bluuebunny/crossref_metadata_2025 huggingface dataset:
Observations of dislocations in [011] symmetrical tilt boundaries near Σ9 C.S.L. in aluminium
Authors: Silcock J. M. , Kegg G. R. , Horton C. A. P.
Published: August 2011

Bicrystals with [011] symmetrical tilt boundaries rotated 36° have been examined by transmission electron microscopy. The boundary which was near a (41) plane showed networks of structural grain boundary dislocations. Possible vectors were derived from Bollmanns coincident site lattice theory for the nearest C.S.L., i.e. Σ9. The networks have been examined in a number of reflections and are considered to be composed of dislocations with b2 (i.e. 1/9 [12]) and b3 (1/6 [121] or 1/18 [127]) vectors. Four b3 vectors can change from one to the other by interactions with other structural dislocations. Evidence of iron additions reducing the mobility of dislocations is presented, and evidence of lattice dislocation dissociations are discussed. The mobility of dislocations in this Σ9 C.S.L. boundary is compared with a Σ27 coincidence lattice.
Grain boundary dislocations and the mechanism of sliding in symmetrical [011] tilt Al bicrystals
Authors: Horton C. A. P. , Silcock J. M.
Published: August 2011

Observations of grain boundary dislocations in [011] tilt bicrystals of aluminium after high temperature shear tests have led to a concept for grain boundary sliding that involves extrinsic dislocations moving through an array of structural dislocations. Each extrinsic dislocation consists of a group of structural dislocations with closer than normal network spacing caused by the presence of an extra dislocation with the same Burgers vector. The extrinsic dislocation exhibits a long range strain field and can move individually through the array of structural dislocations. The movement involves displacements in the structural network analogous to atom displacements during crystal slip. The width of the extrinsic dislocation on the grain boundary plane is dependent on the degree of accommodation of the extra dislocation by the structural array and this appears to increase with increasing density of structural dislocations.
A simple film speed regulator for microcinematography
Authors: Troyer David
Published: August 2011

A regulator is described which holds the film speed of a very economical 16 mm camera constant at filming speeds of 5–35 frames/s.
Exposure level and image quality in electron micrographs
Authors: Farnell G. C. , Flint R. B.
Published: August 2011

Single electrons of the energies used in transmission electron micrography can render developable one or more emulsion grains. From this fact the following deductions can be made.

Photographic contrast in an electron micrograph is a function of the mean density only.

The signal/noise ratio in an electron micrograph improves with increasing exposure, irrespective of the means adopted to enable an increased exposure to be used.

If the exposure of the specimen is limited to some maximum then the visibility of noise‐limited detail in prints representing a given total magnification is independent of the negative material used in the microscope.

Experimental tests based largely on electron micrographs are presented which provide good support for these deductions. It is generally concluded that the behaviour patterns examined in this work should always be considered when limitations are being encountered in the image quality of electron micrographs.
A method for adapting the Leybold device for obtaining complementary replicas to the Balzers unit
Authors: Sleytr Uwe B.
Published: August 2011

A simple method is described for adapting the Leybold complementary replica device, which is equally useful for the examination of suspensions and tissue fragments, to the Balzers freeze‐etching unit. The only change necessary for using the device in the Balzers unit, is to unscrew the Balzers specimen table from the cold stage and replace it with an adapter. If prolonged etching is required, a contamination shield is mounted on the microtome arm in place of the razor blade.
Positive displacement holder for critical point drying of small particle materials*
Authors: Baker F. L. , Princen L. H.
Published: August 2011

A specimen holder has been designed specifically to contain small particulate matter, such as microorganisms, fibres or powders, during the fluid exchange cycle and final evaporation step of the critical point drying process. The mode of fluid exchange is positive displacement rather than diffusion. The holder can accommodate up to ten different samples without loss of material or cross‐contamination during the dehydration process. The samples are separated by silver membrane filters, and fluid exchange is accomplished in minimal time by only slight positive pressure. Experiments with soluble dyes have shown that any fluid can be displaced completely with another in less than 2 min, whereas diffusion requires more than 30 min. The holder and individual capsules have been tested with different materials and a standard water/ethyl alcohol/amyl acetate/carbon dioxide fluid sequence. This paper describes the design, production, and testing of the holder and capsules, and presents selected examples of results.
The myofibrillar M‐band in the cryo‐section—analysis of section thickness
Authors: Thornell Lars‐Eric , Sjöström Michael
Published: August 2011

Information regarding the formation and the thickness of cryo‐sections is of importance for an adequate interpretation of cryo‐sectioned biological material. In this study we have taken advantage of the regular arrangement of filaments in myofibrils in an analysis of these matters. It is concluded that the sections are formed partly by fracturing in a way similar to that visualized in replicas made by the freeze‐fracturing and ‐etching procedure.
Optical microscopy of charcoal
Authors: Cousins W. J.
Published: August 2011

A method for microtome sectioning of charcoal is described and optical micrographs of some naturally occurring charcoals are shown. The morphology of charcoal as seen in the transmission optical microscope is very similar to that of wood.
The preparation, examination and analysis of frozen hydrated tissue sections by scanning transmission electron microscopy and X‐ray microanalysis
Authors: Saubermann Albert J. , Echlin Patrick
Published: August 2011

A method is reported for preparing, examining and analysing frozen hydrated tissue sections using transmission electron microscopy and X‐ray microanalysis. Use of this method permits localization and measurement of water soluble or diffusible elements within the hydrated cell matrix. Since any change in total fresh weight of the specimen will affect the concentration of all components, great care has been taken to demonstrate that the mass neither increases nor decreases and to ensure that the tissue remains frozen‐hydrated. Criteria for assessing whether or not the tissue remains frozen‐hydrated are reported.

After quench freezing, 1–2 μm thick sections of mouse liver were cut at 193°K and picked up on a specially designed annular specimen holder covered with an aluminium coated nylon film. Using a transfer device which prevents contamination of the tissue sections while maintaining them at a low temperature (below 143°K), the sections are transferred either to the vacuum evaporator cold stage or the scanning microscope cold stage. The tissue sections may be coated with an aluminium layer to improve electrical and thermal conductivity. The specimens are examined in the scanning transmission imaging mode and analysed using an energy dispersive X‐ray analyser. Concentration of intra‐nuclear and intracytoplasmic K, P, S and Cl are reported for mouse hepatocytes as ratios of the characteristic radiation to the continuum radiation used as a measure of mass. Ratios for all four elements were higher in the nucleus than the cytoplasm. Examples are given of this method as applied to plant and insect tissue.
The use of moiré patterns to determine the source and degree of adistortion in scanning electron microscopes
Authors: Bradley S. A. , Thielen P. N. , Hilliard J. E.
Published: August 2011

Scanning electron microscope images are subject to an appreciable amount of non‐linear distortion which must be allowed for when quantitative analyses are made. A method is described for measuring the distortion by the use of moiré patterns. These greatly magnify any non‐linearities and it is possible to measure distortions as small as 0ṁ1%. In addition, the use of moiré patterns permits a separation of the distortion produced in the cathode‐ray display tube from that occurring in the microscope itself.
A microspectrofluorometer with on line real time correction of spectra
Authors: Wreford N. G. M. , Schofield G. C.
Published: August 2011

A microspectrofluorometer incorporating analogue computing segments and suitable for recording corrected spectra instantaneously on an X‐Y recorder is described.
Plant‐cell structures in vitrinite chars
Authors: Goodarzi F. , Murchison D. G.
Published: August 2011

This paper describes the occurrence of plant‐cell structures retained in particles of the principal coke‐forming constituent (vitrinite) of a coking coal, which has passed through its decomposition point during carbonization using several rates of heating. The benefits of wider application of the study of organic constituents with high optical absorptions under crossed polars in reflected light are emphasized. Relief‐polished surfaces of certain of the vitrinite‐char particles, which appear virtually structureless in plane‐polarized light under oil immersion, when viewed under crossed polars not only possess well‐preserved plant‐cell structures, but also show development of a mosaic structure from a mesophase in situ with virtually no disturbance of even the cell walls. Retention of the original cell structure is almost certainly governed by a reduced reactivity of this vitrinite induced by oxidation of the original plant tissues at the time of their deposition in the coal‐forming swamp.
A technique for preparing holey carbon films for high resolution electron microscopy
Authors: Gannon J. R. , Tilley R. J. D.
Published: August 2011

A simple and reproducible method of preparing holey carbon nets for use as support films for high resolution electron microscopy is described.
Stereo photomicrography of Golgi preparations
Authors: Fahrenbach Wolf H.
Published: August 2011

Photomicrographs of thick sections taken with reciprocal, lateral illumination in a compound microscope produce stereo‐pairs. The method is particularly useful with thick celloidin sections of nervous tissue impregnated with the Golgi selective silver technique.
The use of direct deposition electron microscope autoradiography in studies of protein transport
Authors: Hemmings W. A. , Williams E. W.
Published: August 2011

The use of direct deposition autoradiography in studies of the localization of proteins labelled with radio‐iodine or tritium in the epithelia of fetal, suckling, and adult animals is described. Using a single marker in the first place, rabbit IgG and bovine IgG have been seen both in the vacuolar apparatus and also free in the cytoplasm of endodermal cells of the rabbit yolk‐sac splanchnopleur. This has been confirmed in those cells using a combination of bovine IgG marked with tritium and rabbit IgG marked with 125I, presented simultaneously to the cells. Both proteins are present, apparently equally, attached to the brush border and distributed through the cytoplasm, as well as within vacuoles. Selection does not take place before or during entry to the cell, as has been suggested by quantitative results which have been reported elsewhere. It is hoped that the use of two markers together will permit localization of the selective process. In the adult rat gut, both isotopes have been demonstrated entering and within and leaving the ileal cell, confirming quantitative results reported elsewhere.
Hyperactivity and faster replicating property of the two arms of the male X of Drosophila pseudoobscura*
Authors: Mukherjee A. S. , Chatterjee S. N.
Published: August 2011

The two arms of the X chromosome of Drosophila pseudoobscura have different phylogenetic origin, the XL being homologous to the X and the XR homologous to the 3L of D. melanogaster. The replicative and transcriptive activities of the two arms have been examined in order to understand how such phylogenetically different components of the X contribute toward the chromosomal basis of dosage compensation. The 3H‐uridine labelled autoradiograms of the polytene chromosomes of larval salivary glands reveal that the intensity of labelling in the XL and XR of the male is not significantly different from that in the two arms of the female, respectively. The number of grains on the two arms plotted against the grain number on an autosome follows a linear regression, and neither slope in the male is significantly different from its counterpart in the female. The 3H‐thymidine autoradiograms show that in all phases of replication, viz. initial, middle and terminal, both arms of the X chromosome in the male are advanced by one step in the cycle. Results, therefore, suggest that both arms of the X of D. pseudoobscura, are hyperactive and faster replicating in the male. Such a situation might arise due to a primary signal coming from autosomally located regulators controlling the super‐operon structure of the X chromosomal genes.
An in situ field‐ion microscope research of radiation damage in tungsten
Authors: Tamaki Shozo
Published: August 2011

Results of experiments in which tungsten was irradiated in situ in the field‐ion microscope with inert gas ions are described. Tungsten field‐ion specimens were irradiated at 78 K with ions in the 0.5–9 keV energy range. Sputtering and displacement of surface atoms which had occurred during irradiation were observed directly in field‐ion images. Large scale damage such as vacancy clusters were rarely found. From the ion acceleration voltage and the accommodation coefficient, the displacement energy of tungsten surface atoms in the electric field of about 44 MV/mm is estimated as nearly 22 eV. Damage was observed on the shielded side of the tip apex as well as on the ion incident side, and this fact is discussed in comparison with the channelling of ions in tungsten.
Identification of particles of coal and processed solid fuels in airborne dust
Authors: Smith A. H. V.
Published: August 2011

Methods of mounting dusts for observation by incident light using an oil immersion objective are described. The optical properties of coals, chars and cokes are briefly referred to as an introduction to the description of dusts from six types of solid processed fuel.
Stereological microstructure analysis as a tool for quantitative quality control and property determination
Authors: Ondracek Gerhard , Pejsa R.
Published: August 2011

In the present paper the use of stereological microstructure analysis is considered—to describe quantitatively the microstructure by stereological factors and to determine indirectly the properties of two‐phase matrix materials.

Three stereological factors are determined from quantities measured in optical images (microscope/epidiascope‐electronic image analyser) concerning the shape, orientation and concentration of the particles of the dispersed phase. Using these the microstructure of a two‐phase matrix material can be described sufficiently quantitatively. These stereological factors take into account the effect of the microstructure on properties such as the electrical resistivity, Youngs modulus or thermal expansion coefficient, if used in microstructure‐property equations. Using equations of this type the calculation of such properties without measuring them directly becomes possible assuming that the stereological factors of the microstructure of a two‐phase material and its phase properties are known. The way to do this is demonstrated for WC‐Co hard metals. As a consequence it follows that the combined quantitative description of microstructures and property determination (stereological microstructure analysis) extends the application of microstructure analysis in quality control and opens the way to calculate optimum microstructures to obtain special property values (tailor‐made‐materials).
Electron irradiation of dilute aluminium alloys
Authors: Mayer R. M.
Published: August 2011

Zone‐refined aluminium and dilute alloys with silicon and indium have been irradiated inside a high voltage electron microscope. Interstitial dislocation loops nucleated and grew in all samples, but no voids could be observed. The precipitation of silicon was observed during irradiation. The effect of alloying on the loop growth rate is discussed.
Biological freezing and cryofixation
Authors: Franks F.
Published: August 2011

Freezing and freeze fixation are commonly used to achieve ultrastructural and biological preservation. Freezing in biological materials is complex because of their heterogeneous nature—water is unevenly distributed and the various domains are separated by semi‐permeable membranes. Processes to be considered include: (1) osmotic gradients leading to redistribution of water, (2) nucleation and uncontrolled growth of ice crystals, (3) recrystallization of nucleated aqueous substrate.

To avoid ultrastructural deformation in biological specimens cryofixatives are commonly employed. These are water soluble molecules, able to penetrate cell membranes (e.g. glycerol and dimethylsulphoxide). Interacting strongly with water, ions and bipolymers, they give rise to metabolic and physiological changes which render them useless for X‐ray microprobe analytical studies. However, they can enable tissues to survive low temperature storage. Some plants and animals develop in vivo mechanisms which enable them to avoid or tolerate freezing.

Alternative means of cryofixation have recently been developed. They rely on non‐penetrating polymers of high and specific water binding capacity. These polymers enable the extracellular spaces to be vitrified rather than frozen. Such suppression of ice nuclei enables the cell contents to be maximally subcooled, resulting in the formation of nm dimension ice crystals. Since the polymers have a low osmotic activity and do not penetrate membranes, the interior of the cell is substantially undisturbed. Also hydrophilic polymers used as cryofixatives are physiologically less active than conventional cryoprotectants at equivalent weight concentrations, and their mechanical properties render them useful as matrices for cryosectioning.
Structural and functional aspects of biological freezing techniques
Authors: Farrant J. , Walter C. A. , Lee H. , Morris G. J. , Clarke K. J.
Published: August 2011

The cooling procedures used to prepare samples for ultrastructural examination at low temperatures often differ markedly from those used to recover optimal function of cells on thawing. The implications of these differences are reviewed. Damage and alteration to the structure and function of the cells may be caused by the high concentrations of cryoprotective agents such as glycerol or dimethyl sulphoxide (DMSO) often added to reduce ice crystal artefacts. Under the rapid cooling conditions commonly employed for structural studies, these additives are not cryoprotective; low rates of cooling are necessary for them to be effective. Rapidly cooled cells that contain intracellular ice are only injured during re warming so their structure may be as yet unaltered by any damaging effects at low temperatures. Most cells able to recover on thawing are grossly shrunken at low temperatures but since they are potentially functional they are of interest structurally. These cryobiological principles are illustrated with freeze‐fracture, freeze substitution and functional assays. The cell types chosen were Chlorella sp. and mammalian tissue culture cells.
Cold stage for electron probe microanalyser
Authors: Taylor Peter G. , Burgess Antony
Published: August 2011

Investigators wishing to examine and analyse biological specimens in the electron probe microanalyser (EPMA) in as near the original physiological and morphological state as possible have found that a cold environment is necessary to reduce the rate of sublimation and radiation damage to a low level.

A low temperature cold stage has been designed and constructed for this purpose, to be used with a J.E.O.L. JXA 50A microanalyser. The cold stage will maintain the specimen holder at a temperature of 108 K for a period of 2 h before refilling of the liquid nitrogen Dewar flask becomes necessary. The fitting of a cold stage in place of the regular room temperature standard stage greatly increases the risk of contamination from the condensation of residual gases present in the specimen chamber. We have constructed an ami‐contamination plate (cold plate) that prevents this.
Freeze‐fracture for scanning electron microscopy
Authors: Haggis G. H. , Phipps‐Todd Beverly
Published: August 2011

Two different freeze‐fracture methods are explored for preparation of biological material for scanning electron microscopy. In the simpler method the tissues are first fixed and dehydrated. They are then frozen and fractured, and after thawing, critical‐point dried. This method has already been used in a number of studies of animal tissues (heart, liver, kidney). It is applied here to the examination of plant material (leaf mesophyll cells). In the second method tissues, or cells, are first infiltrated with cryoprotectant (dimethylsulphoxide) then frozen and fractured, and not fixed until after thawing. The fixed tissues are finally dehydrated and critical‐point dried. This method also has previously been used in the study of animal tissues, and is applied here to carrot protoplasts, chicken erythrocytes, and leaf mesophyll cells.
Cryo‐ultramicrotomy and myofibrillar fine structure: a review
Authors: Sjöström Michael , Squire John M.
Published: August 2011

In the past, the techniques of electron microscopy and X‐ray diffraction have both been very informative about the ultrastructure of the muscle myofibril. But X‐ray diffraction patterns are difficult to interpret unambiguously and until now specimen preservation in plastic embedded muscle has been sufficiently poor to make it difficult to use electron micrographs of muscle as a means of interpreting the available X‐ray diffraction evidence.

The possibility of using ultrathin sections of frozen muscle, in which the disruptive steps of chemical dehydration and plastic embedding can be avoided, promises to help to bridge the information gap between present X‐ray and electron microscope results. For this reason we here review the application of the cryosectioning technique to muscle, we assess the technique in terms of the improvements in preservation which have so far been obtained and which might be expected and we discuss some of the many potential advantages and uses of this technique for studies of muscle ultrastructure and function.

It is concluded that this technique should be developed vigorously since it promises to play a very important role in muscle research in the future.
A light microscope attachment for isolating small specific areas from slide embedded monolayers: an aid in electron microscopy
Authors: Bird R. G. , Chapman P.
Published: August 2011

Based on the idea of a spring‐loaded microscope objective, a boring attachment has been designed and constructed to fit a standard revolving multi‐objective holder. It enables many small specific areas of a slide embedded specimen to be selected, ringed and bored out without removing the slide from the microscope stage.
Principles of sampling, preparation and constituent selection for microphotometry in measurement of maturation of sedimentary organic matter
Authors: Bostick N. H. , Alpern B.
Published: August 2011

Samples may be obtained from outcrops, cuttings, cores, modern sediments and old collections. Coals, brown or grey siltstones and fine‐grained sandstones generally yield the most satisfactory organic matter for maturation analysis, while red beds and evaporites are often barren. Shales with a high organic content are not especially desirable for optical studies of maturation because the organic matter is likely to be very fine‐grained and high in pyrite. The whole rock or a concentrate of organic particles may be prepared for microscopical study, the former being preferred for analysis of solid bitumens and fluorescence study, the latter for measurement of vitrinite reflectance, microspore translucency and refractive index. Crushing, ultrasonic disintegration, handpicking, heavy liquid separation, flotation, settling, sieving and demineralization with HC1 and HF are used to concentrate organic particles. Preparations include polished rock slabs, concentrate briquettes and strew mounts.

The constituents with the lowest maturation in a rock must be selected if maturation indigenous to the rock is to be measured. Organic matter that has been previously altered at its site of origin, reworked and altered during diagenesis, or redeposited from older rocks, must be excluded from consideration. The organic constituents are recognized most easily by reflected light microscopy. A combination of fluorescence and reflectance techniques is useful for low rank samples.
Optical properties of oxidized vitrinite and exinite
Authors: Prado J. G.
Published: August 2011

The optical properties of vitrinite and exinite from a low‐rank coal (volatile matter = 37.3% dry ash free) oxidized with air on a fluidized bed at 300°C over periods up to 24 h have been studied. Reflectivities in air and oil of the unoxidized maceral areas within the particles and of the oxidized rims were measured at five wavelengths between 436 and 644 nm and the absorptive and refractive indices calculated using Beer's equation. The reflectivity spectra and the variation of the optical properties of the oxidized macerals with time of oxidation are discussed. It is concluded that the spectrum of oxidized exinite is a good parameter to indicate oxidation and that in low‐temperature oxidation experiments, when no oxidation rims appear, the inner part of the particles may not be oxidized.
Quantitative characterization of the texture of coke
Authors: Patrick J. W. , Sims M. J. , Stacey A. E.
Published: August 2011

Coke texture can be shown to be a factor of prime importance in considerations of coke strength and a method has been developed whereby relevant details of the coke texture can be obtained from the microscopic examination of polished coke sections using a Quantimet 720 image analyser. The specimens examined consisted of 10 mm cylindrical cores of the same type as those used for the diametral‐compression test of tensile strength, the cores being mounted in resin and prepared as polished blocks. For a variety of cokes produced on the laboratory scale, and covering a range of porosity from 40 to 60%, the median sizes of pores and pore walls, as determined under the experimental conditions used, varied from about 50–80 μm and 60–120 μm respectively. The number of pores per field of view examined, varied widely from 20 to 220 and the average pore perimeter per field analysed, varied from 70 to 140 mm. The results indicated correlations between the median tensile strength and several of the textural parameters, such as the volume porosity and the average pore‐wall thickness.
The use of light and electron microscopy in the study of experimentally altered spores and pollen grains
Authors: Sengupta S. , Muir M. D.
Published: August 2011

Plant spores and pollen grains were heated to different temperatures, from room temperature to 350°C at atmospheric pressure, in a nichrome‐wire resistance furnace, and to different temperatures from 100 to 500°C at 1 kb pressure in a modified apparatus normally used for triaxial rock‐deformation studies. In the temperature and pressure experiments, the grains were mixed with silica sand and sea water in the proportions of 1:4:5. For optical microscopy, the pollen grains were mounted in glycerine jelly: for SEM, they were mounted on aluminium stubs rinsed with water and sputter‐coated with gold. STEM and HVEM were used on thick sections of spores of Lycopodium clavatum embedded in Epon‐Araldite.

The different layers of the spore or pollen‐grain (i.e. exine+intine) degrade differently. The ornamented part of the exine (the sexine−mainly composed of sporopollenin, lipids and polysaccharides) begins to degrade at approximately 300–350°C and 1 kb pressure, exposing the non‐ornamented nexine layer. The nexine seems able to withstand high temperatures and pressures. Between 300 and 500°C with 1 kb pressure, the grains begin to form an amorphous mass. Compared with other work in which the outer exine layer of L. clavatum was removed by oxidation with ozone, here the same layer was gradually removed by pressure and temperature effects. The smell of phenolic compounds is very prominent at higher temperatures (400°C with 1 kb pressure and upwards) and production of other gas, unidentified so far, is evident from about 300°C and 1 kb pressure.

The degraded exposed nexine layer at 500°C resembles thin plates in the SEM. A similar structure was also found in L. clavatum heated at 300°C and 1 kb pressure. The exposed nexine of L. clavatum was sectioned and examined in the TEM, which showed the trilamellar units, of which the main bulk of the nexine is composed, to be very resistant to high temperatures and pressures. STEM and HVEM have been used to study globular structures observed in the L. clavatum spore cavity.
A note on spherical structures in chars from vitrinites of coking rank
Authors: Goodarzi F. , Murchison D. G.
Published: August 2011

Spherulitic aromatic structures with relatively simple optical characters that form as a transitional phase in the development of mosaic textures are well known in pitch fractions and certain polymers when carbonized. Their occurrence in coal macerals that soften prior to the formation of a mosaic is less certain. Other spherulitic structures, much larger in size than mesophase spherules, can, however, develop from vitrinites with a high potential fluidity under certain carbonization conditions, when fast heating rates are employed. These bodies, besides displaying optical characters that indicate structural symmetry, also show mosaic textures.
Organometallic and organometalloid compounds as standards for microprobe analysis of epoxy resin embedded tissue
Authors: Roomans Godfried M. , Gaal Henk L. M. van
Published: August 2011

X‐ray microanalysis of phosphorus, transition elements and heavy metals in biological tissue is frequently carried out on thin sections of specimens embedded in epoxy resin. A logical choice for the quantitive microprobe analysis of these specimens is a standard, consisting of a homogeneous solution of the elements of interest in the epoxy resin. Four kinds of compounds were found suitable for this purpose: (1) phenyl compounds containing group Vb elements, (2) cyclopentadienyl‐derivatives, (3) a pentanedione derivative (acetylacetonate) and (4) complexes of metals with dialkyldithiocarbamates. In the latter case, the standard also contains sulphur. Standards for P, Sb (1) Mn, Fe (2) Ni (3) Cu, Zn, Cd, Hg, Pb, Bi (4) were prepared in Epon 812 or Spurr epoxy resin. The compounds were mixed with the resin (without accelerator) to which some propylene oxide may be added, and dissolved immediately or after short heating. The maximal concentration of metal was in the order of magnitude of several promilles to 1%. Solubility in the Spurr resin was better than in Epon 812. After addition of the accelerator, polymerization was carried out as usual. The compounds used are commercially available at low cost or can be easily prepared.
How dangerous is sodium cacodylate?
Authors: Weakley Brenda S.
Published: August 2011

Circumstantial evidence suggests that sodium cacodylate may be a far greater health hazard than has been generally assumed. Until further information is available, electron microscopists should see that extreme care is exercised during the preparation of cacodylate buffers by their staff.
X‐ray, light and scanning electron microscopy of manganese sulphide and lead inclusions in free‐cutting steel
Authors: Dench W. A. , Pugh D. J. , Stoddart C. T. H.
Published: August 2011

MnS and Pb inclusions in some commercial free‐cutting steel bars are of high length‐to‐thickness ratio and are also sinuous in form. Individual inclusions are then not seen in their entirety in metallographically polished longitudinal sections examined in the light or scanning electron microscope. X‐ray microradiography of thinned specimens forms images of inclusions that lie completely within the thickness of the specimen. By using both Co and Fe radiation, MnS, Pb and the steel matrix may all be clearly distinguished.
On The Feasibility of Imaging, By High Resolution Electron Microscopy, Isolated Individual Sheets of Graphitic Carbon
Authors: Millward G. Robert , Jefferson David A. , Thomas John M.
Published: August 2011

A comparative survey of computer simulated and experimentally obtained images shows that it is feasible to observe, end‐on, isolated single sheets of trigonally bonded carbon atoms in graphitic substances directly by electron microscopy, provided that certain imaging conditions are employed. For a typical commercial instrument (Philips EM300 with a spherical aberration coefficient of 1.6 mm) authentic images are found whenever the objective lens is set at underfocus positions between 65 and 110 nm, with optimum contrast occurring near the ‘Scherzer’ imaging condition of 95 nm underfocus.

At this latter focus position the fringe contrast is maximal when the sheet extends in the direction of the electron beam for a distance of about 5.5 nm; but sheets as narrow as 1.0 nm (i.e. containing some four widths of benzene rings in the direction of the electron beam) should be detectable.
Particle Number or Density Can Be Stereologically Estimated By Wedge Sections
Authors: Miles R. E. , Davy Pamela
Published: August 2011

The information derivable from the traces of a two‐phase medium on the faces of a wedge probe close to its edge is systematically investigated. It is shown that in principle the integral of gaussian curvature over a smooth phase‐phase interface can be estimated from this information. In simple terms, the method allows one to estimate the number of cherries in a cherry‐cake (or more generally the Euler topological characteristic of the cavities in an Emmental cheese) on the basis of observations on and near the edge of a wedge‐shaped slice of the cake (or cheese).
Recovery of Osmium Tetroxide From Used Fixative Solutions
Authors: Kiernan J. A.
Published: August 2011

A technique has been developed whereby osmium tetroxide (OSO4) is reclaimed from solutions used as fixatives in electron microscopy. The osmium compounds in the collected residues are oxidized to OSO4, which is then extracted into carbon tetrachloride. Osmium dioxide is precipitated with alcohol, recovered by filtration and dried. This is a safe and convenient form in which to store the reclaimed material. An aqueous solution of OSO4 is prepared by oxidizing an aqueous suspension of osmium dioxide with hydrogen peroxide.

The reclaimed product has been used for post‐fixation of aldehyde‐fixed specimens for transmission and scanning electron microscopy and for histochemical procedures in light microscopy. It is evidently just as satisfactory for these purposes as the newly bought substance. The equipment and reagents required for the reclamation procedure are readily available and inexpensive. 5 g can be recovered for the cost of less than 150 mg of new osmium tetroxide.
A Convenient Method to Remove Lipid Contamination From Freeze Fracture Replicas
Authors: Vail William J. , Stollery John G.
Published: August 2011

This paper describes a convenient method to remove lipid contamination from freeze fracture replicas.
A Simple Sectioning Technique For Use in Conjunction With Scanning Electron Microscope Examination of Polymer‐Treated Textile Materials
Authors: Kershaw Alan , Lewis James
Published: August 2011

A technique is described which allows relatively thick but fragile assemblies to be examined without damaging their internal structure.
An inexpensive controlled temperature stage which allows high resolution optical microscopy
Authors: Mersey Brent , McCully M. E. , Fatica Enzo
Published: August 2011

Specifications are given for an inexpensive controlled temperature microscope stage which facilitates observation of living cells at temperatures down to 268 K. The design makes it possible to use an oiled 1.4 N.A. condenser thus allowing observation at high resolution and giving phase contrast and Nomarski interference contrast images of high quality.
Charging effect in electron‐irradiated ice
Authors: Fuchs Wolfgang , Brombach Jobst D. , Trösch Walter
Published: August 2011

To maintain the original distribution pattern of diffusible elements in biological samples, electron probe microanalysis is carried out with frozen hydrated bulk specimens and cryosections, analysed at temperatures below 130 K. Ice has a very low intrinsic conductivity at this working temperature and surface‐ and space‐charging appears, when uncoated specimens are irradiated with non‐penetrating electrons. Although coating with a grounded conductor abolishes the surface potential, the build‐up of an internal space‐charge field is possible, depending on the sample thickness and beam voltage used. Consequently, the geometry of the X‐ray source volume and the spectral distribution of the emitted continuous and characteristic X‐rays are affected. To simulate the situation for microanalysis of frozen hydrated specimens the charging process in electron irradiated ice is studied by recording simultaneous specimen currents from the top and bottom of ice layer preparations. The external currents yield information on the build‐up of internal space‐charge fields which result from the balance of charge injection, storage, and transport.

Irradiation of uncoated bulk specimens with a finely focused beam results in the build‐up of a space‐charge field close to the surface, which causes a reduction of the depth of microprobe analysis. In coated bulk specimens the induced conductivity renders possible a current flow to the front electrode, thereby limiting the space‐charge field. Sections with an effective rear electrode will not charge appreciably if the electron range is larger than about half the section thickness.
Interference reflection microscopy of adhesion of Amoeba proteus
Authors: Opas Michal
Published: August 2011

A simple method of observing the adhesive behaviour of large cells by means of interference reflection microscope is described, and some observations of mono‐podial Amoeba proteus are presented. Amoebae may contact with the substratum at any point along the long axis of the cells. Points of contact are usually few, small and temporary. Frequently the cell surface within the contact points oscillates, changing the separation distance from the substratum.
Nascent cellulose fibrils in green plants
Authors: Leppard Gary G. , Colvin J. Ross
Published: August 2011

The notion of a hydrated, swollen, linear aggregation of extended β1 → 4 polyglucosans as a transient nascent phase in the biosynthesis of a bacterial cellulose microfibril from Acetobacter xylinum may be broadened to include cellulose biosynthesis by green plants, on the basis of present experimental evidence.
Differential leucocyte counts: A comparison of results using light and electron microscopy
Authors: Gillett R. , Hancock P. M. , Williams D. M. , Hill M. W.
Published: August 2011

A method is described for handling leucocytes from an inflammatory peritoneal exudate prior to electron microscopy, which allows differential counts from ultrathin sections to be made. The results of counts from ultrathin sections, viewed on the electron microscope, are compared with samples from the same cell populations prepared on a cytocentrifuge and counted by light microscopy. The results from several cell populations of widely different compositions show clearly that with suitable care taken over preparation and orientation, ultrathin sections can yield comparable differential counts to those obtained by standard light microscope procedures. Possible sources of error are discussed and the advantages of ultrastructural counting assessed. The method has a wide application wherever accurate differential counts are required from cell suspensions processed for electron microscopy.
The use of EM tissue processor capsules for enzyme cytochemical incubations
Authors: Gradidge T. J.
Published: August 2011

A method is described using EM tissue processor capsules to enclose and protect thin tissue slices during enzyme cytochemical incubations and their subsequent processing for electron microscopy.
Scanning electron and light microscope correlation of individual human bone marrow cells before and after culture in nutrient agar
Authors: Lytton D. G. , Yuen E. , Rickard K. A.
Published: August 2011

This study was undertaken with the aim of identifying the different cell types found in human bone marrow by examining their surface morphology. In an attempt to obtain a homogeneous cell population, cells were both fractionated by discontinuous albumin density gradient centrifugation (DADGC) and selectively grown in nutrient agar. Both cell preparations underwent the critical point drying technique before examination under both the scanning electron microscope (SEM) and subsequently the light microscope (LM). When the SEM image of individual cells was compared with the corresponding LM image, it was not easy to identify the different cell types, because of the shrinkage and distortion that occurred during their preparation. The shrinkage observed under the SEM amounted to a 45% reduction in mean cell diameter. This shrinkage was confirmed by comparing the SEM and LM images of the same cell. Although shrinkage occurred throughout the dehydration sequence, critical point drying was responsible for a 25% reduction in mean cell diameter. Furthermore, direct observation under LM of fixed cells drying in air from ethanol, revealed visible contraction of the cell and distortion of the cell membrane. We assume that a similar morphological change occurred during critical point drying. We conclude that the shrinkage and distortion, caused by the dehydration process involved in SEM preparation, severely limit the value of a study of surface morphology by SEM in the identification of the different cell types found in human bone marrow.
Techniques Utilizing Real Time Stereo Scanning Electron Microscopy In The Microdissection Of Biological Tissues
Authors: Barber V.C. , Emerson C.J.
Published: August 2011

The use of the scanning electron microscope (SEM) for the microdissection of biological tissue is described. The dissections were accomplished by the use of electrolytically pointed needles that were positioned in a simply constructed holder. The operations were viewed using real time stereo SEM, and recorded on videotape. Various methods for photographing the videotape recordings are outlined.
Lead And Uranium Stain Artefacts In Electron Microscopy: A Technique For Minimizing Their Occurrence
Authors: Thaete Larry G.
Published: August 2011

A new technique is presented which significantly reduced the occurrence of artefacts by eliminating the air‐stain interface when staining thin sections of biological material. It is designed for simultaneous treatment of large numbers of samples. The experiment described deals mainly with the specific staining problems encountered when using grids coated with Formvar.
A Scanning Microinterferometer With Correction Of Errors Caused By Overlapping ‘Ghost’ Images
Authors: de Jong J. E. De Josselin , Loeve J. , Richter H. , de Sterke H. , Ploem J. S.
Published: August 2011

An experimental setup has been built to correct the errors caused by overlapping‘ghost’ images when scanning and integrating measurements are carried out with the Jamin‐Lebedef interference microscope. First a reference field with the object, producing the‘ghost’ image, is scanned and the values of the optical path difference (OPD) of each point in the reference field are stored in a computer. Subsequently, the OPD of the object to be measured is calculated for each point by adding the measuring result to the average OPD of five points, located around the corresponding point in the reference field. The applicability of the setup has been tested by measurements with Sepharose beads, Hela cells and the Zeiss microinterference refractometer. The difference between measurements on the same object with and without overlapping‘ghost’ image was about 10%. The reproducibility was tested by repeated measurements on the same cell whereby a standard deviation of 1·1% was found.
Optimized Energy Dispersive X‐Ray Microanalysis With A Siemens Elmiskop 102 Electron Microscope
Authors: Hutchison J. L. , Lucas J. H.
Published: August 2011

This paper describes modifications made to the objective lens of a Siemens Elmiskop 102 electron microscope which enable a Kevex Si(Li) detector to be brought to within 20 mm of the optic axis, and which give rise to a relatively‘clean’ X‐ray microanalysis system. The modifications do not affect the performance of high resolution, double‐tilt capability of the instrument.
Some Microstructural Observations Of Transformations In A Copper‐Titanium Alloy
Authors: Ecob Roger C. , Bee John V. , Ralph Brian
Published: August 2011

This paper describes the microstructures observed when a dilute copper‐titanium alloy (Cu‐4wt%Ti) is isothermally transformed. The β phase which forms on transformation is observed in both Widmanstätten and cellular morphologies. It is shown, using light and electron microscopy, that some Widmanstätten plates become the nuclei of cellular plates and that there is often an association between cellular plates of the β phase and more than one twin variant of the matrix α. Dislocation arrays on the α/β interfaces have been resolved and a continuity of this structure between the migrating transformation interface and dislocation arrays on the habit plane has been found.
Precipitation Procedures For Sodium, Potassium And Chloride Localization In Leaf Cells Of The Halophyte Suaeda Maritima
Authors: Harvey Diana M. R. , Flowers T. J. , Hall J. L.
Published: August 2011

Attempts have been made to localize sodium and potassium with antimonate and cobaltinitrite reagents in Suaeda leaf segments by rapid aqueous and freeze‐substitution precipitation procedures and to localize chloride by freeze‐substitution precipitation with silver ions. Substantial sodium losses occurred from the tissue during both types of preparation although potassium and chloride losses were considerably reduced by the use of freeze‐substitution when compared with the rapid aqueous procedures. The losses during freeze‐substitution resulted from the required use of ethanol as substitution solvent (rather than acetone or diethyl ether, in which the reagents were much less soluble). Analytical electron microscopy showed that silver and cobaltinitrite specifically precipitated chloride and potassium respectively, but antimonate did not specifically precipitate sodium. The vacuoles were important sites of silver and antimonate deposits, although the chloroplasts were the major sites of cobaltinitrite localization. The value of these techniques in ion localization studies is discussed.
A Tilt‐Stage Designed For Light Microscopic Stereoscopy
Authors: Stagno Paul A. , Friedenbach David J.
Published: August 2011

This contribution describes in detail the construction and utilization of a reasonably priced, fully adjustable, tilt‐stage for light microscopic stereoscopy of nervous tissue prepared by modified Golgi methods.
Some Considerations Involved In The Automation Of Reflectance Measurement On Coal
Authors: Pitt G. J. , Dawson K. M.
Published: August 2011

The technological importance of the reflectance of coal is now widely accepted and there is a good case for automating the measurement. A number of factors requiring consideration to ensure satisfactory results are discussed and possible solutions to the problems are indicated.