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Microscopy Methods (microscopy + methods)
Selected AbstractsMicrostructural analysis of iron aluminide formed by self-propagating high-temperature synthesis mechanism in aluminium matrix compositeJOURNAL OF MICROSCOPY, Issue 1 2006ANITA OLSZÓWKA-MYALSKA Summary An aluminium matrix composite with iron aluminide formed in situ as a result of self-propagated high-temperature synthesis was examined. The structural characteristics of the reinforcement investigated by scanning electron microscopy and transmission electron microscopy methods are presented. Iron aluminide particles with a very fine grain size and of two shapes, cubic and needle-like, were observed. No differences in their phase composition were found by the selective electron diffraction pattern method. The composite reinforcement formed in the early stage of self-propagating high-temperature synthesis consisted only of the Al3Fe phase. [source] Radon track imaging in CR-39 plastic detectors using confocal scanning laser microscopyJOURNAL OF MICROSCOPY, Issue 3 2005N. PETFORD Summary Confocal scanning laser microscopy (CSLM) has been used to provide the first images of radon track populations in two external CR-39 plastic detectors. Measurements of variables including track area distribution and estimates of the angle of track inclination (dip) derived from surface CSLM sections are presented. CSLM depth slices, combined with three-dimensional (3D) visualization techniques, provide a new, non-destructive way of examining the 2D and 3D geometry of the etched tracks within solid-state nuclear track detectors that may prove useful in complementing existing optical microscopy methods. [source] Quantification and characterization of subvisible proteinaceous particles in opalescent mAb Formulations Using Micro-Flow ImagingJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2010Deepak K. Sharma Abstract Micro-flow imaging (MFIÔ) has been shown to be more sensitive than light obscuration (LO) methods for measuring subvisible proteinaceous particles in protein formulations. Given the potential challenges in detecting particulates in opalescent mAb formulations, the accuracy of MFI to size and count particles in opalescent solutions was investigated and compared to LO and membrane microscopy methods. Proteinaceous monoclonal antibody (mAb) particles, generated either by chemical denaturation or agitation stress, polystyrene and glass particles were used as model systems for measurements in opalescent mAb solutions. The sizing and counting accuracies of MFI were unaffected by the opalescence of the medium. Using glass particles as a model system for proteinaceous particles, MFI was able to detect relatively low particle concentrations (,10/mL) in opalescent solutions. MFI showed excellent linearity (R2,=,0.9969) for quantifying proteinaceous particles in opalescent solutions over a wide range of particle concentrations (,20,160,000/mL). Analyses of MFI particle image intensities revealed significant differences in the transparency of proteinaceous particles as a function of their size and mode of generation. LO method significantly underestimated proteinaceous particles, particularly those in the 2,10,µm size range. The less opaque proteinaceous particles were relatively more underestimated by the LO method in opalescent solutions. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 2628,2642, 2010 [source] Multiple microscopy modalities applied to a sea urchin tooth fragmentJOURNAL OF SYNCHROTRON RADIATION, Issue 5 2003S. R. Stock Two synchrotron X-ray microscopy methods, phase-contrast microradiography (the propagation method) and absorption microCT (high-resolution computed tomography or microtomography), and laser-scanning confocal microscopy (visible wavelength) were used to study a fragment of the keel of a tooth of the sea urchin Lytechinus variegatus. Stripes observed in the phase-contrast images of the fragment were also seen in confocal micrographs. MicroCT showed that the stripes were due to two parallel planar arrays of low-absorption channels within the bulk of the keel. In the phase microradiographs, maximum contrast stripes appear when a channel image from one row coincides with a channel image from the second row; otherwise, contrast is minimal. Long channels do not appear to have been observed previously in keels of sea urchin teeth. [source] Microwave Dielectric Properties of SrRE4Si3O13 (RE=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, Yb, and Y) CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2009Sherin Thomas The apatite type SrRE4Si3O13 (RE=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, Yb, and Y) ceramics have been prepared by the conventional solid-state ceramic route. The phase purity and surface morphology of the sintered ceramics were studied using X-ray diffraction and scanning electron microscopy methods. These materials showed poor sinterability and was improved by the addition of a small weight percentage of zinc borosilicate glass. The microwave dielectric properties of these materials were studied for the first time. SrRE4Si3O13 ceramics have a low relative permittivity (,r) in the range 9,16, a Q-factor (Qu×f) upto 26 000 GHz and a low temperature coefficient of resonant frequency (,f). The SrLa4Si3O13 ceramics possessed a high Qu×f of nearly 26 000 GHz but with a high negative ,f of ,46 ppm/°C. The ,f of SrLa4Si3O13 ceramics was tuned by the addition of suitable amount of TiO2. [source] PVC modification through polymerization of a monomer absorbed in porous suspension-type PVC particlesJOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 3 2004M. Narkis In-situ polymerization is the polymerization of one monomer in the presence of another polymer. It can be performed by sequential emulsion polymerization, or by reactions in the melt, in the solid phase, or in solution. The current report describes two methods to obtain poly(vinyl chloride) (PVC) modification through polymerization of a monomer absorbed in commercial porous suspension-type PVC particles. The generated modified PVC products differ significantly in their structure and properties. The first approach includes absorption of a monomer/peroxide solution within porous suspension-type PVC particles, followed by polymerization/crosslinking in the solid state at 80°C in an aqueous stabilizer-free dispersion. The monomer/crosslinker pairs selected are styrene/DVB (divinyl benzene), methylmethacrylate/EGDMA (ethylene glycol dimethacrylate), butyl acrylate/EGDMA, and ethylhexyl acrylate/EGDMA. The influence of composition and nature of the polymerizing/crosslinking constituents on the modified PVC particle structure was studied by microscopy methods, porosity measurements, and dynamic mechanical behavior (DMTA). The level of molecular grafting between PVC and the modifying polymer was determined by solvent extraction experiments. This work shows that the different monomers used represent distinct courses of monomer transport through the PVC particles. The characteristics of the modified PVC particle indicate that the polymerization/crosslinking process occurs in both the PVC bulk, i.e., within the walls constituting a particle, and in the PVC pores. No indication of chemical intermolecular interaction within the modified PVC particles was found. In the second approach, a solution of monomer, initiator, and a crosslinking agent is absorbed in commercial suspension-type porous PVC particles, thus forming a dry blend. This dry blend is subsequently reactively polymerized in a twin-screw extruder at an elevated temperature, 180°C, in the molten state. The properties of the reactively extruded PVC/PMMA blends are compared with those of physical blends at similar compositions. Owing to the high polymerization temperature, short-chain polymers are formed in the reactive polymerization process. Reactively extruded PVC/PMMA blends are transparent, form single-phase morphology, have a single Tg, and show mechanical properties comparable with those of the neat PVC. The resulting reactively extruded PVC/PMMA blends have high compatibility. J. Vinyl Addit. Technol. 10:109,120, 2004. © 2004 Society of Plastics Engineers. [source] 3D reconstruction of high-resolution STED microscope imagesMICROSCOPY RESEARCH AND TECHNIQUE, Issue 9 2008Annedore Punge Abstract Tackling biological problems often involves the imaging and localization of cellular structures on the nanometer scale. Although optical super-resolution below 100 nm can be readily attained with stimulated emission depletion (STED) and photoswitching microscopy methods, attaining an axial resolution <100 nm with focused light generally required the use of two lenses in a 4Pi configuration or exceptionally bright photochromic fluorophores. Here, we describe a simple technical solution for 3D nanoscopy of fixed samples: biological specimens are fluorescently labeled, embedded in a polymer resin, cut into thin sections, and then imaged via STED microscopy with nanoscale resolution. This approach allows a 3D image reconstruction with a resolution <80 nm in all directions using available state-of-the art STED microscopes. Microsc. Res. Tech., 2008. © 2008 Wiley-Liss, Inc. [source] Using dynamically scattered electrons for three-dimensional potential reconstructionACTA CRYSTALLOGRAPHICA SECTION A, Issue 5 2009Christoph T. Koch Three-dimensional charge-density maps computed by first-principles methods provide information about atom positions and the bonds between them, data which are particularly valuable when trying to understand the properties of point defects, dislocations and interfaces. This paper presents a method by which three-dimensional maps of the electrostatic potential, related to the charge-density map by the Poisson equation, can be obtained experimentally at 1,Å resolution or better, especially at low accelerating voltages. The method requires data acquired by holographic transmission electron microscopy methods such as off-axis electron holography or focal series reconstruction for slightly (e.g.±2°) different directions of the incident electron beam. The reconstruction of the three-dimensional electrostatic (and absorptive) potential is achieved by making use of changes in the dynamical scattering within the sample as the direction of the incident beam varies. [source] | ||||||||||||||||