Microscopy Research Papers - Academia.edu (original) (raw)

Microscopic objects including living cells on a planar substrate are investigated in bio-medical applications of scanning acoustic microscopy. Beside of the observation of lateral structures, the determination of sample properties such as... more

Microscopic objects including living cells on a planar substrate are investigated in bio-medical applications of scanning acoustic microscopy. Beside of the observation of lateral structures, the determination of sample properties such as density, sound velocity, and attenuation is desired, from which elastic properties can be derived. This can be achieved with the aid of the acoustic phase and magnitude contrast represented in a polar plot. For homogeneous and sufficiently planar objects the contrast in magnitude and phase is a function of the properties of the substrate and the coupling fluid, which both can easily be determined, and of the mechanical properties of the sample under observation. For observation in reflection and variable thickness of the sample the signal will depend on the actual thickness. This signature of the object can be fitted based on a conventional ray model for the sound propagating in the coupling medium and the sample. The model includes also the refraction and reflection at all interfaces between transducer, lens material, coupling fluid, object, and substrate. The method is demonstrated for a chitosan film deposited on a glass substrate. The scheme presented here is capable to reach a resolution of about and even below 1% for relevant quantities in applications involving imaging at 1.2 GHz in aqueous coupling fluids.

Two still-life paintings were scientifically examined in order to gain insights about Dutch painter Jan van Huysum's (1682-1749) purportedly secretive paintings techniques, comparing the actual works to information obtained in the few... more

Two still-life paintings were scientifically examined in order to gain insights about Dutch painter Jan van Huysum's (1682-1749) purportedly secretive paintings techniques, comparing the actual works to information obtained in the few available historical technical sources. Surface investigations included macroscopic and microscopic examination, infrared reflectography and x-radiography, while material characterization of the ground, organic and inorganic pigments and binding media was carried out with a range of non-destructive and destructive analytical techniques. The belief that the two works were an original pair of pendant paintings was disproved due to substantial technical differences in the wood support, ground layers and use of yellow pigment. It was also found that Van Huysum's use of newly developed pigments (Prussian blue, Naples yellow) had lead to changes in his painting technique, which no longer corresponded to those described in the period's manuals, an...

A representative case in which a polymicrobial infection involving Fusobacterium nucleatum, Actinomyces israelii and Aggregatibacter (formerly Actinobacillus) actinomycetemcomitans was initially diagnosed as malignancy in an edentulous... more

A representative case in which a polymicrobial infection involving Fusobacterium nucleatum, Actinomyces israelii and Aggregatibacter (formerly Actinobacillus) actinomycetemcomitans was initially diagnosed as malignancy in an edentulous patient. Additional history obtained after the nature of the syndrome was elucidated revealed that he had had his two remaining teeth extracted four months prior to this episode.

Virtual microscopy is being introduced in medical education as an approach for learning how to interpret information in microscopic specimens. It is, however, far from evident how to incorporate its use into existing teaching practice.... more

Virtual microscopy is being introduced in medical education as an approach for learning how to interpret information in microscopic specimens. It is, however, far from evident how to incorporate its use into existing teaching practice. The aim of the study was to explore the consequences of introducing virtual microscopy tasks into an undergraduate pathology course in an attempt to render the instruction more process-oriented. The research questions were: 1) How is virtual microscopy perceived by students? 2) Does work on virtual microscopy tasks contribute to improvement in performance in microscopic pathology in comparison with attending assistant-led demonstrations only? During a one-week period, an experimental group completed three sets of virtual microscopy homework assignments in addition to attending demonstrations. A control group attended the demonstrations only. Performance in microscopic pathology was measured by a pre-test and a post-test. Student perceptions of regular...

Tissue clearing and subsequent imaging of intact transparent tissues have provided an innovative way to analyze anatomical pathways in the nervous system. In this study, we combined a recent 3-dimensional imaging of solvent cleared organ... more

Tissue clearing and subsequent imaging of intact transparent tissues have provided an innovative way to analyze anatomical pathways in the nervous system. In this study, we combined a recent 3-dimensional imaging of solvent cleared organ (3DISCO) procedure, light-sheet microscopy, fluorescent retrograde tracer, and Imaris software to 3D map corneal sensory neurons within a whole adult mouse trigeminal ganglion (TG). We first established the optimized steps to easily and rapidly clear a fixed TG. We found that the 3DISCO procedure gave excellent results and took less than 3 h to clear the TG. In a second set of experiments, a retrograde tracer (cholera toxin B Alexa 594-conjugated) was applied to de-epithelialized cornea to retrograde-labeled corneal sensory neurons. Two days later, TGs were cleared by the 3DISCO method and serial imaging was performed using light-sheet ultramicroscopic technology. High-resolution images of labeled neurons can be easily and rapidly obtained from a 3D...

This paper provides direct evidence to support the role of capping agents in controlling the evolution of TiO2 seeds into nanocrystals with a specific shape. Starting with Ti(OBut) 4 and using oleid acid, oleylamine, dioleamide,... more

This paper provides direct evidence to support the role of capping agents in controlling the evolution of TiO2 seeds into nanocrystals with a specific shape. Starting with Ti(OBut) 4 and using oleid acid, oleylamine, dioleamide, 11-aminoundecanoic acid, arginine, trifluroacetic acid or HF as capping agents, mainly TiO 2 truncated octahedrons enclosed by {1 0 1} and {0 0 1} facets were obtained. We could also selectively obtain square, rods and rounded rhombic-shaped nanoparticles by growing of {0 1 0} facets by adding oleic acid and oleyl-amine in ratio 6:4, respectively, while all other parameters were kept the same. This research not only offers new insights into the role played by a capping agent in shape-controlled synthesis but also provides, a versatile approach to controlling the shape of metal oxide nanocrystals.

A new circuit was designed to automatically compensate for measurement errors of an electronic apex locator in various electrolytes. Thirty-one root canals were clinically tested for accuracy. A file was inserted into the canal until the... more

A new circuit was designed to automatically compensate for measurement errors of an electronic apex locator in various electrolytes. Thirty-one root canals were clinically tested for accuracy. A file was inserted into the canal until the apex signal was obtained, at which point the file was immobilized with glass-ionomer cement. After extraction, the apical area was exposed and the position of the file tip was examined under an operating microscope. Distances from the major foramen and cemento dentinal junction (CDJ) were recorded. The average distance from the major foramen was -0.13 mm with a range of -1.28 mm and +0.46 mm. The average distance in 26 detectable CDJ samples was +0.18 mm with a range of -0.98 mm and +0.65 mm. The measurements, which were within +/- 0.5 mm, were 94% (29/31) from the major foramen and 92% (24/26) from the CDJ. Measurement consistencies within one SD were 81% for the major foramen and 65% for the CDJ, respectively. Measurements within two SD were 97% f...

The growing demand of gold nanoparticles in medical applications increases the need for simple and efficient characterization methods of the interaction between the nanoparticles and biological systems. Due to its nanometre resolution,... more

The growing demand of gold nanoparticles in medical applications increases the need for simple and efficient characterization methods of the interaction between the nanoparticles and biological systems. Due to its nanometre resolution, modern scanning electron microscopy (SEM) offers straightforward visualization of metallic nanoparticles down to a few nanometre size, almost without any special preparation step. However, visualization of biological materials in SEM requires complicated preparation procedure, which is typically finished by metal coating needed to decrease charging artefacts and quick radiation damage of biomaterials in the course of SEM imaging. The finest conductive metal coating available is usually composed of a few nanometre size clusters, which are almost identical to the metal nanoparticles employed in medical applications. Therefore, SEM monitoring of metal nanoparticles within cells and tissues is incompatible with the conventional preparation methods. In thi...

This paper presents a color object recognition scheme which proceeds in three sequential steps: segmentation, features extraction and classification. We mainly focus on the first and the third steps here. A color watershed using global... more

This paper presents a color object recognition scheme which proceeds in three sequential steps: segmentation, features extraction and classification. We mainly focus on the first and the third steps here. A color watershed using global and local criteria is first described. A color contrast value is defined to select the best color space for segmenting color objects. Then, an architecture of binary neural networks is described. Its properties relies on the simplification of the recognition problem, leading to a noticeable increase in the classification rate. We conclude with the abilities of such a recognition scheme and present an automated cell sorting system.