bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved technique for pipetting solutions during tissue processing for electron microscopy
Authors: Mollenhauer Hilton H.
Published: August 2011

Disposable pipette tips are ideally suited for pipetting solutions during tissue processing for electron microscopy.
Determination of membrane thickness distribution from orthogonal intercepts
Authors: Jensen E. B. , Gundersen H. J. G. , Østerby R.
Published: August 2011

This report deals with the reconstruction of the distribution of membrane thickness T from that of orthogonal intercept length L0, measured in random section planes. In such planes the membrane appears as a band and the linear distance from one of its boundaries perpendicular to the opposite one is the length of the orthogonal intercept. Using a membrane model, an integral equation relating the probability density functions of orthogonal intercept length f(l0) and membrane thickness g(τ) is derived. Relations between moments are derived and the analytic solution to the problem of reconstructing g(τ) from f(l0) is given. The parametric approach by which it is assumed that g(τ) has some known analytic form with unknown parameters is considered, and the use of a suggested analytic form for describing the thickness distribution of the human glomerular basement membrane is discussed.
Measurement by Quantimet 720 of the proportion of actively growing cells in tissue cultures of human lymphocytes
Authors: Brown R. A. , Mcwalter R. , Slidders W. , Gibbs J. , Beck J. Swanson
Published: August 2011

The size‐distribution of normal human lymphocytes growing in tissue culture was measured with a Quantimet 720 image‐analysing computer. The proportion of cells undergoing volumetric growth after phytohaemagglutinin (PHA) stimulation was derived from a simple mathematical model describing the growth patterns of the cells up to the first mitotic division. The approach may have general application in biology as a method for measuring the proportion of growing cells by microscopy.
Modification of an EM6G electron microscope for X‐ray microanalysis
Authors: Fitzgerald A. G. , Storey B. E.
Published: August 2011

A dual purpose stage has been constructed for an EM6G 100 kV transmission electron microscope. With this stage the composition of thin films and bulk specimens can be determined by X‐ray microanalysis. With thin films a change of specimen cartridge then enables a full analysis of crystal defects in the film to be made using tilt controls incorporated in the stage. Modifications to the stage to reduce background effects in X‐ray microanalysis spectra are also described.

The alternative use of this system in the bulk analysis of specimens by an X‐ray fluorescence technique is also discussed.
Freeze substitution for preservation of ciliated surfaces for scanning electron microscopy
Authors: Barlow D. I. , Sleigh M. A.
Published: August 2011

A technique is described for arresting rapid movement of living cells and preserving their fine surface structures for scanning electron microscopy. Rapid freezing is recommended as the method of immobilization and freeze substitution has been employed to fix and dehydrate the specimens; this technique is more reliable than osmium fixation, both in terms of obtaining a much higher proportion of good results and in the improved preservation of detail. Various techniques of substitution have been investigated for best preservation, and the roles of the constituents of the substitution mixture have been discussed.
Vertical plane serial sectioning of identified tissue culture cells
Authors: Hopkins W. G.
Published: August 2011

Identifying marks can be made around specific cells on the culture surface of plastic tissue culture dishes. When the cultures are embedded in situ and the plastic dish is split away, the marks are reproduced around the cells. The marks permit trimming and complete serial sectioning of specific cells in the vertical plane.
The construction of a membrane slide support for the observation of living cells
Authors: Miles P. , Dott H. M.
Published: August 2011

The construction of a slide for examining living cells under the microscope under controlled conditions is described.
A Rapid Method For Estimating Volume Ratios
Authors: Orive L. M. Cruz , Myking A. O.
Published: August 2011

A rapid stereological method is proposed for estimating the volume ratio V(K2)/V(K1) of two bodies K1, K2 such that K2 is embedded in K1. If K1, K2 fit approximately into a ‘star specimen’ model, then a single section, taken at a certain level through K1, provides a rather accurate estimate of V(K2)/V(K1). For a population of moderately similar star specimens, a constant sectioning level can be estimated from a sample using a least squares criterion.

A pilot experiment involving mouse lymph nodes, aimed at estimating the mean and the variance of the individual fractions V(paracortex)/V(node), indicates a fair robustness against deviations from the model.
Microscopical Image Analysis: Problems And Approaches*
Authors: Bradbury S.
Published: August 2011

This article reviews some of the problems which have been encountered in the application of automatic image analysis to problems in biology. Some of the questions involved in the actual formulation of such a problem for this approach are considered as well as the difficulties in the analysis due to lack of specific contrast in the image and to its complexity.

Various practical methods which have been successful in overcoming these problems are outlined, and the question of the desirability of an opto‐manual or semiautomatic system as opposed to a fully automatic version is considered.
A New Method For Scanning Electron Microscopic Visualization Of Dermal Elastic Fibres
Authors: Tsuji Takuo , Lavker Robert M. , Kligman Albert M.
Published: August 2011

Autoclaving sections of dermis for 8 h followed by fixation, dehydration and xylol‐air drying yields a pure preparation of elastic fibres for scanning electron microscopy which retains the native architecture of this component. Elastic fibres were intertwined in a complex fashion with numerous branches. Fibres were predominantly cylindrical in the upper dermis and became larger and more elliptical in the deeper dermis. This method produces a means to study the organization of elastic fibres in a variety of disorders in which dermal changes are prominent.
Histologie Investigation Of Glycol Methacrylate Embedded Chick Embryonic Tissue
Authors: Swartz William J. , Nusbickel Fred R.
Published: August 2011

Specific light microscopic investigations (i.e. histochemical) of early embryonic material have always been beset by difficulties in processing and obtaining tissue sections of good quality. The advent of glycol methacrylate (GMA) as an embedding medium now provides a means to overcome these inherent problems with this tissue. Investigations were carried out to assess the histological results produced by different fixatives and times of fixation of GMA embedded 5‐day chick embryonic tissue. Optimum cellular preservation of all tissues occurred following fixation in a mixture of acetic acid, 95% ethanol and neutral buffered formalin (AAF). With the procedures described in this study, a new method is available for more comprehensive examination of all types of early embryonic material.
Visibility Of Diffraction Patterns And Bend Contours In Thick Composite Amorphous‐Crystalline Specimens Observed In Stem And Ctem
Authors: Craven A. J. , Valdreè U.
Published: August 2011

For a number of reasons, the specimens used to try to correlate the electrical and structural properties of commercial semiconductor devices often consist of a thick amorphous layer (e.g. silicon oxide) and a thinned layer of crystalline material (e.g. silicon) containing the p‐n junctions. Diffraction patterns and diffraction contrast images from such specimens recorded in conventional and scanning transmission electron microscopes at 80 and 500 kV are shown. The visibility of these diffraction patterns and images depends on the mode of operation, the aperture sizes and the side on which the electrons enter the specimen. The interpretation of these results is discussed and the practical implications for imaging of such specimens are pointed out.
A Double Embedding Technique For The Electron Microscopic Analysis Of The Liver Acinus
Authors: Miller Deborah L. , Gumucio Jorge J.
Published: August 2011

A double embedding technique allowing accurate and systematic sampling of zones of the hepatic acinus by electron microscopy was developed. The method involved the primary embedding of large (10 mm × 30 mm × 0·5 mm) liver slices and the preparation of 10 μm thick tissue sections by means of a rotary microtome with a steel knife. Veins 20–40 μm in diameter, the landmarks of the hepatic acinus, were localized by light microscopy, dissected from surrounding tissue and re‐embedded for ultramicrotomy. The method facilitated the systematic evaluation of hepatocyte ultrastructure in each zone of the microcirculatory unit of the liver, the hepatic acinus.
A Modified Levanol Fast Cyanine 5Rn Staining Method For Myoepithelial Cells
Authors: Van Bogaert Louis‐Jacques , Quinones Jorge Abarca , Maldague Paul
Published: August 2011

The specificity of the tannic acid‐phosphomolybdic acid‐Levanol Fast Cyanine 5RN procedure for myosin‐like proteins in myoepithelial cells is hampered by the affinity of the dye for other structures. The selectivity of myoepithelial cell staining is enhanced by oxidation of sections, nuclear staining by Safranin‐O, and differentiation with Tartrazine.
A Microscopic Examination Of Void Formation In Superplastic Materials
Authors: Langdon Terence G.
Published: August 2011

There are two distinct groups of superplastic materials, depending on whether the final fracture surface has a large cross‐sectional area at optimum ductility or the specimen gradually pulls down to a very fine point. Experiments on a commercial superplastic copper alloy and the Zn‐22% Al eutectoid indicate that the formation of internal voids is important in materials of both groups. In addition, the results show that the size and shape of the internal voids is dependent both on the material and the testing conditions.
Irregular Helium Bubbles In Niobium Alloys
Authors: Tyler S. K. , Goodhew P. J.
Published: August 2011

Helium bubbles have been produced in niobium‐1% Zr by ion implantation and their growth has been studied by transmission electron microscopy of annealed specimens. Bubbles are normally faceted and develop from tetrakaidodecahedra at short times to cuboids bounded by {100} faces after long annealing periods. This behaviour, together with the observation of steps on the faces of many bubbles, is accounted for in terms of competition between the conditions necessary for thermodynamic equilibrium and the kinetics of bubble motion. The larger bubbles must contain an excess gas pressure.
Tem Study Of Amorphous Alloys Produced By Ion Implantation
Authors: Johnson E. , Wohlenberg T. , Grant W. A. , Hansen P. , Chadderton L. T.
Published: August 2011

Ion implantation is a technique for introducing foreign elements into surface layers of solids. Ions, as a suitably accelerated beam penetrate the surface, slow down by collisions with target atoms to produce a doped layer. This non‐equilibrium technique can provide a wide range of alloys without the restrictions imposed by equilibrium phase diagrams.

This paper reports on the production of some amorphous transition metal‐metalloid alloys by implantation. Thinned foils of Ni, Fe and stainless steel were implanted at room temperature with Dy+ and P+ ions at doses between 1018 and 1021 ions m−2 at energies of 20 and 40 keV respectively. Transmission electron microscopy and selected area diffraction analysis were used to investigate the implanted specimens.

Radial diffracted intensity measurements confirmed the presence of an amorphous implanted layer. The peak positions of the maxima are in good agreement with data for similar alloys produced by conventional techniques. Only certain ion/target combinations produce these amorphous layers. Implantations at doses lower than those needed for amorphization often result in formation of new crystalline phases such as an h.c.p. phase in nickel and a b.c.c. phase in stainless steel.
The Imaging Of Surface Step Structures By Dark Field Electron Microscopy
Authors: Levitt J. P. F. , Howie A.
Published: August 2011

The dark field imaging of monatomic surface steps is studied by weak beam electron microscopy using reflections in higher order Laue zones. Dynamical theory calculations of the step intensities and of the diffuse background intensity in various diffracting conditions are in moderately good agreement with experimental observation on (111) thin films of gold. From grooving effects visible at incoherent twin boundaries, the boundary energy is estimated to be about one‐third of the surface energy. The extension of the method to other crystal surfaces or other materials is discussed.
The Measurement Of Excess Volume At Grain Boundaries Using Transmission Electron Microscopy
Authors: Pond R. C.
Published: August 2011

A technique enabling accurate measurements of relative displacements between adjacent coincidence related crystals has been described previously. The technique depends on intensity measurements of stacking‐fault‐like fringes by comparison of experimental and theoretically simulated fringe profiles. This matching procedure is illustrated in the present work for a (l̄2l̄) boundary between twin related aluminium crystals. The main part of the paper describes the application of the technique for measuring excess volume at certain coincidence boundaries, and considers in detail the measurement for (l̄2l̄) boundaries. The excess volume per unit area at (l̄2l̄) boundaries is found to be 0·02 nm.
Interaction Of Grain Boundary Dislocations With Precipitates During High Temperature Creep
Authors: Dunlop G. L. , Nilsson J.‐O. , Howell P. R.
Published: August 2011

The interactions between grain boundary dislocations (GBDs) and intergranular TiC precipitates in an austenitic stainless steel (Alloy 800) have been investigated after creep at very low stresses at 800°C. The absence of Orowan looping suggests that the GBDs by‐pass the precipitates by glide/climb in the particle/matrix interfaces. An approximate calculation shows that the stress for bowing of GBDs between TiC precipitates is consistent with a measured value of the threshold stress for diffusion creep. However, it is suggested that an additional factor may be present in the threshold stress due to attractive forces between the precipitates and the GBDs.
The Austenite/Ferrite Interface In A Duplex Alloy Steel: Structure And Associated Diffraction Effects
Authors: Howell P. R. , Southwick P. D. , Honeycombe R. W. K.
Published: August 2011

This paper describes the structure of the austenite/ferrite interface in a duplex alloy steel. Specifically, it is shown that a single periodic set of dislocations exists in this interface. This dislocation array can act as a diffraction grating, and the extra reflections observed in selected area diffraction patterns are shown to be consistent with the dislocation structure observed in the image mode.
The Preservation Of Surface‐Associated Micro‐Organisms Prepared For Scanning Electron Microscopy
Authors: Garland C. D. , Lee Adrian , Dickson M. R.
Published: August 2011

Scanning electron microscopy (SEM) has become a popular means of studying micro‐organisms which associate with surfaces. However, as yet no detailed examination has been made of the influence of specimen preparation on the number of organisms finally seen on the SEM screen. In this investigation critical assessment is made of the influence of a wide range of preparative factors on the preservation of filamentous bacteria associated with the epithelial surfaces of rat intestine. Organisms were quantitated using a rigorous counting method (transect line analysis); statistical testing of these counts enabled the comparison of different preparative factors. The composition of the fixative was found to significantly influence the number of organisms preserved; of the fifteen fixatives studied, Karnovsky's fixative with ruthenium red best preserved surface‐associated organisms. The influence of other factors on the number and appearance of preserved organisms was also examined. These factors included the washing of specimens prior to fixation, the storage of fixed specimens, and the handling and storage of critical point dried specimens. The results are discussed with reference to the optimal methods for preparing specimens for SEM.
A Stereoscopic Method Of Viewing Internal Structures In Resin‐Embedded Biological Specimens
Authors: Best A. C. G.
Published: August 2011

The internal arrangement of biological specimens, embedded in resin, may be studied by the described method, which is particularly applicable to calcified structures.
Electron Micrographs Of Metal Shadowed Materials: A Simple Technique For Making Negative Prints
Authors: Towe Kenneth M.
Published: August 2011

Negative prints that are useful for all but the most exacting studies can be prepared simply and rapidly by using the positive print as an internegative in a contact printer. No special chemicals, papers or intermediate negatives are required.
Domains Of Microscope Photometry In Materials Science
Authors: Piller Horst
Published: August 2011

The application of microscope photometry in non‐biological fields is reviewed. The objects in microscope photometry are micro‐particles or small areas of macro‐scopical bodies which, because of their size, cannot be examined by macrophotometry. The commonly measured properties in microscope photometry are as follows: transmittance, specular or diffuse reflectance, relative intensity of light emission by self‐luminous objects, e.g. luminescence or fluorescence, in the spectral (wavelengths) range ca. 250–1000 nm.

The paper gives examples of how coloured solid bodies, e.g. gemstones and ore minerals, can be identified, rock‐forming minerals differentiated, diamonds classified, paper quality assessed, organic constituents in rocks characterized, crime detection aided, the chemistry of alloys established, and information on structural organization in inorganic and organic crystals supplemented.
Automated Microscope‐Absorption‐Spectrophotometry Of Rock‐Forming Minerals In The Range 40,000–5000 Cm−1 (250–2000 Nm)
Authors: Langer K. , Frentrup K.R.
Published: August 2011

To measure polarized absorption spectra of microcrystals of 3dn‐ion bearing silicate minerals, computer processed, microscope‐spectrophotometric methods have been developed. Absorbance, log (I0/I), can be measured with high relative accuracy (near u.v. and vis: ±0·002 to 0·001; n.i.r.: ±0·004 to 0·002), and relatively small spectral band widths are available. Hence, weak spin‐forbidden dd‐bands of 3dn‐ions can be recognized alongside spin‐allowed dd‐transitions without artificial broadening of absorption bands due to finite resolution. The smallest area from which absorption spectra can be taken is 8 μm in diameter. As one example of the many applications in mineralogy and material sciences, absorption spectra of a natural spessartine garnet, Spess69·7Alm30·0Gross0·05, containing Mn2+, Fe2+, and traces of Fe3+ as 3dn‐ions, and of a pure Mn2+‐garnet, Spess67Gross33, are presented. From these it is evident that bands in natural spessartines at ∼ 26,900, 23,200 cm−1 which were assigned to dd‐transitions in Fe3+(6), have to be reassigned to Mn2+(8). Comparison of spectra obtained with the microscopic equipment described with those obtained by means of conventional macroscopic equipment prove that the methods described produce true spectra.
Microscope Photometry In Studies Of The Molecular Structure Of Carbonized Bitumens And Pyrobitumens
Authors: Khavari‐Khorasani G. , Blayden H. E. , Murchison D. G.
Published: August 2011

Four bitumens and pyrobitumens (gilsonite, grahamite, impsonite and shungite), varying considerably in their initial properties, have been carbonized over the temperature range 0–1400 °C. Reflectances of the carbonized products in air and immersion oil were measured at 546 nm using a conventional microscope photometer, and the effective bireflectances. refractive indices and absorption coefficients calculated for the samples from the reflectances. The results obtained support an earlier suggestion that the derived optical data can be used to supplement X‐ray lattice parameters as a means of tracing the general course of molecular and structural organization of organic materials when these are carbonized, viz: (a) continuously rising bireflectance and absorption coefficient with rise of preparation temperature respectively indicate progressive ordering of the aromatic lamellae and increasing average diameter of the sheets of aromatic layers forming the‘crystallites’; while (b) systematic changes of the effective refractive index point to interruptions in the growth of the heights of the aromatic‐layer stacks in the crystallites. The optical variations are paralleled by changes in the patterns of the X‐ray lattice parameters for the same samples, which estimate directly the aromatic‐layer diameters (La), the average number of aromatic layers in the stacks (Lc) and the average spacing of the aromatic layers (d). Although the trends followed by the optical properties of the carbonized products of the bitumens and pyrobitumens are generally similar, in detail they show variations that can be related to the initial character of the fresh materials. The carbonization process, as it affects bitumens and pyrobitumens, is briefly discussed in the light of these results.
Reflection Measurements Used In The Analysis Of Structural Colours Of Beetles
Authors: Mossakowski Dietrich
Published: August 2011

Reflectance measurements have been carried out on the elytral cuticle of two beetles. Great differences arise in the tiger beetle Cicindela campestris depending on the extremely structured surface and colour variation from point to point. In comparison the buprestid beetle Chrysochroa vittata appears more even. Indeed macroscopically it looks completely smooth, but there are microscopical structures complicating reflection measurements.

The advantages and disadvantages of working with a macro‐ and a microspectrophotometer are listed. The structural properties of the colour producing multilayer system are the same in both species. Measured spectral reflectance curves show the typical form of interference colours. A second order reflectance maximum in the UV region was found.

Calculations of the reflectance curves were done by the equations given by Huxley for the non‐ideal type of multilayer reflectors.
Microphotometric Techniques In Intravital Microcirculatory Studies
Authors: Witte Siegfried
Published: August 2011

Intravital microscopic techniques were developed in order to measure plasma proteins: (1) circulating in the streaming blood of microcirculatory vessels of the exposed rat mesentery, (2) permeating the vessel wall, and (3) moving through the perivascular interstitial tissue. By means of the ultramicrospectrophotometry, the absorbance of proteins containing aromatic amino acids at 280 nm is measured. Absolute amounts of proteins in the range of picograms are measured in a circular measuring field with a diameter of 17 μm. Problems of calibration and of un‐specific light scattering are discussed.

The scanning microfluorometry makes use of the fluorescent labelling of the plasma proteins. Interstitial tissue with a capillary vessel containing labelled proteins is measured at high speed. A motor‐driven object stage synchronized with a measuring system uses scanning lines to traverse the tissue. The data are then processed by a computer. In this way we get continuous quantitative information about the dynamics of protein permeability, starting from time zero.

The measuring of the fluorescence intensity and the speed of the fluorometric system are further improved by a computerized 10 kHz scanning device.
Electron Microscope Stage Design And Applications
Authors: Valdrè U.
Published: August 2011

There is plenty of evidence that future developments in electron microscopy instrumentation will be strongly orientated towards in situ experimental versatility and multisignal exploitation. Based on this assertion, a layout is presented of the achievements in specimen chambers and stages, in attachments for analysis and non‐conventional imaging, and in miscellaneous accessories. Their compatibility and best location is discussed, and general considerations are made on stage design. An example is given of a multipurpose specimen chamber and of a multifunction electron microscope, together with some results of their application for the characterization of semiconductor devices.
Projection Microradiography
Authors: Sharpe R. S.
Published: August 2011

A considerable amount of additional fine microstructural detail is latently available in radiographs but high resolution techniques are necessary to derive the information in a useful form. This paper explains how the research and enthusiasm of Cosslett and his team (notably Nixon) at the Cavendish Laboratory around the early 1950s resulted in the first practical projection microradiographic system. This not only opened up the possibility of extreme resolution of radiographic detail (down to 0·1 μm) but triggered off a sequence of events that has ensured that high definition radiographic techniques are now an accepted technique for both biological and medical research and routine industrial diagnostics.
The Melbourne proton microprobe
Authors: Legge G. J. F. , McKenzie C. D. , Mazzolini A. P.
Published: August 2011

A scanning proton microprobe is described which operates in ultra‐high vacuum with a resolution of 10 μm. The operating principles and main features of the design are discussed and the ability of such an instrument to detect trace elements down to a few parts per million by mass is illustrated.
Effect of sodium azide on the ultrastructural preservation of tissues
Authors: Minassian Hassmig , Huang Shao‐nan
Published: August 2011

An electron microscopic study was carried out to examine the quality of ultra‐structural preservation of parenchymatous and mesenchymatous tissues and isolated cells fixed in glutaraldehyde with sodium azide (NaN3) as an additive.

The dense tissues fixed with conventional glutaraldehyde containing calcium chloride demonstrated only a narrow zone of good tissue preservation on the surface of the specimens. Addition of azide at a concentration of 0·1% greatly improved the cellular preservation in the deeper region of tissues, in particular with respect to the mitochondrial morphology. There was no adverse effect on other cell organelles. The improvement in mitochondrial preservation and the enhancement of penetration of the fixative is presumably due to selective and instantaneous inhibition of mitochondrial metabolic activity by the azide, thus retarding anoxic degenerative effects on cellular structures until permanent fixation is completed by the comparatively slow‐acting aldehyde. However, the addition of azide offers no significant improvement in the ultrastructural preservation of isolated lymphocytes and liver cells, or fibroblasts maintained in culture.
Combined autoradiography and histochemistry: the simultaneous detection of 6‐3H thymidine and acid phosphatase activity in cryostat sections
Authors: Lewis G. H. J. , Bowen I. D. , Bellamy D.
Published: August 2011

A method is described for the simultaneous demonstration of 6‐3H thymidine incorporation and acid phosphatase activity in cryostat sections of mouse thymus. The method enables a comparison of mitosis and acid hydrolase activity to be made in the same tissue section. In 8‐week‐old mice acid phosphatase positive cells represent 1·23 ±0·06% of the total population and 8·4 ± 0·27% of the cells incorporate tritiated thymidine. Acid phosphatase activity can be used to estimate cell autolysis and death. The implications of the method in relation to tissue dynamics is discussed.
Negative staining‐carbon replica method, a new procedure to reveal ultrastructure of freeze‐fractured membrane
Authors: Fujikawa Seizo
Published: August 2011

The present study was undertaken to report a new method which reveals the ultrastructure of freeze‐fractured membrane faces. The method consists of initial replication of fractured surfaces of frozen specimens with evaporated carbon and treatment of the replicas with a negative staining solution after dissolution of specimens. This negative staining‐carbon replica method reveals clear distribution, ultrastructures and precise size of intramembrane particles on the fractured membrane faces by means of density difference of negative staining solution which is deposited on the surfaces of carbon replicas.
Irradiation effects in the electron microprobe quantitation of mineralized tissues
Authors: Edie John W. , Glick Paul L.
Published: August 2011

The accuracy of absolute quantitation within thick, mineralized tissue specimens is influenced by count rate variations of characteristic X‐rays during electron microprobe analysis. The variations occur for electron doses 10−10 C/μm2 and are primarily dependent upon the light element fraction within the irradiated volume. Specimen preparation procedures affect both count rate dynamics and interpretation of microanalytical results. X‐ray intensity data acquired at initial electron exposure and utilized in standard matrix correction schemes will project valid elemental concentrations for known calcium compounds over wide ranges of specimen density. Measurement error could approach ±2–3% for the major elemental constituents in mineralized tissues, but only with appropriate control or interpretation of electron irradiation phenomena.
Apparent holes in rotary shadowed proteins: dependence on angle of shadowing and replica thickness
Authors: Neugebauer D.‐Ch. , Zingsheim H. P.
Published: August 2011

The influence of experimental conditions during rotary shadowing on the apparent particle size and the production of apparent holes or channels in the centre of a solid spherical particle are illustrated using ferritin.
Evaluation of IgG molecules, Fab' fragments and IgG‐horseradish peroxidase conjugates as surface labels for freeze‐etched membranes
Authors: Carter David P. , Staehelin L. Andrew
Published: August 2011

Sheep red blood cell (SRBC) ghosts were incubated with preparations of anti‐SRBC IgG, antigen‐binding fragments of IgG (Fab') or IgG coupled to horseradish peroxidase (HRPO). Frozen samples of the labelled ghosts were deep‐etched and replicated with platinum‐carbon to visualize their surface features in the transmission electron microscope. The surfaces of control ghosts contain a very low number of ‘background’ particles (42 ± 8 particles/μm2) that vary in size from 4·5 to 25 nm. After labelling with whole IgG the density of surface particles (average diameter 12–3 nm) increases dramatically to 480 ± 54 per μm2. Fab'‐labelled ghosts exhibited both significantly fewer (87 ± 14 particles/μm2) and smaller (average diameter 9·8 nm) surface particles. Ghosts labelled with IgG‐HRPO conjugates possessed 590 ± 45 particles/μm2 with an average diameter of 15·3 nm. When these ghosts were incubated with diaminobenzidine and hydrogen peroxide the average size but not the density of the particles increased. Based on these and other observations we conclude that an organic surface marker for freeze‐etched membranes has to have a diameter of > 15 nm if it is to be consistently seen over extended areas and against the background granularity of the surface of a red blood cell ghost. Somewhat better resolution may be expected if markers consisting of inorganic crystals with a distinct shape and coupled to Fab' fragments can be made.
Application of differential interference contrast with inverted microscopes to the in vitro perfused nephron
Authors: Horster Michael , Gundlach Heinz
Published: August 2011

The study of in vitro perfused individual nephron segments requires a microscope which provides: (1) easy access to the specimen for measurement of cellular solute flux and voltage; (2) an image with high resolution and contrast; (3) optical sectioning of the object at different levels; and (4) rapid recording of the morphological phenomena. This paper describes an example of commercially available apparatus meeting the above requirements, and illustrates its efficiency.

The microscope is of the inverted type (Zeiss IM 35) equipped with differential‐interference‐contrast (DIC) with a long working distance, and an automatically controlled camera system. The microscopic image exhibits cellular and intercellular details in the unstained transporting mammalian nephron segments despite their tubular structure and great thickness and makes obvious function‐structure correlations (e.g. cell volume changes); luminal and contraluminal cell borders are well resolved for controlled microelectrode impalement.
On defining the thermal history of cells during the freezing of biological materials
Authors: Bald W. B. , Crowley A. B.
Published: August 2011

An explicit numerical finite difference scheme for defining the thermal history of a cell or group of cells contained within a biological sample of prescribed shape is described. Solutions are presented for three different cases of freezing of biological materials prior to microscopic examination.

It is concluded that a surface boundary condition must be specified in any experiment before cell ultrastructure or viability can be related to thermal history or cooling rate.
A new light microscopic method for the synchronous bidirectional illumination and viewing of living cells in different contrast modes, and/or at different focal levels or magnifications
Authors: Malý M. , Vesely P.
Published: August 2011

A new method of light microscopy for the analysis of the behaviour of living cells in vitro exploits two objects for simultaneous image formation, each serving the other as a condenser. Simultaneous viewing from opposite sides allows the specimen to be examined at: (a) two different magnifications, permitting the locomotion of whole cell (groups) to be studied at a low magnification and details of interaction of colliding surfaces at a high magnification; (b) two different focal levels, permitting, for example, details near the substrate surface to be recorded at the same time as information concerning the behaviour of the free, dorsal surface; and (c) two different contrast modes, such as negative and positive phase contrast, and dark and bright field illuminations.

These possibilities can be combined, for example, to contrast a high magnification view in negative phase contrast at one focal level with a low magnification image in ordinary brightfield at another focal level in the same living cells.
How effective is ‘high‐speed’ autoradiography?
Authors: Woodcock C. L. F. , D'Amico‐Martel A. , McInnis C. J. , Annunziato A. T.
Published: August 2011

A number of methods have recently been described for enhancing silver grain production in light microscope autoradiography by impregnating the emulsion with a 2,5‐diphenyloxazole‐based fluor system. After extensive testing of these methods it was found that none gave a significant increase in silver grain count. In the course of this work a number of observations were made which seem to account at least partially for these failures, and which question the feasibility of this type of fluorography.

Tetrahymena nuclei, pulse labelled with 3H‐thymidine, contain sufficient radioactivity to produce useful autoradiographs after 2 h exposure without fluorographic enhancement.

Although fluorographic autoradiography of this type requires that the fluor penetrate the photographic emulsion, direct evidence was obtained that such penetration does not occur. Thus it is unlikely that true fluorographic enhancement occurs with methods based on 2,5‐diphenyloxazole impregnation of the emulsion. (This is in contrast to the widely used gel fluorography techniques in which it is the gel rather than the photographic emulsion which is impregnated with fluor.)

In DNA fibre autoradiography, it is possible to obtain artefactual arrays of silver grains which closely resemble those expected of replicating DNA. This phenomenon alone, however, does not explain a recent report of successful DNA fibre autoradiography after an exposure of only 3 days. Calculations based on the maximum dpm per length of labelled DNA raise further questions concerning this result.
A simple apparatus for staining and washing a batch of grids
Authors: Forsdyke J. B.
Published: August 2011

An efficient device for the staining and washing of up to fourteen grids simultaneously is described. It is simply constructed from inexpensive laboratory materials and is easy to load and operate.
The Structure And Electrical Properties Of Dislocations In Semiconductors
Authors: Hirsch P. B.
Published: August 2011

Evidence from weak beam electron microscopy shows that dislocations introduced by deformation of crystals of tetrahedrally coordinated semi‐conductors are dissociated into partials, and suggests that these lie on the‘glide’ rather than the‘shuffle’ planes. Models of the structures of the cores of such partials are described, and it is proposed that the bonds in the cores of the 30° and 90° partials constituting screw and 60° dislocations are reconstructed, forming one dimensional super‐lattices, and that dangling bonds occur only at kinks, antiphase defects, and possibly in the cores of 60° partials constituting edge dislocations. The implications regarding electronic and optical properties are discussed briefly. Consideration of the charge carried by dislocations suggests that significant Coulomb forces between partials may arise only when Cottrell atmospheres of charged point defects or impurities are present.
Tem Of Dislocations Under High Stress In Germanium And Doped Silicon
Authors: Alexander H. , Eppenstein H. , Gottschalk H. , Wendler S.
Published: August 2011

The stacking fault energies y of silicon (58 ± 6 mJ m−2) and germanium (75 ± 10 mJ m−2) were determined. Within the limits of accuracy γ was not found to change on doping with (13·8 mol m−3 (8 × 1018 cm−3) boron, and 1·17 mol m−3 (7 × 1017 cm−3) phosphorus). Freezing in dislocations under high shear stress reveals a different behaviour of screw dislocations: whereas these dislocations become wider in pure and p‐silicon, they become narrower in n‐silicon. From this we conclude the ratio of mobilities of the two 30° partials to be different in n‐ and p‐silicon. Other observations on frozen dislocations are mentioned.
Electron Microscope Studies Of Ion Implanted Silicon And Gallium Arsenide After Laser And Furnace Annealing
Authors: Sadana D. K. , Wilson M. C. , Booker G. R.
Published: August 2011

In the present investigation, three separate projects are described. First, P+ implanted Si is laser and furnace annealed, and the resulting structures as observed by TEM are compared. Second, similar studies are made of Zn+ implanted GaAs, the laser annealing being performed either with or without a surface encapsulating layer. Third, As+ implanted Si is laser annealed, and the uniformity of the annealing process as determined by SEM EBIC studies is assessed. The results have shown that different damage structures can be produced by laser annealing compared to furnace annealing, and by different laser energy densities. For the laser annealed specimens, the TEM observations provided evidence for the formation of a molten surface layer. The results demonstrated for GaAs that encapsulation was still required for laser annealing, and for Si that laser annealing can give a varying p‐n junction depth within individual slices. The latter is explained by a molten surface layer extending to different depths during the annealing process, this being attributed to spatial variations in laser intensity across the area illuminated.
Surface Structure Studies Of Electron Beam Annealed Ion Implanted Silicon
Authors: Mcmahon R. A. , Ahmed H.
Published: August 2011

A method of annealing ion implanted silicon with a scanned electron beam is described. Annealing can be achieved without visible damage to silicon or silicon oxide in resistor structures. At excessively high powers, uncontrolled melting can be seen. The structure of the implanted surface layer is shown with SED to change from amorphous to single crystal after annealing.
Transmission Electron Microscope Investigations Of Defects Produced By Individual Displacement Cascades In Si And Ge
Authors: Ruault M. O. , Jäger W.
Published: August 2011

Monocrystalline {111} Si and Ge specimens have been irradiated with atomic and molecular heavy ions in order to study the influence of the cascade energy density and the interaction between displacement cascades on the defect production. Transmission electron microscope (TEM) studies were performed to investigate the defect parameters. After atomic irradiation of Si and Ge the defects analysed (typical size 3–5 nm) are of interstitial type. Both defects with three‐dimensional strain centres and defects with a strongly asymmetric strain field were observed. An analysis of the yield and the defect size in Si as a function of ion dose suggests that the defects are formed within individual cascades rather than by a process involving overlapping cascades. Changes of the energy density locally deposited in the lattice do not affect yield and size significantly. Under otherwise similar experimental conditions, the average defect depth is significantly larger for Bi2+ irradiations than for Bi+ irradiations.
Extended Screw Dislocation Networks In Silicon
Authors: Gwinner D. , Packeiser G. , Labusch R.
Published: August 2011

Twisting silicon single crystals around a <111>‐axis and subsequent annealing produces a high fraction of screw dislocations that are arranged in hexagonal networks as is shown by TEM investigations. A maximum fraction of screws is obtained with a twist angle of 24° mm−1 and an annealing time of 4 h at 1420 K. Using stereopairs, the spatial structure of the networks was investigated. The dislocation structure in as‐deformed samples is regarded as an initial state from which hexagonal networks can be formed during heating. A weak beam analysis reveals two types of intrinisic‐extrinsic node pairs, one of which is considered to be a possible intermediate stage of the formation processes. An explanation is given, taking dislocation cross‐slip and climb into consideration.
Microscopy Of Semi‐Insulating Gallium Arsenide
Authors: Augustus P. D. , Stirland D. J.
Published: August 2011

Optical and electron microscopy examinations of a wide range of semi‐insulating, n‐type and (one) p‐type single crystal {001} gallium arsenide specimens have been made. It has been found that grown‐in line dislocations are decorated with small (50–100 nm diam.) precipitates in all these specimens. Energy dispersive X‐ray analysis and spark source mass spectrometry data have been employed in attempts to identify the precipitates.
Use of fast X‐ray film for low‐fluence biological electron microscopy at 100 kV and 1000 kV
Authors: Parsons Donald F. , Marko Michael , King Murray Vernon
Published: August 2011

A user evaluation has been made by electron microscopists of an X‐ray film for routine electron microscopy. The recent improvements in mammographic X‐ray films, with the attempt to reduce the patient dose required to produce a high‐resolution mammogram, have resulted in some useful films for medium‐ and high‐voltage electron microscopy. They can yield essential cytological information with a reduction of the electron fluence (exposure) applied to the specimen of more than an order of magnitude compared with conventional electron‐microscope films. Their use is indicated in situations where beam damage is severe.
A simple preparation, for microscopical investigations, of monolayered cells at specific cell‐cycle stages
Authors: Gwynn I. Ap , Meredith R. W. J.
Published: August 2011

A technique is described whereby cells at the mitotic stage are washed off into specially designed culture tubes. Because these tubes have a small culturing area in relation to the volume of medium they contain, and the area of the original culture flask, a usable number of cell‐cycle synchronized cells are obtainable for microscopical study.
Phase separation in alcohol/liquid carbon dioxide solvent systems facilitates critical point drying
Authors: Mckanna James A. , Lempka Tim
Published: August 2011

Carbon dioxide and methanol or ethanol, although miscible, form alcohol/CO2 solutions that do not easily mix with additional pure liquid CO2. If the CO2 inlet is situated at the top of a critical point drying apparatus chamber, pure CO2 will entirely displace the alcohol/CO2 phase (which is more dense) while keeping the chamber filled with liquid. This unexpected phenomenon is invaluable in critical point drying delicate biological tissues which remain continuously immersed, avoiding surface or convection currents. By providing an objective criterion for intermediate solvent displacement, the protocol also eliminates ambiguous ‘flushing’ steps.
A method for providing comparative counts of small particles in electron microscopy
Authors: Roberts I. M.
Published: August 2011

A method for estimating the relative concentrations of particles by electron microscopy is described. The method involves the determination of the area of the field of view in the microscope binoculars, relative to a standard area, and is independent of grid type, magnification, operator or microscope. Particle counts using this method are in close agreement with counts made from electron micrographs. The method is simple, rapid and reproducible, and, for low numbers of particles, more accurate than conventional methods.
Advances in the electrical assessment of semiconductors using the scanning electron microscope
Authors: Davidson S. M. , Dimitriadis C. A.
Published: August 2011

Recent developments in the application of the SEM to semiconductor assessment are described. Formulae are presented for the calculation of the mean carrier density injected by the electron beam. A procedure for the correction of diffusion length measurements for surface recombination is outlined. Measured diffusion lengths and lifetimes in GaP agree well. Lifetime measurements, when applied to the study of dislocations in GaP, show that recombination occurs mainly at a Cottrell atmosphere of impurities/defects surrounding the dislocation.
Electron beam depth profiling in semiconductors
Authors: Possin G. E. , Kirkpatrick C. G.
Published: August 2011

A technique for depth profiling of semiconductors is described based upon the measurement of induced junction currents as a function of beam energy. Using the known energy loss relation and electron hole pair generation rate it is possible to infer quantitative information about the semiconductor structures as a function of depth between ∼0·02 and ∼5 μm for silicon. Examples of the application of the technique to implanted and electron beam pulse annealed silicon and to a JFET transistor are described. Calculations of diffusion length limits, junction depths, poly‐silicon thickness, epitaxial layer thickness and surface recombination velocity are discussed.
A scanning optical microscope for the inspection of semiconductor materials and devices
Authors: Wilson T. , Gannaway J. N. , Johnson P.
Published: August 2011

A scanning optical microscope is described which exhibits a form of super‐resolution. Examples of its application to semiconductor device inspection are presented.
A correlation between the electrical breakdown of silicon bipolar transistors and impurity precipitates
Authors: Augustus P. D. , Knights J. , Kennedy L. W.
Published: August 2011

The contamination of Si integrated circuits during B diffusion is shown to produce an α‐Fe precipitate which electrically degrades p‐n junctions. The precipitates are shown to strain the Si lattice inducing dislocations which can glide to other parts of the circuit.