Incident Light Microscopy Research Articles

Finding the First Fires with Microscopes

Abstract Coal is remnants of plant matter that were compressed and held at a high temperature for eons. However, if plants are charred first, they become hard and brittle, and may resist compression. Under appropriate circumstances, anatomic detail can be elegantly retained. Ian Glasspool, Dianne Edwards, and Lindsey Axe have performed detailed studies on plant fossils recovered in England, near the Welsh border, that can be considered to be evidence for the earliest wildfire yet described on our planet. They examined a series of mesofossils, about one millimeter in size, which required microscopic study. It is well known that chemical and structural changes occur to organic tissues during charring. This can mean that charcoal is resistant to decay and compression and it is also more reflective than non-charred material. Glasspool et al. used incident light and scanning electron microscopy to reveal 3-dimensional cellular detail of the specimens. Additional specimens were embedded and polished for reflectance microscopy. The results indicated that the specimens were charcoal.

Assessment of Elemental Composition, Microstructure, and Hardness of Stainless Steel Endodontic Files and Reamers

The purpose of this study was to determine the elemental composition, microstructure, and hardness of commercially available reamers, K files, and H files. Five instruments of each type from different manufacturers (Antaeos, FKG, Maillefer, Mani, and Micromega) were embedded in epoxy resin along their longitudinal axis. After metallographic grinding and polishing, the specimens were chemically etched and their microstructure investigated under an incident light microscope. The specimens were studied under a scanning electron microscope, and their elemental compositions were determined by energy dispersive X-ray microanalysis. The same surfaces were repolished and X-ray diffraction was performed. The same specimen surface was used for the assessment of the Vickers hardness (HV200) by using a microhardness tester with a 200-g load and 20-s contact time. The hardness results were statistically analyzed with two-way ANOVA and Tukey's test (a = 0.05). All files demonstrated extensively elongated grains parallel to longitudinal file axis because of cold drawing. The elemental composition of Maillefer and Mani reamers, Antaeos K files, and Mani H files were found in the range of AISI 303 SS, whereas all the rest were determined as AISI 304 SS. Two different phases (austenite SSt and martensite SSt) were identified with X-ray diffraction for all files tested. The results of hardness classified reamers in the following decreasing order (HMV200): Micromega = 673 +/- 29, Mani = 662 +/- 24, Maillefer = 601 +/- 34, Antaeos = 586 +/- 18, FKG = 557 +/- 19, and the K files (HV200): FKG = 673 +/- 16, Mani = 647 +/- 19, Maillefer = 603 +/- 41, Antaeos = 566 +/- 21, Micromega = 555 +/- 15, and the H files (HMV200): Mani = 640 +/- 12, FKG = 583 +/- 31, Maillefer = 581 +/- 5, Antaeos = 573 +/- 3, Micromega = 546 +/- 14. Although only two stainless steel alloys were used for the production of endodontic files, the differences in hardness are independent to the alloys used, implying that other factors, such as the production method or the thermomechanical history of the alloys, play an important role on the mechanical properties of endodontic files.

Materialmikroskopie unter besonderer Berücksichtigung der Kunststoffe Teil II: Beobachtende Lichtmikroskopie an Kunststoffen / The Microscopy of Materials and in Particular of Plastics Part II: The Light Microscopy of Plastics

Apart from the established methods of incident light microscopy used for classical metallic surfaces, the examination of polymers requires the use of new and often unfamiliar methods of microscopy. In particular in the case of the broad pallet of filled plastics, all of the tried and trusted metallographical techniques used for the examination of opaque materials, such as bright and dark field microscopy, may also be used. In addition, for the examination of polymers, the entire spectrum of transmission microscopic techniques is also required. This is especially true in the case of colourless, amorphous plastics where the entire component e.g. in an optical stress tester can be examined non-destructively. For coloured, partially crystalline or filled and reinforced polymers, these methods can only be used on thin sections of at least adequate translucence to those with almost optically transparent properties. In this article the instrumentation required to carry out such investigations and methods of observation and evaluation which can be used are described. Further possible reasons of erroneous measurements and their prevention are explained detailed with reference to actual practical examples. In addition, the possible artefacts which might be produced are discussed, and methods by which they may be avoided suggested.

Failure Mechanism of Hedstroem Endodontic Files In Vivo

Intracanal fracture of endodontic Hedstroem files (H-files) jeopardizes the outcome of endodontic therapy. The aim of this study was to evaluate the fracture mechanism of H-files after multiple in vivo uses. Five each of size #20 and #25 ISO H-files fractured during clinical use were collected from different dental clinics. Four fractured files of each size and three unused files of each corresponding size were embedded in a resin along their longitudinal axis and after metallographic grinding and polishing studied under an incident light microscope. One specimen in the fractured group was investigated under a scanning electron microscope. Light microscopy results showed that unused files were free of structural defects (cracks, pores, etc.), whereas fractured files demonstrated the presence of many cracks mostly located at the flute depth region. Secondary cracks were identified beyond the fracture plane of fractured files both with a light microscope and a scanning electron microscope. Experimental results demonstrated that fatigue is closely associated with the fracture mechanism of H-files (#20, #25) under clinical conditions.

Influence of annealing temperature on simultaneous vapor deposited calcium phosphate thin films

The effect of annealing temperature on the characteristics of thin film calcium phosphate coatings fabricated by a novel simultaneous vapor deposition method was investigated. Heat treating the as-deposited films was necessary to change the amorphous coating into a crystalline coating. The films were annealed for 3 h at 400, 700, 1000, and 1200 °C in air. After annealing, the structure and the chemical composition of these films were characterized with incident light microscopy, x-ray diffraction, and energy dispersive x-ray spectroscopy. A scratch test was conducted to measure the strength of the adhesion of the coatings to the substrate. The results showed that after annealing at a temperature higher than 700 °C, crystalline hydroxyapatite appeared to coexist with tricalcium phosphate and tetracalcium phosphate phases. A Ca/P ratio close to that of stoichiometric hydroxyapatite was obtained with certain process parameters. The adhesion of the coatings was highly affected by the annealing temperature. From the results, it can be suggested that 1000–1200 °C is the best annealing temperature range for calcium phosphate coatings produced by the simultaneous vapor deposition method.

Dermoscopy of pigmented skin lesions – a valuable tool for early

The clinical use of dermoscopy has uncovered a new and fascinating morphological dimension of pigmented skin lesions. Dermoscopy is a non-invasive diagnostic technique that links clinical dermatology and dermatopathology by enabling the visualisation of morphological features not seen by the naked eye. Close examination of pigmented skin lesions in this way increases the effectiveness of clinical diagnostic tools by providing new morphological criteria for distinguishing melanoma from other melanocytic and non-melanocytic pigmented skin lesions. In the past, dermoscopy has been known by various names, including skin surface microscopy, epiluminescence microscopy, incident light microscopy, dermatoscopy, and videodermatoscopy. However, the term 'dermoscopy', first used by Friedman and colleagues in 1991, is the most widely used.

Materialmikroskopie unter besonderer Berücksichtigung der Kunststoffe/ The Microscopy of Materials and in Particular of Plastics/

In addition to the classical methods of incident light microscopy used to examine metallic materials, polymers require new and often unknown methods of preparation devised by the technician. In addition to polished specimens and thin sections, other types of specimen materials may also need to be examined such as thin slices, films, fibres and granular material. Together with the tried and tested methods of preparing specimens of such materials, the possible artefacts which may be produced and methods of preventing them are described in detail with reference to practical examples. In this multi-part article, this first part deals with the preparation of plastics. In the following parts, the numerous methods of optical light microscopic observation and measurement which can be used to investigate such materials will be presented.

Fluorescent Chromatophore Detected in the Guppy Poecilia reticulata

Fluorescent chromatophores with bluish white fluorescence were detected in the guppy Poecilia reticulata. These chromatophores were observable only by means of a fluorescence microscope, and could not be observed by a standard transmission light microscope or incident light microscope. Resembling other common chromatophores, these fluorescent chromatophores were dendrictic cells and similar to other chromatophores in the size, about 50–100 μm.Of the 17 strains examined, these fluorescent chromatophores were detected only in the R strain, and in all 12 R strain individuals examined, each presented fluorescent chromatophores.These differences in the occurence of fluorescent chromatophores among strains suggest that the formation of these chromatophores is the result of genetic polymorphism.

INSECTOS POLINIZADORES DEL AGUACATERO EN LOS ESTADOS DE MÉXICO Y MICHOACÁN, MEXICO

Avocado (Persea americana Mill.), pollinators were colleted in orchards in Coatepec Harinas. (State of Mexico) and Ziracuaretiro (MichoacÅn), Mexico. from January to March of 1998 and 1999. The insects were studied with incident light microscopy in order to identify and count the avoacado pollen grains attached to each body region. A higher diversity of pollinators were detected in the State of Mexico orchards and a lower in MichoacÅn. There were 45 species of Diptera, belonging to 5 families, 20 species (6 families) of Hymenoptera, and 5 species of five families of Coleoptera. Apis mellifera L. (Apidae), Eristalis tenax L. (Syrphidae), Phaenicia mexicana Macquart (Calliporidae) and Palpada mexicana Macquart (Syrphidae) were the most abundant species in both localities. Geotrigona acapulconis Strand (Apidae), Brachygastra mellifica Say (Vespidae), Chrysomya megacephala (Calliphoridae) A. mellifera and had the greater amount of avocado pollen attached to the vertex, ventral thorax and legs, surpassing the species efectiveness. Nevertheless, G. acapulconis appeared in very low number, which implies that the honey bee is the main pollinator in the avocado tree complemented by the other species. These results will be integrated into to a greater projet on the avocado pollinators efectiveness. related with their behavior and with the avocado flowering nature.

Depositional Environment and Oil Generation in Ordovician Source Rocks from Southwestern Ontario, Canada: Organic Geochemical and Petrological Approach

The Ordovician Trenton Group (Sherman Fall and Cobourg formations) and the Lindsay (Collingwood Member) and Blue Mountain formations of southwestern Ontario were examined using Rock-Eval pyrolysis, gas chromatography, gas chromatography-mass spectrometry, and incident-light microscopy to evaluate their paleodepositional environments, thermal maturities, and source rock potential. All units contain sufficient amount of oil-prone (type II), predominantly marine organic matter to be considered as petroleum source rocks. Unstructured bituminite with varying proportions of unicellular alginite are the dominant dispersed organic matter macerals. The bituminite typically occurs in massive to laminated, granular or patchy populations that commonly show microtextural relationships. Persistent inclusions of Leiosphaeridia telalganite demonstrate that planktonic algal debris was a primary organic substrate for blooming microbes. Disseminated coccoidal Gloeocapsomorpha prisca is found in minor amounts, usually in association with common to abundant acritarchs. Zooclasts (chitinozoa, graptolites, scolecodonts) and solid bitumen also are present as maceral inclusions within the bituminite network. The biomarker distributions for all of the studied units are those expected for marine organic matter deposited in a clastic-dominated environment. The extracts are characterized by a smooth n-alkane profile, with low abundance of C20+ members, typical for marine derived organic matter. Pristane/phytane ratios range from 0.97 to 1.72, indicating dysoxic conditions during deposition. Smooth C31-C35 homohopane profiles, Ts/Tm ratios (typically above 1.0), and a higher concentration of diasteranes relative to regular steranes all appear to indicate the clay-bearing character of these rocks. The predominance of C30 hopane over C29 regular sterane is interpreted to reflect a primary microbial input and extensive reworking of the organic matter. Optical (reflectance, fluorescence) and geochemical (Tmax, biomarker data) thermal maturity parameters indicate that the Trenton and Blue Mountain strata are within the zone of prolific oil generation throughout the whole area of study. The Collingwood shales are mature with respect to petroleum generation in the eastern part (Toronto area) and only marginally mature in the northern part (Georgian Bay area) of the study area. In general, the biomarker composition of the extracts from all examined units is compatible with that of the oils found in the Trenton reservoirs of southwestern Ontario; however, geochemical and geological evidence suggests that the organic-rich shaly laminae within the Trenton Group are the principal source of these oils. Accumulation of organic carbon in the Ordovician sediments of southern Ontario is suggested to derive from low-energy, normal-marine environments grading from shallow-shelf into deep-shelf and open-basinal settings. The nutrient availability and, consequently, higher bioproductivity, more intense consumption of oxygen, and progressing anoxia, controlled by a low-latitude location, diminished water circulation, stratification of the water column, and a depressed pycnocline resulted in high preservation rates. The amorphous nature of kerogen reflects significant microbial interaction at the water/ sediment interface and within the sediments where reducing conditions must have periodically predominated.

The origin of pyrobitumens in upper Devonian Leduc formation gas reservoirs, Alberta, Canada: an optical and EDS study of oil to gas transformation

Pyrobitumens are common within deep basin, Devonian carbonate gas reservoirs of the Western Canada Sedimentary Basin. Incident light microscopy and SEM-EDS have been used to study the origin of pyrobitumens from Upper Devonian isolated reefs of the Leduc Formation, west central Alberta. Reflectance properties (%Ro max and %Ro min), coke microtextures and relative S/C ratios are used to classify the pyrobitumens. In portions of reservoir units where NSO-enriched, low aromaticity crudes may have been dominant, oil to gas transformations produced mainly low-reflecting isotropic to fine-grained mosaic coke microtextures within the reservoir pyrobitumens (Type A). In contrast, where ‘normal’ crudes were most likely dominant in the reservoir units prior to thermal cracking, pyrobitumens with high bireflectance and very anisotropic coarse flow to domain cokes dominate (Type B). Oil to gas cracking within some of the reservoir units resulted in overpressuring and is represented by highly deformed pyrobitumens with fibrous coke textures and high bireflectance. Relative concentrations of Type A and B pyrobitumens vary vertically and temporally in some of the reefal buildups. The variations in the dominant pyrobitumen types are attributed to crude oil alteration which preceded crude oil to gas transformation (e.g. tar mats) in some zones whereas other zones may have been altered contemporaneously with crude oil cracking. The later may have resulted from the oxidation and sulphur enrichment of the crude oil during thermochemical sulphate reduction. This reaction is prevalent within Devonian evaporite-carbonate strata of the Western Canada Sedimentary Basin, generating copious volumes of H 2S. The interaction between crude oil and sulphur-enriched, highly alkaline fluids is suggested by the presence of high S/C, very fine-grained, late stage calcined needle cokes within brecciated pyrobitumens.

Microscopic in situ diffuse reflectance spectroelectrochemistry of solid state electrochemical reactions of particles immobilized on electrodes

An instrumental setup is described which allows electrochemical measurements to be performed with solid particles immobilized on the surface of a graphite electrode with in situ recording of diffuse reflectance spectra under an incident light microscope. The instrument used includes a special electrochemical cell and a microscope which is interfaced by a light␣guide to a transputer-integrated photodiode-array spectrometer allowing measurements ranging from 320 to 950 nm with a resolution of 3.2 nm/pixel and a PC-interfaced potentiostat. The 0R0 geometry of the optical arrangement and the use of crossed polarization filters for blocking specular reflectance makes it possible to use the Kubelka-Munk function for quantifying the optical measurements. The above instrument has been used for the study of the electrochromic system of solid silver octacyanomolybdate(IV/V) adjacent to a silver nitrate solution. The in situ diffuse reflec tance spectroelectrochemical measurements prove that the electrochemical reaction starts at the graphite/sample interface and then advances into the bulk of the sample towards the sample/electrolyte interface. The ratios Red:Ox determined by spectrometry and chronocoulometry as a function of electrode potentials are identical.

Vascular structures are an important feature for diagnosis of melanoma and other skin tumors by incident light microscopy

Vascular structures are an important feature for diagnosis of melanoma and other skin tumors by incident light microscopy

Organic petrology and organic geochemistry of Devonian black shales in southwestern Ontario, Canada

The hydrocarbon source rock potential of the Devonian Marcellus and Kettle Point black shales in southern Ontario has been assessed using Rock-Eval pyrolysis, gas chromatography, gas chromatography-mass spectrometry and incident-light microscopy. Both formations contain sufficient hydrogen-rich organic matter (Type II) to be considered possible source rocks. The kerogen is predominantly marine in origin. This organic matter was deposited in a clastic algal-dominated environment, and mainly consists of unstructured bituminite and unicellular alginite. The organic microfacies indicate shelf paleodepositional settings with a transition to an open basinal region. The optical (reflectance, fluorescence) and geochemical (Rock-Eval Tmax, extract yields, distributions of steranes and terpanes) maturity data indicate that the organic matter in the Kettle Point Formation is immature, whereas in the Marcellus Formation it has reached the early stages of hydrocarbon generation and expulsion. Some Devonian oils occurring in this area have characteristics similar to the Marcellus extracts, suggesting that more mature equivalent units from the Appalchian Basin could be their source.

Microwear and Metric Analysis of Threshing Sledge Flints from Greece and Cyprus

Flaked stone implements formed an important part of the agricultural tool assemblage in the Eastern Mediterranean from the origins of domestication to the 20th century. The identification of specific tool function commonly has depended on morphological and macroscopic traits visible on these lithics. Over the past two decades, examination of lithics using the high power (up to 500×) incident light microscopy technique has revealed the presence of use–wear traces (striations, polish, and edge damage) that are diagnostic of direction and duration of motion, and material worked. The present study analyses a collection of threshing sledge flints collected from several areas of Greece to isolate the wear patterns that are unique to these lithics and that distinguish them from other tools, such as sickle elements, used to cut plants. These ethnographic examples provide the experimental control sample against which pieces collected from a survey in Cyprus can be compared. The paper also considers the implications for agricultural production of the introduction of threshing sledges in the Eastern Mediterranean.

A cell for in situ incident-light microscopy for the study of electrochromism of solid state electrochemical reactions.

A cell is described which allows in situ incident-light microscopy to be used for the analysis of solid state electrochemical reactions studied by abrasive stripping voltammetry. The cell provides the possibility to screen solid compounds with respect to their electrochromic properties without requiring the preparation of special electrodes on transparent and conducting materials. Silver octacyanomolybdate(IV) and silver octacyanotungstate(IV) have been used to study the performance of the cell because both compounds exhibit a stable electrochromic and voltammetric behaviour.

Incident light microscopic characterization of vascular patterns in skin tumors

The search for vascular structures in skin tumors by incident light microscopy has revealed a surprisingly high proportion of vascularized tumours. Characteristic vascular patterns, in some cases highly tumour-specific, have been defined. The vascular structure is a valuable feature for characterization and differentiation of skin tumours, especially for amelanotic malignant melanoma. We propose a flowchart procedure for analysis and diagnosis of skin tumours using incident light microscopy, which appears to be valuable for advanced image analytic techniques.

Influence of annealing temperature on RF magnetron sputtered calcium phosphate coatings

The effect of different annealing temperatures on the characteristics of thin calcium phosphate coatings fabricated by radiofrequency magnetron sputtering was studied. Annealing of the as-sputtered films was necessary to change the amorphous coating to a crystalline coating. The films were annealed for 2 and 4 h at 400, 600, 800,1000 and 1200 °C under dry argon or argon and water vapour flow. After annealing, the structure and the chemical composition of these films were characterized with incident light microscopy, Rutherford backscattering spectrometry (RBS), X-ray diffraction (XRD), and Fourier transform infrared absorption spectrometry (FTIR). Incident light microscopy showed cracks in the coatings annealed at a higher temperature than 400 °C. RBS revealed that the as-sputtered coatings had a high Ca/P ratio which decreased with increasing annealing temperature. After annealing at a temperature of 600 °C or more the XRD showed crystalline hydroxyapatite (HA) coatings. However, the second phase, present in the coatings, changed from tetra-calcium phosphate to calcium oxide to β-tricalcium phosphate with increasing annealing temperature. FTIR measurements showed the existence of OH- and PO- bonds in all coatings, although the PO- bonds varied for different annealed coatings, from the PO- bonds due to HA to PO- bonds due to other calcium phosphates. From the results of this study we suggest that 600 °C is probably the best annealing temperature to obtain a better characterization and understanding of the coating.

Mineral Matter in the Lrajmahal Coals: Study Through Incident Light Microscopy and Scanning Electron Micrography

Abstract The Lower Gondwana coals of the Rajmahal group of coalfields have been studied, in detail, under the Petrological and the Scanning Electron Microscopes to elucidate the mode of occurrence of mineral matter and their microstructural relations with organic constituents. Observations of both the methods reveal the occurrence of mineral matter as massive impregnation, intimate inter growth, superficial mounting, superficial blanketting, pore filling and solution cavity filling. The absence of microstructures, when observed via incident light microscopy such as superficial blanketting and superficial mounting in the macerals and microlithotypes, in general. suggests their elimination during the course of grinding and polishing of the coal pellets. This suggests skewing of the mineral matter assessment through microscopic examination. The quantitative distribution of mineral matter in the coal lithotypes as observed in SEM is Durain> Clarain > Vitrain > Fusain while the ash analysis of different lithotypes shows the order of dominance of ash (equivalent to mineral matter) as Durain > Fusain> Vitrain > Clarain.

Mesolithic plant exploitation at the Roc del Migdia, Catalonia

Charred plant remains from the mesolithic site of Roc del Migdia have been analysed in detail. Hazel shell and endocarp fragments of sloe ( Prunus spinosa L.) have been identified by incident light microscopy and an attempt has been made at the identification of quantities of parenchymatous plant remains through the use of the scanning electron microscope. A number of different classes of tissue are described and the implications of the results discussed.