THE HOMOGENEOUS UNIMOLECULAR DECOMPOSITION OF GASEOUS ALKYL NITRITES: VII. A GENERAL DISCUSSION OF THE EFFECT OF CHEMICAL CONFIGURATION ON THE REACTION RATE

1936 ◽  
Vol 14b (7) ◽  
pp. 268-274 ◽  
Author(s):  
E. W. R. Steacie ◽  
S. Katz ◽  
S. L. Rosenberg ◽  
W. McF. Smith
Keyword(s):  
Special Reference ◽  
Experimental Evidence ◽  
Homologous Series ◽  
Reaction Rate ◽  
Progressive Increase ◽  
Point Of View ◽  
Unimolecular Decomposition ◽  
Alkyl Nitrites

A general discussion is given of the rate of unimolecular decomposition of an homologous series of compounds from the point of view of the Kassel theory. The experimental evidence is discussed with special reference to the decomposition of the alkyl nitrites. It is concluded that existing theories are unable to account for the progressive increase in rate as one ascends the homologous series.

THE FAMILY HISTORY OF SPINA BIFIDA CYSTICA

PEDIATRICS ◽  
1965 ◽  
Vol 35 (4) ◽  
pp. 589-595
Author(s):  
John Lorber
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Spina Bifida ◽  
Index Case ◽  
Progressive Increase ◽  
Point Of View ◽  
The Family ◽  
History Of ◽  
The Central Nervous System ◽  
Spina Bifida Cystica

1. The family histories of 722 infants who were born with spina bifida cystica were studied. 2. The index cases were referred for surgical treatment and were not selected in any way from the genetic point of view. 3. Intensive inquiries were made to obtain a complete family pedigree, including a prospective follow-up of siblings born after the index case. 4. Of 1,256 siblings 85 or 6.8% had gross malformation of the central nervous system: spina bifida cystica in 54, anencephaly in 22, and uncomplicated hydrocephalus in 9. 5. Of 306 children born after the index case 25 (8%) or 1 in 12 were affected. 6. There was a progressive increase in multiple cases in the family with increasing family size. In sibships of five or more, multiple cases occurred in 24.1%. 7. In 118 families cases of gross malformation of the central nervous system were known to have occurred among members of the family other than siblings. Cases occurred in three generations. 8. It is possible that spina bifida cystica might be a recessively inherited condition.

scholarly journals Psychology—Normal and Morbid

1901 ◽  
Vol 47 (198) ◽  
pp. 553-553
Keyword(s):  
Special Reference ◽  
Point Of View ◽  
General Survey ◽  
Mental Processes ◽  
Royal Institution ◽  
Large Audience ◽  
Considerable Detail

We are well pleased to be able to state that Dr. Mercier's forthcoming work is now in the hands of the printers. It has been an open secret that his work for some years past has been nearing completion, and that it has at length assumed definite shape. The germ of Dr. Mercier's thesis has been already made known to us in his earlier writings, and now he is to produce the results of his matured thought and experience. The book is primarily intended as an introduction to the study of insanity, and under the title of Psychology, Normal and Morbid, it will constitute a general survey of mental processes with special reference to their bearing upon Conduct. The processes of reasoning, usually omitted from psychological works, are dealt with in considerable detail, this part of the book being practically a New Logic. Belief, with its morbid variant, Delusion; Truth; the theory of Probability which is extended from the domain of psychology; Will and Desire, in their normal and morbid manifestations; the significance of Pleasure and Pain; and the obscure region of Self-Consciousness are all dealt with from a new point of view, which permits of new conclusions being reached. Dr. Mercier's reputation as a psychologist drew a very large audience to the Royal Institution in May, when he delivered a lecture on Memory. No doubt that is promise of a still larger circle of readers intent to learn and to debate what is soon to be set forth in the systematic style above indicated.

XXVIII.—The Arrangement of Fibre Follicles in some Mammals, with special reference tothe Ovidæ

1939 ◽  
Vol 59 (3) ◽  
pp. 763-771 ◽  
Author(s):  
J. E. Duerden
Keyword(s):  
Special Reference ◽  
Point Of View ◽  
Research Association ◽  
General Development ◽  
Initial Form ◽  
Genetic Unit ◽  
Different Types

At the time of his death Dr Duerden was contemplating the preparation of a paper of this nature, and it is felt by Mrs Duerden that had he been able to express his wishes in this connection he would appreciate a record of the conclusions made by him. No one realised more than Dr Duerden himself the gaps which are still present in our knowledge and interpretation of the grouping of follicles and fibres in the mammalia, and this work is certainly not meant to be taken as representing Dr Duerden's final view or those of his colleagues at the Wool Industries Research Association. In view of the unique value of much of the material the present notes are intended, therefore, to form a basis and reference, firstly, for workers engaged in the general development of any mammalian coat from a morphogenic and phylogenetic point of view, and secondly, for those interested particularly in factors concerned in the formation of different types of fleeces in sheep. The conception of the follicle bundle as a discrete and basic genetic unit largely determining the initial form of the wool staple is of the highest importance in studies on the inheritance and developmentof fleece characters.

scholarly journals The spectrum of beryllium fluoride

1922 ◽  
Vol 101 (709) ◽  
pp. 187-194 ◽  
Keyword(s):  
Special Reference ◽  
Homologous Series ◽  
Alkaline Earth ◽  
The Other ◽  
Empirical Equations ◽  
Molecular Weights ◽  
Beryllium Fluoride ◽  
Previous Communication

In a previous communication, an account was given of an investigation of the spectra of the fluorides of magnesium, calcium, strontium, and barium, which was undertaken with a view to determine the numerical relations existing between these spectra. It was shown that the homologous series of the different spectra can be connected by empirical equations, involving only the constants of the series equations and the molecular weights or the molecular numbers of the respective compounds. It therefore seemed desirable to extend the investigation in order to ascertain if these relations are maintained in the spectrum of beryllium fluoride. Unlike the other alkaline earth compounds, the spectra of compounds of beryllium have previously received but little attention, and it has even remained doubtful whether the well-known groups of bands between λ4426 and λ5446 belong to the element itself or to the oxide. The present investigation has special reference to the spectrum of beryllium fluoride, which has not previously been recorded.

scholarly journals The homogeneous unimolecular decomposition of gaseous alkyl nitrites - IV—The decomposition of Iso -propyl nitrite

1935 ◽  
Vol 151 (874) ◽  
pp. 685-693 ◽  
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Pressure Change ◽  
Methyl Ethyl ◽  
Unimolecular Decomposition ◽  
Decomposition Rates ◽  
Straight Chain ◽  
Alkyl Nitrites ◽  
Branched Chain ◽  
Reaction Vessels

It has already been shown that the first three straight chain members of the nitrite homologous series, i. e ., methyl, ethyl, and n -propyl nitrites, have exhibited in their thermal decomposition the characteristics pertaining to homogeneous unimolecular reactions. This paper deals with the investigation carried out on iso -propyl nitrite decomposition. This member of the series is particularly interesting as it allows comparison to be made between a straight-chain and a branched-chain isomer. The effect of these chemical configurations on the activation energy and the decomposition rates can be very effectively studies as no complications enter into the reactions to confuse measurements. Experimental Reaction velocities were measured as before by observing the rate of pressure change in a system at constant volume. The reaction vessels were Pyrex glass bulbs with a capacity of about 125 cc. The apparatus was similar to that used in previous experiments. The connecting tubing was heated to 105° C to prevent any of the products of the reaction condensing out. Control and measurement of the temperature was carried out as before. The temperature could be maintained constant to within 0·25° C.

The Kirkendall Plane in Binary Interdiffusion Systems

2004 ◽  
Vol 233-234 ◽  
pp. 61-76 ◽  
Author(s):  
A.A. Kodentsov ◽  
A. Paul ◽  
F.J.J. van Loo
Keyword(s):  
Experimental Evidence ◽  
Kirkendall Effect ◽  
Point Of View ◽  
Chemical Approach ◽  
Diffusion Controlled ◽  
Physico Chemical ◽  
Considerable Body

There is now a considerable body of experimental evidence to indicate that in a volumediffusion controlled interaction the Kirkendall plane need not be unique. The Kirkendall plane can microstructurally be stable as well as unstable (it does not exist!). Under predictable circumstances, it can also bifurcate and even trifurcate. This can be rationalised in terms of Kirkendall velocity construction as well as from a purely chemical point of view considering diffusion-controlled interactions at the interphase interfaces. The physico-chemical approach is also used to explain significance of the Kirkendall effect in the morphogenesis of interdiffusion systems.

The Control of Two Antagonistic Locomotor Activities in a Predatory Insect

Behaviour ◽  
1977 ◽  
Vol 60 (1-2) ◽  
pp. 122-177 ◽  
Author(s):  
Ariane S. Etienne
Keyword(s):  
Target Tracking ◽  
Progressive Increase ◽  
Point Of View ◽  
The Other ◽  
Hand Tracking ◽  
Sudden Increase ◽  
Predatory Behaviour ◽  
Other Hand ◽  
Predatory Insect ◽  
Full Intensity

AbstractAeschna cyanea larvae are ambush hunters which, however, may readily pursue an escaping prey. Target tracking at first consists of lively swimming movements, and later of rapidly decelerating walking and creeping movements. If a dummy prey is removed after having been presented for 40 to 80 seconds, the insect 1) freezes and simultaneously looks in the direction where the prey stimulus has just disappeared. 2) Then it steps backwards repeatedly, and finally 3) it changes its body orientation by a series of (clockwise and/or counterclockwise) turning movements. Experiments in which the duration of the presentation of a moving dummy prey was extended from 5 to 80 seconds showed that the longer the insect spends tracking, the more probable and the more intense its subsequent backing-turning responses, and the sooner these responses occur after the disappearance of the prey. The occurrence and intensity of the backing-turning pattern seems to be more closely related to the insect's preceding tracking time than to the simultaneously covered tracking distance, which depends on the tracking speed. Intense backing-turning responses were not only primed by an extended presentation of the dummy, but also by a series of discontinuous brief presentations. Short tracking spells therefore exert a cumulative after-effect upon backing-turning. When the prey stimulus had been presented for longer than 80 seconds, backing-turning started to compete with fixation and approach reactions towards the prey. Under these circumstances, the insect backed and turned away from the dummy prey, as if the latter were no longer located in its visual field. The variation of both 1) the internal and 2) the external variables which activate predatory behaviour influenced the balance between tracking and backing-turning. i) During the first two days of food deprivation, the insects showed a progressive increase in the intensity of their tracking behaviour as well as in the probability and strength of their subsequent backing-turning responses. At the same time, the onset of the first backing response was delayed. 2) During a prolonged period when two artificial prey stimuli were presented alternately, the two differing in their degree of conspicuousness, more backing-turning responses occurred when the less conspicuous prey stimulus was present. Thus, not only a total disappearance, but also a partial reduction in the intensity of the prey stimulus, favoured the appearance of backing-turning. On the other hand, during a prolonged presentation of the prey stimulus, a sudden increase in its intensity while the insect was initiating the first backing response, was not followed up by the immediate resumption of predatory approach behaviour. During a sequence of brief presentations of the dummy prey, the insects increased their relative amount of tracking after they had displayed backing-turning for the first time. This suggests that the performance of the stereotyped pattern facilitates the subsequent resumption of tracking. The backing-turning pattern appeared only during or after the presentation of a prey stimulus and it was always preceded by approach or tracking behaviour orientated towards the prey. It seems therefore that only predatory locomotion - i.e. approach reactions orientated towards a static prey and target tracking towards a moving prey- prime backing-turning, itself a form of locomotion. A model is proposed according to which the performance of tracking exerts a negative feedback effect upon itself and at the same time progressively lowers the threshold of the mechanism controlling backing-turning. Therefore, after a prolonged pursuit, backing-turning starts to interfere with tracking. As long as the prey stimulus remains present, fixation and approach reactions alternate with backing and turning away from the prey. If the prey, however, is completely removed, positive appetitive behaviour towards the prey can no longer compete with backing-turning, and the stereotyped pattern can appear in its full intensity. On the other hand, tracking itself seems to be facilitated by the previous performance of backing-turning. From a functional point of view, the stereotyped pattern of locomotion may be conceived as a device 1) to stop the larva's unsuccessful attempts to reach a rapidly escaping prey, and 2) to diminish the probability that the insect may re-encounter this prey after its momentary disappearance.

scholarly journals Common Features on Damage Mechanisms Identified on Various Metal and Ceramic on Polyethylene Articulating Surfaces of Total Hip Prostheses

2007 ◽  
Vol 539-543 ◽  
pp. 629-634
Author(s):  
Denis Najjar ◽  
Francois Hennebelle ◽  
Alain Iost ◽  
H. Migaud
Keyword(s):  
Foreign Bodies ◽  
Demographic Data ◽  
Joint Space ◽  
Progressive Increase ◽  
Point Of View ◽  
Acetabular Cup ◽  
Systematic Assessment ◽  
Common Features ◽  
Total Hip

This paper presents a methodology for assessing the in-vivo degradation mechanisms of articular components of total hip replacement (THR) prostheses of Charnley type. The experimental procedure revealed that common features can be observed even if the clinical cases under investigation were quite different with regard to the demographic data. It particularly emphasises the detrimental effects of foreign bodies on the damage of the articulating surfaces. These foreign bodies can migrate into the joint space before embedding definitely into the Ultra High Molecular Weight Polyethylene (UHMWPE) acetabular cup surface where they further participate to a third body wear mechanism accelerated by a progressive increase of the femoral head roughness. Our experimental results underline, from a practical point of view, the need for careful manufacturing and clinical handling of porous surfaces, advocate for a systematic assessment of retrieved components, particularly when changed because of unexplained wear, and make questionable the clinical use of multifilament trochanteric cables.

Description of the Atomic Positions Around Interfacial Ledges in Terms of the Somigliana Dislocation Model

1991 ◽  
Vol 238 ◽  
Author(s):  
R. Bonnet ◽  
M. Loubradou
Keyword(s):  
Experimental Evidence ◽  
Displacement Field ◽  
Elastic Field ◽  
Point Of View ◽  
Low Energy ◽  
Elastic Displacement ◽  
Dislocation Model ◽  
Structural Units ◽  
Hexagonal Crystals ◽  
Translation State

ABSTRACTIn many materials, crystalline interfaces are facetted. The experimental evidence is that on each side of an interfacial ledge, or along the facets meeting along a common line, low energy atomic structural units are preserved which accommodate elastically angular or/and length misfit(s). Each facet can be considered as a Somigliana dislocation (SD) whose core is extended on the facet. The elastic displacement field of a SD is derived in an anisotropic continuum, for any orientation of the facet relative to a given Cartesian frame. From an atomic point of view, the translation state of the two crystals on each side of the facet is defined. The dislocation content attached to a ledge or a dihedral angle formed by two joining facets along a common side is also analyzed. The local elastic field related to these cases are derived and applications are presented for depicting the positions of the atomic columns in theoretical plots. Comparisons are made with some other theoretical works and HRTEM images. Examples illustrate the application of the Somigliana model to grain boundaries in hexagonal crystals (Mg, WC), and an interphase interface Ni3AI/Ni3Nb.

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