Twisted Fibrils are a Structural Principle in the Assembly of Interstitial Collagens, Chordae Tendineae Included

1987 ◽  
Vol 42 (11-12) ◽  
pp. 1303-1306 ◽  
Author(s):  
Waltraud Folkhard ◽  
Daniela Christmann ◽  
Werner Geercken ◽  
Ernst Knörzer ◽  
Michel H. J. Koch ◽  
...  
Keyword(s):  
Connective Tissue ◽  
General Principle ◽  
Type Iii Collagen ◽  
Type I ◽  
X Ray Diffraction ◽  
Chordae Tendineae ◽  
Tissue Samples ◽  
X Ray ◽  
Structural Principle ◽  
Interstitial Collagens

X-ray diffraction analysis of connective tissue samples, which contain type I and type III collagen shows that twisted collagen fibrils are a general principle of assembly. The occurrence of twisted fibrils in native wet Chordae tendineae, skin and Aorta is combined with a shorter axial periodicity of about 65 nm. This shorter D period is shown to be directly related to the tilt of the molecules, which have to be curved to build-up twisted fibrils.

A new model for packing of type-I collagen molecules in the native fibril

1981 ◽  
Vol 1 (10) ◽  
pp. 801-810 ◽  
Author(s):  
Karl A. Piez ◽  
Benes L. Trus
Keyword(s):  
Type I Collagen ◽  
Hexagonal Lattice ◽  
Three Dimensional ◽  
Equatorial Region ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Left Handed ◽  
Crystal Model ◽  
Collagen Molecules

A specific fibril model is presented consisting of bundles of five-stranded microfibrils, which are usually disordered (except axially) but under lateral compression become ordered. The features are as follows (where D = 234 residues or 67 nm): (1) D-staggered collagen molecules 4.5 D long in the helical microfibril have a left-handed supercoil with a pitch of 400–700 residues, but microfibrils need not have helical symmetry. (2) Straight-tilted 0.5-D overlap regions on a near-hexagonal lattice contribute the discrete x-ray diffraction reflections arising from lateral order, while the gap regions remain disordered. (3) The overlap regions are equivalent, but are crystallographically distinguished by systematic displacements from the near-hexagonal lattice. (4) The unit cell is the same as in a recently proposed three-dimensional crystal model, and calculated intensities in the equatorial region of the x-ray diffraction pattern agree with observed values.

The Effect of Different Methods to Pretreat Reed Pulp on the Crystallinity of Microcrystalline Cellulose

2014 ◽  
Vol 1056 ◽  
pp. 12-15 ◽  
Author(s):  
Wen Long Zhang ◽  
Wen Long Zhao ◽  
Ya Jie Dai
Keyword(s):  
Crystallite Size ◽  
Microcrystalline Cellulose ◽  
Average Crystallite Size ◽  
Comprehensive Analysis ◽  
Raw Material ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dimethyl Acetamide ◽  
Crystal Type

Reed Pulp was Raw Material that Pretreated by Four Methods {ultrasonic, Microwave, N, N-Dimethyl Acetamide (DMAc) and Tetrahydrofuran (THF)}. Reed Microcrystalline Cellulose (MCC) was Prepared by the Dilute Hydrochloric Acid Hydrolysis from Pretreated Reed Pulp. the Influences of Pretreatment Methods on Crystalline Type, Crystallinity and Crystallite Size of MCC were Investigated by X-Ray Diffraction (XRD). the Results Showed that the Crystallinity of MCC with Four Pretreatment Methods was 68.45%, 62.28%, 63.21% and 69.56%, Respectively. the Average Crystallite Size of MCC Prepared by Hydrolysis after Pretreated by Dmac was the Largest. whereas, the Crystal Type of MCC was Not Changed, it was still the Cellulose Type I. Comprehensive Analysis Indicated that the Effects of MCC Prepared by Hydrolysis after Pretreated by Ultrasonic were the Best.

X-ray diffraction studies on the connective tissue polysaccharides

1975 ◽  
Vol 91 (2) ◽  
pp. 153-163 ◽  
Author(s):  
J.K. Sheehan ◽  
E.D.T. Atkins ◽  
I.A. Nieduszynski
Keyword(s):  
Connective Tissue ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals The impact of crystal size and temperature on the adsorption-induced flexibility of the Zr-based metal–organic framework DUT-98

2019 ◽  
Vol 10 ◽  
pp. 1737-1744 ◽  
Author(s):  
Simon Krause ◽  
Volodymyr Bon ◽  
Hongchu Du ◽  
Rafal E Dunin-Borkowski ◽  
Ulrich Stoeck ◽  
...  
Keyword(s):  
Crystal Size ◽  
Metal Organic Framework ◽  
Adsorption Behavior ◽  
Switching Behavior ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Metal Organic ◽  
The Impact ◽  
Organic Framework

In this contribution we analyze the influence of adsorption cycling, crystal size, and temperature on the switching behavior of the flexible Zr-based metal–organic framework DUT-98. We observe a shift in the gate-opening pressure upon cycling of adsorption experiments for micrometer-sized crystals and assign this to a fragmentation of the crystals. In a series of samples, the average crystal size of DUT-98 crystals was varied from 120 µm to 50 nm and the obtained solids were characterized by X-ray diffraction, infrared spectroscopy, as well as scanning and transmission electron microscopy. We analyzed the adsorption behavior by nitrogen and water adsorption at 77 K and 298 K, respectively, and show that adsorption-induced flexibility is only observed for micrometer-sized crystals. Nanometer-sized crystals were found to exhibit reversible type I adsorption behavior upon adsorption of nitrogen and exhibit a crystal-size-dependent steep water uptake of up to 20 mmol g−1 at 0.5 p/p 0 with potential for water harvesting and heat pump applications. We furthermore investigate the temperature-induced structural transition by in situ powder X-ray diffraction. At temperatures beyond 110 °C, the open-pore state of the nanometer-sized DUT-98 crystals is found to irreversibly transform to a closed-pore state. The connection of crystal fragmentation upon adsorption cycling and the crystal size dependence of the adsorption-induced flexibility is an important finding for evaluation of these materials in future adsorption-based applications. This work thus extends the limited amount of studies on crystal size effects in flexible MOFs and hopefully motivates further investigations in this field.

Effects of alternating strain on the structure of a metal

1953 ◽  
Vol 220 (1141) ◽  
pp. 255-266 ◽  
Keyword(s):  
Fatigue Crack ◽  
Crystalline Structure ◽  
Fatigue Failure ◽  
General Principle ◽  
Small Strain ◽  
Local Deformation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sharp Distinction ◽  
Tension And Compression

The work is part of researches into the cause of fatigue failure in metals. The effects on the crystalline structure of successive unidirectional tensile strains are compared with the effects of the same strains applied alternately in tension and compression. It is found that X-ray diffraction shows a sharp distinction between the direct and alternating deformation. This is interpreted as showing as a general principle that alternating reversals of a sufficiently small strain do not significantly extend the regions in the grain disturbed by its first application, though they may intensify this local deformation. It is shown that the theory of dislocations could account qualitatively for the localizing of the deformation and the forming of the fatigue crack in the affected regions.

X-ray structure determination of the monoclinic (121 K) and orthorhombic (85 K) phases of langbeinite-type dithallium dicadmium sulfate

2000 ◽  
Vol 56 (6) ◽  
pp. 921-935 ◽  
Author(s):  
A. Guelylah ◽  
G. Madariaga ◽  
W. Morgenroth ◽  
M. I. Aroyo ◽  
T. Breczewski ◽  
...  
Keyword(s):  
Orthorhombic Symmetry ◽  
Type I ◽  
Type Ii ◽  
Monoclinic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Distortion Analysis ◽  
Precise Analysis ◽  
Monoclinic Distortion

The structures of the monoclinic and the orthorhombic phases of type I langbeinite Tl2Cd2(SO4)3 have been determined at 121 and 85 K, respectively, by X-ray diffraction. A precise analysis of these structures shows the existence of some differences compared to langbeinites of type II. The monoclinic structure differs very little from the high-temperature cubic structure and the distortion relating the monoclinic structure to the cubic one is very small. SO4 tetrahedra seem to rotate under orthorhombic symmetry in the monoclinic phase. A symmetry distortion analysis of the ferroelectric monoclinic distortion discloses the importance of the secondary modes with orthorhombic symmetry, especially for the O atoms of the SO4 groups.

Heat Treatment Strengthens Human Dentin

2008 ◽  
Vol 87 (8) ◽  
pp. 762-766 ◽  
Author(s):  
M. Hayashi ◽  
E.V. Koychev ◽  
K. Okamura ◽  
A. Sugeta ◽  
C. Hongo ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Stress Intensity ◽  
Type I Collagen ◽  
Type I ◽  
Third Molars ◽  
X Ray Diffraction ◽  
Intensity Factors ◽  
X Ray ◽  
Human Dentin ◽  
Triple Helices

The flexural strength of Type I collagen, the major organic component of human dentin, increases with heat. We hypothesized that human dentin can be strengthened by heating, which may help prevent fracture of non-vital teeth after restoration. Beam-shaped dentin specimens were obtained from the crowns of human third molars. The dentinal tubular orientations were arranged to run parallel or perpendicular to loading surfaces. The flexural and microtensile strengths of dentin in the parallel specimens were 2- to 2.4-fold greater after being heated between 110°C and 140°C for 1 hr. The stress intensity factors at fracture also increased after specimens were heated. The x-ray diffraction analyses suggested that shrinking of the lateral packing of the collagen triple-helices from 14 Å to 11 Å was the probable cause of the strengthening of heated dentin. We conclude that heat treatment strengthens human dentin.

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