bluuebunny/crossref_metadata_2025 huggingface dataset:
A film projection system for use in quantitative morphological studies
Authors: Deter Russell L.
Published: August 2011

A film projection system is described which permits stereological measurements to be made on negatives enlarged 2.7–6.7 times. The unique feature of this system is its use of the Zeiss TGZ 3 particle size analyser for determining profile size distributions. Elimination of negative printing greatly facilitates investigations requiring analysis of a large number of micrographs.
Freeze‐substitution: a method for the rapid arrest and chemical fixation of spermatozoa
Authors: Woolley D. M.
Published: August 2011

A procedure for the freeze‐substitution fixation of spermatozoa has been developed. Physical fixation of the motile cells is effected very rapidly by immersing the sperm in Freon‐22 at −146°C. Chemical fixation, with glutaraldehyde, is then imposed on the immobilized sperm after substitution of the ice matrix at −50°C. The substitution is achieved with the solvent ethylene glycol in the manner described by Pease (1967). (Subsidiary experiments confirm that substitution of ice does occur at −50°C and that chemical fixation by glutaraldehyde occurs at temperatures at least as low as −20°C.) The spermatozoa are then embedded in Epon and examined as thin sections. Other techniques—substitution in acetone containing osmium tetroxide, the inclusion of formaldehyde with ethylene glycol as a chemical fixative, and the inclusion of agar in the diluent used to suspend the spermatozoa—have been tried but were unsatisfactory.

Freezing stops the movement very rapidly and, as little subsequent disturbance occurs, it should be possible to preserve transient changes in the fine structure of the flagellum which might be related to a mechanism for the generation of bends. The observations in this paper are confined to the behaviour of the proximal part of the midpiece of the rat spermatozoon. It is demonstrated that bending of this part of the flagellum is restricted, to a remarkable degree, to one plane, the plane in which the sperm nucleus is flattened. This plane is almost exactly perpendicular to the plane containing the two central tubules of the axoneme. It has been confirmed that the axonemal complex has a straight course through the midpiece during those beats of the flagellum which are not accompanied by rotation of the entire cell. Lastly, it appears that the nine dense fibres do not undergo transient displacements as the flagellum bends.
Measurement of lacunar volume in bone using a stereological grid counting method evolved for the scanning electron microscope
Authors: Boyde A. , Howell P. G. T. , Jones S. J.
Published: August 2011

A stereological grid method has been evolved for scanning electron microscopy using a self‐generated superimposed grid which compensates for the non‐linearity of the CRT image. The method was applied to determine the volume proportion of lacunae in monkey humerus cortical bone. Flat cut specimens of bone were prepared and photographed with a superimposed grid, and the number of lacunae on intersections of the grid were counted and compared with the total number of intersections on bone matrix. The lacunar volume proportion was 1.06% ± 0.50%.
An on‐line computer system for point counting stereology
Authors: Rätz H. U. , Gnägi H. R. , Weibel E. R.
Published: August 2011

Efficient application of point counting stereological methods in quantitative microscopy in biology and materials science depends on the availability of powerful and rapid counting and computing facilities. An on‐line computer system is described which is easily programmed without knowledge of a special programming language to perform counting, computation of parameters, and statistical tests automatically. By means of a master program, provided with the system, specific user's programs are compiled on a teletype in conversation with the computer by following simple instructions. The program is distinguished by great flexibility; it provides for statistical tests on the reliability of the sample analysed at any time during analysis. The final results are printed in tabular form as means and standard errors of the mean.
The development of a zoom macroscope for radioactive nuclear materials
Authors: Banks D. A. , Eggers A. G.
Published: August 2011

The macroscopic examination of irradiated reactor materials presents special problems in handling due to the necessity of shielding the instrument from the worker with a thick lead wall. The lack of availability of a suitable instrument has prompted the design of a special inverted stage macroscope equipped for remote operation. As the size of lens prevents turret mounting, a commercial 35 mm camera telephoto lens has been adapted in a special focusing mount. This permits the illuminator and stage assembly to be made non‐adjustable, simplifying the problems of remote working. An electronic drive is fitted to each stage movement, both of which are provided with remote position indicators.
A defect produced in low power electron micrographs by thin‐foil objective apertures
Authors: Rostgaard J.
Published: August 2011

An annoying phenomenon in many low power electron microscope negatives is a centrally located overexposed spot. It is shown that its occurrence is associated with the use of thin‐foil objective apertures, and that the spot most probably is produced by electrons permeating the thin‐foil material. The overexposed spot can be avoided either by using a concentrated nearly focused illuminating beam, in practical terms by using a short exposure time, or by using a thick, disc‐shaped objective aperture.
A new specimen mounting system for scanning electron microscopy*
Authors: Lamvik M. K. , Lin S. D.
Published: August 2011

A system of specimen mounting discs and holders has been developed for use in high vacuum. Discs are held in place with a tightly fitting cap, thus avoiding the use of adhesives. The mounting discs are especially convenient for biological preparations, are much less expensive than conventional SEM ‘stubs’ and are easier to handle and store.
Image formation in optical and electron transmission microscopy
Authors: Barnett M. E.
Published: August 2011

In this tutorial article, some basic concepts of image formation in conventional transmission microscopy are reviewed, particular attention being given to the meaning and role of partial coherence.

The application of these ideas to scanning transmission microscopy is also discussed.
Estimation of the size and orientation distribution of filamentary features from measurements on a two‐dimensional section
Authors: Hilliard J. E. , Anacker D. C.
Published: August 2011

A procedure is described for determining the joint distribution Lv(r, ø, θ) of the radii (r) and orientation (ø, θ) of a filamentary structure from measurements on a single section. For tubular filaments it is also possible to determine the wall‐thickness distribution. The following assumptions are made: (1) that the filaments have a circular cross‐section; (2) that the length and radius of curvature of the filaments are large compared with their radii.

The analysis is also applicable to transmitted images if the thickness of the slice is small compared with the average radius of the filaments.
A Fourier approach to optical shadowing with a transmission electron microscope
Authors: Scales Donald J.
Published: August 2011

Optical shadowing offers the possibility of combining the high resolution of the transmission electron microscope with the study of surface detail, commonly investigated with the scanning electron microscope.

Image formation in this mode of operation is treated according to the formalism of Fourier optics, where we consider the objective aperture to be a spatial filter in a coherent imaging system. For a simple specimen it is shown theoretically as well as experimentally that the image appears to be a shadowed representation of the object, when the objective aperture is moved off centre so that half of the zero‐order diffraction spot is blocked. A computer model is presented that gives a faithful description of the theoretical and experimental image intensity profile for the simple test specimen. The computer model is then used to predict image profiles for more complicated (or more realistic) specimen profiles. The calculations show that a certain ambiguity arises when one attempts to interpret the optically‐shadowed image profiles: it would be difficult to distinguish the three different edge contours based only on their appearance in this mode of operation. As with any other EM technique, then, results obtained with optical shadowing must be compared with the results obtained using the others.
The application of X‐ray analysis in the transmission electron microscope to a study of drug distribution in the parasite Schistosoma monsoni (Platyhelminthes)
Authors: Erasmus David A.
Published: August 2011

The distribution of sodium antimony dimercaptosuccinate in the helminth parasite Schistosoma monsoni was determined using a transmission electron microscope (TEM) fitted with an X‐ray non‐dispersive analysis system. Both Araldite and cryosections of the parasite were examined.

The drug was found to have a marked effect on some cells of the ovary and vitelline gland and it was within these cells that the drug was demonstrated. Within the vitelline cells the drug was confined to the vitelline droplets and the analysis of both Araldite and cryosections confirmed that the absence of drug from other tissues was genuine and not due to loss during processing. Maximum retention of elements was achieved in cryosections and this type of material also enabled one to distinguish elements genuinely associated with the tissues from those present in the Araldite matrix.

The combination of X‐ray analysis with TEM and cryosectioning has provided a most valuable tool for the study of drug distribution at tissue and subcellular levels and also enabled the elemental characteristics of the tissue at the precise drug locus to be determined.
The periodic wave pattern in native tendon collagen: correlation of polarizing with scanning electron microscopy
Authors: Gathercole L. J. , Keller A. , Shah J. S.
Published: August 2011

A definite correlation and continuity has been obtained between the observations of ultrastructure of collagen fibres teased from rat tail tendon, by two different techniques; (1) polarizing optical microscopy and (2) scanning electron microscopy (SEM). The stereographic micrographs of the fibres taken by SEM shows that the surface periodicity is of the planar form and is similar to the model proposed by Diamant et al. (1972) from polarizing microscopic observations.
A vibration monitor for ultramicrotomy laboratories
Authors: Nicholson P. W.
Published: August 2011

A simple and inexpensive device is described which allows the monitoring of structural vibrations present in ultramicrotomy laboratories. Information obtained with this device is described.
Cathodoluminescence spectra of organic compounds
Authors: De Mets M. , Howlett K. J. , Yoffe A. D.
Published: August 2011

Cathodoluminescence spectra of a selected group of organic substances have been obtained on cooled samples using a SEM‐spectrometer combination. Room temperature spectra were also recorded when possible. The emission intensity and the beam effect are favourably influenced at low temperatures. The main emission occurs in the 300–600 nm wavelength range.
Accuracy and precision of a scanning and integrating microinterferometer
Authors: Goldstein D. J. , Hartmann‐Goldstein I. J.
Published: August 2011

Instrumental factors affecting the precision and accuracy of measurements with the Vickers M86 scanning and integrating microinterferometer were investigated. ‘Spot’ measurements of OPD (optical path difference) could be made to a precision better than 0.001 Λ (wavelengths); the coefficient of variation of scanning measurements of IOPD (integrated OPD) depended on the object, typical values being approximately ± 5% for a human erythrocyte in water, and ± 10% for a mouse sperm head in water. Repeated measurements enabled the dry mass of a specimen to be estimated to any desired precision.

Instrumental calibration to give results in absolute units is described. Early prototypes required frequent calibration, but with production instruments the calibration varies little from day to day, and very similar results are obtained if a specimen is measured in different parts of the scanned field.

A slight, approximately sinusoidal deviation from linearity was sometimes observed when the apparent OPD or IOPD was plotted against expected values. The error, which probably occurs with all instruments employing a Jamin double‐refracting interference system, was maximally about ± 0.02 Λ for a specimen of true OPD 0.25 Λ or 0.75 Λ, but was zero for a specimen of true OPD 0.5 Λ. The error could be minimized or eliminated by the correct choice of an interference fringe for ‘spreading’, careful adjustment of the condenser and background OPD, and especially by reduction of the condenser aperture.

Scanning measurements of IOPD were shown experimentally and theoretically to be insensitive to changes in the measuring‐spot diameter or errors in focus. Valid measurements of dry mass can therefore be made even if the three‐dimensional specimen (e.g. a living cell or isolated nucleus) is considerably thicker than the depth of focus of the objective used.
A direct recording corrected microspectrofluorometer
Authors: Mayer R. T. , Novacek V. M.
Published: August 2011

The construction of a microspectrofluorometer with automatic correction capabilities is given. The instrument uses a quantum counting system for correction of excitation spectra and an interpolating function generator for correction of emission spectra. An inexpensive analogue computer is an integral part of the electronic portion of the instrument and allows a number of mathematical manipulations to be performed on the sample and reference signals prior to recording or display. Under the conditions stated, the sensitivity of the instrument is in the 10−9 M range for quinine sulphate irradiated at 365 nm. The linear response range for quinine sulphate is 10−3 to 10−9 M. The operational wavelength range of the machine is between 226 and 700 nm.
Problems in ultraviolet polymerization of embedding media for electron microscopy
Authors: Rostgaard J. , Buchmann B.
Published: August 2011

A study was made of ultraviolet polymerization of methacrylate, Vestopal and Epon embedding media. By placing thermocouples in the monomeric resin during UV irradiation, it was found that the temperature of the resins was 5–10°C above the ambient temperature recorded by mercury thermometers placed adjacent to the capsules. When the resins were maintained at room temperature (22–24°C), Epon could not be polymerized with UV irradiation, but methacrylate and Vestopal polymerized within 1–2 days. By using unilateral UV irradiation directed perpendicular to thin sheets of Vestopal‐infiltrated tissue specimens, the depth of polymerization in osmium‐blackened (fixed) tissues was determined to be 0.06–0.08 mm.
A temperature‐regulated stage for the light microscope using a Peltier element
Authors: Troyer David
Published: August 2011

An apparatus to control the temperature of a specimen under observation in the light microscope is described. It consists of a Peltier element and its heat sink which are built into a standard rotating microscope stage. An electronic control unit regulates the temperature.
Use of an electron microscope hydration chamber to study condensation problems
Authors: Chang Wei , Parsons D. F.
Published: August 2011

A preliminary exploration has been made of the feasibility of using an electron microscope environmental chamber to study the earlier stages of water drop nucleation and condensation.
Observation of grain boundaries
Authors: Goux C.
Published: August 2011

The observation of grain boundaries using the optical microscope, the electron microscope and the field‐ion microscope has considerably aided our understanding of grain boundary structure. The study of etch pits in the optical microscope has proved that low angle boundaries are composed of dislocations.

A large number of grain boundary observations have been made by transmission electron microscopy. Here, various classes of boundary structural features have been characterized in grain boundaries; they can be classified into three categories: (1) features which are essentially independent of the true structure of the boundary (thickness fringes, moiré fringes); (2) accidental features which result from a perturbation of the boundary by phenomena originating in the adjacent grains (dislocations, ledges); (3) features of the true structure of the grain boundary (features of the equilibrium structure‐features of the perturbed structure). It must be appreciated that certain features of the structure are not resolved because of their poor contrast in the electron microscope image.

The field‐ion microscope has been used for a relatively short time in studies of grain boundaries. Nevertheless it has yielded very interesting results. Unfortunately, at the present time, it seems that the positions of the atoms may not be determined sufficiently accurately in this instrument to allow a precise determination of the structure. Only in a limited number of cases has it been possible to account for the observed features on the basis of theoretical considerations.
The theory of two‐phase interfacial structure
Authors: van der Merwe J. H.
Published: August 2011

The theory of interfaces between crystals of different structure and/or composition is briefly reviewed. The review is limited to planar semi‐coherent interfaces with an abrupt transition from one crystal to the other. Equilibrium, obeying minimum (free) energy requirements, is introduced as a governing principle. Thus the energy dependence on misfit, strain, atomic bonding, crystal thickness and other parameters is needed for minimization.

The following approaches to this problem are dealt with briefly. The coincidence lattice and ball‐and‐wire models, introduced to describe systems with isotropic and covalent bonding respectively, simply correlate low energy with good matching across the interface. The variational approach uses pairwise interface forces and adjusts the positions of atoms adjoining the interface to minimize the energy. The Volterra approach introduces dislocations explicitly for misfit accommodation and to facilitate energy considerations. The Frank‐van der Merwe model recognizes the lattice periodicity by employing an interfacial periodic interaction potential. In this model the resolution of the interface into a sequence of misfit dislocations is a natural consequence of the analysis. It is believed that the latter model has the widest predictive power, while the variational method has greatest potential for accuracy.

Possibly the most prominent prediction is the joint accommodation of misfit by overall strain and misfit dislocations. However, the equilibrium theory failed to predict the correct dependence of the contributions of dislocations and strain to misfit accommodation on increasing film thickness. This is now accounted for in terms of the imperfection and difficulty of acquiring misfit dislocations.

Some of the consequences of the interface structure of small epitaxial islands are briefly mentioned.
Periodic structures and grain boundaries in magnesium
Authors: Loberg B. , Smith D. A.
Published: August 2011

The orientation relationships which lead to three‐ and two‐dimensional coincidence site lattices in hexagonal lattices are defined. Electron microscopy results on magnesium grain boundaries show dislocation structures which are discussed in terms of theories of coincidence and near coincidence.
The Denver Universal Microspectroradiometer (DUM)
Authors: David G. B. , Galbraith W.
Published: August 2011

This paper discusses the design and describes the construction of an accurate digital microspectrophotometer, microspectrofluorimeter and microrefractometer known as the ‘Denver Universal Microspectroradiometer’ (DUM).

The instrument operates in the spectral range of between 428.3 and 1303.4 THz (700–230 nm). Microscopic objects are scanned digitally in two dimensions and absolute digital spectra of various kinds are obtained automatically. Optical path differences can be measured automatically in the same microdomains in which absorbance, fluorescence and bioluminescence are studied. Measurements on solutions in standard cuvettes, and other macroscopic objects, can be made without altering the alignment of the optical components used in microanalysis. The multi‐detector radiometric system is based on the principle of synchronous single photoelectron counting. The operation of the entire system is controlled by an integral computer which is also used for on‐line data‐processing, reduction and analysis. Automatic multiparametric and multicomponent analyses can be carried out with relative ease.

The quality of the images obtained is largely diffraction‐limited, and the instrumental uncertainty of measurement is essentially that imposed by the quantum statistics of the radiation captured by the detectors. The linear dynamic range is about 108. The limit of detectability of absorbance is of the order of 0.0001. The system is sensitive enough to measure paucimolecular photoemissive events, such as cellular bioluminescence, yielding about 0.1s−1 photoelectrons (equivalent photocathode current ≃3 times 10−22 A).

The absolute accuracy of the system is limited principally by uncertainties inherent in currently available methods of calibrating the spectral response of detectors.
Stabilization and clarification of sections mounted on Formvar‐coated slot grids by deliberate irradiation in the electron beam
Authors: Yang Grace C. H. , Morrison Ashton B.
Published: August 2011

Epon‐Araldite sections supported on Formvar‐coated slot grids can be stabilized by exposing the area of interest in the column of the electron microscope to irradiation of 0.5 C/cm2. With this procedure one can obtain electron micrographs of high quality, without drift or distortion, from any part of the open slot area. After treatment the support film is not only stable and transparent but robust enough to permit repeated removal and replacement of the specimen in the microscope column. We illustrate the method with a series of electron micrographs with initial magnifications ranging from × 300 to × 500,000 to show the quality of image that can be achieved. The effect of the irradiation on tissue architecture is checked by resectioning the irradiated sections. We recommend this method of local irradiation of sections for investigations using low or intermediate magnifications for the wide field it permits, for the durability it confers on the specimen and for its convenience.
An autoradiographic study of the binding of 3H‐chlorambucil to cells of a drug‐sensitive and drug‐resistant strain of the Yoshida ascites sarcoma
Authors: Birbeck M. S. C. , Robertson D. , Hill B. T.
Published: August 2011

The binding of chlorambucil to drug‐sensitive and drug‐resistant Yoshida sarcoma cells has been investigated by an autoradiographic technique. The cells were treated with the drug at various concentrations both in vitro and in vivo. Using both light and electron microscope techniques, and by counting grains on various areas of the cell, the following conclusions were reached.

(1) At all drug concentrations there was general cytoplasmic and nuclear uptake by both cell lines. There was no evidence of a specific localization in one site only or for specific exclusion of any one site.

(2) At high dose levels (∼2 mM) the binding was approximately equal in both cell lines, although a few damaged cells bound much greater amounts of drug.

(3) At low dose levels (∼3 μM) there was a higher uptake by the nucleus of the sensitive cells compared with the nucleus of the resistant cells; the cytoplasmic binding was similar.
High resolution scanning electron microscopy at the subcellular level*
Authors: Lin Shau‐Da , Lamvik M. K.
Published: August 2011

Recently developed scanning electron microscopes provide sufficient resolution to allow useful observation of subcellular biological objects. Preparation methods for such objects need not be limited to the traditional coating and mounting procedures. Many methods developed for transmission electron microscopy are immediately adaptable to scanning electron microscopy. We show that a number of techniques are available to the microscopist which yield adequate contrast and high resolution. As examples we show skeletal muscle myofibrils dispersed to reveal thick filaments, uncoated on a thin carbon film; a tropomyosin tactoid, negatively stained with uranyl acetate; oncornavirus, conventionally coated; and T4 bacteriophage on an aluminium substrate.
A robust micromanipulator for the scanning electron microscope
Authors: Pawley J. B. , Boyde A.
Published: August 2011

A simple device for holding and moving mechanical tools in the region of a sample being viewed in the scanning electron microscope is described. The unit has a 20:1 mechanical reduction and when fitted with a tungsten carbide dental chisel, it is sufficiently rigid to cut biological hard tissues. Alternately, when fitted with an electro‐etched tungsten needle, it can be used, in conjunction with specimen stage controls, to remove individual cells from the surface of soft tissues. Examples of these applications are illustrated.
A new universal and variable flash device for visual examination and photomicrography: VISUFLASH
Authors: VAN Maaren P. W. , Hamann D. J.
Published: August 2011

A recently developed illumination device for microscopes, VISUFLASH, is a universal and variable flash steering device for visual examination, photomicrography and cinematomicrography. The spectral energy distribution of light from the flashtube is suitable for UV‐ visible‐ and IR‐light examination. Furthermore it is, with the aid of the customary filters, possible with this light source to carry out microscopic examinations with transmitted and incident light, and make observations when use is made of dark‐field illumination, phase contrast (+ and ‐), interference contrast, INTERPHACO®, fluorescence contrast and polarized light. Problems in connection with ultra‐short‐time‐effect and the Schwarzschild effect do not occur. In comparison to existing gas discharge light sources VISUFLASH is economical.
A device for determining the film speed of short microcinematographic runs
Authors: Troyer David
Published: August 2011

An apparatus is described which enables the beginning and end frames of filming runs to be marked with an electronic flash in order to calculate the film speed. The maximum error inherent in the method is considered.
A microscope cold stage
Authors: Gallup A. L. , Greenwood B. , Wilson J. F.
Published: August 2011

This inexpensive cold stage consists of a perspex box through which cooled nitrogen gas continuously passes. The nitrogen is cooled by being piped, after drying, through liquid nitrogen. Misting is prevented by continuous gas flow, and strategically placed low‐output heating wires.

The two foremost problems in the use of a cold stage are to produce adequate and rapid cooling, and to prevent misting of surfaces in the optical pathway if effective cooling is achieved. These problems have been solved in at least one commercial cold stage known to us, but at considerable expense.

The stage now described solves both these problems, producing cooling of the specimen down to about — 40°C within a few minutes, and completely obviating misting. It is inexpensive, and can be made without any specialized workshop skills.
Inorganic ion‐doped glass fibres as microspectrofluorimetric standards
Authors: Velapoldi R. A. , Travis J. C. , Cassatt W. A. , Yap W. T.
Published: August 2011

Uranyl and europium ion‐doped fibres of 5–45 μm diameter were prepared which emit in the green and red spectral regions, respectively. Measurements were made of fluorescence flux as a function of fibre length, dopant concentration, slit shape and fibre diameter. The flux was found to be proportional to fibre length and fluorophor concentration and proportional to the square of the fibre radius. In addition, the fluorescence flux as a function of aperture size and shape and fibre position has been measured experimentally and compared to computer generated fluorescence flux envelopes. It is suggested that inorganic ion‐doped fibres are suitable for use as microspectrofluorimetric standards.
A combined freeze chamber and low temperature stage for an electron microscope
Authors: Valdrè U. , Horne R. W.
Published: August 2011

A low‐temperature freeze‐drying or freezing preparation chamber and specimen stage has been designed and constructed for use with an electron microscope. The system allows biological specimens to be prepared under conditions of temperature and pressure and their subsequent direct transfer to a cold stage maintained at — 175°C within the microscope. Attachment of both the chamber and stage is a simple procedure and does not interfere with the normal electrical and mechanical operation of the microscope.

The stage is cooled with the aid of a liquid nitrogen reservoir system and can be maintained at — 175°C for about 80 min without the use of any continuous cooling system. Test specimens have shown that a resolution of about 1.0–1.5 nm can be maintained at — 175°C for 80 min once thermal equilibrium has been established.
An approximate variance for line intersection counts
Authors: Scheaffer Richard L.
Published: August 2011

Let λ denote a rectifiable line in a plane for which the length per unit area is to be estimated by counting the intersections with random test lines dropped on the plane. The asymptotic distribution and variance of the number of intersections with a single test line is derived for a model which assumes λ to be the boundary of particles or random area. Numerical examples illustrate the applicability of the derived variance expression.
Wood anatomy of Crypteroniaceae sensu lato*
Authors: Vliet G. J. C. M. van
Published: August 2011

The wood anatomy of Alzatea from South America, Axinandra, Crypteronia and Dactylocladus from South East Asia, and Rhynchocalyx from South Africa is described in detail. Special attention has been given to the ultrastructure of vestured pits in the five genera. The grouping of these genera into one family as suggested recently is not supported by wood anatomy. Alzatea andRhynchocalyx differ widely from the three other genera and appear to share many characters with both Lythraceae and Melastomataceae; the latter family shows a wide wood anatomical range. The wood anatomical affinities of Axinandra, Crypteronia and Dactylocladus are with Melastomataceae. Comparisons with some other Myrtalean families, notably Oliniaceae and Sonneratiaceae, indicate intimate relationships between Melastomataceae, Lythraceae, Oliniaceae, Sonneratiaceae and Crypteroniaceae s.l. because of overlapping of the wood anatomical range among these families.
Immersion fixation of rapidly frozen, untreated tissues and suspensions of cells including spermatozoa
Authors: Cummins J. M. , Loper M. N.
Published: August 2011

Small pieces of tissue, and cell suspensions in plastic artificial insemination (AI) ‘straws’, were frozen rapidly in Freon‐12 at — 155°C, without pre‐treatment. Peripheral fragments were thawed directly in 2% glutaraldehyde at 0°C, and processed for transmission electron microscopy (TEM) studies. Preservation of ultrastructure was satisfactory, and freezing artifacts were minimal.
The ‘through focus plate’: a simple method for obtaining images through focus on a single photographic plate in the electron microscope using a tilting stage
Authors: Rowlatt C.
Published: August 2011

Tilting the specimen in an electron microscope by a relatively small angle can provide a continuous through focal series on a single plate, as the displacement of the object at the edge of the field can be adjusted to be of the same order of magnitude as the alteration of focal point by the fine lens controls. This simple rapid manoeuvre could have applications in the microscopy of uniform preparations, particularly if the specimen is subject to beam damage, and in assessing microscope performance rapidly.
Quantitative evaluation of autoradiographs by X‐ray spectroscopy
Authors: Hodges Gisele M. , Muir Marjorie D.
Published: August 2011

Measurements of mass of developed silver in autoradiograms have been made using X‐ray microanalysis. This procedure has been applied to a scanning electron microscopic study of protease‐induced cell stimulation in 3H‐thymidine‐labelled bladder tissues in vitro. Differences in silver concentrations over individual nuclei were demonstrated by X‐ray analysis and quantitative data was obtained showing an increased rate of 3H‐thymidine incorporation in protease‐treated cultures. The initial evidence indicates that X‐ray microanalysis could provide a potentially useful quantitative procedure for autoradiography.
New techniques for the preparation of uniform layers of nuclear emulsions for use in micro‐autoradiography
Authors: Sanderson J.
Published: August 2011

A procedure is described whereby liquid emulsion can be used to coat glass coverslips to produce films of emulsion suitable for quantitative evaluation of grain density in micro‐autoradiographs.

Any thickness of emulsion layer can be produced from 3 μm upwards, depending on the volume and dilution of the emulsion dispensed.

The uniformity and reproducibility of the films have been tested by observing light transmission of undeveloped preparations using a microscope photometer.
Microscopic tracing of deuterium
Authors: Kisieleski Walter , Ringo Roy
Published: August 2011

The development of the ion microprobe analyser has made it possible to follow stable isotopes with microscopic resolution in biological and other materials. An ion microprobe using an oxygen primary beam has been found to produce relatively few mass 2 ions (+ or ‐) on organic samples. This technique should permit the use of deuterium as a practical tracer with a resolution of about 1μm in the plane of the section and 2 nm in the depth dimension with available instruments.
Removal of glass coverslips from cultures flat embedded in epoxy resins using hydrofluoric acid
Authors: Moore M. J.
Published: August 2011

A technique is described by which the glass coverslip of a culture, flat embedded in epoxy resins can be removed easily using hydrofluoric acid. Removal by this method leaves the surface of the resin quite smooth and suitable for subsequent thin or ultrathin sectioning for electron microscopy.
Changes of particle frequency in freeze‐etched erythrocyte membranes after fixation
Authors: Parish G. R.
Published: August 2011

The frequency of particles on the membrane fracture faces of freeze‐etched human erythrocytes was measured, and the effect of fixation procedures on the particle frequencies was studied. Fresh blood, buffer washed cells and cells fixed in one of the following ways were examined: glutaraldehyde, glutaraldehyde followed by osmium tetroxide, osmium tetroxide alone. Quantitative analyses showed that some treatments produced a significant reduction in the number of particles on the fracture faces as compared with the fresh cells. After both osmium tetroxide fixations, the loss of particles was greater from the outer fracture face (OFF) than the inner fracture face (IFF), whilst after the other treatments approximately the same number of particles were lost from both fracture faces. The results are discussed with respect to some current concepts of the molecular architecture of the erythrocyte membrane and the action of fixatives. The reduction of particle frequencies is thought to be due to both leaching of membrane proteins, and deviations of the usual fracture plane within the membrane. Glutaraldehyde alone was shown to have less effect on particle frequency than the other fixatives and it is therefore a suitable fixative for the preparation of freeze‐etch specimens.
A simple technique for examining frozen hydrated specimens in the scanning electron microscope
Authors: Robinson V. N. E.
Published: August 2011

The use of a wide angle backscattered electron detector in a scanning electron microscope, which has the capability of the specimen chamber pressure being controlled independently of the column pressure, provides a simple technique for examining frozen hydrated specimens. Large specimens have been examined within 1 min of being placed on the stub and have been examined for many hours without charging artefacts or distortion due to dehydration.
A container for processing small volumes of cell suspensions for critical point drying
Authors: Newell D. G. , Roath S.
Published: August 2011

The attachment of lymphocytes to glass or filters, in order to facilitate handling for processing prior to scanning electron microscopy, may introduce artefacts in surface topography. A container has therefore been adapted, from an embedding capsule, for the preparation of small volumes of cell suspensions.
A technique for obtaining scanning electron micrographs in colour
Authors: Swift J. A. , Brown A. C.
Published: August 2011

A digital electronic unit is described which, by modifying the video signal of the scanning electron microscope (SEM), permits the selection of images in separate tonal or grey‐scale levels. By the sequential exposure of these grey levels onto colour film with the intervention of colour filters, coloured scanning electron micrographs have been obtained. Full details of the procedure are given. The process is applicable to any normal image capable of being displayed at the scanning electron microscope.
Determination of the principal distance and the location of the perspective centre in low magnification SEM photogrammetry
Authors: Boyde A.
Published: August 2011

The principal distance, D, from the centre of perspective in the SEM optical projection to the tilt axis of the specimen stage must be accurately determined before photogrammetric evaluation of stereoscopic pairs of micrographs can proceed. A precise procedure for measuring D is described in which the specimen stage X micrometer is used to measure the width of the field scanned for a particular width of the CRT, when the specimen stage is moved along the electron beam axis by amounts measured with the stage Z micrometer. The Z micrometer is calibrated with an external dial gauge. A plot of field width against Z extrapolated to zero gives the location of the perspective centre.

In SEM photogrammetry, it is usual to leave the lens currents unchanged whilst recording the stereo‐pairs. The values of D measured with a constant final lens current show that the perspective centre is located close to the final aperture in its conventional position. Previous determinations of D for Stereoscans have used a changing lens current to keep the specimen in focus at varying Z, and found a virtual centre several millimetres above the final aperture. The value of D so obtained should only be used if the micrographs were recorded with dynamic or automatic focusing systems.
A simple method for exposing plastic embedded structures for scanning electron microscopy
Authors: Jarvis L. R.
Published: August 2011

Surfaces of structures which may be identified in sections of plastic embedded tissue can be exposed for examination using scanning electron microscopy by removal of the embedding medium from the sectioned block with sodium methoxide. Correlation of the information provided by sections and scanning electron microscopy is therefore possible. This technique has been used in examining the developing peristome teeth of the moss Funaria hygrometrica.
Abel type integral equations in stereology: I. General discussion
Authors: Jakeman A. J. , Anderssen R. S.
Published: August 2011

In developing numerical methods for the solution of computational problems of an involved and pragmatic nature, as occur for example in stereology, the approach should be first to classify the distinct types of numerical problems which arise. If available, appropriate results from numerical analysis can then be used to develop stable numerical processes for their solution. In fact, many of the results relating to the construction of basic numerical methods, such as spectral methods for the stable differentiation of experimental data and product integration methods for the evaluation of integrals with oscillatory and singular integrands, have been resolved. Thus, we are now in a position to apply the above approach to the more complex computational problems which arise in stereology.

Many of these problems belong to one of the following two classes: (i) the solution of integral equations of Abel type; and (ii) the solution of some numerical differentiation problem.

In Part I of this paper, we illustrate the generality in stereology of the Abel type integral equation and numerical differentiation formulations. As well, we derive the specific properties required in Part II which is mainly concerned with the construction of stable computational methods for (i). Included among these properties are the explicit inversion formulae which are known for general Abel type integral equations. It is these inversion formulae which we use to construct stable computational methods.

Often, when estimates for linear properties of the solutions of (i) and (ii) are required, the numerical solution of (i) and (ii) can be circumvented by estimating the linear properties directly from the given observational data. In deriving such estimates, use of the properties of the Abel type integral equation and differentiation formulations plays an essential role. Because of the close connection between such estimation problems and (i) and (ii), the estimation of linear properties from truncated observational data is also examined in Part I.
The ultrastructural localization of calcium in the avian shell gland
Authors: Solomon Sarah E. , Fryer J. R. , Baird T.
Published: August 2011

Fluctuating concentrations of calcium in the blood supplying the avian shell gland are not reflected at tissue level. Analyses of oviducal mucosa throughout the laying cycle show that the concentration of calcium remains relatively unaltered even at peak activity thereby implying a rapid transfer process. These experiments describe the use of potassium pyroantimonate as a localizing agent. The precipitate produced by injecting the latter via the aorta was identified as calcium pyroantimonate by electron diffraction and the efficiency of the precipitant estimated by neutron activation analysis of eggshells present in the shell gland at the time of operation. Results indicate that calcium is transferred across the surface epithelial cells of the shell gland (tubular and pouch regions). Its localization in the former is taken as an indication of the involvement of this region in the production of the mammillary mantle.
A method of collecting and processing nematode larvae for electron microscopy
Authors: Smith K.
Published: August 2011

A method is described using simple apparatus for separating and concentrating nematode larvae from host faecal material and a recommended procedure is given for processing the helminths for transmission electron microscopical examination.
The Denver Universal Microspectroradiometer (DUM): II. Computer configuration and modular programming for radiometry
Authors: Galbraith W. , Geyer Sharon B. , David G. B.
Published: August 2011

This paper describes and discusses for microscopists and spectroscopists the choice of computer equipment and the design of programs used in the Denver Universal Microspectroradiometer (DUM). This instrument is an accurate computerized photon‐counting microspectrophotometer, microspectrofluorimeter and microrefractometer. The computer is used to control the operation of the system, to acquire radiometric data of various kinds, and to reduce, analyse and output the data in a readily usable form.

Since the radiometer was designed to carry out many kinds of measurements in a variety of micro‐ and macroscopic specimens, and since different methods of microscopy or spectroscopy have to be combined in various ways for the study of any one specimen, no single master‐program could fulfil efficiently all foreseeable requirements. Therefore, the programming developed is interactive, modular, hierarchical and hybrid. Modular interactive programming makes it possible for almost any kind of main program, applicable to almost any kind of measurement, to be assembled quickly from a collection of hierarchical subroutines. Main programs are short and composed mainly of Fortran statements calling subroutines; subroutines, in turn, automatically call other subroutines over many levels. The subroutines are independently written and optimized for maximum operational efficiency in the computer system used, or for maximum ease of transfer to other systems.

This approach to programming enables someone unfamiliar with computer languages to operate the radiometric system from the console of the CRT terminal. The writing of new main programs, by linking groups of existing subroutines, requires only a minimum acquaintance with Fortran; only the writing and revision of subroutines requires programming experience.

Differences and similarities in the method of computer operation between the present system and other computerized radiometers are briefly discussed.
A universal metal and carbon evaporation accessory for electron microscopy techniques and a method for obtaining repeatable evaporations of platinum carbon
Authors: Harris W. J.
Published: August 2011

A simple accessory has been designed which can be used for all types of metal or carbon evaporation in either an upwards or downwards direction as required. A method of preparing platinum carbon rod sources which makes possible successive repeatable evaporations of platinum carbon is also described.
Radiation damage in electron microscopy of organic materials: effect of low temperatures
Authors: Salih S. M. , Cosslett V. E.
Published: August 2011

As measured by the life‐time of their electron diffraction patterns, the radiation sensitivity of anthracene and coronene at 500 kV is reduced by a factor of three to four at liquid helium temperature in comparison to room temperature. Forl‐valine the ratio is about 1·8 but there is a wide variation in the results, possibly due to differences in crystal thickness. The end‐dose at 20°K for valine is equivalent to 13 electrons/Å2; for anthracene and coronene it is about 600 electrons/Å2at room temperature. The variation of end‐dose with temperature shows that at least two mechanisms must be involved in damage to such compounds, possibly concerning the breaking of intermolecular and intramolecular bonds, respectively.
Electron microscopy of monomolecular films*
Authors: Neuman Ronald D.
Published: August 2011

Calcium stearate monomolecular films were examined by electron microscopy using replica techniques. The effects of two evaporants, palladium and platinum, on the structure of Langmuir‐Blodgett monolayers and multilayers were investigated. The fine structure appears to be altered unless precautions are taken to minimize the radiation heat transfer during the shadow‐casting procedure. The structural features of deposited monolayers are also influenced by the underlying solid substrate.
Topographic intensity profiles in the scanning electron microscope—cubes
Authors: George E. P. , Robinson V. N. E.
Published: August 2011

Two‐dimensional Monte Carlo computations have been used to predict the backscattered and secondary electron intensity profiles when a plane surface has a square of side d standing out from it. This was taken as a model for a gold cube of dimensions d situated on a thick gold substrate. This latter situation has been approximately reproduced experimentally and the predicted intensity profiles show quite good agreement with the observed intensity profiles for a range of values of the dimension d.