scholarly journals Preparo inicial em periodontia: avaliações perfilométricas e microscópias pós-remoção de excesso cervicais de restaurações

2021 ◽  
pp. 73-80
Author(s):  
Raul G. Caffesse ◽  
José D. Freitas Vale
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Class Ii ◽  
Measuring Instrument ◽  
Combined Use ◽  
The Mean ◽  
Amalgam Restorations ◽  
Scanning Electron ◽  
Better Than

Forty recently extracted teeth with Class II amalgam restorations with overhangs were divided in four groups of ten teeth each. The overhangs were removed using one of the following instruments in each gruop: trimmer, chisel, surgical blade and reciprocating.motor.driven diamond tip. Instrumentation was performed until no irregularity could be detected clinically with a nº 3 explorer. The tooth.amalgam interfaces were examined by combined use of a surface measuring instrument and a scanning electron microscope. Four tracings from each specimen were recorded and the vertical discrepancy at the tooth.restoration interfaces measured. The mean score for tooth was determined, and the results were photographed aí 140 magnification with the SEM. The results indicated that all instruments tested were effective in removing overhangs, since none of the discrepancies registered after instrumenntation exceeded 4 Um. The surgical blade, and especially the reciprocting-motor.driven diamond tip eliminated overhangs better than the chisel. Both SEM photographs and the profilometric tracing revealed gaps at the tooth amalgam interface, rancing from 10 t o 50 Um in width.

Resolution and measurement in the scanning electron microscope

1987 ◽  
Vol 45 ◽  
pp. 534-537 ◽  
Author(s):  
Michael T. Postek
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Engineering Design ◽  
Resolving Power ◽  
Practical Applications ◽  
Instrument Resolution ◽  
Accurate Definition ◽  
Definition Of ◽  
Scanning Electron ◽  
Better Than

The term ultimate resolution or resolving power is the very best performance that can be obtained from a scanning electron microscope (SEM) given the optimum instrumental conditions and sample. However, as it relates to SEM users, the conventional definitions of this figure are ambiguous. The numbers quoted for the resolution of an instrument are not only theoretically derived, but are also verified through the direct measurement of images on micrographs. However, the samples commonly used for this purpose are specifically optimized for the measurement of instrument resolution and are most often not typical of the sample used in practical applications.SEM RESOLUTION. Some instruments resolve better than others either due to engineering design or other reasons. There is no definitively accurate definition of how to quantify instrument resolution and its measurement in the SEM.

scholarly journals Why Pressure Scales Cause So Much Confusion

1993 ◽  
Vol 1 (8) ◽  
pp. 5-6
Author(s):  
Anthony D. Buonaquisti
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Ambient Pressure ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Scanning Auger Microprobe ◽  
The Mean ◽  
Scanning Electron

Pressure scales can be extremely confusing to new operators. This is not surprising. To my mind, there are three primary areas of confusion.Firstly, the pressure of gas inside an instrument changes over many orders of magnitude during pumpdown. The change is about 9 orders of magnitude for a traditional Scanning Electron Microscope and about 13 orders of magnitude for an ultra-high vacuum instrument such as a Scanning Auger Microprobe.To give an idea about the scale of change involved in vacuum, consider that the change in going from ambient pressure to that inside a typical ultra high vacuum system is like comparing one meter with the mean radius of the planet Pluto's orbit. The fact is that we don't often get to play with things on that scale. As a consequence, many of us have to keep reminding ourselves that 1 X 10-3 is one thousand times the value of 1 X 10-6 - not twice the value.

Voltage and Dopant Concentration Measurements of Semiconductors using a Band-Pass Toroidal Energy Analyzer Inside a Scanning Electron Microscope

2015 ◽  
Vol 21 (4) ◽  
pp. 910-918 ◽  
Author(s):  
Avinash Srinivasan ◽  
Anjam Khursheed
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Dopant Concentration ◽  
High Signal ◽  
Energy Analyzer ◽  
Order Of Magnitude ◽  
Band Pass ◽  
Concentration Measurements ◽  
Scanning Electron ◽  
Better Than

AbstractThis paper presents experimental results obtained from a scanning electron microscope (SEM) second-order focusing toroidal electron energy analyzer attachment. The results demonstrate that the analyzer can be used to obtain high signal-to-noise voltage and dopant concentration measurements on semiconductors in the presence of different electric field conditions at the sample. The experimentally calculated relative error of measurement typically varies from 31 to 63, corresponding to secondary electron (SE) signal mean shifts of 9–18 mV. The millivolt accuracy of these results is over one order of magnitude better than earlier quantitative dopant concentration measurements made by a retarding field analyzer.

Further scanning electron microscope studies of the preparation of class II cavities

BDJ ◽  
1972 ◽  
Vol 132 (11) ◽  
pp. 447-457 ◽  
Author(s):  
A Boyde ◽  
P J Knight ◽  
S J Jones
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Class Ii ◽  
Scanning Electron

scholarly journals Study of corrosion in archaeological gilded irons by Raman imaging and a coupled scanning electron microscope–Raman system

2016 ◽  
Vol 374 (2082) ◽  
pp. 20160046 ◽  
Author(s):  
Marco Veneranda ◽  
Ilaria Costantini ◽  
Silvia Fdez-Ortiz de Vallejuelo ◽  
Laura Garcia ◽  
Iñaki García ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Chemical Imaging ◽  
Portable Equipment ◽  
Iron Matrix ◽  
X Ray ◽  
Non Invasive ◽  
Combined Use ◽  
Stratigraphic Succession ◽  
Scanning Electron

In this work, analytical and chemical imaging tools have been applied to the study of a gilded spur found in the medieval necropolis of Erenozar (Bizkaia, Spain). As a first step, a lot of portable equipment has been used to study the object in a non-invasive way. The hand-held energy-dispersive X-ray fluorescence equipment allowed us to characterize the artefact as a rare example of an iron matrix item decorated by means of a fire gilding technique. On the other hand, the use of a portable Raman system helped us to detect the main degradation compounds affecting the spur. Afterwards, further information was acquired in the laboratory by analysing detached fragments. The molecular images obtained using confocal Raman microscopy permitted us to characterize the stratigraphic succession of iron corrosions. Furthermore, the combined use of this technique with a scanning electron microscope (SEM) was achieved owing to the use of a structural and chemical analyser interface. In this way, the molecular characterization, enhanced by the magnification feature of the SEM, allowed us to identify several micrometric degradation compounds. Finally, the effectiveness of one of the most used desalination baths (NaOH) was evaluated by comparing its effects with those provided by a reference bath (MilliQ). The comparison proved that basic treatment avoided any side effects on the spur decorated by fire gilding, compensating for the lack of bibliographic documentation in this field. This article is part of the themed issue ‘Raman spectroscopy in art and archaeology’.

Some observations on concentrically structured, intracellular granules in the hepatopancreas of the shore crab Carcinus maenas (L.)

1979 ◽  
Vol 59 (4) ◽  
pp. 867-877 ◽  
Author(s):  
S. P. Hopkin ◽  
J. A. Nott
Keyword(s):  
Electron Microscope ◽  
B Cells ◽  
Scanning Electron Microscope ◽  
Carcinus Maenas ◽  
Shore Crab ◽  
Mean Diameter ◽  
The Mean ◽  
Scanning Electron

The R, F and B cells of the hepatopancreas of Carcinus maenas are derived from undifferentiated (E) cells at the distal end of the tubules. Observations with the scanning electron microscope on freeze fractured tubules show that (a) most of the concentrically structured granules are confined to the R cells with few in F or B cells, (b) within individual R cells, granules are of similar size, and (c) the further R cells are situated from the distal end of the tubule, the greater is the mean diameter of the granules that they contain.

scholarly journals Evaluating the Emergence and Biochemical Changes of Primed Seeds in Proso Millet (Panicum miliaceum L.)

2019 ◽  
pp. 1-7
Author(s):  
R. Sridevi ◽  
V. Manonmani
Keyword(s):  
Cell Proliferation ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Pseudomonas Fluorescens ◽  
Biochemical Parameters ◽  
Free Sugars ◽  
Proso Millet ◽  
Scanning Electron ◽  
Better Than

The present study aimed in exploring the performance of primed seeds in enhancing the quality of proso millet. The primed seeds along with nonprimed seeds were evaluated for emergence, cell proliferation in radicle cells using scanning electron microscope and biochemical parameters. Seeds primed with Pseudomonas fluorescens 20% possessing higher germination and anatomical changes observed through scanning electron microscope revealed more cell proliferation which was found to show rapid cell elongation and cell division of the radicle when compared to nonprimed seeds. The biochemical causes responsible for higher invigorative effect were identified as enhanced enzyme activity recorded through α-amylase content, dehydrogenase activity, protein content, lipase activity, antioxidative enzymes like catalase activity, peroxidase activity and superoxide dismutase with lower electrical conductivity, free amino acid and free sugars of the seed leachate. It is concluded in this study that primed seeds of Pseudomonas fluorescens 20% performed better than other treatments through their exhibition of higher emergence, more cell proliferation and enhanced biochemical parameters.

scholarly journals Influence of Dental Humidity on Marginal Adaptation of Biodentine Restorations

2019 ◽  
Vol 56 (3) ◽  
pp. 578-582
Author(s):  
Gianina Iovan ◽  
Sorina Solomon ◽  
Simona Stoleriu ◽  
Angela Cristina Ghiorghe ◽  
Irina Nica ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Class Ii ◽  
Optical Microscope ◽  
Tricalcium Silicate ◽  
Marginal Adaptation ◽  
Restorative Dentistry ◽  
Dental Tissues ◽  
Scanning Electron

Biodentine is a tricalcium silicate cement used as a dentin replacement in restorative dentistry. The aim of this study was to assess the influence of cavity moisture on the immediate sealing and morphology of the interface between Biodentine and the dental tissues. 20 class II cavities were prepared in extracted teeth. 10 cavities were dried using the air spray before restoring with Biodentine and 10 cavities were preserved moist for the restorative procedure. The teeth were subjected to a microleakage test and then the axial sections were observed under optical microscope and scanning electron microscope. In most situations Biodentine provided an immediate good marginal sealing and a tide contact with adjacent tissues in both occlusal and cervical margins which did not seem to be influenced by the moisture of the dental supporting tissues.

High Resolution Scanning Electron Microscope Using Lathanum Hexaboride Cathode Electron Gun

1968 ◽  
Vol 26 ◽  
pp. 372-373
Author(s):  
A. N. Broers
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Spherical Aberration ◽  
Lanthanum Hexaboride ◽  
Electron Gun ◽  
Maximum Brightness ◽  
Working Distance ◽  
Scanning Electron ◽  
Better Than

A new scanning electron microscope has been built which uses a lanthanum hexaboride cathode electron gun. The microscope has three magnetic lenses which are prealigned in the electron optical column to better than 20 micron. The final lens has a design spherical aberration of 1.8 cm for a 6 mm working distance. The pole-pieces of the final lens have been machined round within 0.25 micron and are aligned with respect to the axis of the lens to better than 10 micron. The electron gun which has been described previously uses a lanthanum hexaboride rod cathode. The cathode has approximately two orders of magnitude longer life than a 5 mil tungsten hairpin and is capable of producing an electron beam with a maximum brightness of 5.6 x 105 A/cm2 /ster at 12 KV. This brightness is approximately five times greater than that produced by a 5 mil tungsten hairpin under similar conditions.

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