam Münch ◽

Anna Wirz-Justice ◽

Martha Merrow ◽

Till Roenneberg

Keyword(s):

Circadian Rhythms ◽

Biological Clock ◽

The Elderly ◽

Early Morning ◽

Behavioral Changes ◽

Older Age ◽

Age Related ◽

Theoretical Considerations ◽

Sleep Difficulties ◽

Circadian Biology

Abstract: Among many other changes, older age is characterized by advanced sleep-wake cycles, changes in the amplitude of various circadian rhythms, as well as reduced entrainment to zeitgebers. These features reveal themselves through early morning awakenings, sleep difficulties at night, and a re-emergence of daytime napping. This review summarizes the observations concerning the biological clock and sleep in the elderly and discusses the documented and theoretical considerations behind these age-related behavioral changes, especially with respect to circadian biology.

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