ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1985.tb02639.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SUMMARYThe phase difference between two plane polarized light rays whose electric field vectors (planes of polarization) are at right angles is often determined by Senarmont analysis. In this analysis, a quarter‐wave plate whose vibration axes lie at an azimuth of ±45° to the planes of polarization of the two rays is inserted. The rotation of the analyser that leads to extinction is then determined by manual adjustment. This classical method has been significantly improved by, instead, measuring light intensities at thirty‐two evenly spaced analyser angles which span 180° of analyser rotation. An unbiased estimate of the phase difference may then be extracted with high accuracy by analysis as a designed experiment.Of the several numerical analysis methods investigated, harmonic analysis is particularly attractive for routine use—especially with small computers. Iterative non‐linear least‐squares analysis on a mainframe computer was taken as the standard of numerical accuracy, against which direct algebraic solutions on a personal computer were evaluated. An ‘accuracy’ statistic (which measures the goodness‐of‐fit to the theoretical cosine function) has proven invaluable in assessing the validity of actual data.Data of exceptional quality are produced by the Leitz Jamin–Lebedeff optical system using intensities measured with a photodiode detector placed in the camera tube of the microscope. These data will support analysis to better than 0.0001° of analyser position, or<6×10−7periods. Since alignment of the optics with comparable accuracy is impossible, a method for accurately quantitating the contribution to the observed retardation that originates from within the optics, by performing the analysis on an ai

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1985.tb02640.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SUMMARYA microscope diffusion chamber has been developed which allows direct observation of the dynamic osmotic response of individual cells in micro‐volume suspensions. Continuous observation of stationary cells is possible including short experimental times while the extracellular chemical composition is changed. Multiple changes of solute type or concentration are easily imposed upon a single sample volume. Response times are a function of chamber configuration but response times as low as 1–10 s are possible with negligible solute concentration gradients within the sample region. The chamber is simple and economical to construct and use. It is the size of an ordinary glass microslide and it can be adapted easily to any common laboratory microscope. All standard optical techniques may be used with the chamber. Construction details and operating characteristics including important limitations are discussed. Example photomicrographs and osmotic data are inclu

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1985.tb02641.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SUMMARYA new preparation method is introduced to reveal intracellular structures in the scanning electron microscope and its application to mitotic cells in root meristems of Vicia faba is demonstrated. The root tips are fixed with a mixture of formaldehyde and glutaraldehyde and the fixed tissues are frozen and fractured in liquid nitrogen. They are then incubated successively in dilute solutions of aldehyde (formaldehyde or glutaraldehyde) and osmium tetroxide. By this treatment, the excess cell‐matrix is removed from the fractured surface of the cell, and a deep view into the cell‐interior can be obtained with the scanning electron microscope. Varied levels of substructure are observed on the surface of chromoso

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1985.tb02642.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SUMMARYA method is described for obtaining and analysing the absorption spectra of microscopic specimens, using readily available laboratory equipment. Spectra obtained from the primary image with a hand spectroscope are recorded photographically and the negative images subsequently analysed, in terms of optical density relative to a standard spectrum, using a gel scanner densitometer and chart recorder. The system has been used to recognize and characterize the haemoglobin of a symbiotic flatworm, absorption peaks being resolved to within 5.0 nm. Separation of the recording and analytical stages confers flexibility since records can be made, if desired, in the field or by co‐workers elsewhere and analysed later in the base laborator

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1985.tb02643.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SUMMARYIf the axis of anisotropy of oriented, tubular or lamellar objects is unknown, the unbiased stereological estimation of length density and surface density (Lvand Sv) requires counts on sections with isotropic uniform random (IUR) orientation. It is shown theoretically that in homogeneous, anisotropic specimens the precision of Lvand Svestimation is considerably augmented if IUR‐oriented sets of three mutually perpendicular sections (orthogonal triplet probes=ortrips) are used instead of three directionally independent IUR sections. The mechanism of variance reduction results from a negative covariance between sections within ‘ortrips’ and corresponds to the antithetic variate principle of Monte Carlo work. Heterogeneity decreases the efficiency of the ortrip method, but this effect can often be counteracted by systematic sampling of ortrips within specimens. Practical estimation of length and surface area of the highly anisotropic, tubular myocardial capillaries per tissue volume in the left ventricles of eight normal, adult, male perfusion‐fixed Wistar rats provided estimates of excellent precision with CEs of 3.3% (Lv) and 2.1% (Sv) of the group mean. The method will hopefully allow stereologists dealing with arbitrary anisotropic structures to apply the same simple, efficient, and unbiased sampling designs that have long been used in the study of liver, lung, and kidney

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1985.tb02644.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SUMMARYA quick‐freeze, freeze‐substitution method is described which employs glutaraldehyde as well as osmium tetroxide (OsO4) in a ‘double‐fixation’ protocol comparable to that used for conventional transmission electron microscopy. Cultured cells are quick‐frozen in Freon 22 and freeze‐substituted in an ethanolic solution of glutaraldehyde. Specimens destined for TEM are postfixed in OsO4in acetone, embedded in Epon‐Araldite, and sectioned. This method yielded ultrastructural preservation which was comparable to that obtained from methods employing OsO4alone as a freeze‐substitution fixative. However, if glutaraldehyde is used alone as a freeze‐substitution fixative, specimens can be processed for immunocytochemistry without additional treatment with pe

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1985.tb02645.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SUMMARYBenzoyl peroxide is widely applied as an initiator–accelerator system in combination with tertiary amines for the polymerization of water‐miscible methacrylates. However, this system is very sensitive to the ambient temperature and the evolution of exothermic heat is, especially at room temperature (293 K), difficult to control. Temperatures involved may increase beyond 373 K. A linear correlation between a graded series of benzoyl peroxide (0.2–1.0 g% benzoyl peroxide/glycol methacrylate) and the maximum temperature within the polymerizing plastic was established using a commercially‐available embedding system. Commercially‐available glycol methacrylates contain various concentrations of inhibitor in order to prevent spontaneous polymerization of the monomer. We tested a series of 200–300–400–800 ppm of the inhibitor hydroquinone and found a significant influence exerted upon the maximum temperature and the moment at which the maximum temperature was reached. Supplementary addition of inhibitors to the GMA monomer may effect a decrease of the maximum temperature within polymerizing GMA mixtures. Possibilities for standardizing the polymerization of glycol methacrylate by means of the benzoyl peroxide/tertiary amine initiator–accelerator system at room temperat

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1985.tb02646.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SUMMARYAnnealing behaviour of amorphous layer in S+implanted GaAs is studied by employing transmission electron microscopy technique. The amorphous layer is annealed inside the electron microscope by withdrawing the condenser aperture. The transformation of amorphous layer into polycrystalline layer is found to occur in the near surface region. Formation of twins is observed near the interface of amorphous crystalline region. Coarsening of grains occur on further annealing. The findings of the present experiment is compared with the explosive recrystallization behaviour of amorphous Si under laser and electron irradiation (Narayan et al., 1983). It has been concluded that both solid phase and liquid phase epitaxial regrowth of the amorphous GaAs layer have taken place upon electron irradiation.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1985.tb02647.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SUMMARYA simple and reproducible method is described for the preparation of cell cultures for light and transmission electron microscopy. Mixed testicular cells are grown on collagen layered, PTFE‐coated coverslips. Thin sheets of plastic‐embedded cells are packed together and re‐embedded permitting the examination of sections cut perpendicular to the plane of the culture and, thus, the intercellular relationships at different levels throughout the cu

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1985.tb02648.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY