摘要:

SUMMARYConsiderable strides have been made in the application of the cathodoluminescent and beam‐induced current modes of operation of the scanning electron microscope to the high resolution characterization of semiconductor materials. These techniques can be used to measure parameters such as resistivity, carrier concentration, mobility, composition, diffusion length, minority carrier lifetime, luminescence efficiency, dislocation density and temperature from regions of semiconductors as small as one micron across. The theoretical and experimental factors which limit the range of values over which measurements are possible and the accuracy attainable are discussed in detail. Each technique is illustrated by recent experimental result

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb00032.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYThe modulation contrast microscope produces an image of high contrast and resolution. The image has a three‐dimensional appearance wherein a rounded object appears dark on one side, bright on the other with grey in between against a grey background. The performance features are optical sectioning, directionality, high resolution and control of contrast and coherence. A bright field microscope is converted to the modulation contrast microscope by adding the modulator, a special amplitude filter, in the objective. A slit aperture part of which is polarized is placed before the condenser. Below this is a rotatable polarizer. The modulator processes light from opposite gradients oppositely, that is brighter for one and darker for the other; thereby preserving the sign. The diffraction theory has been extended to show that gradient image intensity is the intensity of the zero order and when modified by the modulator creates a high contrast image.The modulation contrast microscope is simple and easy to adjust. It is useful in reflected and transmitted light systems, with plastic and glass vessels as well as in combination with fluorescence systems and polarization techniques. There is virtually no limit to the type of specimen that can be studie

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb00033.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYThe solid states formed by vitrified and frozen aqueous solutions of some hydrophilic polymers, able to act as biological cryoproteetants, have been studied by differential scanning calorimetry and freeze fracture electron microscopy. Glass transitions, devitrification, recrystallization and melting behaviour of aqueous solutions of polyvinylpyrrolidone, hydroxyethyl starch and dextran have been established. The vitrified polymer solutions exhibit a characteristic microspherical morphology which is not induced by the quench cooling process but is an inherent feature of the solutions themselves.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb00034.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYA study has been made of the physiological effects of three non‐penetrating polymeric cryoprotective agents on sixteen different plant and animal cells and tissues. The cryoproteetants, when used at concentrations at which they are effective in preventing ice‐crystal formation, generally have a lower toxicity to cells and tissue than similar concentrations of glycerol. The relatively low toxicity of these substances suggests that they would be more suitable as cryoproteetants for morphological and analytical studies than the commonly used low molecular weight compou

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb00035.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYTwo high molecular weight polymers, polyvinylpyrrolidone (PVP) and hydroxyethyl starch (HES), have been used as cryoproteetants for preparing specimens to be freeze fractured. Solutions of 25% (w/w) suppress the formation of intracellular ice in single cells and tissue blocks from both plants and animals to the extent that fine structural details of the cell can be elucidated. The mode of action of these cryoproteetants, together with the structures they reveal and the peculiar advantages attached to their use, is discussed.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb00036.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYAs part of a larger project aimed at clarifying some of the uncertainties that exist concerning the structural basis for an explanation of the mechanical behaviour of elastin, an examination was made of purified porcine aortic elastin under the scanning electron microscope. In order to avoid structural changes caused by impregnation with organic solvents, specimens were prepared directly from their water‐saturated state by either air‐drying or freeze‐drying processes. Comparison of the results obtained by these techniques demonstrates that freeze‐drying of elastin has the advantage of enhancing fine detail, minimizing distortion and reducing specimen sh

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb00037.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYUltrathin sections of unfixed kidney tubular cells were obtained by cryo‐ultramicrotomy using the ‘wet’ method. The results showed that extremely thin sections permit high resolution studies on unfixed plasma membranes. Structural units on the inner surface of the plasma membrane could be det

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb00038.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYThis note describes how damaged Philips electron microscope specimen holders may be repaired simply and cheaply. The damaged part is replaced by a length of 18‐gauge syringe needle which is silver‐soldered into position. This simple and rapid repair caused no subsequent electrical distort

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb00039.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb00040.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY