摘要:

AbstractTransmission electron microscopy (TEM) and energy dispersive X‐ray microanalysis (EDS) were used to localize manganese from KMnO4, and bromine, as ultrastructural stains for lignin in an herbaceous plant. The Spookie cultivar of pumpkin is susceptible to infection by the fungusColletotrichum lagenariumand served as a model system to compare the Br and KMnO4techniques. Bromine was used in a fixation/staining procedure, and in separate experiments, KMnO4was used as either a fixative or as a postsection stain. The technique for using bromine was modified from the woody plant procedure by adding a paraformaldehyde prefixation step. With the bromine procedure, cell walls were well‐preserved, but the cytoplasm was heavily extracted. The KMnO4procedures produced well‐fixed cytoplasm, but with some staining artifacts. With all procedures, EDS dot mapping demonstrated lignin deposition in the cell walls specifically associated with sites of fungal infection. Lignin was also localized in secondary walls of tracheary elements, sites known to be highly lignified. The bromine procedure provided the most specific localization of lignin with a minimum of artifact. The specific applications of these stains provided data on the ultrastructural localization of lignin which contributed to the elucidation of its role in the interactions between pathogenic fungi in both their resistant and susceptible plant hosts. © 1992 Wiley‐L

ISSN:1059-910X    

DOI:10.1002/jemt.1070230302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractVacuum‐deposited Te crystals, composed of endless chains of the right‐handed or left‐handed spiral, have been investigated by high‐resolution electron microscopy with the aid of image simulation. A (010) grain boundary, which accompanies edge dislocations having an extra layer of the width of one Te chain, has been observed. A through‐focal series of images reveal that it is not a reflectional nor a rotational twin boundary but a small angle grain boundary in a single crystal or an inversion twin. The lattice on one side of the boundary is shifted from that on the other side by [001]c/3 + [120]a/8, and inclined at 1.1° around thec‐axis of the other side. Also found between crystallites of [100] and [011]orientation is a grain boundary which is built with the (011) facets on one side of the boundary and the (211) or (0,1,10) facets on another side. © 1992 Wi

ISSN:1059-910X    

DOI:10.1002/jemt.1070230303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractMonastral blue (MB) has been described as an inexpensive, nontoxic vascular label. Discrepancies as to its rate of removal from circulation and physiological side effects prompted this study in which retention time of MB in the vascular system and effects of MB upon arterial blood pressure with different anesthetics (halothane, isoflurane, and pentobarbital) were measured in rats. Arterial pressure was monitored during intravenous infusion of MB with or without Evans blue, an albumin label. Localized areas of leakage were created by injecting 30 μL of 10−4M histamine into abdominal dermis at −2, 0, 5, 7, 10, and 15 minutes from infusion of MB. Mean arterial pressure decreased by 25–30% after MB infusion when halothane or isoflurane was used, but not with pentobarbital. Sites which leaked at 10 and 15 minutes did not usefully label with MB, although Evans blue‐labelled albumin appeared in the interstitium. Younger, lighter rats (125–200 vs. 200–250 gm) retained MB longer in circulation, and had a shorter duration of MB‐induced hypotension. Spectrophotometric analysis of rat serum showed rapid elimination of MB from the vascular system, with a half‐life of 3.5 ± 1.9 minutes. While MB remains a useful vascular label, its rapid removal from the circulation and its hypotensive effect must be recognized. © 19

ISSN:1059-910X    

DOI:10.1002/jemt.1070230304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe fine structure of the zona pellucida (ZP) covering the oocyte and of the mucus covering the surface of the intestinal villi was investigated by using a new method employing ruthenium red (RR), saponin, and osmium‐thiocarbohydrazide impregnation.The glycoproteic matrices both appeared constituted by thin filaments (ranging from 22 to 50 nm in thickness) anastomosed to form a very fine network.RR prevented the dissolution and/or alteration of glycoproteins and polyanionic carbohydrates induced by acqueous fixatives. Saponin was a detergent of the soluble proteins. Osmium‐thiocarbohydrazide preserved the glycoproteic matrix filaments from the mechanical stress induced by dehydration and critical point drying and reduced filaments packing and shrinkage. The technical improvement was demonstrated by the following results: 1) a regular arrangement of the filaments network; 2) a thickness of mucus filaments smaller than that obtained with other methods of preparation; 3) a homogeneous thickness of ZP filaments.This method allowed a very detailed study of the fine structural organization of the ZP and intestinal mucus. Therefore, this technique can be useful for a better evaluation of the morphodynamic of these and other glycoproteic matrices. © 1992 Wiley‐Lis

ISSN:1059-910X    

DOI:10.1002/jemt.1070230305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe effects of crystal and beam tilt on high‐resolution transmission electron microscope (HRTEM) images of planar coherent interfaces were investigated by multislice image simulations. It was found that a beam tilt of 0.5 Bragg angle (θB) was sufficient to introduce detrimental artifacts into most images of interfaces in crystals only 1/8ξ000thick, while crystal tilt had a much smaller effect even for crystals 1ξ000thick. Effects produced in HRTEM images of interfaces by crystal and beam tilt included the introduction of additional periodicities and loss of compositional detail across a boundary, translation of a boundary from its actual position, and apparent mismatch of atomic planes across a perfectly coherent interface. These results indicate that alignment of the electron beam parallel to the optic axis is critical for reliable HRTEM imaging of interfaces in materials. Techniques for obtaining accurate alignment are also discussed. © 1992 Wiley‐Li

ISSN:1059-910X    

DOI:10.1002/jemt.1070230306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractAn improved method for the preparation of cross‐sectional thin foils of coated WC‐Co samples for studies by analytical electron microscopy is described. A braze alloy is used to join the sections of the sample together and the resulting sample is stable during subsequent grinding, dimpling, and milling operations. Cross‐sectional micrographs provide examples of the efficacy of this method. No microstructural alteration associated with the brazing operation was observed. © 1992 Wiley‐L

ISSN:1059-910X    

DOI:10.1002/jemt.1070230307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractExperimental d‐spacing values are criteria towards the identification of crystallites by electron diffraction. Conclusive identifications often rely on accurate d‐spacings. It is shown here that accurate orthogonal components (in mm) for the primitive unit vectors of a zero‐level diffraction pattern can be obtained through least‐squares processing of (x,y) coordinates for all spots on the film. Valid vectors hom the origin spot to any spot in the plane of the film are integer linear combinations of the two selected unit vectors. Accurate lengths and standard deviations for such vectors therefore can be calculated from the least‐squares results. Corresponding d‐spacings can then be calculated from the vector lengths on the film and the camera constant. In order to obtain d‐spacing values that are not only precise, but also accurate, an accurate value of the camera constant should be used. This requires calibration of the experimental setup with reference materials in the same experimental conditions, with careful control of the sample height. For the same quality of measurements, the improvement in the accuracy of the d‐spacings obtained with the proposed method is approximately proportional to the square root of the number of measurements taken. Practically, typical improvement in accuracy is about threefold, and accuracies of a fraction of a percent in d‐spacings are achievable in this way. The above approach has been programmed as an option in the NRCBED program. © 19

ISSN:1059-910X    

DOI:10.1002/jemt.1070230308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe technique which is described combines the advantages of the techniques formerly proposed in the literature in each stage of the preparation of transmission electron microscopy (TEM) specimens including a single metal‐ceramic interface. It allows easy handling of the thin foils in spite of their brittleness. Preferential thinning of the softer material in the two‐phase foil is prevented, and both sides of the interface are thinned down to comparable thicknesses. The nickel‐alumina bicrystal interface observed in TEM is neat and free from any reaction layer. This method is easily adaptable to other metal‐ceramic systems. © 1992 Wiley

ISSN:1059-910X    

DOI:10.1002/jemt.1070230309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractPhotochemical etching (PCE) as a method for preparation of InP semiconductor plan view samples for the transmission electron microscope is demonstrated and compared to the methods of ion milling and chemical thinning. PCE can produce small area samples for TEM analysis quickly and accurately. Also, the resulting thin regions are surrounded by a built‐in stabilizing structure that improves handleability and reduces the occurrence of handling induced fracture. © 1992 Wiley‐Liss,

ISSN:1059-910X    

DOI:10.1002/jemt.1070230310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:1059-910X    

DOI:10.1002/jemt.1070230311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY