Matrix-Mineral Relationships-A. Morphologist's Viewpoint

1979 ◽  
Vol 58 (2_suppl) ◽  
pp. 922-929 ◽  
Author(s):  
M.U. Nylen

The literature on the ultrastructural morphology of the enamel matrix and its relationship to the crystals is reviewed. Two morphological entities of the matrix are discussed: One is the so-called stippled material which may be the initial cell product; the other, variously described as fibrillar, lamellar, tubular or helical, is thought by many to play a crucial role in nucleation and orientation of the crystals. A number of observations, however, suggest that the latter structures form secondarily to the crystals and that in reality they represent organic material adsorbed to the crystal surface and maintained as independent structures upon removal of the mineral. The need for additional studies is stressed including systematic studies of interactions between constituents of the organic matrix and the apatite crystals.

1979 ◽  
Vol 58 (2_suppl) ◽  
pp. 943-949 ◽  
Author(s):  
S.A. Leach

This discussion is presented as an attempt to interrelate the matrix and mineral in terms of our existing knowledge as presented at this Symposium, and to relate it, where possible, to what is being accomplished in allied disciplines and research areas elsewhere. The present author is fully aware of the difficulties involved in this task and of his own inadequacies in attempting to perform it. As a general rule, with perhaps the morphologists being the exception to it, the matrix and crystal components have been investigated independently of each other. This, of course, is quite justifiable, as the presence of one can often interfere with the investigation of the other, and each needs to be examined initially in as pure a state as possible.


2005 ◽  
Vol 84 (11) ◽  
pp. 1075-1078 ◽  
Author(s):  
Y. Nishitani ◽  
M. Yoshiyama ◽  
F.R. Tay ◽  
B. Wadgaonkar ◽  
J. Waller ◽  
...  

The bond strengths of resins to caries-affected dentin are low. This could be due to weakened organic matrix. The purpose of this work was to determine if the ultimate tensile strength (UTS) of excavated carious dentin is weaker than that of normal dentin. Soft caries was excavated from extracted human molars, and the tooth was vertically sectioned into slabs. Each slab was trimmed to an hourglass shape, parallel or perpendicular to the tubule direction. Half of the specimens were mineralized, while the other half were completely demineralized in EDTA. ANOVA on ranks showed that the three-factor interactions (mineralization, caries, tubule direction) were all significant (p < 0.0001), indicating that mineralization and tubule direction gave different UTS results in normal and caries-affected dentin. No significant differences were seen between the UTS of normal and and that of caries-affected demineralized dentin in the parallel or perpendicular group. The matrix of demineralized caries-affected dentin was as strong as that of normal demineralized dentin when tested in the same direction.


1972 ◽  
Vol 50 (8) ◽  
pp. 735-739
Author(s):  
K. C. Hong ◽  
K. Iida ◽  
R. L. Cruess

The 85Sr uptake and the phospholipid, collagen, and mucopolysaccharide content of metaphyseal and diaphyseal rat bone were investigated. 85Sr uptake was higher in the metaphysis, which contains more organic material, than in the diaphysis. Metaphyseal bone contained more phospholipid, proline, hexosamine, and hexuronic acid, but less hydroxyproline, than diaphyseal bone. Lecithin, phosphatidylethanolamine, and sphingomyelin were the principal phosphatides of both regions of bone; metaphyseal bone contained slightly more lecithin but there were no significant differences in the percentages of the other two neutral phosphatides. The ratio of hexosamine to hexuronic acid was 1.1 for the metaphysis and 2.4 for the diaphysis. Intravenous administration of polyuronides led to a significant decrease in the strontium uptake of bone.


2014 ◽  
Vol 6 (2) ◽  
pp. 46-51
Author(s):  
Galang Amanda Dwi P. ◽  
Gregorius Edwadr ◽  
Agus Zainal Arifin

Nowadays, a large number of information can not be reached by the reader because of the misclassification of text-based documents. The misclassified data can also make the readers obtain the wrong information. The method which is proposed by this paper is aiming to classify the documents into the correct group.  Each document will have a membership value in several different classes. The method will be used to find the degree of similarity between the two documents is the semantic similarity. In fact, there is no document that doesn’t have a relationship with the other but their relationship might be close to 0. This method calculates the similarity between two documents by taking into account the level of similarity of words and their synonyms. After all inter-document similarity values obtained, a matrix will be created. The matrix is then used as a semi-supervised factor. The output of this method is the value of the membership of each document, which must be one of the greatest membership value for each document which indicates where the documents are grouped. Classification result computed by the method shows a good value which is 90 %. Index Terms - Fuzzy co-clustering, Heuristic, Semantica Similiarity, Semi-supervised learning.


2011 ◽  
Vol 20 (08) ◽  
pp. 1663-1675 ◽  
Author(s):  
A. BHAGWAT ◽  
Y. K. GAMBHIR

Systematic investigations of the pairing and two-neutron separation energies which play a crucial role in the evolution of shell structure in nuclei, are carried out within the framework of relativistic mean-field model. The shell closures are found to be robust, as expected, up to the lead region. New shell closures appear in low mass region. In the superheavy region, on the other hand, it is found that the shell closures are not as robust, and they depend on the particular combinations of neutron and proton numbers. Effect of deformation on the shell structure is found to be marginal.


1979 ◽  
Vol 58 (2_suppl) ◽  
pp. 883-895 ◽  
Author(s):  
P.L. Glick

Investigations of the maturation pattern of rat incisor enamel by quantitative electron microscopy and electron-probe microanalysis indicate that mineralization of rat enamel can be regarded, as in humans, as a regular and progressive process pattern of enamel matrix formation. The species variations that have been proposed in the pattern of enamel mineralization can be related to differences in both the rate of formation of the enamel matrix and in the total thickness of the enamel produced. Neither the microradiographic appearance of developing enamel, nor the solubility and staining characteristics of the organic matrix accurately reflects the mineral concentration gradients established during the mineralization process as indicated from electron microprobe analysis.


1979 ◽  
Vol 58 (2_suppl) ◽  
pp. 871-882 ◽  
Author(s):  
C. Robinson ◽  
H.D. Briggs ◽  
P.J. Atkinson ◽  
J.A. Weatherell

An investigation of the changes taking place in the enamel and the enamel organ during enamel development has been carried out by analyzing small samples of tissue dissected from developing incisors of rat and bovine incisors. Observations showed that the synthesis of the enamel matrix and its subsequent loss were associated chiefly with a change in the major matrix components. This consisted of a selective loss of amelogenin components prior to secondary mineralization. Before this loss, some increase in the proportion of smaller molecular weight components suggested the possibility of limited breakdown. Even at the earliest stages examined, significant concentration of mineral ions was present. This increased steeply after most of the organic matrix had been removed. The Ca/P ratio of this mineral was constant throughout development. The concentration of minor inorganic ions (F, Mg and CO3) decreased as the tissue developed and a tendency was observed for certain ions (F, 32PO4) to penetrate and concentrate in the enamel, apparently as a consequence of the lost matrix being replaced by water, just prior to the steep increase in mineral content of the tissue.


1991 ◽  
Vol 113 (4) ◽  
pp. 425-429 ◽  
Author(s):  
T. Hisatsune ◽  
T. Tabata ◽  
S. Masaki

Axisymmetric deformation of anisotropic porous materials caused by geometry of pores or by distribution of pores is analyzed. Two models of the materials are proposed: one consists of spherical cells each of which has a concentric ellipsoidal pore; and the other consists of ellipsoidal cells each of which has a concentric spherical pore. The velocity field in the matrix is assumed and the upper bound approach is attempted. Yield criteria are expressed as ellipses on the σm σ3 plane which are longer in longitudinal direction with increasing anisotropy and smaller with increasing volume fraction of the pore. Furthermore, the axes rotate about the origin at an angle α from the σm-axis, while the axis for isotropic porous materials is on the σm-axis.


2021 ◽  
Vol 60 (3-4) ◽  
pp. 363-398

Abstract The Roman father and son of the same name, P. Decius Mus, became paragon heroes by deliberately giving their lives in battle that Rome might win over a fierce enemy. Both engaged in a special ritual called devotio (from which our word “devotion” derives) to offer themselves to the gods of the Underworld, with whom regular people have very little interaction and to whom they rarely sacrifice. While the Mus family is the most famous for this act, it turns out the willingness to sacrifice oneself for Rome frequently occurs within stories of great patriots, including the story of Horatius Cocles, Mettius Curtius, Atilius Regulus, and even the traitors Coriolanus and Tarpeia. Romans regarded self-sacrifice as a very high, noble endeavor, whereas they loathed and persecuted practitioners of human sacrifice. It is therefore quite amazing to read that the Romans thrice engaged in state-sponsored human sacrifice, a fact they rarely mention and generally forget. The most famous enemy practitioners of human sacrifice were the Druids, whom the Romans massacred on Mona Island on Midsummer Night's Eve, but the Carthaginians, the Germans, the Celts, and the Thracians all infamously practiced human sacrifice. To Romans, the act of human sacrifice falls just short of cannibalism in the spectrum of forbidden practices, and was an accusation occasionally thrown against an enemy to claim they are totally barbaric. On the other hand, Romans recognized their own who committed acts of self-sacrifice for the good of the society, as heroes. There can be no better patriot than he who gives his life to save his country. Often the stories of their heroism have been exaggerated or sanitized. These acts of heroism often turn out to be acts of human sacrifice, supposedly a crime. It turns out that Romans have a strong legacy of practicing human sacrifice that lasts into the historic era, despite their alleged opposition to it. Numerous sources relate one story each. Collecting them all makes it impossible to deny the longevity of human sacrifice in Rome, although most Romans under the emperors were probably unaware of it. The paradox of condemning but still practicing human sacrifice demonstrates the nature of Roman religion, where do ut des plays a crucial role in standard sacrifice as well as in unpleasant acts like human sacrifice. Devotio was an inverted form of sacrifice, precisely because it was an offering to the gods of the Underworld, rather than to Jupiter or the Parcae. Romans may have forsaken devotio, but they continued to practice human sacrifice far longer than most of us have suspected, if one widens the current narrow definition of human sacrifice to include events where a life is taken in order to bring about a better future for the commonwealth, appease the gods, or ensure a Roman victory in battle.


Author(s):  
Alexander Batson

This chapter argues that the concept of equity plays a crucial role in Calvin’s early writings, especially in the Commentary on Seneca and the 1536 edition of the Institutes. Calvin embraces two distinct yet inseparable meanings of the term ‘equity’. One sense is as an interpretative principle of natural law, and the goal at which all civil law aims. The other sense is an application of the interpretative sense, in which a ruler or judge amends a civil law that is too strict or too general to take into account all the particularities of a certain case. Calvin’s concept of equity displays both his humanist legal training as well as the critical place of natural law in his theology.


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