摘要:

SummaryUsers of analytical electron microscopy lack easy‐to‐use standards for assessing the consistency and quality of analytical performance. We propose using a Cr thin film of known thickness to measure three important characteristics related to performance: the Cr Kα peak‐to‐background (P/B) ratio, the X‐ray spectrometer relative efficiency, and the spectrometer energy resolution. We used a Cr specimen to determine the instrumental factors which influence the P/B ratio, finding that the highest P/B ratios are achieved in scanning transmission mode at the highest available accelerating voltage. We present values of the P/B ratio, and the detector relative efficiency and energy resolution which can be used for comparison in other laboratories using the sta

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb04318.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryThe application of atomic force microscopy (AFM) to photodimerization of crystalline chalcones provides new insights into the detailed mechanisms of solid‐state reactions on the molecular level. Well‐directed long‐range transport phenomena are found which reach far beyond the crystal lattice distances. Reactions occur in the surface region where the light is absorbed. Characteristic features are built up that depend on crystal structure and crystal face. This could not be foreseen by previous theories based solely on a topochemical postulate/principle. There is now a much more intimate correlation of crystal structure with solid‐state reactivity and this is directly studied and proven experimentally by AFM. Even solid‐state reactions which are in opposition to topochemistry can be studied and understood on a molecular basis. The three‐dimensional resolution of undisturbed insulating surfaces which is obtained by AFM is not available by any othe

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb04319.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryRegression methods are used to perform automated image thresholding and colour pixel classification. This is done by considering threshold levels and pixel classification labels as pattern attributes. A regression equation that performs a mapping from theJdimensional feature‐pattern space to theKdimensional attribute space is derived. The approach is non‐parametric and deterministic, hence no assumptions about the statistical properties of the input patterns or images need be made. Initially a known set of input patterns with associated attributes are used to constitute a training set. A mapping function is then determined from the training patterns and used for estimating attribute values from unknown input patterns, such as ima

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb04320.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryThis paper presents a global solution from acquisition to visualization for the three‐dimensional reconstruction of cell sections. Original techniques are proposed for the correct handling of the geometrical section distortions, and a new interpretation based on the logarithmic image processing (LIP) model is applied in order to create normalized grey‐level sections where these are missing. Finally, a new method for generating a mesh of triangles to describe the envelope of the reconstructed cell is proposed, as well as a visualization mixing image synthesis and grey‐level information. The product allows the user to explore the reconstructed cellular block in any desired direction, by showing user‐defined grey‐level sections inside the block mixed to a synthetic view of the cell

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb04321.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryThe fine structure of silkmoth sense hair surfaces has been investigated by freeze etching with Pt/C rotary shadowing. To do this, the hydrophobic layer in the cuticle was removed using 20–25% methanol or ethanol. Freeze‐etch patterns of sense hair surfaces, as well as the pore structure and pore distribution, are shown. The hair surface has a nonhelical ‘band’ structure, in which every ‘band’ lies at an oblique angle with respect to the axis of the hair. Each ‘band’ is separated from its neighbour by a 30‐nm step. The average density of pores is 11·3 + 2·4 pores μm−2. Freeze‐etch patterns of the single and multiple pore tubules are shown. Evidence for direct contact between the pore tubule and dendrite membrane of an olfactory rece

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb04322.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryCalibration standards for quantitative X‐ray microanalysis of resin‐embedded plant tissue were prepared by adding 6600 mM KC1 to 5% agar. Agar blocks with an edge length of 1–2 mm were rapidly frozen, freeze‐dried and embedded in styrene‐methacrylate. Dry sections 1 μm thick were mounted on adhesive‐coated grids. Apart from fine‐scale inhomogeneities caused by ice crystal formation, the KC1 is evenly distributed in the agar blocks. The peak‐to‐continuum values of K and Cl were highly linearly correlated to the K and Cl contents over the whole c

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb04323.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryA simple method for handling individual specimens that must be processed either for scanning or transmission electron microscopy studies is described. For scanning microscope processing, dehydration is carried out with samples enclosed in small cages made from TAAB capsules in which top and bottom are substituted by plankton nets, and for transmission electron microscopy, samples are pre‐embedded in agarose. This procedure significantly reduces mouth pipetting, dissecting microscope observations, is less labour intensive and, most importantly, reduces sample los

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb04324.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryAn electron‐transparent layer of adhesive is used to restrain magnetic particles from being stripped off the support film by the magnetic field of an objective lens in a TE

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb04325.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1994.tb04326.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY