bluuebunny/crossref_metadata_2025 huggingface dataset:
Smoking and relation to other risk factors in postmenopausal women with coronary artery disease, with particular reference to whole blood viscosity and β‐cell function
Authors: Os I. , Høieggen A. , Larsen A. , Sandset P. M. , Djurovic S. , Berg K. , Os A. , Birkeland K. , Westheim A.
Published: March 2003

Abstract.  Os I, Høieggen A, Larsen A, Sandset PM, Djurovic S, Berg K, Os A, Birkeland K, Westheim A (University of Oslo; Ulleval University Hospital; and Aker University Hospital, Oslo, Norway). Smoking and relation to other risk factors in postmenopausal women with coronary artery disease, with particular reference to whole blood viscosity and β‐cell function. J Intern Med 2003; 253: 232–239.

Objectives.  To investigate possible associations between smoking habits and other coronary risk factors in postmenopausal women with known coronary heart disease (CHD).

Setting.  The study was conducted at a university clinic.

Subjects.  A total of 118 postmenopausal women with CHD verified with angiography, consecutively recruited.

Interventions.  Conventional treatment for CHD. The women were randomized to hormone replacement therapy (HRT) with transdermal 17‐β oestradiol and medroxyprogesterone acetate, or to a control group.

Results.  Smokers were younger (P = 0.005), had lower body mass index (P = 0.04) and lipoprotein Lp(a) levels (P = 0.02) compared with nonsmokers. Smokers had reduced β‐cell function (homeostasis model assessment, P = 0.006), whereas whole blood viscosity (WBV) was higher at all shear rates. WBV was not affected by HRT over a 12‐month period. Oestrone levels were higher in smokers.

Conclusions.  Smoking adversely affects insulin secretion (β‐cell function) and WBV in postmenopausal women with established CHD, which could be of importance as a mechanism for the increased risk of CHD in smokers. The importance of smoking as a risk factor, overrides the effect of Lp(a), which is lower in smokers compared with nonsmokers.
Electron microscopy of interfaces in a wollastonite — tricalcium phosphate bioeutectic®
Authors: DE Aza  , Luklinska  , Anseau  , Guitian  , DE Aza
Published: March 2003

The study investigated the morphology and structure of interfaces between a pseudowollastonite (psW) and α‐tricalcium phosphate (α‐TCP) eutectic ceramic material (Bioeutectic®) obtained by slow solidification (0.5 °C h−1) through the eutectic temperature region (1402 ± 3 °C) of the binary system.

The eutectic material contained 60 wt% psW and 40 wt% α‐TCP and was composed of spherical colonies formed by alternating radial lamellae of psW and α‐TCP phases. Small quantities of impurities were found to affect the microstructure and ultrastructure of adjacent colonies. The observations showed the presence of dislocation loops and dislocation pairs in the psW phase away from the interfaces with α‐TCP. The α‐TCP phase remained defect‐free. Two types of interface were identified between the triclinic high‐temperature form of wollastonite (psW) and orthorhombic α‐TCP.

In single colonies, the phases were aligned with [011¯]psW and [001¯] α‐TCP. High‐resolution electron microscopy revealed differences in morphologies between the two interfaces, and showed that the lattice planes in the interfaces were defect‐free.
Reconstruction and display of curvilinear objects from optical section data using 3‐D curve fitting algorithms
Authors: Shelden  , Knecht
Published: March 2003

Biological objects resembling filaments are often highly elongated while presenting a small cross‐sectional area. Examination of such objects requires acquisition of images from regions large enough to contain entire objects, but at sufficiently high resolution to resolve individual filaments. These requirements complicate the application of conventional optical sectioning and volume reconstruction techniques. For example, objective lenses used to acquire images of entire filaments or filament networks may lack sufficient depth (Z) resolution to localize filament cross‐sections along the optical axis. Because volume reconstruction techniques consider only the information represented by a single volume element (voxel), views of filament networks reconstructed from images obtained at low Z‐resolution will not accurately represent filament morphology. A possible solution to these problems is to simultaneously utilize all available information on the path of an object by fitting 3‐D curves through data points localized in 2‐D images. Here, we present an application of this approach to the reconstruction of microtubule networks from 2‐D optical sections obtained using confocal microscopy, and to synthesized curves which have been distorted using a simple mathematical model of optical sectioning artefacts. Our results demonstrate that this strategy can produce high resolution 3‐D views of filamentous objects from a small number of optical sections.
Fabrication of a Cr thin‐film AEM characterization standard
Authors: Repa K.A. , Williams D.B.
Published: March 2003

The need for an analytical electron microscope (AEM) characterization standard capable of determining the consistency and relative quality of analytical performance has become increasingly evident as advances in the instrumentation are made. In this paper the fabrication of a Cr thin‐film AEM standard by conventional thermal evaporation techniques is described. A 100‐nm‐thick Cr film on a 20‐nm C‐support film provided by the National Institute of Standards and Technology (NIST) served as a model against which the present film was evaluated. Improvements over the NIST film in terms of diffraction pattern clarity and simplification of parallel electron energy‐loss spectrometry (PEELS) analysis were achieved by removal of the C‐support film and the creation of a self‐supported Cr (SS‐Cr) film. Qualitative grain‐size comparisons between the NIST model and the SS‐Cr films made by scanning transmission electron microscopy found the SS‐Cr films to have a slightly larger grain size. Thickness measurements were verified by X‐ray energy dispersive spectrometry, PEELS and field‐emission gun scanning electron microscopy. SS‐Cr film standard specimens are available for use by the AEM community, by contacting the authors directly.
Reliability of atom column positions in a ternary system determined by quantitative high‐resolution transmission electron microscopy
Authors: Kienzle O. , Ernst F. , Möbus G.
Published: March 2003

Employing an iterative structure refinement procedure, we have determined the atomistic structure of the Σ3 (111) grain boundary in strontium titanate (SrTiO3) from high‐resolution transmission electron microscopy (HRTEM) images. This grain boundary serves as a model system to study the effect of column occupancies on the reliability of the column positions. In this paper we introduce a method to derive confidence regions for the positions of individual atom columns at crystal defects. Based on a statistical approach we first determine the reliabilities of different types of atom columns in regions of unfaulted crystal. Next we extrapolate these reliabilities to obtain the reliabilities of individual atom columns at the grain boundary. The method accounts correctly for random errors and promises to be generally applicable provided that repetitive units of unfaulted crystal structure are contained in the HRTEM image. Under the conditions of the present study, the reliability of a column position correlates with the projected electrostatic potential of the column. Accordingly, the reliabilities of the column positions at the boundary vary with the column type: 0.008 nm for Sr–O columns, 0.014 nm for Ti columns, and 0.018 nm for O–O columns.
Crystal structure determination by direct inversion of dynamical microdiffraction patterns
Authors: Spence J. C. H.
Published: March 2003

The intensity at points where coherent convergent‐beam transmission diffraction discs overlap is shown to be described by interference between elements of the same row but different columns of the dynamical scattering matrix for an axial orientation. These intensities are used as the basis for an exact, nonperturbative inversion of the multiple electron scattering problem, allowing crystal structure factors to be obtained directly from the intensities of multiply scattered Bragg beams. Eigenvectors of the structure matrix are obtained using coherent CBED patterns from many crystal orientations. Unique eigenvalues are obtained from these patterns recorded at two accelerating voltages. The inevitable variation in electron probe position at different crystal tilts is considered. The analysis applies to centrosymmetric crystals with anomalous absorption, to centrosymmetric projections of acentric crystals and to acentric crystals if the mean absorption potential only is included. The method would allow the direct synthesis of charge‐density maps of unknown crystal structures at high resolution from multiple scattering data, using a scanning transmission electron microscope (STEM). The resolution of this map may be much higher than the first‐order d‐spacing; however, the STEM need only be capable of resolving this first‐order spacing. Such a charge‐density map provides fractional atomic coordinates and the identification of atomic species (as in X‐ray crystallography) from microcrystalline samples and other multiphase inorganic materials for which large single crystals cannot be obtained or X‐ray powder patterns obtained or analysed. In summary, we solve the inversion problem of quantum mechanics for the case of electron scattering from a periodic potential, described by the nonrelativistic Schrödinger equation, in which the scattering is given as a function of some parameter, and the potential sought.
Quantitative atomic structure determination from HREM: viewpoints on accuracy and reliability
Authors: Van Dyck D.
Published: March 2003

The state of the art of atomic structure determination from HREM is discussed in the framework of parameter estimation. The role of direct holographic methods is to yield a starting structure for further quantitative refinement. The reason for the quantitative mismatch between theoretical and experimental images is discussed and an improved algorithm is suggested to speed up the calculations.
A new 200 kV Ω‐filter electron microscope
Authors: TANAKA  , TSUDA  , TERAUCHI  , TSUNO  , KANEYAMA  , HONDA  , ISHIDA
Published: March 2003

A new 200 kV Ω‐filter electron microscope was developed under a project supported by a Grant‐in‐Aid for Specially Promoted Research of the Ministry of Education, Science, Sports and Culture of Japan. The performance of the microscope is described.
Quantitative electron spectroscopic imaging studies of microelectronic metallization layers
Authors: MARIEN  , PLITZKO  , SPOLENAK  , KELLER  , MAYER
Published: March 2003

The combination of focused ion beam (FIB) sample preparation and quantitative electron spectroscopic imaging is an ideal tool for the investigation of layered structures used in microelectronic metallization schemes. In the present work, Si3N4/Cu/Si3N4/SiO2/Si and Al/TiN/Ti/SiO2/Si metallization layers produced by physical vapour deposition are investigated. We apply series of energy filtered images in the low loss region for a mapping of the sample thickness which makes it possible to refine the parameters of the FIB process. We also show how series of energy filtered images in the core loss region can be used to obtain elemental distribution images and chemical bonding information on these samples on a nanometre scale. For materials with a small grain size and/or a strong variation in Bragg orientation, the intensity distribution of the elemental map is strongly influenced by the superimposed Bragg contrast. This detrimental effect can be reduced greatly by using hollow cone illumination, as is demonstrated for polycrystalline Cu. One striking feature observed in Cu layers prepared with FIB is strong, regularly arranged contrast variations caused by subsurface defects in the Cu grains. We suppose that these defects are a consequence of a strong interaction of Ga atoms from the FIB with Cu.
Direct versus iterative structure retrieval for a Cu/Ti misfit dislocation: a comparison of various 1Å HREM technologies
Authors: MÖBUS  , WAGNER
Published: March 2003

Using an interface between Cu/Ti as an example, two HREM‐based image analysis techniques, strain mapping and iterative digital image matching, are compared. The validity limit of these techniques is discussed as a function of specimen thickness and microscope technology. Two criteria are used to assess the limits: (i) the difference between two geometric phase maps, one calculated in image plane and one in object plane, and (ii) a difference image from two HREM simulations of two structure models differing in one atomic column. The latter displays the overall delocalisation of information by the microscope due to diffraction and imaging. It is outlined how far images and strain maps, obtained for high‐voltage microscopy at 1250 kV and CS correction at 200 kV, are identical. Both techniques exhibit a significantly increased regime of applicability of strain mapping near defect cores. Simulations for a 400 kV HREM and a 300 kV FEGTEM with and without focal series reconstruction complement the study.
A method for characterizing longitudinal chromatic aberration of microscope objectives using a confocal optical system
Authors: Juškaitis  , Wilson
Published: March 2003

We describe a novel method of characterizing the longitudinal chromatic aberration of microscope objectives by recording a series of axial responses as a function of wavelength as a plane reflector is scanned through the focal region of a confocal microscope. Measurements are presented for a variety of objectives with differing degrees of correction. The use of the chromatic focal shift to measure surface profiles is also discussed.
Plasmon transmissivity and reflectivity of narrow grooves in a silver film
Authors: Bouhelier A. , Huser TH. , Freyland J. M. , Güntherodt H.‐J. , Pohl D. W.
Published: March 2003

Surface plasmon (SP) reflectivity and transmissivity of narrow grooves in silver films are studied. The SP source is the probe of a scanning near‐field optical microscope. Locally detected leakage radiation from the SP provides detailed information on the paths of SP propagation, in particular the influence of perturbations. Global detection provides representative average data on the SP properties of a given metal film and its structures. A groove of 200 nm width, for instance, reflects/transmits about 15%/80% of ‘blue–green’ SP radiation at normal incidence.
Spectroscopy with scanning near‐field optical microscopy using photon tunnelling mode
Authors: Takahashi S. , Futamata M. , Kojima I.
Published: March 2003

We have demonstrated Raman spectroscopy using scanning near‐field optical microscopy (SNOM). Photon tunnelling mode was employed, in which the sample is illuminated using an attenuated total reflection (ATR) configuration and the evanescent wave perturbed by the sample is picked up by a sharpened optical fibre probe. By this experimental arrangement Raman scattering from the optical fibre probe was greatly reduced, therefore we were able to excite the sample using more intense laser light compared to the illumination mode SNOM. Raman spectra of copper phthalocyanine (CuPc) were obtained in the off‐resonance condition and without using surface‐enhanced Raman scattering (SERS).
Spectrally resolved cathodoluminescence analyses in the optical near‐field
Authors: Cramer R. M. , Sergeev O. V. , Heiderhoff R. , Balk L. J.
Published: March 2003

By implementing a scanning near‐field optical microscope into the specimen chamber of a scanning electron microscope, cathodoluminescence can be locally detected in the optical near‐field. The achievable spatial resolution in this set‐up is only limited by the size of the aperture in a coated fibre probe and its separation from the sample, rather than by the energy dissipation volume of the primary electrons and diffusion processes of excess carriers inside the specimen. We demonstrate how electronically active defects in polycrystalline diamond can be distinguished and localized with sub‐wavelength lateral resolution by spectral filtering of the cathodoluminescence signal.
Study of dislocation structures near fatigue cracks using electron channelling contrast imaging technique (ECCI)
Authors: AHMED J. , WILKINSON A. J. , ROBERTS S. G.
Published: March 2003

The fatigue of copper single crystals, orientated for single slip, has been studied using electron channelling contrast imaging in a scanning electron microscope. With the incident beam set at the Bragg condition, changes in the backscattered electron intensity occur as the beam is scanned over dislocations that cause a local tilting of the diffraction planes. This technique allows the evolution of dislocation structures over large areas to be followed through different stages of the fatigue life. Furthermore, it enables direct imaging of dislocation configurations at crack tips. The technique is compared with transmission electron microscopy and electron backscatter diffraction in its application to fatigue studies.
Backscattered electron imaging of titanium dioxide in frozen hydrated preparations
Authors: Hallegot
Published: March 2003

Backscattered electron (BSE) imaging was used to study ultrafine TiO2 crystals distribution in a test cream. The cream was fast frozen, cryofractured and observed uncoated at low temperature. The BSE detector was a microchannel plate. The results demonstrate that up‐to‐date photoprotective preparations can be investigated by this technique.
Transmission electron microscopy of interfaces in structural ceramic composites
Authors: Knowles  , Turan  , Kumar  , Chen  , Clegg
Published: March 2003

Ceramic composites based either on a particulate, fibre or a lamellar architecture are potentially useful as damage‐tolerant high‐temperature engineering materials. The ability of the interfaces in such systems to deflect cracks is vital to the damage tolerance of these materials. Transmission electron microscopy techniques enable the chemical and physical characterization of these interfaces, providing information on interlayer thicknesses, chemical species, local bonding and the microstructural features which give rise to the interfacial properties, thereby enabling a full understanding not only of composites after processing, but also after exposure to aggressive environments such as air at high temperature. Examples of the application of transmission electron microscopy to all three composite architectures are described.
Effect of SiC reinforcement on the deformation and fracture micromechanisms of Al–Li alloys
Authors: Poza  , Llorca
Published: March 2003

The effect of SiC reinforcement on the microstructure of a naturally aged 8090 Al alloy as well as on the deformation and fracture micromechanisms was investigated. To this end, the microstructural characteristics (grain and reinforcement morphology, precipitate structure) were determined in the unreinforced alloy and in the composite reinforced with 15 vol.% SiC particles. The materials were tested under monotonic tension and fully reversed cyclic deformation and then carefully analysed through scanning and transmission electron microscopy to find the dominant deformation and failure processes for each material and loading condition. It was found that the dispersion of the SiC particles restrained the formation of elongated grains during extrusion and inhibited the precipitation of Al3Li. As a result, the plastic deformation in the composite was homogeneous, while strain localization in slip bands was observed in the unreinforced alloy specimens tested in tension and in fatigue. The unreinforced alloy failed by transgranular shear along the slip bands during monotonic deformation, whereas fracture was initiated by grain boundary delamination, promoted by the stress concentrations induced by the slip bands, during cyclic deformation. The fracture of the composite was precipitated by the progressive fracture of the SiC reinforcements during monotonic and cyclic deformation.
Multiple frequency fluorescence lifetime imaging microscopy
Authors: Squire  , Verveer  , Bastiaens
Published: March 2003

The experimental configuration and the computational algorithms for performing multiple frequency fluorescence lifetime imaging microscopy (mfFLIM) are described. The mfFLIM experimental set‐up enables the simultaneous homodyne detection of fluorescence emission modulated at a set of harmonic frequencies. This was achieved in practice by using monochromatic laser light as an excitation source modulated at a harmonic set of frequencies. A minimum of four frequencies were obtained by the use of two standing wave acousto‐optic modulators placed in series. Homodyne detection at each of these frequencies was performed simultaneously by mixing with matching harmonics present in the gain characteristics of a microchannel plate (MCP) image intensifier. These harmonics arise as a natural consequence of applying a high frequency sinusoidal voltage to the photocathode of the device, which switches the flow of photoelectrons ‘on’ and ‘off’ as the sinus voltage swings from negative to positive. By changing the bias of the sinus it was possible to control the duration of the ‘on’ state of the intensifier relative to its ‘off’ state, enabling the amplitude of the higher harmonic content in the gain to be controlled. Relative modulation depths of 400% are theoretically possible from this form of square‐pulse modulation. A phase‐dependent integrated image is formed by the sum of the mixed frequencies on the phosphor of the MCP. Sampling this signal over a full period of the fundamental harmonic enables each harmonic to be resolved, provided that the Nyquist sampling criterion is satisfied for the highest harmonic component in the signal. At each frequency both the phase and modulation parameters can be estimated from a Fourier analysis of the data. These parameters enable the fractional populations and fluorescence lifetimes of individual components of a complex fluorescence decay to be resolved on a pixel‐by‐pixel basis using a non‐linear fit to the dispersion relationships. The fitting algorithms were tested on a simulated data set and were successful in disentangling two populations having 1 ns and 4 ns fluorescence lifetimes. Spatial invariance of the lifetimes was exploited to improve the accuracy significantly. Multiple frequency fluorescence lifetime imaging microscopy was then successfully applied to resolve the fluorescence lifetimes and fluorescence intensity contributions in a rhodamine dye mixture in solution, and green fluorescent protein variants co‐expressed in live cells.
Microcalorimeter energy‐dispersive spectrometry using a low voltage scanning electron microscope
Authors: Wollman D. A. , Nam S. W. , Hilton G. C. , Irwin K. D. , Bergren N. F. , Rudman D. A. , Martinis J. M. , Newbury D. E.
Published: March 2003

We describe the current performance of the prototype microcalorimeter energy‐dispersive spectrometer (µcal EDS) developed at NIST for X‐ray microanalysis. We show that the low‐energy µcal EDS, designed for operation in the energy range 0.2–2 keV, offers significant advantages for low‐beam‐energy microanalysis. We present several examples in which the prototype µcal EDS has been used to solve problems in low‐voltage microanalysis, including the analysis of tungsten silicide (WSi2), titanium nitride (TiN) and barium titanate (BaTiO3) and the measurement of chemical shifts in Fe and C compounds.
Peculiarities of imaging one‐ and two‐dimensional structures in an emission electron microscope. 1. Theory
Authors: Nepijko S. A. , Sedov N. N. , Ziethen CH. , Schönhense G. , Merkel M. , Escher M.
Published: March 2003

Local changes in work function cause deviations of the electrical microfield near a sample surface as a result of the uniform accelerating field distribution between the sample (cathode) and the extractor electrode (anode). This results in a change in the electron trajectories. As a consequence, the microscope image shows remarkable changes in position, size, intensity and lateral resolution of distinct details, which can be quantitatively described by the calculations presented here. Analysing these effects in the image gives an opportunity to determine the real lateral size of the observed structures and the distribution of local contact potentials.
Strategies for the compensation of specimen‐induced spherical aberration in confocal microscopy of skin
Authors: Booth M. J. , Wilson T.
Published: March 2003

We consider various strategies for confocal imaging of human skin which seek to reduce the effects of the specimen‐induced aberrations. We calculate the spherical aberration introduced by the stratified structure of skin and show how the confocal signal is affected when attempting to image at various depths within the dermis. Using simple methods it is shown how images might be improved by compensating for the induced aberration. The methods include the use of an iris to reduce the pupil area, changing the refractive index of the immersion medium and using a lens with variable coverglass correction.
Blind deconvolution of 3D transmitted light brightfield micrographs
Authors: Holmes T. J. , O'connor N. J.
Published: March 2003

The blind deconvolution algorithm for 3D transmitted light brightfield (TLB) microscopy, published previously (Holmes et al.Handbook of Biological Confocal Microscopy (1995), is summarized with example images. The main emphasis of this paper is to discuss more thoroughly the importance and usefulness of this method and to provide more detailed evidence, some being quantitative, of its necessity. Samples of horseradish peroxidase (HRP)‐stained pyramidal neurones were prepared and evaluated for the ability to see fine structures clearly, including the dendrites and spines. It is demonstrated that the appearance of fine spine structure, and means of identifying spine categories, is made possible by using blind deconvolution. A comparison of images of the same sample from reflected light confocal microscopy, which is the conventional light microscopic way of viewing the 3D structure of these HRP‐stained samples, shows that the blind deconvolution method is far superior for clearly showing the structure with less distortion and better resolution of the spines. The main significance of this research is that it is now possible to obtain clear images of 3D structure by light microscopy of absorbing stains. This is important because the TLB microscope is probably the most widely used modality in the life‐science laboratory, yet, until now, there has been no reliable means for it to provide visualization of 3D structure clearly. The main importance of the blind deconvolution approach is that it obviates the need to measure the point spread function of the optical system, so that it now becomes realistic to provide a 3D light microscopic deconvolution method that can be pervasively used by microscopists.
Low temperature near‐field luminescence studies of localized and delocalized excitons in quantum wires
Authors: Intonti F. , Emiliani V. , Lienau C. , Elsaesser T. , Nötzel R. , Ploog K. H.
Published: March 2003

Excitons in a GaAs quantum wire were studied in high‐resolution photoluminescence experiments performed at a temperature of about 10 K with a spatial resolution of 160 nm and a spectral resolution of 100 µeV. We report the observation of quasi‐one‐dimensional excitons which are delocalized over a length of up to several micrometres along the quantum wire. Such excitons give rise to a 10 meV broad luminescence band, representing a superposition of transitions between different delocalized states. In addition, we find a set of sharp luminescence peaks from excitons localized on a sub150 nm length scale. Theoretical calculations of exciton states in a disordered quasi‐one‐dimensional potential reproduce the experimental results.
Reducing chemical vapour infiltration time for ceramic matrix composites
Authors: Timms L. A. , Westby W. , Prentice C. , Jaglin D. , Shatwell R. A. , Binner J. G. P.
Published: March 2003

Conventional routes to producing ceramic matrix composites (CMCs) require the use of high temperatures to sinter the individual ceramic particles of the matrix together. Sintering temperatures are typically much higher than the upper temperature limits of the fibres. This paper details preliminary work carried out on producing a CMC via chemical vapour infiltration (CVI), a process that involves lower processing temperatures, thus avoiding fibre degradation. The CVI process has been modified and supplemented in an attempt to reduce the CVI process time and to lower the cost of this typically expensive process. To this end microwave‐enhanced CVI (MECVI) has been chosen, along with two alternative pre‐infiltration steps: electrophoretic infiltration and vacuum bagging. The system under investigation is based on silicon carbide fibres within a silicon carbide matrix (SiCf/SiC).

The results demonstrate that both approaches result in an enhanced initial density and a consequent significant reduction in the time required for the MECVI processing step. Dual energy X‐ray absorptiometry was used as a non‐destructive, density evaluation technique. Initial results indicate that the presence of the SiC powder in the pre‐form changes the deposition profile during the MECVI process.
Excitation energy transfer of porphyrin in polymer thin films by time‐resolved scanning near‐field optical microspectroscopy
Authors: Miura A. , Yanagawa Y. , Tamai N.
Published: March 2003

Thin films of water‐soluble free‐base porphyrin, 5,10,15,20‐tetraphenyl‐21H, 23H‐porphinetetrasulphonic acid (TPPS) mixed with poly(diallyldimethyl ammonium chloride) (PDDA) have been prepared by a spin‐coating method, in which the monomeric species were observed in the spin‐coat film, whereas dimer was formed in the cast film prepared from TPPS/PDDA solution. Mesoscopic structures and dynamics of excitation energy migration and trapping of TPPS/PDDA spin‐coat film have been analysed by time‐resolved scanning near‐field optical microspectroscopy (SNOM) and atomic force microscope. The observed film structure can be classified roughly into two parts: one is a large, flocculated polymer part, and the other is a smooth part widely spread around the flocculated polymers. In the smooth part, the observed spindle‐like structure and circular hills and dips are essentially due to PDDA. The ellipsoidal small structures with ∼2µm length and <1 µm width in the flocculated polymer part show non‐exponential fluorescence decays. The non‐exponential dynamics originates from the excitation energy migration among TPPS monomers and energy trapping to dimers. From the analysis of fluorescence decay curves based on the equation developed by Klafter and Blumen, the spectral dimension has been estimated to be ∼1.46 for ellipsoidal structures. These results indicate that the distribution of the chromophore is inhomogeneous and a fractal‐like structure exists even in the small domains determined by the resolution of the SNOM tip.
Space‐multiplexed multifocal nonlinear microscopy
Authors: Hell S. W. , Andresen V.
Published: March 2003

Standard forms of nonlinear microscopy rely on single beam scanning, but the usually weaker signal and the need to image in real‐time call for parallelization of the image formation. Since the nonlinear susceptibilities necessitate a comparatively large illumination power, with current laser systems the brightness or field of view of any parallelized nonlinear microscope is limited by the brightness of the laser. For example, by producing an array of high aperture foci, multifocal multiphoton microscopy (MMM) provides real‐time, light‐efficient three‐dimensional fluorescence imaging at high‐resolution. The available power limits the degree of parallelization and hence codetermines the field of view. As the utilization of all the laser power is imperative, the focal intensity can be adjusted only through altering the number of foci. This compromises to some extent the flexibility to adjust the focal intensity to benign and effective levels. Here we introduce space‐multiplexing (SMX) as a novel option in parallelized nonlinear microscopy, which enables an improved exploitation of the total laser power and facilitates changing the intensity levels in selected regions, without attenuating the total laser power. The basic idea of SMX is to overlap arrays of slightly offset coherent focal fields whose interference modulates the intensity across the sample. For a given degree of parallelization and power, SMX increases the two‐ and three‐photon excited signal of parallelized nonlinear microscopy by a factor of up to 1.5 and 2.5, respectively. To some extent, sensitive regions may be spared out, whereas in regions with weaker nonlinear susceptibilities the intensity is increased. SMX is relevant to all modes of nonlinear microscopy, including parallelized second‐ and third‐harmonic imaging, coherent anti‐Stokes Raman scattering, and widefield multiphoton excitation.
Characterization of textured NiO films for application as buffer layers in high temperature superconducting tapes
Authors: Woodcock T. G. , Abell J. S. , Hall M. G.
Published: March 2003

Textured NiO films have been grown, by thermal oxidation, on biaxially textured Ni substrates. The films have been characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The XRD results showed two texture components, cube texture (001)[100] and (111) with out of plane orientation only. SEM showed much inhomogeneity of grain size on the sample surface. Analysis by EBSD revealed that coarse grained regions were cube textured and fine grained regions were <111> fibre textured. The ability to correlate textural and microstructural data is crucial to the optimization of textured NiO films for use in coated conductor technology.
Axial tomographic confocal fluorescence microscopy
Authors: Heintzmann R. , Cremer C.
Published: March 2003

By physical rotation of the sample, axial tomography enables the acquisition of otherwise inaccessible spatial information from an object. In combination with confocal microscopy, the method can fundamentally improve the effective three‐dimensional (3D) resolution. In this report we present a novel method for high resolution reconstruction of confocal axial tomographic data. The method automatically determines the relative angles of rotation, aligns the data from different rotational views and reconstructs a single high resolution 3D dataset. The reconstruction makes use of a known point spread function and is based on an unconstrained maximum likelihood deconvolution performed simultaneously from multiple (in our case three) angular views. It was applied to simulated as well as to experimental confocal datasets. The gain in resolution was quantified and the effect of choice of overrelaxation factors on the speed of convergence was investigated. A clearly improved 3D resolution was obtained by axial tomography together with reconstruction as compared with reconstruction of confocal data from only a single angular view.
Sampling effects influence heights measured with atomic force microscopy
Authors: Heymann J. B. , Möller C. , Müller D. J.
Published: March 2003

The atomic force microscope (AFM) is an exquisitely delicate probe measuring the height of a specimen at discrete sampling points in a fixed two‐dimensional (2D) raster. The resulting topograph is a 2D digital image, with each pixel representing a distinct height measurement. The height of an object is determined as the average of the maximum heights measured above the supporting surface. We show that such object heights derived from a variety of organic samples depend critically on the sampling or pixel size of the 2D raster. It is concluded that to obtain accurate specimen heights, the pixel size must be small enough to resolve submolecular structures and thus ensure representative sampling of the height variation on the surface.
Analytical electron microscopy as a tool for accessing colloid formation process in natural waters
Authors: Mondi C. , Leifer K. , Mavrocordatos D. , Perret D.
Published: March 2003

Analytical electron microscopy was used to characterize aquatic iron‐rich colloids. We focused our attention on a redox transition medium in the drainage water of a peat soil. In the anoxic peat water, observations by transmission electron microscopy and associated energy dispersive analyses (TEM‐EDS) highlight the presence of spherical entities (∼100–600 nm), containing only traces of iron. The increase of dissolved oxygen concentration favours the formation of iron oxy(hydr)oxides. In the oxygenated drain, particles with the same morphology and size range are present. Statistical TEM‐EDS analyses show that they represent the only colloidal form of iron in the drain samples. Nevertheless, although Fe–K peaks appear clearly on EDS spectra, the proportion of iron in these colloids reaches at most 4% at. (whereas C + O > 90% at.). Structural information completes this study. Both electron spectroscopic imaging (ESI) and electron energy‐loss spectroscopy (EELS) reveal the disparity between element distributions within the drain entities. Iron and calcium are preferably distributed on the outer sphere of the particle, whereas carbon and oxygen follow the theoretical variation of the signal intensity within a plain sphere. The implication of organic matter as nucleation site for iron precipitation is spectacularly demonstrated by the presence of nanometre‐sized iron‐rich phases highlighted by EELS line scans.
SMART – a program to measure SEM resolution and imaging performance
Authors: Joy D. C.
Published: March 2003

It is important to be able to measure the parameters, such as spatial resolution, astigmastism, signal‐to‐noise ratio, and drift and instability, that characterize the performance of a scanning electron microscope. These quantities can be determined most reliably by a Fourier analysis of digital micrographs from the instrument, recorded under conditions of interest. A program designed to implement all of the necessary steps in an automated manner has been developed as a ‘macro’ for the popular, and freely available, NIH Image and SCION Image programs.
Electron and light microscopy studies on the domain structures of Zn3B7O13Cl, Zn3B7O13Br and Zn3B7O13I ferroic boracites
Authors: Campa‐Molina J. , Blanco O. , Correa‐Gomez A. , Czank M. , Castellanos‐Guzman A. G.
Published: March 2003

The domain structures of Zn3B7O13Cl, Zn3B7O13Br and Zn3B7O13I boracite single crystals were studied by means of polarized light in conjunction with electron microscopy. Single crystals of the three compositions were grown by chemical transport reactions in closed quartz ampoules, at a temperature of 900 °C and were examined by polarizing optical microscopy (PLM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). For both PLM and SEM, the same as‐grown samples were used without having to resort to metallization of the crystal faces. For TEM the single crystals were crushed and mounted on holey carbon films. Comparative electron microscope images were useful for revealing the domain structure of these ferroelectric/ferroelastic materials previously observed between the crossed polars of an optical microscope. X‐ray diffraction analysis of the pulverized crystals was performed for this triad of halogen boracites containing zinc as a common metal.
Mapping cholesteryl ester analogue uptake and intracellular flow in Paramecium by confocal fluorescence microscopy
Authors: Ramoino P. , Fronte P. , Fato M. , Beltrame F. , Diaspro A.
Published: March 2003

In Paramecium primaurelia the uptake and intracellular flow of cholesteryl ester was studied by fluorescence confocal laser scanning optical microscopy and by the fluorescent analogue cholesteryl‐BODIPY® FL C12 (BODIPY‐CE). The BODIPY FL fluorophore has the characteristic of emitting green fluorescence, which is red‐shifted as the probe concentrates. In cells incubated with 25 µm BODIPY‐CE for 30 s, fluorescence is found in vesicles located around the cytopharynx in the posterior half of the cell. Successively, the lipid is internalized by food vacuoles, the fluorescent vesicles are distributed throughout the cell and the intracellular membranes are labelled. The food vacuole number is maximum after 10–15 min of continuous labelling, then it decreases until no food vacuoles are found in 30‐min fed cells. BODIPY‐CE accumulates in red‐labelled cytoplasmic droplets located in the anterior half of the cell. When food vacuole formation is inhibited by trifluoperazine, fluorescence is found on cellular membranes and in small green‐labelled vesicles at the apical pole. The inhibition of clathrin‐mediated endocytosis does not interfere in P. primaurelia with BODIPY‐CE intracellular flow: intracellular membranes and storage droplets in the cell anterior part are dyed. Conversely, the use of sterol‐binding drugs prevents the lipid accumulation in droplets, stopping the lipid within the cytoplasmic membranes. Furthermore, the cells treated with monensin and cytochalasin B show a labelling of the cellular membranes and lipid droplets, whereas NH4Cl reduces the lipid storage. Low temperature (4 °C) does not prevent the internalization of BODIPY‐CE that, however, is localized at the cytoplasmic membrane level and does not accumulate in storage droplets. In addition, BODIPY‐CE inhibits phagocytosis, as evidenced by comparing the kinetics of food vacuole formation of control cells, only fed with latex particles, with that of cells fed with latex particles and BODIPY‐CE. In conclusion, this study points out that in P. primaurelia the cholesteryl ester enters the cell via food vacuoles and through the plasma membrane and, inside the cell, it alters cell functions.
First tests of a dipole lens for a scanning electron microscope
Authors: Crewe A. V. , Kapp O. H.
Published: March 2003

We have previously shown that a dipole lens has superior properties that are particularly suited for use in a low voltage scanning electron microscope (SEM) (Tsai & Crewe, 1996). The aberrations are lower than for any other type of lens and lead to a prediction of high resolution. We describe the construction details of a microscope based on this principle and present some early results.
Effects of Increasing Gestation, Cortisol and Maternal Undernutrition on Hypothalamic Neuropeptide Y Expression in the Sheep Fetus
Authors: Warnes K. E. , Morris M. J. , Symonds M. E. , Phillips I. D. , Clarke I. J. , Owens J. A. , McMillen I. C.
Published: March 2003

We have characterized the localization and the ontogenetic changes in Neuropeptide tyrosine (NPY) before birth and investigated the regulation of NPY expression by cortisol and undernutrition in the fetal sheep hypothalamus during late gestation. Using immunohistochemistry, we have identified NPY‐containing neurons in the infundibular nucleus and the internal layer of the median eminence in fetal hypothalami collected between 110 and 147 days gestation. NPY projections were also present in the paraventricular nucleus (PVN) of fetal hypothalami at all ages between 110 days gestation and term. There was a significant increase in the amount of immunoreactive NPY/g hypothalamus between 87 and 113 days and 131–140 days gestation and a further significant increase after 141 days gestation. The total hypothalamic content of immunoreactive NPY increased significantly between 87 and 113 days and 141–145 days gestation. The levels of NPY mRNA: 18S rRNA in the mediobasal region of the fetal hypothalamus were significantly higher at 145–146 days gestation than at any earlier gestational age between 116 and 141 days gestation. Cortisol (2.5–3.0 mg/24 h) was infused intrafetally between 109 and 116 days gestation. The ratio of NPY mRNA: 18s rRNA in the mediobasal region of the fetal hypothalamus was significantly higher in the cortisol‐infused group when compared with the saline‐infused control group at 116 days gestation. Maternal, and hence fetal undernutrition, was induced between 110 and 146 days gestation. At 145–146 days gestation the ratio of NPY mRNA: 18S rRNA in the mediobasal region of the fetal hypothalamus was significantly higher in the undernutrition group when compared with control animals. We have therefore demonstrated that NPY is present in the hypothalamus of the sheep fetus before birth and that hypothalamic NPY content and NPY mRNA increase before delivery. We have also found that glucocorticoids and undernutrition stimulate increases in NPY mRNA levels in the hypothalamus before birth.
Aging Results in Attenuated Gonadotropin Releasing Hormone‐Luteinizing Hormone Axis Responsiveness to Glutamate Receptor Agonist N‐Methyl‐D‐Aspartate*
Authors: Bonavera Juan J. , Swerdloff Ronald S. , Sinha Hikim Amiya P. , Lue Yan H. , Wang Christina
Published: March 2003

Reproductive aging in the Brown Norway rat occurs because of testicular as well as hypothalamic‐pituitary dysfunction. Excitatory amino acids (EAA) participate in the regulation of pulsatile secretion of hypothalamic GnRH and pituitary LH. In the present study, we studied the EAA‐GnRH‐LH axis for possible age‐related alterations in prepubertal (35 days), young (3–4 months), middle‐aged (12–13 months) and old (21–23 months) rats. In the first experiment, an intra‐atrial cannula was implanted in rats of different ages to evaluate the pituitary response to small, physiological intravenous bolus administration of GnRH (0.5 or 1.0 nmol/100 g body weight). The results showed no age‐related significant differences in in‐vivo serum LH or FSH responsiveness to GnRH. In a second experiment, blood samples for the gonadotropins were withdrawn immediately before and 10 min after an iv injection of the glutamate receptor agonist N‐methyl‐
d‐aspartate (NMDA; 5 mg/kg, a dose that induces a physiological LH pulse in young rats). Administration of NMDA induced significant increases in LH and prolactin in all groups of animals (P<0.05) and a significant FSH response in young and middle‐aged but not old rats. NMDA‐induced LH, FSH and prolactin release was higher (P<0.05) in prepubertal rats than in all other age groups. Compared with young rats, NMDA‐induced increase in plasma LH and prolactin was lower (P<0.05) in old rats. In the third experiment, to ascertain whether this reduced LH response to NMDA in old rats was exerted at the hypothalamic level, the effects of NMDA on GnRH release in vitro from preoptic area‐medial basal hypothalamus (POA‐MBH) fragments were compared among rats of different ages. GnRH efflux in response to NMDA was significantly attenuated with increasing age. GnRH release in vitro was higher in prepubertal and lower in old than in young rats (P<0.05). Lastly, we measured amino acid concentrations in hypothalamic tissue (POA‐MBH fragments). Prepubertal rats had higher levels of glutamate and taurine than young rats. Significant reductions in glutamate and γ‐aminobutyric acid (GABA) levels were found in old compared to young rats. In conclusion, these results showed that the hypothalamic NMDA‐GnRH‐LH axis was altered in old rats. The decreased hypothalamic content of some of the EAA and the reduced responsiveness of GnRH neurons to NMDA (both in vivo and in vitro) may contribute to an altered LH pulsatile secretion observed in old rats.