Reproducibility of TMR for the Determination of Longitudinal Mineral Changes in Dental Hard Tissues

1997 ◽  
Vol 11 (4) ◽  
pp. 415-419 ◽  
Author(s):  
J.J.M. Damen ◽  
R.A.M. Exterkate ◽  
J.M. Ten Cate
Keyword(s):  
Quantitative Data ◽  
Surface Structures ◽  
Full Potential ◽  
Research Groups ◽  
Thin Sections ◽  
Dental Hard Tissues ◽  
Principal Method ◽  
Mineral Loss ◽  
Mineral Changes

Transverse microradiography (TMR) of thin sections is the principal method for determining mineral changes in experimental lesions. Because it has become also the standard by which newly-developed methods are validated, demands on all steps of the procedure are high. Thin sections of enamel and dentin require high-precision cutting or lapping to preserve surface structures, but their different brittleness and elasticity preclude a uniform procedure. Image analysis permits the measurement of fine details at a μm scale, but because most studies are aimed at overall mineral changes, they are usually lost on broadening of the scan areas and averaging of experimental groups. Small errors in repositioning of the scan areas for repetitive measurements may yield distorted lesion profiles, while quantitative data such as the integrated mineral loss are hardly influenced. A major reason for "irreproducibility" of TMR are the different definitions of the lesion parameters as used by various research groups. We recommend that these definitions be agreed on if the full potential of TMR as an international standard is to be utilized.

Fabric Description of Archaeological Ceramics

2016 ◽  
pp. 199-216 ◽  
Author(s):  
Ian Whitbread
Keyword(s):  
Quantitative Data ◽  
Raw Materials ◽  
Thin Sections ◽  
Archaeological Ceramics ◽  
Qualitative And Quantitative ◽  
Rock Fragments ◽  
Construction Methods ◽  
Hand Specimen ◽  
Technological Analysis

Fabric description is fundamental to the characterization, technological analysis and provenance determination of archaeological ceramics. It encompasses description of the arrangement, size, shape, frequency and composition of ceramic material constituents. These properties are used to identify the raw materials, their processing, vessel construction methods, and firing conditions. The process of description should, so far as possible, be an objective record of observed fabric properties that is independent of interpretations concerning technology and provenance. Fabric descriptions are made of ceramics in hand specimen and of samples prepared as thin sections for examination under a polarizing microscope. Rapid evaluation of fabric properties in the field is achieved by studying hand specimens using a magnifying glass or stereomicroscope. Laboratory-based analysis of thin sections provides more accurate and comprehensive identification of fabric properties, especially mineral and rock fragments in coarse fabrics, in terms of qualitative and quantitative data.

Demineralization and Remineralization Evaluation Techniques

1992 ◽  
Vol 71 (3_suppl) ◽  
pp. 924-928 ◽  
Author(s):  
J. Arends ◽  
J.J. ten Bosch
Keyword(s):  
Light Scattering ◽  
Mineral Content ◽  
Polarized Light ◽  
Cross Sectional ◽  
Main Emphasis ◽  
Measuring Techniques ◽  
Mineral Loss ◽  
Mineral Changes

This paper compares the experimental techniques utilized to assess the de- or remineralization of enamel or dentin in intra-oral studies. In in situ studies, it is important for one to know how much mineral has been lost or gained, and where the loss or gain occurred. The main emphasis in this paper is on techniques suitable for direct or indirect mineral quantification. The measuring techniques considered are microradiography, iodine absorptiometry, various microhardness tests, polarized light, light-scattering, iodide permeability, and wet chemical analysis. The various techniques are compared concerning suitability for the determination of mineral content in vol% (or wt%), mineral changes in vol% μm (or kg.m–2), and mineral distributions. Furthermore, sample preparation, the importance of protein penetration, nominal mineral loss range, the estimated mineral loss threshold, and the applicability to dentin are compared and considered. It is concluded that, although more than ten techniques are available for the measurement of changes after de- or remineralization in situ, transverse microradiography is the most practical technique for the direct and quantitative measurement of mineral content, mineral changes, and mineral distributions. Cross-sectional microhardness testing and light-scattering are also practical indirect techniques for quantitative mineral loss (or gain) determinations in intra-oral studies.

Determination of the phase structure of polymerblends by electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 492-493
Author(s):  
Dr. G. Kaemof
Keyword(s):  
Screw Extruder ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Single Screw Extruder ◽  
Transmission Electron ◽  
The Matrix ◽  
Twin Screw ◽  
Special Case ◽  
Microscopic Investigations

A mixture of polycarbonate (PC) and styrene-acrylonitrile-copolymer (SAN) represents a very good example for the efficiency of electron microscopic investigations concerning the determination of optimum production procedures for high grade product properties.The following parameters have been varied:components of charge (PC : SAN 50 : 50, 60 : 40, 70 : 30), kind of compounding machine (single screw extruder, twin screw extruder, discontinuous kneader), mass-temperature (lowest and highest possible temperature).The transmission electron microscopic investigations (TEM) were carried out on ultra thin sections, the PC-phase of which was selectively etched by triethylamine.The phase transition (matrix to disperse phase) does not occur - as might be expected - at a PC to SAN ratio of 50 : 50, but at a ratio of 65 : 35. Our results show that the matrix is preferably formed by the components with the lower melting viscosity (in this special case SAN), even at concentrations of less than 50 %.

Ultrathin Platinum Crystal Surface Structures

1985 ◽  
Vol 43 ◽  
pp. 394-395
Author(s):  
R. L. Hines
Keyword(s):  
Crystal Surface ◽  
Surface Structures ◽  
Platinum Surface ◽  
Platinum Surfaces ◽  
Resolution Level ◽  
Experimental Facilities ◽  
Carbon Backing ◽  
Mesh Grid ◽  
Atom Layer

The importance of atom layer terraces or steps on platinum surfaces used for catalysis as discussed by Somorjai justifies an extensive investigation of the structure of platinum surfaces through electron microscopy at the atomic resolution level. Experimental and theoretical difficulties complicate the quantitative determination of platinum surface structures but qualitative observation of surface structures on platinum crystals is now possible with good experimental facilities.Ultrathin platinum crystals with nominal 111 orientation are prepared using the procedure reported by Hines without the application of a carbon backing layer. Platinum films with thicknesses of about ten atom layers are strong enough so that they can be mounted on grids to provide ultrathin platinum crystals for examination of surface structure. Crystals as thin as possible are desired to minimize the theoretical difficulties in analyzing image contrast to determine structure. With the current preparation procedures the crystals frequently cover complete openings on a 400 mesh grid.

DIGITAL ZENITH CAMERA FOR VERTICAL DEFLECTION DETERMINATION

2012 ◽  
Vol 38 (4) ◽  
pp. 123-129 ◽  
Author(s):  
Māris Abele ◽  
Jānis Balodis ◽  
Inese Janpaule ◽  
Ieva Lasmane ◽  
Augusts Rubans ◽  
...  
Keyword(s):  
Data Processing ◽  
Digital Imaging ◽  
High Accuracy ◽  
Reference Star ◽  
Research Groups ◽  
Vertical Deflection ◽  
Digital Imaging Technology ◽  
Prototype Instrument ◽  
Automated Determination

Recent accomplishments in advancement of accurate astrometric reference star catalogues, development of digital imaging technology, high accuracy tiltmeter technology, and geocentric coordinate availability provided by GNSS, have made possible accurate, fast and automated determination of vertical deflections using astrometric methods. Zenith cameras for this kind of measurements have been developed or are being developed by several research groups. The paper describes a research project by Institute of Geodesy and Geoinformation, intended to design a portable digital zenith camera for vertical deflection determination with 0.1” expected accuracy. Camera components are described, proposed data processing algorithm and preliminary results, obtained with prototype instrument, are presented.

The petrology of the Mount Padbury mesosiderite and its achondrite enclaves

1966 ◽  
Vol 36 (276) ◽  
pp. 1029-1060 ◽  
Author(s):  
G. J. H. McCall
Keyword(s):  
Microscopic Analysis ◽  
Host Material ◽  
Refractive Indices ◽  
X Ray Diffraction ◽  
Thin Sections ◽  
X Ray ◽  
Wide Range ◽  
Varied Range ◽  
Optical Determination

SummaryThe petrography of the Mount Padbury meteorite, previously briefly recorded, is described in some detail. Both the metalliferous host material of the mesosiderite and the varied range of silicate-rich, virtually metal-free enclaves (including both familiar achondrite material and unfamiliar achondrite material) are described. Eucrite, brecciated eucrite, and a peculiar ‘shocked’ form of eucrite (resembling some terrestrial flaser-gabbros) are the calcium-rich achondrite types represented; hypersthene achondrite (including typical diogenite material and unfamiliar material) and olivine achondrite (granular aggregates of olivine not entirely similar to the unique chassignite and single crystals up to 4 in. in length) are the calcium-poor achondrite types represented. The eucrite displays more or less uniform mineralogy, but the mineral constituents are present in varying proportions, and there is a wide range of textural variations recognized. The silicate grain fragments enclosed in the metallic reticulation to form the mesosiderite host material are, significantly, entirely of minerals seen within the achondrite enclaves—plagioclase, hypersthene, pigeonite, olivine, and tridymite.These results include microscopic analysis of thin sections and polished sections, X-ray diffraction studies, optical determination of refractive indices using mineral grain mounts, and chemical analyses.The wider implications of this new and unique meteorite find are briefly considered.

scholarly journals First-Principles Determination Of The Effects Of Boron And Sulfur On The Ideal Cleavage Fracture In Ni3Al

1995 ◽  
Vol 409 ◽  
Author(s):  
Sheng N. Sun ◽  
Nicholas Kioussis ◽  
Mikael Ciftan ◽  
A. Gonis
Keyword(s):  
Cleavage Fracture ◽  
First Principles ◽  
Cleavage Plane ◽  
Full Potential ◽  
Fracture Properties ◽  
Electronic Mechanism ◽  
Strain Relationship ◽  
First Time ◽  
The Ideal

AbstractThe effects of boron and sulfur impurities on the ideal cleavage fracture properties of Ni3Al under tensile stress are investigated for the first time using the full-potential linearmuffin- tin-orbital (FLMTO) total-energy method, with a repeated slab arrangement of atoms simulating an isolated cleavage plane. Results for the stress-strain relationship, ideal cleavage energies, ideal yield stress and strains with and without impurities are presented, and the electronic mechanism underlying the contrasting effects of boron and sulfur impurities on the ideal cleavage of Ni3Al is elucidated.

Heuristic determination of quantitative data for knowledge acquisition in medicine

1991 ◽  
Vol 24 (3) ◽  
pp. 261-272 ◽  
Author(s):  
Dario A. Giuse ◽  
Nunzia Bettinsoli Giuse ◽  
Richard A. Bankowitz ◽  
Randolph A. Miller
Keyword(s):  
Knowledge Acquisition ◽  
Quantitative Data
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