bluuebunny/crossref_metadata_2025_split huggingface dataset:
The rank and anisotropy of anthracites: the indicating surface of reflectivity in uniaxial and biaxial substances
Authors: Hevia V. , Virgos J. M. 
Published: August 2011

SUMMARYTheoretical and empirical formulae are given which relate the principal reflectivities of uniaxial and biaxial substances to the mean values of random, maximum and minimum reflectivities measured on particulate samples. Instead of using values of R̄a and R̄a − R̄c determined along the principal directions, a method is described for determining respectively: (a) coal rank through the mean random vitrinite reflectivity, and (b) the bireflectance using the difference between the mean random maximum and minimum reflectivities measured on particulate samples, irrespective of uniaxial or biaxial character.
The accuracy of refractive and absorptive indices derived from reflectance measurements on low‐reflecting materials
Authors: Cook A. C. , Murchison D. G. 
Published: August 2011

SUMMARYErrors in the refractive and absorptive indices derived from reflectance measurements on relatively low‐absorbing organic substances in two media are discussed, with particular reference to coal macerals and cokes. Variation of errors in refractive and absorptive indices at different levels of reflectance, and the effect of different combinations of sign and magnitude of reflectance error on the two parameters, are presented in both tabulated form and as diagrams. The errors in the refractive and absorptive indices vary in relation to reflectance level, the reflectance difference between standard and unknown, the difference between the refractive indices of the unknown and the immersion oil and the wavelength of reflectance measurement within the visible spectrum. Despite the variation, it is possible to obtain useful values for the parameters within the low‐absorbing range. If the absorption is negligible, it may not be possible to obtain realistic values for absorptive index, but even where this is the case, satisfactory values for refractive index can still be obtained. Suggestions are made on how to minimize reflectance errors and to increase the accuracy of dispersion curves for derived refractive and absorptive indices within the visible spectrum.
Microscopical investigation of the transformation (diagenesis) from peat to lignite
Authors: Ting F.T.C. 
Published: August 2011

SUMMARYA silicified Palaeocene peat layer discovered in a lignite bed in western North Dakota, U.S.A., has proved to be excellent material for studying the transformation from peat to lignite. Detailed anatomical structures are well preserved in the peat and similar to the level of preservation of Carboniferous coal balls. A compaction of 4: 1 results when the peat is converted to lignite. Loss in volume is primarily caused by the loss of cellular cavities and intergranular spaces and consequent loss or redistribution of moisture. Huminite formed from secondary xylem and phloem sclereids differs in appearance under the microscope from huminite derived from periderms and young cortical tissues. Resinites are formed from fillings of resin canals, secretory cells and sclereids of secondary phloem and may also originate from resinous materials occurring in the palisade and spongy mesophyll of leaves. Cutinite can form from either cuticles or from compressed cortical tissues of young roots. Charred leaves and charred secondary xylem and phloem comprise an important portion of the fusinitic and semifusinitic fractions of the coal. Pyrite grains tend to occupy the cell cavities of early wood and ray cells. Differences between collinite and telinite developed during the peat stage, while progressive coalification tends to accentuate the lack of structure in the collinite.
Prediction methods in coal and coke microscopy
Authors: Mackowsky M.‐Th. 
Published: August 2011

SUMMARYPrediction of coke strength based on measurements of vitrinite reflectance and data from group‐maceral analyses requires information about the coking power of the different coal macerals in relation to rank. A range of bases are considered by different individuals to be important in prediction studies, e.g. the optimum ratio of reactive to inert constituents for each ‘V‐step’ (vitrinite oil reflectance step × 10); the proportion of vitrinite and clarite and rank; the amount of inertinite with no consideration given to an optimum ratio of reactives to inerts; the rank with little regard given to varying maceral composition. Entirely satisfactory results can be obtained by all investigators for coke‐strength predictions from certain coals under given coking conditions. For other coals, some of the determined values lie well outside the permissible limits of error. Reasons for these deviations may lie in an erroneous, or at least in an inadequate evaluation, of the different microscopical parameters. With this introduction, different predictive methods are discussed and tested. Limits of applicability are demonstrated. Possible improvements are suggested and questions, which have so far not been answered entirely satisfactorily, are posed. Above all, the underlying importance of light microscopy to a major industrial field is stressed.
High resolution electron microscopy of carbon structure
Authors: Crawford D. , Marsh H. 
Published: August 2011

SUMMARYAn investigation is made of the inherent performance of a high‐resolution transmission electron microscope applied to the study of developing graphitic‐sheet structures in heat‐treated, coal‐tar pitch carbons. Image detail is shown to be highly dependant on instrumental defocus. It is not obvious which form will be assumed by artefacts in these images; consequently, anomalous features are illustrated by reference to a specific electron‐optical case and a corresponding light‐optical analogy. Despite the difficulties associated with locating an optimum level of focus, optical diffractometry confirms that adequate conditions of microscopy are attainable on a routine basis. In a quantitative analysis of morphology in coal‐tar pitch carbons, the technique reveals the cause of incipient, thermally‐induced, molecular distortions which evidently result in a regression in the improvement of order otherwise developing with progressive heat‐treatment.
Elateritic hydrocarbon from South Crofty Mine, Cornwall: a preliminary note
Authors: Harrison R. K. , Beer K. E. 
Published: August 2011

SUMMARYBlack, viscous, subelastic elateritic hydrocarbon associated with ‘peach’ (tour‐maline‐quartz‐chlorite‐rock), forms a seepage in a movement zone in granite near its contact with killas at South Crofty Mine, near Redruth, Cornwall. The hydrocarbon is paragenetically associated with granular pyrite, but infiltrates the ‘peach’. Readily soluble in aromatic and halogenated alkane solvents, the hydrocarbon is insoluble in paraffinic solvents suggesting a condensed structure. Infrared spectroscopy and N.M.R. spectroscopy indicate a mainly aliphatic content with some aromatic component. Both carbonyl (>C=0) and hydroxyl (−OH) functions are present. Strong methyl absorption bands show a considerable amount of branching or methyl side groups. Gel permeation chromatography and visual spectrometry show no detectable porphyrins. The origin of the hydrocarbon is uncertain; it may represent a distillate of carbonaceous killas (Mylor Series) entrapped in granite at depth, but an abiogenic origin cannot be ruled out.
Determination of the mass thickness of biological sections from electron micrographs
Authors: Misell D. L. , Burdett I. D. J. 
Published: August 2011

SUMMARYTheoretical results are given for the evaluation of the mass thickness of unstained and stained biological sections based on the scattering contrast model for in‐focus electron microscope images. Densitometer measurements on photographic images enable the scattered electron intensity (I) and the incident electron intensity (I0) to be determined, and it is shown that the ratio I/I0 can be related to the mass thickness ρt of a particular region of the specimen by I/I0 = exp (−Spρt). The parameter Sp is given for a range of incident electron energies (E0 = 20–100 keV) and objective aperture sizes (semi‐angle α subtended at the specimen 5–15 mrad). Experimental results on thin stained sections of Bacillus subtilis for E0 = 40–100 keV and α = 3.8–17.5 mrad demonstrate the internal consistency of the theoretical curves for the calculation of mass thickness of both the embedding medium and the biological material. The sensitivity of this method for the determination of mass thickness depends on E0 and α; variations in mass thickness of ±2 mg m−2 can be determined for E0 = 40 keV and α = 5 mrad, becoming less sensitive as E0 and α are increased, so that for E = 80 keV and α = 10 mrad the sensitivity is reduced to ±5 mg m−2. This means that density variations of ±40 and 100 kg m−3, respectively, can be determined in sectioned biological material. Because of the requirement of a linear relation between log (I/I0) and ρt, the theoretical calculations are limited to a maximum mass thickness of 200 mg m−2 or a section thickness of about 200 nm for material of density 1000 kg m−3.These calculations are relevant to applications in microbiology, stereology and autoradiography.
Cryomicrotomy applied to the preparation of frozen hydrated muscle tissue for transmission electron microscopy
Authors: Varriano‐Marston E. , Gordon J. , Davis E. A. , Hutchinson T. E. 
Published: August 2011

SUMMARYA method is described by which frozen hydrated bovine muscle is prepared for the transmission electron microscope. The importance of maintaining specimen temperatures at −110°C (163°K), or below, during the preparation of frozen thin sections and during specimen transfer and microscopical observations is emphasized and documented.Electron micrographs of a section of muscle were followed through three levels of dehydration. Electron micrographs of frozen hydrated muscle were compared with micrographs of fixed and embedded muscle. In general, the micromorphology of muscle prepared by the two methods was found to be quite similar.
Autoradiographic studies on the cellular uptake of Technetium‐99m and Chromium‐51
Authors: Barth Rolf F. , Jr John Clancy , Pugh Jill M. 
Published: August 2011

SUMMARYThe present study was designed to investigate the cellular uptake of technetium‐99m (99mTc) and chromium‐51 (51Cr) by autoradiographic methods and to compare these data to those obtained by gamma scintillation counting. HeLa cells, a fibrosarcoma of murine origin (Sarcoma I) and human peripheral blood lymphocytes were labelled with either 99mTc‐sodium pertechnetate or 51Cr‐sodium chromate. Cells were non‐uniformly labelled with both radionuclides. Nevertheless, uptake as determined by both autoradiography and gamma scintillation counting revealed that each cell type had a characteristic labelling pattern which appeared to have a relationship to cell surface area. This was determined to be linear for 99mTc when counts per minute were plotted as a function of area (μm2). Grains were randomly scattered over the entire cell surface and occasionally tracks could be seen as a trail radiating out from the periphery. HeLa cells had the largest surface area, the highest grain counts and the greatest uptake of both 99mTc and 51Cr as determined by gamma counting. Lymphocytes had the smallest surface area, the lowest grain counts and the least uptake. Both radionuclides are non‐specific cell labels which are taken up independently of mitosis and protein synthesis. The favourable chemical properties of 99mTc‐sodium pertechnetate have led to its use as a label for a wide variety of inorganic and organic compounds which are employed as radiopharmaceuticals. Autoradiographic methods could be useful in determining the cellular localization of these compounds, as well as any protein molecule with which pertechnetate forms chelates. Although the 6 h half life of 99mTc limits its use to short term experiments, it does permit brief exposure times prior to development.
A combined top and side entry specimen stage for a Hitachi H500 transmission electron microscope
Authors: Chapman S. K. 
Published: August 2011

SUMMARYThe Hitachi H500 transmission electron microscope has been modified in order that both the top and side entry specimen stages may be fitted simultaneously. This made possible top entry multi‐specimen operation up to a maximum magnification of × 100,000 and a resolution of 1.8 nm, combined with the normal side entry stage facilities of ±60° tilt, 0.45 nm resolution and × 400,000 magnification.
Use of an automated image analyser to quantitate cellular hyperplasia in urinary bladder epithelium
Authors: Stinson S. F. , Sporn M. B. 
Published: August 2011

SUMMARYThe feasibility of using an automated image analyser to evaluate quantitatively hyperplasia caused by N‐butyl‐N‐(4‐hydroxybutyl) nitrosamine in bladder epithelium was studied. The number of cells per unit length of epithelium was counted manually, and compared with automated measurements of: (1) the number of nuclei, (2) the number of positive tangents to the lower edge of nuclei, (3) the nuclear cross‐sectional area, and (4) the epithelial cross‐sectional area per unit length respectively. Regression of each of the automated measurements on the manual counts all revealed close linear relationships with correlation coefficients in excess of 0.9. Coefficients of variation for repetitive automated measurements were less than or equal to 0.06 in each of the four modes. The automated system resulted in a great saving in time over manual counting. It is concluded that the automated image analyser provides an accurate, precise, and efficient tool for estimatimg epithelial cell numbers in normal and hyperplastic bladder epithelia.
Preparation of Biological Material For X‐Ray Microanalysis of Diffusible Elements
Authors: Sevéus Lahja 
Published: August 2011

SUMMARYAny method used for the analysis of diffusible elements within a cell should involve conditions which eliminate the redistribution of those elements. Redistribution of diffusible substances is caused by (a) ice damage during freezing, (b) thawing during sectioning, and (c) thawing during handling of sections. To eliminate this sections were cut (a) in the 5–8 μm ice crystal free surface layer obtained by freezing in melting nitrogen, (b) at a specimen temperature of 133 K and a knife temperature of 173 K to 153 K, and the temperature of the chamber was kept low by evaporating nitrogen from an extra reservoir inside the chamber, by regulating the output of a foil heater. A grid carrier was designed to simplify the section collection and the sections were affixed on to the grid in a press assembly. The sections were hard and translucent, and showed faint interference colours.
Preparation of Biological Material For X‐Ray Microanalysis of Diffusible Elements
Authors: Barnard Tudor , Sevéus Lahja 
Published: August 2011

SUMMARYThe appearance of ultrathin, dry‐cut cryosections of brown adipose tissue and liver was found to be strongly dependent upon adequate freeze‐drying. If freeze‐drying was inadequate, diffusion of substances could be demonstrated and freezing damage was not apparent. Diffusion was manifested as an electron dense film over structural features such as triglyceride droplet profiles and the edges of the section; when this film was thick, X‐ray signals for P, S, Cl, K and Ca could be detected from it, in different proportions to those found in the section. The frequency and intensity of diffusion were lowered by decreasing the temperature in the cryochamber from about 200 K ± 5 K to 163 K ±5 K by forced evaporation of liquid N2 using an extra heater. The lowest incidence of diffusion was obtained in conjunction with this device, by leaving the sections in the cryochamber for at least 2 h during drying, either over a drying agent or under moderate vacuum. Such sections showed a narrow zone (A) at the edge that lacked obvious ice‐crystal damage, a thicker zone (B) of moderate ice‐crystal damage and the bulk of the interior (zone C) severely damaged by freezing. Qualitatively different, reproducible X‐ray spectra could be obtained from ultrastructural features even in areas showing some signs of diffusion.
Holographic Microscopy of Glycerination of Amoeba Proteus
Authors: Opas Michal 
Published: August 2011

SUMMARYThe process of glycerination of Amoeba proteus was observed under the holographic microscope with coherent noise elimination. It was found that during glycerination redistribution of cell material occurs, and is accompanied by reversible deformation of the cell cortex. The role of the cortex in shape maintenance in glycerinated models was demonstrated.
Direct Deposition Autoradiography: Can it Really Be Detecting Radioactivity?
Authors: Williams M. A. 
Published: August 2011

SUMMARYThe literature concerning the ‘direct deposition method’ of electron microscope autoradiography has been examined and certain calculations made. Studies have been made on the interaction of gold chloride with protein films, tissue sections and ultrathin sections. It is concluded that in its present form the direct deposition method does not offer an autoradiographic approach of practical value.
A Method For The Study of Internal Spaces in Hard Tissue Matrices By SEM, With Special Reference to Dentine
Authors: Martin D. M. , Hallsworth A. S. , Buckley T. 
Published: August 2011

SUMMARYInfiltration of a porous hard tissue with methyl methacrylate, followed by dissolution of the tissue provides a three‐dimensional methacrylate cast of spaces within the tissue. Examination of such a cast by scanning electron microscopy provides information on the nature and extent of the pore system to a degree that cannot readily be visualized by the direct examination of fractured surfaces. The findings described concern human dentine but the technique may have a wider application in studies on the internal structure of other hard tissues.
Low Cost Internegatives From Electron Micrographs of Metal Shadowed Objects
Authors: Boye Hans , Rønne Mogens 
Published: August 2011

SUMMARYSome observers prefer a contrast reversal of electron micrographs of metal shadowed objects, so that the metal‐free shadows appear dark on the print. There are several ways of obtaining contrast reversal, and the reasons for using 35 mm internegatives are given and a setup for re‐photography of electron microscopy films is described together with a modified enlarger. Both are equipped with near‐point illumination, which can be diffused in a simple manner with minimal loss of intensity. Other features are a particularly rigid camera stand combined with a numbering device, and a glass‐ and scratch‐free negative holder for the enlarger. The choice of lens for the re‐photography is discussed.
Optical Anisotropy of Poly (P‐Phenylene Terephthalamide) Fibres
Authors: Hamza A. A. , Sikorski J. 
Published: August 2011

SUMMARYThe principal polarizabilities of poly(p‐phenylene terephthalamide)—PPT—fibres were calculated using the molecular model of Northolt, together with the values of bond polarizabilities given by Denbigh and also by Bunn & Daubeny. Following generally accepted practice, the Lorentz‐Lorenz expression was utilized to derive the principal refractive indices (and the birefringence) of the PPT fibres.The experimental values of the refractive indices, for four different PPT samples, were obtained with the aid of the Pluta polarizing interference microscope; some comments on the relevant procedures being included.Finally, discussion on the discrepancy between the calculated and observed values of refractive indices is attempted.
Stereology of the Dermal System of Fruit
Authors: Considine J. A. 
Published: August 2011

SUMMARYMethods for determining cell numbers and cell size in the skin or dermal system of fruit have been examined, using as an example the grape, Vitis vinifera. Though the cells are commonly six‐sided, projected cell area is more accurately determined if the cells are assumed to be circular. Sources of error and assumptions are considered.
A Method For the Removal of Epoxy Resins From Tissue in Preparation For Scanning Electron Microscopy
Authors: Steffens W. L. 
Published: August 2011

SUMMARYA method for unmounting entire resin‐embedded samples for SEM observation is described. This technique is particularly useful when correlation of TEM and SEM images is desired for material that is no longer available for conventional SEM preparative procedures. Samples embedded in a variety of epoxy‐type resins were trimmed of excess resin and placed in a concentrated solution of sodium methoxide. After complete dissolution of the resin, the tissue was washed in a graded series of sodium methoxide in methanol‐benzene, transferred to acetone, critical point dried, mounted on stubs, and coated with gold‐palladium. Upon viewing in the SEM, the tissue samples showed remarkable preservation of detail at relatively high magnifications.
The Sampling, By Quadrats, of Planar Aggregates
Authors: Miles R. E. 
Published: August 2011

SUMMARYThe estimation, for planar particle aggregates, of their number or density per unit area and of their distributions (e.g. of area or perimeter), by means of randomly placed quadrats, is complicated by the question of deciding whether or not to include particles truncated by the quadrat boundaries. Previous unsatisfactory solutions to this problem have led to unnecessary bias in the estimates. A general ‘associated point’ solution is presented, and its theory is developed in some detail.
X‐ray microanalysis of epon sections after oxygen plasma microincineration
Authors: Barnard Tudor , Thomas Richard S. 
Published: August 2011

SUMMARYDark gold sections of osmium tetroxide‐fixed, Epon‐embedded brown adipose tissue before and after low‐temperature oxygen plasma microincineration were examined using a high‐resolution scanning transmission electron microscope and an energy‐dispersive X‐ray spectrometer. Microincineration produced ash patterns which were free of organic matrix, chlorine (from the Epon) and probably osmium (from the fixative). X‐ray sensitivity was improved by a factor of 2–4 owing to decreased background, and sulphur, calcium and probably phosphorus were detected in the ash. Fidelity of the ash patterns permitted microanalytical spatial resolution of 0.1 μm or better. Oxygen plasma microincineration is thus shown to offer advantages for high resolution X‐ray microanalysis of conventionally sectioned biological material. Its future application to shock‐frozen, frozen‐dried, unstained sections is indicated.
Ring counting in field‐ion micrographs
Authors: Webber R. D. , Walls J. M. , Smith R. 
Published: August 2011

SUMMARYRing counting is an important technique in the quantitative analysis of field‐ion micrographs since the information derived is independent of magnification and projection both of which vary in a complex way over the image. However, although the technique is important, its direct use has previously been restricted to the region within which the particular ring system is discernible. In this paper, techniques and procedures are described which usefully extend the range over which the ring count can be performed. The methods are based on determining the numerical interrelationship of the various ring structures. This not only allows ring counting to be effected over large angular distances, but also enables counts to be performed in any direction so that the number of rings of a high‐index plane can be determined through more prominent low‐index regions.