摘要:

SUMMARYThe increase in viscosity resulting from mixing concentrated solutions of albumin with dilute glutaraldehyde has been investigated. The viscosity changes are slow at first, very sensitive to small changes in glutaraldehyde concentration, and non‐linear with time. The cross‐linking of the albumin by glutaraldehyde seems to be retarded by the weak mechanical shear forces produced by the viscometer. The significance of these findings to the events in tissue fixation is discus

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1992.tb03235.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARYVery large doses of ionizing radiation were delivered quickly to concentrated albumin solutions by pulses of 500 keV in air. The electrons penetrated the aluminium foil bottom of the test cell and into the solution. A dose of 4.6 Mrad (4.6 × 104Gy) produced a gel in the albumin solution comparable to the long‐term effect of 0.36% glutaraldehyde in the same albumin solution. The cross‐links created by the radiation leading to gel formation are probably irreversible and quite different from those leading to gelation in the glutaraldehyde‐albumin reaction. Single large pulses of ionizing radiation may be useful for fast fixation of cells and tissues for micr

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1992.tb03236.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARYThe preparation of frozen‐hydrated samples for scanning electron microscopy to observe symbionts inAzollais described and compared to the conventional method of chemical fixation followed by critical‐point drying. The frozen‐hydrated specimens preserve the structure of the associating symbionts and the liquid phase in theAzollaleaf cavity. The leaf cavity structure and the endosymbionts in the frozen‐hydrated specimens were intact and unharmed throughout the fixation. The cyanobiont cells were distributed along the envelope of the leaf cavity, and did not aggregate around the hair cells, as reported for chemical fixation specimens. The mucilage layer removed by the chemical fixation could be observed in the cryo‐fixation specimens, especially at the lower part of t

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1992.tb03237.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARYA description is given of a simple device, which, when attached to the fine adjustment vernier of a regular light microscope, alerts the operator by sound to the vertical distances travelled by the microscope stage without losing visual contact with the specimen. Depending on whether the depth calibration is deemed to be accurate or not, this device can be used as a practical stereological disector or a selector in routine light microscopy, or as an unbiased brick in confocal microscopy.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1992.tb03238.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARYIt is shown that quantitative light‐element (Z, using X‐ray energy‐dispersive spectroscopy. The extrapolation technique was used to determine the κ‐factors, κOAI= 0.88 ± 0.10 and κNAI= 1.61 ±0.22 at zero thickness. These values are found to be in good agreement with theoretically calculated κ‐factors. The limitations and applicability of the extrapolation technique for light‐element analyses are discussed. An example of light‐element quantification is provided in the analysis of oxygen segregation to inversion domain boundarie

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1992.tb03239.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARYThe method of images is used to calculate the temperature increase produced in a circular film when the film is illuminated at any point by an electron beam of circular cross‐section and constant current density over its cross‐section. Formulae are given in dimensionless form for (i) the temperature increase anywhere along the line joining the centres of the beam and of the film, (ii) the temperature increase at the centre of the beam(vc), and (iii) the position and value of the maximum temperature increase in the filmvm. The relative sizes ofvcandvmare discussed and it is shown that (vm–vc)/vm≤ 0.079. The theory applies best to metallic films where power loss by means of thermal conductivity is dominant. A brief discussion is given of the cases where thermal radiation is important, sample calculations are given for carbon and copper films, and the effect of focusing the electron beam at constant current is con

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1992.tb03240.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARYRecently, joint spatial and spatial‐frequency representations have been used in signal processing of non‐stationary signals due to their natural local property and high joint resolution in both the spatial and spatial‐frequency domain. However, a major obstacle to their implementation is their large computation requirements. This paper presents a fastn‐dimensional Gabor transform and signal reconstruction algorithm employing multi‐level parallel decomposition and fast Fourier transform techniques. The algorithm structure lends itself to implementation using VLSI/ASIC technology. Examples of two‐dimensional Gabor transform and reconstruction performed on a AT computer demonstrate the substantial computational saving that can be achieved using the fast Gabo

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1992.tb03241.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SUMMARYTwo methods of sample preparation, originally developed for transmission electron microscopy and better at preserving bacterial exopolymers than the traditional fixation with glutaraldehyde, were adapted for scanning electron microscopy. The first involves a glutaraldehyde‐lysine mixture as a fixative. The second, based on the use of polycationic ferritin, was modified to include a post‐fixation step with either glutaraldehyde or a glutaraldehyde‐lysine mixture. These techniques were found to improve considerably the preservation of exopolymers secreted by three bacterial st

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1992.tb03242.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1992.tb03243.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY