scholarly journals X-Ray studies of the structure of hair, wool, and related fibres. II.- the molecular structure and elastic properties of hair keratin

1933 ◽  
Vol 232 (707-720) ◽  
pp. 333-394 ◽  
Keyword(s):  
Molecular Structure ◽  
Elastic Properties ◽  
Historical Development ◽  
Complex Nature ◽  
X Ray ◽  
Hair Keratin ◽  
Structural Principles ◽  
Series Of Experiments ◽  
The Subject ◽  
Ray Methods

In a previous communication* an account was given of a preliminary exploration, chiefly by X-ray methods, of the problem of the molecular structure of animal hairs. The present paper is a natural continuation of the record, in which earlier tentative suggestions are either confirmed or rejected, and an attempt is made to lay bare the general structural principles underlying the properties of the protein, keratin . It will be unnecessary here to outline once more the historical development of the subject; we shall proceed at once to the main point of this introductory section, which is to give what appears to be the solution of the problem before setting out in detail the experimental facts and arguments leading up to it. Such a procedure is advisable because of the complex nature of the properties under discussion ; such a long series of experiments have been involved in their elucidation, that without some sort of preliminary statement of the chief conclusions, the issue is apt to grow confused.

scholarly journals X-rays studies of the structure of hair, wool, and related fibres. II. - The molecular structure and elastic properties of hair keratin

1934 ◽  
Vol 114 (788) ◽  
pp. 314-316 ◽  
Keyword(s):  
Molecular Structure ◽  
Elastic Properties ◽  
X Rays ◽  
Natural Silk ◽  
X Ray ◽  
Hair Keratin ◽  
Elastic Mechanism

From the examination of several hundred X-ray photographs of mammalian hairs, spines, etc., under a great variety of conditions, and comparison with the results of numerous collateral studies, the following conclusions have been complex, which is the basis of all such epidermal growths. The X-ray fibre photograph of stretched hair (β-keratin) is analogous to that of natural silk (fibrion), whether stretched or unstretched. Stretched hair (α-keratin) must consist of the same chains in a folded state, so that the elastic mechanism is that of a reversible intra-molecular transformation.

Chalkogenolat-Ionen und ihre Derivate, V Kristall- und Molekülstruktur von 2.8-Dimethyldibenzo [c.g] [1.2.5.6] tetrathiacyclooktadien, einem Oxidationsprodukt von 4-Methylbenzol-1.2-dithiol/Chalcogenolates and their Derivatives, V Crystal and Molecular Structure of 2.8-Dimethyldibenzo[c,g][1,2,5,6]tetrathiaocin, an Oxidation Product of 4-Methylbenzene-1,2-dithiol

1979 ◽  
Vol 34 (1) ◽  
pp. 48-51 ◽  
Author(s):  
Jürgen Kopf ◽  
Klaus von Deuten ◽  
Bahman Nakhdjavan ◽  
Günter Klar
Keyword(s):  
Molecular Structure ◽  
Dihedral Angle ◽  
Oxidation Product ◽  
Crystal And Molecular Structure ◽  
X Ray ◽  
The Mean ◽  
Ray Methods ◽  
Anti Form

Abstract The structure of 2,8-dimethyldibenzo[c,g][1,2,5,6]tetrathiaocin (1b) has been determined by X-ray methods and discussed in connection with the preferred conformations of diaryl disulfides. The compound has the anti-form I. The SS-distance is 205.8 pm, the mean CSS-angle 104.1°, and the CSS/SSC-dihedral angle 111.1°.

scholarly journals IX—investigations on magne-crystallic action III—Further studies on organic crystals

1935 ◽  
Vol 234 (739) ◽  
pp. 265-298 ◽  
Keyword(s):  
Molecular Structure ◽  
Crystal Lattice ◽  
Convenient Method ◽  
Organic Crystals ◽  
Double Refraction ◽  
Magnetic Susceptibilities ◽  
X Ray ◽  
Benzene Rings ◽  
The Individual ◽  
Ray Methods

In Part I* of this paper a convenient method of measuring the principal magnetic susceptibilities of single crystals was described, and several organic crystals, among others, were studied by this method. The results were discussed particularly in relation to the structure of the molecules and their orientations in the crystal lattice, and it was shown how a correlation of the principal magnetic susceptibilities of the crystal with those for the individual molecules (obtained from measurements on magnetic double-refraction in the liquid state, or from considerations of molecular structure) gives us useful information regarding the orientations of the molecules in the crystal lattice. Indeed, in favourable cases the molecular orientations may thus be determined much more easily, and some of the parameters defining the orientations also more accurately, than by X-ray methods of analysis. Conversely, where the molecular orientations in the crystal lattice are already known from X-ray studies, a knowledge of the principal magnetic susceptibilities of the crystal enables us to obtain the magnetic constants of the individual molecules, which are of interest. For example, it is thus found that as one proceeds from benzene to naphthalene and from naphthalene to anthracene, the numerical increase in susceptibility that occurs, is directed predominantly along the normal to the plane of the benzene rings

scholarly journals IV. The molecular structure and elastic properties of the biological cells

1938 ◽  
Vol 166 (924) ◽  
pp. 76-96 ◽  
Keyword(s):  
Molecular Structure ◽  
Elastic Properties ◽  
Elastic Behaviour ◽  
Biological Cells ◽  
Structural Elements ◽  
Cortical Cells ◽  
Histological Features ◽  
X Ray ◽  
Different Types ◽  
Keratin Fibres

Amongst the difficulties encountered in the study of the structure of hair not the least is its heterogeneity, whether considered crystallographically or histologically. From the former viewpoint progress has been made possible by assuming that there is no clear demarcation between “crystalline” and “amorphous” keratin, but rather that there is a continuous gradation of organization, so that the properties of “crystalline” keratin, which lies at one end of the scale, may be linked by a series of almost imperceptible changes with those of the keratin of any other degree of regularity. The X-ray photographs of the better organized parts have been regarded as signposts pointing the way to an understanding of what is happening, in the molecular sense, in the rest of the fibre substance. Histologically, it is possible to define to a certain extent the part played by the various structural elements by comparing the properties of different types of hair. In this way we find that all hairs have certain basic similarities in their behaviour, and if we confine our attention to these we may at once eliminate, as being of no fundamental importance, such special histological features as the cuticle or the medulla, which occur in certain types of hair only, or can be removed from the specimen. There remains, as the seat of the characteristic properties of keratin fibres, only the cortex, which in all hairs consists of a mass of biological cells apparently fused together by an “intercellular medium”. The present work is an attempt to discriminate between the cortical cells and the intercellular material in their relation to the elastic behaviour of the fibre.

η3- Allymetall-Schwefel-Cluster des Nickels, Palladiums und Platins / η3-Allyl Metal Sulfur Cluster Compounds of Nickel, Palladium, and Platinum

1979 ◽  
Vol 34 (4) ◽  
pp. 609-613 ◽  
Author(s):  
Borislav Bogdanović ◽  
Richard Goddard ◽  
Peter Göttsch ◽  
Carl Krüger ◽  
Klaus Schlichte ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Structural Similarity ◽  
Molecular Data ◽  
Cluster Compounds ◽  
Sulfur Cluster ◽  
Space Group ◽  
X Ray ◽  
Coordination Sites ◽  
Cell Data ◽  
Ray Methods

AbstractNovel cluster compounds of the composition [(η3-C3H5)2M2S]x, wherein M represents nickel, palladium or platinum are obtained by reaction of 2,5-disubstituted-1,6,6a-trithiopentalenes or H2S with (η3-C3H5)2M in THF solution. The molecular structure of one of these new cluster types [(η3-C3H5Ni)2S]3 has been established by X-ray methods. It is best described as being a fraction of a NiS-framework in which peripheral coordination sites are occupied by partial disordered η3-allyl groups. Molecular data (cell data: a = 19.868(4), b = 8.988(2), c = 14.501(3) Å, β = 115.30(2)°, space group C2/c, Z = 4, R = 0.106) are compared with the parent Bs-NiS lattice. Spectroscopic evidence for the structural similarity of the related Pd- and Pt-compounds is given.

A Ring Destruction Approach to Some Benzo-Fused Medium-Sized Heterocycles by Means of Cyanogen-Bromide Under Solvolytic Conditions - X-Ray Structure of a '1h-2,6-Benzoxazecine-6-Carbonitrile and a '2h-3,6-Benzoxazecine-6-Carbonitrile Derivative

1986 ◽  
Vol 39 (6) ◽  
pp. 893 ◽  
Author(s):  
JB Bremner ◽  
CL Raston ◽  
GL Rowbottom ◽  
AH White ◽  
KN Winzenberg
Keyword(s):  
Molecular Structure ◽  
Tertiary Amine ◽  
Cyanogen Bromide ◽  
Crystal And Molecular Structure ◽  
X Ray ◽  
Concomitant Reduction ◽  
Heterocyclic Derivatives ◽  
Isoquinoline Derivatives ◽  
Ray Methods ◽  
Medium Ring

Reaction of the reduced pyrrolo [2,1-a] isoquinoline amine (1a) with cyanogen bromide in the presence of methanol gave the medium-ring cyanamide derivative 7,9,10-trimethoxy-2,3,4,5,6,7-hexahydro-1H-3- benzazonine-3-carbonitrile (2a). Analogous products were also obtained from reaction of the reduced 5H-oxazolo[2,3-a] isoquinoline , 2H- benzo [a] quinolizine , 2H,6H-[1,3] oxazino [2,3-a] isoquinoline and [1,4] oxazino [3,4-a] isoquinoline derivatives (1b-e), whereas the reduced 3H-oxazolo[4,3-a] isoquinoline and 5H-oxazolo[2,3-a] isoquinoline derivatives (1f) and (8) gave 1-(2,4-dioxapentyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline-2-carbonitrile (5a) and N-[2-(2-benzoyl-4,5-dimethoxyphenyl)ethyl]-N- methylcyanamide (9) respectively, the latter in low yield. The medium-sized heterocyclic derivatives (2f-h) were also obtained from cyanogen -bromide-mediated water solvolysis reactions of (1a), (1c) and (1e). The cyanamides (2a-h), (5a) and (9) have been converted into the respective tertiary amine derivatives (3a- h), (5c) and (11), with concomitant reduction of the carbonyl group in the last case. The crystal and molecular structure of 1,10,11- trimethoxy-3,4,5,6,7,8-hexahydro-1H-2,6-benzoxazecine-6-carbonitrile (2d) and 1-hydroxy-10,11-dimethoxy-1,4,5,6,7,8-hexahydro-2H-3,6- benzoxazecine-6-carbonitrile (2h) have been determined by single- crystal X-ray methods.

Lewis-Säure/Base Addukte von TiCl4 und Methylpyridinen / Lewis Acid/Base Adducts of TiCl4 and Methylpyridines

2000 ◽  
Vol 55 (9) ◽  
pp. 877-881 ◽  
Author(s):  
Karl Hensen ◽  
Alexander Lemke ◽  
Michael Bolte
Keyword(s):  
Molecular Structure ◽  
Lewis Acid ◽  
Equatorial Position ◽  
Acid Base ◽  
Nitrogen Base ◽  
X Ray ◽  
Nitrogen Bases ◽  
Distorted Trigonal Bipyramid ◽  
In Trans ◽  
Ray Methods

By the reaction of 2-methyl- and 2,6-dimethylpyridine the first neutral TiCl4L complexes (L = single bonded ligand) could be synthesized. The structures have been determined by single crystal X-ray methods. The best description of the molecular structure is a distorted trigonal bipyramid with the nitrogen base occupying an equatorial position. With 2,4-dimethylpyridine, a 1:2 adduct is formed, where the nitrogen bases are in trans-positions of a TiCl4N2-octahedron, as also confirmed by an X-ray analysis

An X-ray examination of some potash-soda-felspars

1939 ◽  
Vol 25 (165) ◽  
pp. 338-350 ◽  
Author(s):  
S. H. Chao ◽  
D. L. Smare ◽  
W. H. Taylor
Keyword(s):  
Systematic Classification ◽  
X Ray ◽  
Natural Minerals ◽  
Thermal Investigations ◽  
Potash Felspar ◽  
Complete Survey ◽  
The Subject ◽  
First Time ◽  
Ray Methods

The systematic classification of the potash-soda-felspars is of the greatest interest and importance to the mineralogist, but problems demanding physical investigation are raised in work carried out recently by Dr. Edmondson Spencer, who has described the results of exhaustive chemical, optical, and thermal investigations of a representative collection of these minerals. Dr. Spencer has very kindly allowed us to examine by X-ray methods a large number of his specimens, so that for the first time it has been possible to make a fairly complete survey of potash-soda-felspars of known chemical composition and with accurately measured optical properties.This paper presents the results of our general survey of potash-soda-felspars with compositions ranging from nearly pure potash-felspar to approximately 50 % soda-felspar. The natural minerals, and the same minerals after specified heat-treatment, have been examined. We do not discuss in detail the interpretation of our results in terms of the atomic structure of felspars; the subject is extremely complicated, and it is necessary to await the results of other investigations now in progress in this laboratory before attempting a complete structural interpretation.

Solutions of Aluminium Trichloride in Tetramethylurea and the Molecular Structure of an Aluminium Trichloride Tetramethylurea Adduct

1986 ◽  
Vol 41 (5) ◽  
pp. 587-591 ◽  
Author(s):  
Astrid Bittner ◽  
Detlef Männig ◽  
Heinrich Nöth
Keyword(s):  
Molecular Structure ◽  
Nmr Spectroscopy ◽  
Oxygen Atom ◽  
Free Ligand ◽  
Addition Product ◽  
X Ray ◽  
Molecular Adduct ◽  
Aluminium Trichloride ◽  
Ray Methods

Abstract Aluminium trichloride forms a 1:1 addition product with tetramethylurea (1) the structure of which has been determined by X-ray methods. Tetramethylurea is bound to the AlCl3 unit via its oxygen atom; consequently, a lengthening of the CO bond is observed. The (CH3)2N units are less twisted relative to the OCN2 plane than in the free ligand. Solutions of AlCl3·OC(NMe2)2 in diethylether contain both the initial molecular adduct 1 and the ether adduct AlCl3·OEt2. In tetramethyl urea, compound 1 dissociates predominantly into the ions AlCl4- and {Cl2Al[OC(NMe2)2]2}+ . These solutions have been studied by 27Al NMR spectroscopy.

Synthesis of 2,3-Dihydro-1,4,5-benzodioxazocines. X-ray structure of 6-Phenyl-2,3-dihydro-1,4,5-benzodioxazocine

1983 ◽  
Vol 36 (12) ◽  
pp. 2555 ◽  
Author(s):  
EJ Browne ◽  
LM Engelhardt ◽  
AH White
Keyword(s):  
Molecular Structure ◽  
Single Crystal ◽  
Crystal And Molecular Structure ◽  
Ring System ◽  
Cyclic Dimer ◽  
X Ray ◽  
Ray Methods ◽  
By Products

Derivatives (6a-c) of the 1,4,5-benzodioxazocine ring system have been prepared in low-to-moderate yields by hydrazinolysis of {2-[2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)oxyethyloxy]aryl}phenylmethanones(5a-c), and cyclization of the products at pH c. 4. Only in the case of (6b) was a trace of a cyclic dimer (7b) detected, in contrast to the analogous preparations of the 2H-1,5,6-benzodioxazonine derivatives (1a-c) where 18-membered cyclic dimers (8a-c) formed as by-products. The crystal and molecular structure of 6-phenyl-2,3-dihydro-1,4-5-benzodioxazocine (6a) has been determined by single-crystal X-ray methods.

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