One micrometre paraffin sections: an aid to interpretation of immunoperoxidase staining of immunoglobulins

A technique is described for obtaining 1 μm sections of tissue embedded in modified paraffin wax using long-edged glass knives. Serial sections can be cut and stained by the immunoperoxidase method to demonstrate multiple antigens in a single cell or to confirm that the immunoglobulin within a cell is monotypic. The improved cytological detail seen in thin paraffin sections permits the more precise localization of intracellular staining.     

An apparatus for fixation and continuous dehydration of specimens for paraffin sections

Stimulated by the paper describing an apparatus for continuous dehydration by Evans (1966) we have developed an apparatus of our own. The chief differences between this and that mentioned above are: (1) The use of a hypodermic needle which assures an absolutely constant flow of dehydrating fluid. Any given speed is reproducible by a simple change of needle and is not influenced by normal changes of temperature or by the quantity of liquid in the reservoir. (2) The elimination of a stirrer shaft, whereby space is gained and the use of one large basket is made possible. (3) The apparatus can be connected to a vacuum pump for fixation, or to a water tap for rinsing. (4) The apparatus can be placed in an oven. One of our aims was to eliminate handling of the specimens as far as possible. The apparatus, which has now been successfully in use for over a year, allows us to leave the specimens untouched from the fresh state right up to the transfer to paraffin.     

A contribution to the theory of friction

The nature of the interaction between a rigid spherical asperity and an asperity governed by the stress/strain law $\text{}\text{?}\text{gs = B}\text{}\text{?}\text{ge}{}^{\mathrm{n}}$ is studied. The interfacial shear stress is defined by fτ_max where $\text{0 </ ? </ 1}$, τ_max being the maximum allowable shear stress at the contact. By integrating the total effect of a population of such surface asperities expressions for the total frictional forces and the total load are derived. The value of the coefficient of friction is thus obtained and the special conditions for perfectly plastic and elastic behaviour are considered. In both cases the friction coefficient is seen to contain a term defined by the deformation and dependent on surface roughness and a term totally defined by ?.     

A contribution to the theory of mechanical wear

An attempt is made to predict the wear behaviour, particularly of metals, when wear arises from asperity interactions alone. It incorporates the concept of fatigue failure and also of simple plastic deformation failure which is considered as fatigue failure in one cycle of loading. The analysis demonstrates that fatigue mechanisms of wear are not inconsistent with observed behaviour and indicates an approach to a better appreciation of the effects of such factors as material constants and surface topographical features.     

A contribution to the theory of lubricated wear

A system of mathematical analysis is proposed to describe a complex interdisciplinary theory involving some controversial subsidiary topics. The new model is based upon Archard's theory and Halling and Finkin's solution, and incorporates the concept of the fractional film defect and the theory of Johnson et al. concerning the division of the load between the lubricating film and the contacting asperities under circumstances where both contribute to supporting the load. Theoretical and experimental results are compared.     

The preparation of flexible thin sections of rocks and coals

A method for the preparation of flexible thin sections is described, which allows their use for macro- and micro-examinations.     

A contribution to the history of kinematics—I

The present paper is the first part of a contribution to the history of kinematics consisting of two parts. The paper deals with the invention of Watt's approximate straight-line linkages in 1784 and the early French contributions to the theory of the planar 4-bar coupler curve by de Prony, Hachette and Vincent. In addition to this the paper treats the way in which Peaucellier discovered the first exact planar straight-line linkage.     

Correlated light optical and scanning electron microscopy of Gram smears of bacteria and paraffin sections of cardiac muscle

Light-microscope slides (3 in. × 1 in.) bearing Gram smears of Erysipelothrix rhusiopathiæ, or Staphylococcus aureus, after preliminary examination under the light-optical microscope (LM), were cut down in size, glued onto specimen stubs, coated with gold and examined in the scanning electron microscope (SEM). These preparations served as a control for investigations into bacteria-cell junctions in tissue. Cover-slips from stained sections of staphylococcal or swine erysipelas endocarditis mounted on 3 in. × 1 in. microscope slides (which had been intensively studied previously with conventional light microscopy) were floated off by immersing the slides in xylol. After dehydration of the tissues on the slides, the preparations were treated similarly to the Gram smears, and were examined with the SEM. Lesions of endocarditis were thus examined, and the information gained from these preliminary examinations shed new light on the pathogenesis of the disease. This information had not previously been available by any other technique. Because of this, and in view of the simplicity of preparing sections for scanning electron microscopy, it is suggested that the SEM might be a useful tool to be applied to routine histological sections.     

A contribution to determining the friction coefficient in hydroforming of tubes

Hydroforming is a relatively new technology, which enables complex shaped hollow parts to be produced efficiently. Compared to alternative methods, this technology is characterised by significant potential advantages, such as complex shape production, lightweight design, high accuracy, and process integration. The tribological aspects of hydroforming are very significant, as friction influences all the main process parameters practically in a direct or indirect way. However, there is a paucity of information relating to hydroforming tribology. In most reports on this subject only qualitative data regarding the friction coefficient are given. However, for finite‐element method simulation and optimal process and tool design, quantitative data are indispensable. This paper describes an attempt to determine the coefficient of friction in both the elastic and plastic states of a workpiece during tube hydroforming processes. Push‐through tests were carried out in order to determine the coefficient of friction in the elastic state, and tube upsetting tests were conducted for the plastic state. Various commercial lubricants were used in the experiments.