摘要:

SummaryA combination of molecular modelling and atomic force microscopy (AFM) techniques was used to study the surface structure of crystalline cellulose. Two‐dimensional Fourier analysis of the AFM raw data gave crystal parameters as well as a highly filtered inverse‐transformed image. Molecular modelling was used to generate Connolly surfaces based on electron diffraction data for crystalline cellulose. The modelled surfaces were used to interpret the experimental AFM images. Monoclinic () crystal faces were identified. The method used enables the structural analysis of cellulose surfaces at the molecular level, where all biological processes involving cellulose take pl

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1995.tb03573.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryThe image contrast mechanism of three newly proposed AC mode operations under liquid in three different frequency ranges is presented. They all rely on a strong repulsive force to damp the cantilever and the tip still ‘touches’ the sample surface. A direct comparison of the three different modes of operation with the conventional DC mode technique using the same gold sample under isopropanol was conducted. It was found that all the three AC modes exerted a much smaller lateral force than the DC mode although the normal loads were of the same order of magnitude. The suitability of such techniques in imaging physisorbed systems on hard substrates (such as soft biological samples) and the prospect of a true non‐contact repulsive mode operation are disc

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1995.tb03574.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryA new microscope system that has the combined capabilities of a scanning near‐field optical microscope (SNOM) and a scanning tunnelling microscope (STM) is described. This is achieved with the use of a single metallic probe tip. The distance between the probe tip and the sample surface is regulated by keeping the tunnelling current constant. In this mode of operation, information about the optical properties of the sample, such as its refractive index distribution and absorption characteristics, can be disassociated from the information describing its surface structure. Details of the surface structure can be studied at resolutions smaller than the illumination wavelength. The performance of the microscope is evaluated by analysing a grating sample that was made by coating a glass substrate with gold. The results are then compared with the corresponding SNOM and STM images of the gratin

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1995.tb03575.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryThree‐dimensional maps of cellular metabolic oxidation/reduction states of rabbit corneain situwere obtained by imaging the fluorescence of the naturally occurring reduced pyridine nucleotides (both reduced nicotinamide‐adenine dinucleotide, NADH, and reduced nicotinamide‐adenine dinucleotide phosphate, NADPH, denoted here as NAD(P)H). Autofluorescence images with submicrometre lateral resolution were obtained throughout the entire 400 μm thickness of the cornea. Two‐photon excitation scanning laser microscopy with near‐infrared excitation provided high fluorescence collection efficiency, reduced photodamage, and eliminated ultraviolet chromatic aberration, all of which have previously degraded the visualization of pyridine nucleotide fluorescence. Sharp autofluorescence images of the basal epithelium (40 μm within the cornea) show substantial subcellular detail, providing the ability to monitor autofluorescence intensity changes over time, which reflect changes in oxidative metabolism and cellular dynamics necessary for maintenance of the ocular surface. The autofluorescence was confirmed to be mostly of NAD(P)H origin by cyanide exposure, which increased the fluorescence from all cell types in the cornea by about a factor of two. Autofluorescence images of individual keratocytes in the stroma were observed only after cyanide treatment, while in the predominant extracellular collagen (>90% of the stromal volume), fluorescence was not distinguished from the background. Observation of keratocyte metabolism demonstrates the sensitivity made available by two‐photon microscopy for future redox fluorescence imaging of cellular met

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1995.tb03576.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryThe design of a scanned‐cantilever‐type force microscope is presented which is fully integrated into an inverted high‐resolution video‐enhanced light microscope. This set‐up allows us to acquire thin optical sections in differential interference contrast (DIC) or polarization while the force microscope is in place. Such a hybrid microscope provides a unique platform to study how cell surface properties determine, or are affected by, the three‐dimensional dynamic organization inside the living cell.The hybrid microscope presented in this paper has proven reliable and versatile for biological applications. It is the only instrument that can image a specimen by force microscopy and high‐power DIC without having either to translate the specimen or to remove the force microscope. Adaptation of the design features could greatly enhance the suitability of other force microscopes for bi

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1995.tb03577.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryThe initial results of the first dedicated confocal scanning laser microscopy (CSLM) study of fluid inclusions in quartz are presented. CSLM imaging of a large inclusion shows the quartz crystal to contain numerous small (10 μm) occur where two planes of small inclusions intersect, and that the shape of the large inclusions is controlled by the angular relationship between intersecting plane

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1995.tb03578.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryScanning tunnelling microscopy (STM) images of Pt/Ir‐ and Pt/Ir/C‐coated cell plugs ofMethanospirillum hungateishowed paracrystalline structures with P6 symmetry and an 18‐nm lattice constant, in agreement with electron microscopy studies. The three‐dimensional STM images unambiguously distinguished the two morphologically different proteinaceous plug assemblies and led to an improved understanding of the natural internal organization of whole plugs. Tip convolution effects and the grain size of the metal coating complicated interpretation of finer structures. We discuss possible imaging mechanisms to explain observations in which part of the film was removed but the remaining part of the structure was still imaged repro

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1995.tb03579.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryElectron probe microanalysis (EPMA) is a powerful method for the quantitative determination of the elemental composition of micro‐regions of a sample surface. Here, we report on the development of a method of reconstructing compositional depth profiles in thin films from EPMA data measured over a range of electron beam energies, using maximum entropy data processing. The method gives quantitative information on film compositions up to approximately 1 μm in depth, with a lateral spatial resolution of approximately 1 μm. The method is tested using both simulated data and measured experimental data from well‐characterized model sample struc

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1995.tb03580.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryA modification to the knife mounting of a histological microtome is described which can sense the load on the knife when a section is being cut. The performance of this microtome is described in general terms. The variation in force on the knife can be used to give information about the texture of the sample being cut.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1995.tb03581.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryThird toe phalanges of chicks aged 8–13 days in ovo and 7‐day post‐natal rat femoral growth plate were examined to determine whether the interlacunar network (IN), a structure with no lipoprotein membrane component or cytoplasmic organelles, is a genuine component of young growth cartilage. In chick phalanges dehydrated by 70% (v/v) ethanol and LR White resin, variable metachromatic staining of the interlacunar network by toluidine blue and red staining by picro‐Sirius red indicate the presence of glycosaminoglycans and collagen. The network in phalanges dehydrated by 80% (v/v) ethanol appears little different; however, the network is much less widely detectable in phalanges dehydrated by 90% (v/v) ethanol and, after dehydration by absolute ethanol, is almost completely undetectable. In contrast, when the young cartilage is permeated by a thiazine dye such as toluidine blue, using a solution of dye in the aldehyde fixative, the network is widely detectable, following dehydration by absolute ethanol, both in chick phalanges and in rat growth plate. Comparison of projected areas shows that the extent to which whole chick feet are found to have shrunk, by the time that they are photographed under LR White resin, is determined principally by the extent of dehydration, by 70% (v/v) or absolute ethanol; post‐shrinkage areas are 33% or 35% of areas measured in buffer for 70% (v/v) ethanol/LR White resin and 71% or 75% for absolute ethanol/LR White resin (the higher value in each is for the toluidine blue treatment). The network is thus present in radically shrunk tissue, but, significantly, is also fully represented in tissue shrunk by only a conventional margin and is therefore not produced as an artefact by exceptional tissue shrinkage as has been

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1995.tb03582.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY