ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1983.tb04156.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

SUMMARYVideo‐enhanced microscopy combined with the use of a computer frame memory extends considerably the useful range of our video enhanced contrast (AVEC) methods for polarizing, double‐beam interference and differential interference contrast microscopy. Increased visual contrast is achieved by two stages of amplifications: the first optical, by using high bias retardation settings, and the second electronic. These steps are followed by a reduction of background brightness by means of a clamp voltage applied to a DC restoration circuit of the video camera. One of the limitations of the AVEC method alone is the inevitable appearance under high gain conditions of a pattern of mottle due to inaccessible dirt and defects in the lenses even of high quality. This limitation has been circumvented by storing the mottle pattern in the frame memory (frame store) and continuously subtracting it from each succeeding frame to clear the image. A major gain in image quality has resulted. In polarizing microscopy, the frame memory can be used also to subtract the image at one compensator setting from that at the equivalent setting of opposite sign, thus removing from the final image not only most of the mottle pattern but also the contrast due to the bright‐field contrast. In the polarizing microscope, these manipulations of the raw video image make it possible to observe and measure the birefringence of various organelles and elements such as microtubules, intermediate filaments and bundles of as few as a half dozen actin filaments. Since scattered light is also removed from the image, features hidden from view in the unprocessed image become visible. In differential interference microscopy, the AVEC method makes visible (i.e. detectable) many linear elements and particles that are an order of magnitude smaller than the resolution limit and not visible in the optical image. Such features are inflated by diffraction, however, to Airy disk

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1983.tb04157.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

SUMMARYThis review discusses applications of fluorescence microscopy using totally internally reflected excitation light. When totally internally reflected in a transparent solid at its interface with liquid, the excitation light beam penetrates only a short distance into the liquid. This surface electromagnetic field, called the ‘evanescent wave’, can selectively excite fluorescent molecules in the liquid near the interface. Total internal reflection fluorescence (TIRF) has been used to examine the cell/substrate contact regions of primary cultured rat myotubes with acetylcholine receptors labelled by fluorescent α‐bungarotoxin and human skin fibroblasts labelled with a membrane‐incorporated fluorescent lipid. TIRF examination of cell/substrate contacts dramatically reduces background from cell autofluorescence and debris. TIRF has also been combined with fluorescence photobleaching recovery and correlation spectroscopy to measure the chemical kinetic binding rates and surface diffusion constant of fluorescent labelled serum protein binding (at equilibrium) to a

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1983.tb04158.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

SUMMARYHolography can be used to record, on a flat photographic plate, information about a three‐dimensional object. In conventional microscopy a thin slice of an object is observed in focus and recorded. By combining microscopy and holography it is possible to encode, on the same flat record, all the depth information in a three‐dimensional microscopic object, not just a single infocus section. Any section of the three‐dimensional object may be subsequently reconstructed and brought into focus by using a suitable viewing system to decode the hologram. Arrangements for doing this are described. It is shown that in order to achieve the highest resolution imagery of a three‐dimensional object, reversed wave reconstruction is necessary.As holograms are made and reconstructed using a coherent laser light source, holographic microscopes are easily adapted for interferometry and an example of this is described. The differences between coherent and conventional imagery are briefly considered. The coherence of the illumination gives rise to the problems of coherent noise and speckle. Coherent noise is due to stray reflections in the optical system and can be reduced by using as few surfaces as possible or by using holographic lenses. A speckle reduction technique employing a new type of holographic optical element is described and its application to the stereomicroscopy of fossil ostracods con

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1983.tb04159.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

SUMMARYSome considerations on the improvement of the image quality of the phase contrast microscope are presented. The significance of glare and image fidelity discussed theoretically and the dependence of image fidelity and contrast on the phase plate characteristics are investigated on the basis of images calculated for different parameters of the annular phase plate. This paper also describes an anti‐reflection technique for the phase plate and demonstrates its effectiveness in the elimination of glar

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1983.tb04160.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

SUMMARYThe main features of the scanning acoustic microscope are reviewed with particular reference to applications in biology and non‐destructive evaluation. Recent developments on imaging the interior of solids are discussed. Proper interpretation of recorded images can lead to maps of velocity and density via theV(z)response. Further improvements in resolving power (using cryogenic liquids or high pressure gases) should make the acoustic microscope a powerful tool in many areas of science and technolog

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1983.tb04161.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

SUMMARYA new semi‐automatic method is introduced which makes possible the quantitative examination of cresyl‐fast‐violet stained sections of the cerebral cortex. These sections are divided into measuring fields of 20 × 20 μm in a well‐defined area. A scanning procedure then automatically determines the grey level index of every single field. The image of the histological section can be compared with the grey level index data matrix by means of a plotted image, the density of the plotted points of which is proportional to the measured grey level index. By overlaying this plotted image with the original section, the boundaries of the laminae can be fixed in the data matrix. The grey level index profiles—the grey level data plot as a function of the cortical depth—after smoothing and standardization are typical of special cortical areas. The mean thickness and the mean portion of the grey level index profile of the different laminae of the striate area are compared with data from other

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1983.tb04162.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

SUMMARYThe methodology for preparing specimens in the frozen, hydrated state has been assessed using crystals and T4 bacteriophages. The methods have also been demonstrated with lambda bacteriophages, purple membrane ofHalobacterium halobiumand fibres of DNA. For particles dispersed in an aqueous environment, it is shown that optimum structural preservation is obtained from a thin, quench‐frozen film with the bulk aqueous medium in the vitreous state. Crystallization of the bulk water may result in solute segregation and expulsion of the specimen from the film. Contrast measurements can be used to follow directly the state of hydration of a specimen during transition from the fully hydrated to the freeze‐dried state and permit direct measurement of the water content of the specimen. By changing the concentration and composition of the aqueous medium the contrast of particles in a vitreous film can be controlled and any state of negative, positive or zero contrast may be obtained. At 100 K, frozen‐hydrated, freeze‐dried or sugar embedded crystals can withstand a three‐ to four‐fold increase in electron exposure for the same damage when compared with similar sugar‐embedded or freeze‐dried samples at r

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1983.tb04163.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

SUMMARYCryopreservation is the superior technique for viewing leaf surfaces in the SEM. Epidermal cells become distorted when freeze dried and disrupt the orientation of epicuticular wax structures. The latter are largely lost during critical point drying. Nevertheless, the appearance of surface structures after subjecting them to each drying method is valuable in interpreting the features observed by cryopreservation.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1983.tb04164.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1983.tb04165.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY