摘要:

SUMMARYA technique for filtering arrays of images of dispersed molecules is presented which takes advantage of the crystallographic properties of regular arrays and the rapidity of optical treatment. A filter in reciprocal space consisting of perforations in a square or rectangular lattice, as determined by the image arrangement, reduces noise and averages the images simultaneously by transmitting only regularly recurring image structure. The filter is universal for all image contents and introduces no additional biases. The signal to noise improvement approaches √NforNindependent images of the same molecule in the same configuration. The procedure, which is simple, rapid and inexpensive, is demonstrated with the aid of dark field electron micrographs of the protein vasopressin and combined with iodination of that molecule to elucidate its structur

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb01139.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYThe methods of quantitative metallography and stereology have been used to determine the distribution of the diameter of equivalent spheres and hence study the change in particle size of titanium carbide undergoing growth/coarsening in a nickel matrix. The distribution obtained, using the Saltykov method, is in agreement with that proposed theoretically by Hanitzsch for the kinetics of growth controlled by an interface reaction. The change in the Smith shape factor shows that growth of titanium carbide is isotropic.This is thus an example of the possibilities offered by stereology. The crystal size distribution in three dimensions is closest to the theoretical models.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb01140.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYMnS and Pb inclusions in some commercial free‐cutting steel bars are of high length‐to‐thickness ratio and are also sinuous in form. Individual inclusions are then not seen in their entirety in metallographically polished longitudinal sections examined in the light or scanning electron microscope. X‐ray microradiography of thinned specimens forms images of inclusions that lie completely within the thickness of the specimen. By using both Co and Fe radiation, MnS, Pb and the steel matrix may all be clearly distin

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb01141.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYReflectances of natural surfaces of fresh graphite peels parallel to the (0001) plane have been measured throughout the visible spectrum using only slightly modified microphotometric equipment and measuring procedures. There is satisfactory agreement between the level and trends of reflectances of graphites from different metamorphic environments throughout the spectrum, the maximum relative difference in the most difficult conditions in the blue region being approximately 4%. There is less good agreement between the dispersion curves of derived refractive and absorptive indices for which the maximum relative difference is as high as 12% in the red region. At 546 nm, the wavelength at which optical data in organic petrology are principally reported, relative errors below 1% for all the optical parameters were attained between samples. Values ofRair= 31.40%,Roil= 17.85%,n= 2.49 andk= 0.61 compare well with other recent estimates and although there is still not complete agreement between laboratories, the true constants for graphite at this wavelength must lie close to these values. The use of semi‐graphites as metamorphic indicators in a scale with graphite as the end‐point is considered, as are the implications on such a scale of the current use of natural surfaces for reflectance measurement, because of an inability of many laboratories to produce specularly polished surfaces of semi‐graphites and graphites of high uniform qu

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb01142.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYCell bodies of cerebral neurons from rabbits were isolated by hand, transferred to a microscope slide in a ‘199’ medium, and the projected areas of their cytoplasm and nuclei were measured. In sixty‐four cells there was a strong correlation between the projected areas of the cytoplasm and the nuclei (r=0.66,P<0001), and the ratio of the projected areas was 11.6. The medium was then replaced by the following fixatives: formalin (10% v/v), Bouin's, Carnoy's, Susas, glutaraldehyde (5% v/v), and osmium tetroxide (1% w/v). Cerebral slices were obtained from the grey and white matter of rabbit and rat, and were also measured before and after treatment with similar fixatives. Relative to the unfixed areas, glutaraldehyde and osmium tetroxide had no significant effect on the projected areas of isolated cells, Carnoy's fixative shrunk the areas of the cytoplasm by means of 16.26%, Bouin's by a mean of 49%, and Susas by a mean of 65%. The shrinkage of the cytoplasm and the nuclei was not significantly different from that of the nuclei for each of these three fixatives individually, but with formalin the mean shrinkage of the cytoplasm was 46% while the nuclei did not shrink significantly.Using the same fixatives the effect on the areas of the cerebral slides from rabbit and rat were as follows: glutaraldehyde and osmium tetroxide caused no change in area; Carnoy's, formalin and Bouin's fixative diminished the areas by a mean of 10–20%, and Susa's by a mean of 35%.It was concluded that a particular fixative often caused a different degree of shrinkage to the cytoplasm, nuclei and cerebral slice. In general, the lower the osmotic pressure of the fixative, the less shrinkage it

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb01143.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYA method is described in which free cells were dehydrated in suspension, put on double‐coated tape attached to a specimen stub and dried from CO2. The method provides a simple, fast means of handling free cells when using the critical point method of dryin

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb01144.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYPIPES, an organic based buffer, was used in the preparation of a variety of marine and mammalian tissues for electron microscopic study. The ultrastructural results demonstrate that this buffer renders superior ultrastructural details to those obtained with some of the more common inorganic buffers especially when long fixation times are required. Furthermore, this buffer system does not appear to contribute extraneous anions or cations to the tissues and thus permits accurate elemental determinations to be performed on thin sections of the plastic embedded specimens by means of energy dispersive X‐ray analysi

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb01145.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYThe feasibility of using an automated image analyser to evaluate quantitatively hyperplasia caused byN‐butyl‐N‐(4‐hydroxybutyl) nitrosamine in bladder epithelium was studied. The number of cells per unit length of epithelium was counted manually, and compared with automated measurements of: (1) the number of nuclei, (2) the number of positive tangents to the lower edge of nuclei, (3) the nuclear cross‐sectional area, and (4) the epithelial cross‐sectional area per unit length respectively. Regression of each of the automated measurements on the manual counts all revealed close linear relationships with correlation coefficients in excess of 0.9. Coefficients of variation for repetitive automated measurements were less than or equal to 0.06 in each of the four modes. The automated system resulted in a great saving in time over manual counting. It is concluded that the automated image analyser provides an accurate, precise, and efficient tool for estimatimg epithelial cell numbers in normal and hyperplastic bladde

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb01146.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

SUMMARYA simple procedure for estimating the depth to which a ribbon of ultra‐thin sections cuts into a block is described. The average section increment is obtained by dividing the depth by the number of sections in the ribbon. Comparison with measurements of individual sections made using interference microscopy suggests: (a) that loss of resin brought about by the cutting process is insignificant, i.e. that the average section increment equals the average section thickness, and (b) that there can be considerable variation in section thickness along a ribbon. Provided that such variation is taken into account, the method based on measurements of the block face is simple, avoids time‐consuming alternative procedures, and is appropriate when seeking to determine the depth dimension to be used in making three‐dimensional reconstructions from long sequences of sec

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb01147.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Book reviewed in this article:Electron Probe Microanalysis. By S. B. J. ReedPractical Methods in Electron Microscopy Vol. 4: Design of the Electron Microscopy Laboratory. By R. H. AldersonPractical Electron Microscopy in Materials Science, Monograph 4: Typical Electron Microscope Investigations. By J. W. EdingtonGolgi Centennial Symposium: Perspectives in Neurobiology. Ed. by M. SantiniFluorescent Protein Tracing, 4th edition. Edited by R. C. NairnThe Optical Microscope in Biology. By S. Bradbury

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1977.tb01148.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY