bluuebunny/crossref_metadata_2025_split huggingface dataset:
Timber—a review of the structure‐mechanical property relationship
Authors: Dinwoodie J. M. 
Published: August 2011

SUMMARYFollowing a brief introduction concerned with present consumption and future prospects of timber and timber products the principal structure‐property relationships of this low density, cellular, polymeric composite are reviewed and discussed. Structure is examined at four levels of magnitude—macroscopic, microscopic, sub‐microscopic and chemical—and the various models used to interpret its composite nature are described.The dimensional instability of timber and loss of strength on wetting are discussed in terms of its fine structure. At low levels of stressing, and for short periods of time, timber can be treated as an elastic material, but at higher stresses and prolonged periods, especially with alternating humidity, timber behaves as a linear orthotropic viscoelastic material; the various factors influencing the elastic constants and the relationship of creep to fine structure are discussed.The anisotropy of wood is related to cell arrangement and microfibrillar orientation: strength and its variability are discussed in terms of structure at all four levels. Comparison of the strength of timber with that of other constructional materials especially on a weight basis shows timber in a very good light; the combination of high stiffness and high toughness is unique. Recent models using three‐dimensional anisotropic elastic analysis to understand strength and deformation of timber are described. The morphology of fracture under different forms of stressing is illustrated.
Structural components influencing the permeability of ponded and unponded Sitka spruce*
Authors: Bolton A. J. , Petty J. A. 
Published: August 2011

SUMMARYStudy of the gaseous permeability of wood stored in ponds to promote bacterial decomposition of the bordered pit membranes has shown that the pit aperture/pit cavity contributes to the total resistance to flow of liquids through both ponded and unponded wood. In ponded wood the contributions of the pit apertures/pit cavities ranged between 5% and 46% of the total resistance, the tracheid lumina making up the remaining 96–54%. This large variation is attributed to the presence of different proportions of earlywood and latewood in specimens tested. In air‐dried unponded wood, however, the pit membrane pores contribute an average of 81% of the total resistance to liquid flow, the tracheid lumina an average of 16%, and the pit aperture an average of only 3%. An implication of these results is that previously used analytical techniques for the determination of the radius and number of conducting flow paths in wood, based on the assumption that only two structural components offer resistance to flow, are not wholly satisfactory.
Wood substance as a water‐reactive fibre‐reinforced composite
Authors: Cave I. D. 
Published: August 2011

SUMMARYA constitutive relation for an elastic fibre composite material consisting of an inert fibrous phase embedded in a water‐reactive matrix has been derived. The relation is determined in terms of the overall stiffness of the composite, the volume proportion of the matrix, and stiffness and sorption functions of the matrix that are dependent on moisture content. The proposed model of the matrix is believed to be appropriate to wood substance. The constitutive relation is, therefore, applicable to a basic element of wood substance and can be applied to models of wood structure to calculate mechanical properties such as shrinkage, moisture‐induced creep and other moisture‐related properties.
Adsorption of DNA molecules to different support films
Authors: Sogo J. M. , Portmann R. , Kaufmann P. , Roller Th. 
Published: August 2011

SUMMARYProtein‐free adsorption of the DNA of the Escherichia coli bacteriophage T7 to carbon, collodion, aluminium‐beryllium and aluminium films was studied. It was found that the appearance of DNA strands depended greatly upon the kind of support film used. Direct adsorption of DNA to aluminium‐beryllium or aluminium films yielded specimens with ‘thin and long’ and ‘thick and short’ regions along the strand. Well extended, uncoiled and unaggregated DNA molecules were obtained only when DNA was adsorbed to carbon, collodion or mica in the presence of intercalating dyes such as ethidium bromide. Adsorption properties of the different films are well correlated with their surface charge. Aluminium‐beryllium films carry a strong positive surface charge, aluminium films a weak positive charge and carbon films a weak negative charge.It is suggested that for the preparation of specimens by spontaneous adsorption of well extended and unaggregated strands it is necessary that the DNA molecule is stiffened by a ligand such as an intercalating dye, and that the charge on the surface of the support film is opposite to the charge of the macromolecule.
A freeze‐fracture replication apparatus for biological specimens*
Authors: Stolinski C. 
Published: August 2011

SUMMARYA freeze‐fracture apparatus of original design has been constructed which can be fitted onto a standard vacuum evaporator unit. In it, cell suspensions and organized tissue may be processed by inserting a sample into a cylindrical holder. By leaving a small part of the tissue protruding from the holder, pre‐selected and aligned portions of the specimen can subsequently be revealed by fracture under vacuum. After rapid freezing, the specimen remains firmly attached to the inner wall of the sample holder, preventing its possible loss during fracturing. A mechanism, in the form of a double‐sided converging wedge, which is operated from outside the vacuum chamber, is used to produce a fracture in the specimen. The device gently induces a fracture in the desired part of the tissue and lifts the protruding part of the specimen out of the way. In this way, reasonably flat fracture faces are produced for subsequent replication. As the fracturing mechanism comes into contact only with the outer edges of the specimen, damage and contamination liable to occur when the entire specimen is traversed by a blade, is avoided. In addition the specimen stage is surrounded by a cold metal shroud which acts as an efficient trap for contaminants. In this way, favourable vacuum conditions are produced in the vicinity of the specimen. Such effective enclosing of the specimen also facilitates controlled sublimation of the sample.
Abel type integral equations in stereology. II. Computational methods of solution and the random spheres approximation
Authors: Anderssen R. S. , Jakeman A. J. 
Published: August 2011

SUMMARYAs mentioned in Part I of this paper, Part II is mainly concerned with the construction of stable computational methods for the solution of integral equations of Abel type which occur in stereology. However, in order to develop a rationale for the types of methods which we shall propose, it is first necessary to review the different types of methods which have been suggested to date in the stereological literature. This is done in section 2. From the review, we conclude that the construction of stable methods can be based on the use of spectral differentiation and product integration to evaluate appropriate inversion formulae, when they are known. Using the Random Spheres Model as exemplification, we examine the nature of such methods in section 3. The potential of the proposed methods is illustrated in section 4 by examining the reliability of the random spheres approximation—an unsolved problem in stereology proposed by Moran (1972). We conclude from this examination that the random spheres approximation is quite reliable for particles which approximate spheres.
Redundancy of washing in the preparation of biological specimens for transmission electron microscopy
Authors: Ockleford C. D. 
Published: August 2011

SUMMARYA marine unicellular organism, human trophoblast tissue and cultured trophoblast cells of human origin have been satisfactorily preserved for electron microscopy without resort to washing either before dehydration or between different stages of fixation.The time required to fix and dehydrate a specimen using this method is 55 min.
Preparation of vascular endothelium for scanning electron microscopy: a comparison of the effects of perfusion and immersion fixation
Authors: Gertz S. David , Rennels Marshall L. , Forbes Michael S. , Nelson Erland 
Published: August 2011

SUMMARYA comparison of currently used methods of tissue fixation for scanning electron microscopic study of vascular endothelium revealed that in situ fixation by intravascular perfusion is superior to immersion for the preservation of endothelial surface morphology.
High resolution electron microscope study of lattice images in biological apatites
Authors: Spector M. 
Published: August 2011

SUMMARYLattice (Fourier) images of crystallites in human bone and teeth, and calcified atherosclerotic plaque were studied using high resolution transmission electron microscope techniques. The lattice images observed in the normal and diseased calcified tissue were compared with the images of synthetic hydroxyapatite crystallites.
Identification of nerve fibres in the scanning electron microscope
Authors: Sætersdal Thorvald Selmer , Myklebust Reidar 
Published: August 2011

SUMMARYThe use of silver as a ‘stain’ for nerve fibres in scanning electron microscopy (SEM) preparations has been investigated. Samples of cardiac tissues were treated according to the Bielschovsky silver impregnation method. Following embedding in paraffin, successive sections were selected for light microscopy and for SEM studies, respectively. The silver impregnated fibres, when examined in SEM preparations, appeared nearly white against a greyish background of cardiac tissue. They were therefore easy to localize even at a low magnification. These nerve fibres were identified in the same tissue, but different blocks by means of transmission electron microscopy (TEM) studies and by fluoroescence microscopy.
Handling and staining epoxy resin sections for light microscopy
Authors: Roberts I. M. , Hutcheson A. M. 
Published: August 2011

SUMMARYEpoxy resin sections 0.1‐1.0 μm thick of specimens embedded for electron microscopy, were collected from the ultramicrotome using strips of cover slip, and, after drying on a hot plate, were bulk stained in specially made troughs. After treatment with periodic acid, the sections were stained first in basic fuchsin at 70°C and then in alkaline methylene blue at room temperature. The handling technique allows accurate collection of serial sections without interrupting the sectioning process, and the stain combination is suitable for different specimens in different epoxy resins and is unaffected by storage for more than 1 year.
The preparation of human articular cartilage for scanning electron microscopy
Authors: Cameron C. H. S. , Gardner D. L. , Longmore R. B. 
Published: August 2011

SUMMARYThis paper compares sixteen preparative techniques thought to be of advantage in the study by scanning electron microscopy (SEM) of human articular cartilage surfaces. The adequacy of surface preservation obtained with the techniques, was judged subjectively, first, by the reproducibility of secondary electron images of normal cartilage, and second, by comparing the results with those obtained by reflected light microscopy of the fresh unfixed cartilage surface over a magnification range of × 20 – × 240.Adequate surface preservation was confirmed when cartilage surfaces had been dehydrated through ethanol to propylene oxide and vacuum dried; dehydrated through amyl acetate and quenched in Freon before freeze‐drying; dehydrated and passed through amyl acetate at low temperature before freeze drying.Valuable information can be obtained from different specimens by varying the technique of preparation. At different ages, different surface features are best preserved. In a systematic study it has been found essential to adopt a uniform preparative method and to control the results by reflected light microscopy. Even with the most perfect preparation, the surface appearances cannot be identical with those that function under load in vivo.
High resolution microanalysis in materials science using electron energy loss measurements
Authors: Williams D. B. , Edington J. W. 
Published: August 2011

SUMMARYThe physical basis of microanalysis using measurements of electron energy losses associated with atom ionization or plasmon excitation in thin electron microscope specimens is explained in a simple manner. In addition the equipment used to resolve both the high and low energy regions of the loss electron spectrum is described. It is shown that ionization loss analysis is still in its infancy, but plasmon loss analysis has now been providing quantitative microanalytical data on light metal alloys for 8 years. The results obtained from both techniques and their application to specific metallurgical problems are reviewed. Conclusions are drawn concerning the future use of these techniques in high resolution microanalysis.
The identification of asbestos
Authors: Champness P. E. , Cliff G. , Lorimer G. W. 
Published: August 2011

SUMMARYTechniques are described for identifying and distinguishing between the six varieties of asbestos. When the fibres are large and numerous, as is the case for insulation materials, simple optical or X‐ray methods suffice. For environmental samples one must normally resort to electron microscopic techniques for a positive identification. When asbestiform minerals are to be distinguished from other fibrous silicates it is often necessary to use both electron diffraction and X‐ray spectrometry.
Molecular hybridization of RNA and DNA in situ: visualization at the electron microscope level
Authors: Jacob J. , Moar M. H. , Gillies Katherine , Macleod D. , Jones K. W. 
Published: August 2011

SUMMARYElectron microscopic visualization of molecular hybrids formed in situ is feasible at the present time. It can be accomplished by two alternative approaches. In one, the in situ hybridization is carried out on ultrathin sections of target embedded in glycol methacrylate. In the other, whole cells are used for hybridization and they are subsequently prepared for electron microscopy. The choice of the method to be adopted depends on the type of target tissue. When there is a choice, the second approach seems preferable. Some of the important technical steps in the hybridization procedure, such as DNA denaturation in ultrathin sections, have been discussed and attention has been drawn to practical problems that may arise during the preparatory steps. Our light microscope experiments demonstrate that preparations made after glutaraldehyde fixation have a lower hybridization efficiency than those fixed with 3: 1 methanol‐acetic acid. Attempts are therefore being made to explore the possibility of using methanol‐acetic acid for electron microscope in situ hybridization. First results of straightforward fixation show that the preservation of nuclear structure may be fairly satisfactory for the purpose. However, the cumulative effects of subsequent treatments in the procedure still remain to be examined.For electron microscope autoradiographs (EM ARG) of hybridized preparations, the most suitable emulsion at present appears to be Ilford L4. Various factors conducive to optimum resolution consistent with maximum efficiency in this emulsion have been pointed out. Practical problems that may arise in autoradio graphs of hybridized preparations such as background and variation of grain density in adjacent sections have also been considered.
Cell proliferation in the prostate complex of the castrate mouse
Authors: Alison M. R. , Wright N. A. , Morley A. R. , Appleton D. R. 
Published: August 2011

SUMMARYCell proliferation during 100 h of continuous androgen challenge was studied in the seminal vesicle and coagulating gland of Balb/c mice castrated 3 days or 14 days prior to the first daily injection of 250 μg testosterone propionate. Continuous labelling with [3H] thymidine indicated that the seminal vesicle was almost totally responsive to androgen, as early as 3 days after castration, whereas the androgen sensitivity of the coagulating gland increased from 30% at 3 days after castration to 85% at 14 days after castration. In both tissues the magnitude of the proliferative reaction could be related to the extent of cell loss prior to stimulation. The duration of the pre‐replicative phase in the response of the seminal vesicle to androgen was 20–25 h both at 3 and 14 days after castration. In the coagulating gland the pre‐replicative phase was 40 h at 3 days after castration and 20 h at 14 days after castration.The maximum uptake of [7α‐3H] testosterone administered to mice 3 days after castration was significantly greater (P < 001) in the seminal vesicle compared to the coagulating gland. At 14 days the seminal vesicle and coagulating gland exhibited a similar capacity for uptake.The in vivo metabolism of [7α‐3H] testosterone was studied by thin layer chromatography 30 min and 120 min after administration. A high proportion of the radioactivity extracted from all the tissues was associated with highly polar steroids. At 3 days after castration, the seminal vesicle, 2 h after administration of radioactive testosterone, retained a much higher proportion of radioactivity associated with dihydrotestosterone than did the coagulating gland.The localization of steroid in mice 3 days after castration was studied by drymount autoradiography at intervals up to 2 h after the injection of [1,2,6,7(n)‐3H]‐testosterone. A heavier deposition of silver grains was observed over autoradiographs of the seminal vesicle. In the seminal vesicle the grains were primarily located over nuclear areas whereas in the coagulating gland the grains were diffusely distributed over both nuclear areas and over cytoplasmic areas.
Production of multi‐level radioactive source for autoradiographic calibration
Authors: Stevens G. W. W. 
Published: August 2011

SUMMARYMany reactions are known for converting developed silver images into chemical forms containing a wide variety of elements. By application of this principle to step‐wedge images and by use of labelled reagents, multi‐level flat sources for autoradiographic calibration can be made simply. Detailed procedures have already been published for the use of 131I, 110Ag, and 60Co, and the method can probably be extended to other radionuclides.
Anhydrous fixation of dry plant tissue using non‐aqueous fixatives
Authors: Hallam N. D. 
Published: August 2011

SUMMARYNon‐aqueous preparation techniques such as freeze fracture of the dry tissue, fixation using dimethylsulphoxide as a vehicle for glutaraldehyde, and osmium vapour as a fixative have been used to investigate the fine structure of plant material in the dry state. Fixation using anhydrous glutaraldehyde dissolved in dimethylsulphoxide preserves existing cell structure and cell wall characteristics whereas conventional aqueous fixation methods hydrate the tissue during fixation and this gives a distorted impression of true cell structure.
A simple electrode for metallic replication
Authors: Bank Harvey , Robertson J. David 
Published: August 2011

SUMMARYA simple resistive heating electrode has been designed for use in metallic replication procedures. These electrodes are relatively small, reliable, adaptable to most vacuum systems, and are compatible with ultra‐high vacuums. They are easily aligned, have good electrical conductivity and adjustable tensions. Using these electrodes with full wave rectified a.c, we found reduced specimen heating, lower background granularity, and improved resolution compared to commercially available designs.
Quantifying ‘pattern’: A stereological approach
Authors: Orive Luis‐M. Cruz 
Published: August 2011

SUMMARYAt present, a number of stereological techniques are available for the estimation of size parameters of aggregates (such as VV, SV, size distributions, and so forth) from data measured on plane sections.In this paper, an attempt is made to find a suitable quantification of spatial relationships which can be satisfactorily used for discrimination purposes whenever the traditional size parameters fail to do so.The proposed techniques of pattern analysis are very simple and strongly connected with the classical theory and practice of stereology; this should render them very accessible to scientists working in different fields, such as biology, geology, ecology, geography, etc.
Cell surgery by laser micro‐dissection: A preparative method
Authors: Isenberg G. , Bielser W. , Meier‐Ruge W. , Remy E. 
Published: August 2011

SUMMARYA new UV‐laser device is introduced as a micro‐manipulator and micro‐dissection apparatus for experimental cell research. High energy irradiation is produced by a quasi‐continuous N2‐laser. The laser micro‐beam can be focused to a minimal diameter of 0.75 μm. The micro‐laser can be used for cutting and, hence, as a micro‐surgical instrument at the level of cellular organelles.Cytoplasmic actomyosin fibrils (AM fibrils) from tissue culture cells (RMCD–cells) are isolated from the surrounding ground cytoplasm. It is shown that the contractile proteins are not damaged by the laser dissection method to an extent that would prevent their normal function, e.g. contraction.
Precise and general conditions for the validity of a comprehensive set of stereological fundamental formulae
Authors: Miles R. E. , Davy Pamela 
Published: August 2011

SUMMARYThe usual derivations of the well‐known fundamental formulae of stereology are unsatisfactory. Precise and general conditions for the validity of a comprehensive system of such formulae are given. They take the form of unbiased ratio estimators of stereological fractions. These estimators are defined for various types of ‘weighted’ random plane and line sections of the specimen. Thanks to certain probabilistic equivalences, these sections may in practice be implemented fairly easily. The system includes new formulae which allow the estimation of the mean lineal and areal projections of embedded features. The mean square errors of several alternative estimators of the same feature characteristics are compared.
Particle size‐shape distributions: The general spheroid problem
Authors: Orive Luis‐M. Cruz 
Published: August 2011

SUMMARYThe development of stereological methods for the study of dilute phases of particles, voids or organelles embedded in a matrix, from measurements made on plane or linear intercepts through the aggregate, has deserved a great deal of effort.With almost no exception, the problem of describing the particulate phase is reduced to that of identifying the statistical distribution—histogram in practice—of a relevant size parameter, with the previous assumption that the particles are modelled by geometrical objects of a constant shape (e.g. spheres). Therefore, particles exhibiting a random variation about a given type of shape as well as a random variation in size, escape previous analyses. Such is the case of unequiaxed particles modelled by triaxial ellipsoids of variable size and eccentricity parameters. It has been conjectured (Moran, 1972) that this problem is indetermined in its generality (i.e. the elliptical sections do not furnish a sufficient information which permits a complete description of the ellipsoids). A proof of this conjecture is given in the Appendix. When the ellipsoids are biaxial (spheroids) and of the same type (prolate or oblate), the problem is identifiable. Previous attempts to solve it assume statistical independence between size and shape. A complete, theoretical solution of the spheroids problem—with the independence condition relaxed—is presented.A number of exact relationships—some of them of a striking simplicity—linking particle properties (e.g. mean‐mean caliper length, mean axial ratio, correlation coefficient between principal diameters, etc.) on the one hand, with the major and minor dimensions of the ellipses of section on the other, emerge, and natural, consistent estimators of the mentioned properties are made easily accessible for practical computation.Finally, the scope and limitations of the mathematical model are discussed.