| 1. |
- Almqvist, Nils, et al.
(författare)
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Imaging human erythrocyte spectrin with atomic force microscopy
- 1994
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Ingår i: Micron. - : Elsevier BV. - 0968-4328 .- 1878-4291. ; 25:3, s. 227-232
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Tidskriftsartikel (refereegranskat)abstract
- Isolated spectrin covalently attached to a surface in a liquid environment as well as dried on mica has been studied with a contact-mode atomic force microscope. Both pyramidal and conical-type cantilever tip facets were used in the AFM. Our images show structures and give dimensions that correlate well with previous structural studies using transmission electron microscopy.
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| 2. |
- Adegoke, Olutayo, et al.
(författare)
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Scanning electron microscopy and atom probe tomography characterization of laser powder bed fusion precipitation strengthening nickel-based superalloy
- 2023
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Ingår i: Micron. - 0968-4328 .- 1878-4291. ; 171
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Tidskriftsartikel (refereegranskat)abstract
- Atom probe tomography (APT) was utilized to supplement scanning electron microscopy (SEM) characterizationof a precipitation strengthening nickel-based superalloy, Alloy 247LC, processed by laser powder bed fusion (LPBF). It was observed that the material in the as-built condition had a relatively high strength. Using both SEMand APT, it was concluded that the high strength was not attributed to the typical precipitation strengtheningeffect of γ’. In the absence of γ’ it could be reasonably inferred that the numerous black dots observed in thecells/grains with SEM were dislocations and as such should be contributing significantly to the strengthening.Thus, the current investigation demonstrated that relatively high strengthening can be attained in L-PBF even inthe absence of precipitated γ’. Even though γ’ was not precipitated, the APT analysis displayed a nanometer scalepartitioning of Cr that could be contributing to the strengthening. After heat-treatment, γ’ was precipitated and itdemonstrated the expected high strengthening behavior. Al, Ta and Ti partitioned to γ’. The strong partitioningof Ta in γ’ is indicative that the element, together with Al and Ti, was contributing to the strain-age crackingoccurring during heat-treatment. Cr, Mo and Co partitioned to the matrix γ phase. Hf, Ta, Ti and W were found inthe carbides corroborating previous reports that they are MC.
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| 3. |
- Blomgren, Bo, et al.
(författare)
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A computerised, unbiased method for epithelial measurement
- 2004
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Ingår i: Micron. - Amsterdam : Elsevier. - 0968-4328 .- 1878-4291. ; 35, s. 319-329
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Tidskriftsartikel (refereegranskat)abstract
- ObjectiveTo develop and evaluate a standardised method for unbiased measurements of epithelial thickness taking the variability of the dermal papillae in consideration.MethodsA computer-assisted measurement program suitable for haematoxylin and eosin routine stained specimens has been developed.ResultsThe developed program was designed to measure four different distance parameters, taking the number, height and width of dermal papillae into account. The measurement program gave very accurate results compared with manual measurements. The measurement results can be presented as tables or star graphs, and the results can be further processed by multivariate analysis.ConclusionThe computer-assisted measurement program is considered to be a valuable and reliable tool for measurements of epithelial thickness, irrespectively of the variability of the epithelial morphology. Since length, size and number of the papillae may change with certain pathological conditions, age and also under hormonal influence, this method can be a helpful diagnostic tool.
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| 4. |
- Blomgren, Bo, et al.
(författare)
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A novel method for quantification of the folding of elastic laminae in elastic arteries
- 2008
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Ingår i: Micron. - : Elsevier BV. - 0968-4328 .- 1878-4291. ; 39:5, s. 623-630
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Forskningsöversikt (refereegranskat)abstract
- A transgenic mouse overexpressing the human form of semicarbazide-sensitive amine oxidase (SSAO) is known to have an abnormal structure of the elastic laminae and the elastic fibres in the aorta. Compared to the non-transgenic littermates, the elastic laminae are less folded. In order to quantify the undulation of this structure, an image analysis program that identified the elastic laminae was developed. The program measures the area fraction in different sectors from a plane parallel to the aorta wall. Images were taken from unstained aorta specimens where the elastic laminae were visualised with phase contrast microscopy. A contextual operation of the images produced a local orientation estimation for every linear structure. The image was then thresholded in eight sectors from 0 degrees to 180 degrees, with different orientation angles. The results show that the area fraction of the elastic laminae was significantly lower for the transgenic mouse in all sectors measured except for two. At 0-25 degrees, no difference was seen. In the sector at 160-180 degrees, parallel to the aorta wall, the area fraction of elastic laminae was instead significantly higher in the transgenic mouse. A novel method is presented, developed for detection and quantification of pathological changes in the elastic laminae in the aorta wall. The method gave reliable results and is considered to be a useful tool for morphometric studies of aorta with this kind of altered morphology concerning the elastic laminae. When compared with tangent count, the control group had a significantly larger mean curvature.
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| 5. |
- Canovic, Sead, et al.
(författare)
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CVD TiC/alumina multilayer coatings grown on sapphire single crystals
- 2011
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Ingår i: Micron. - : Elsevier BV. - 0968-4328 .- 1878-4291. ; 42:8, s. 808-818
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Tidskriftsartikel (refereegranskat)abstract
- Multilayers of TiC/α-Al(2)O(3) consisting of three (1μm thick) alumina layers separated by thin (∼10nm) oxidized TiC layers have been deposited onto c-, a- and r-surfaces of single crystals of α-Al(2)O(3) by chemical vapour deposition (CVD). The aim of this paper is to describe and compare the detailed microstructure of the different multilayer coatings by using transmission electron microscopy (TEM). The general microstructure of the alumina layers is very different when deposited onto different surfaces of α-Al(2)O(3) single crystal substrates. On the c- and a-surfaces the alumina layers grow evenly resulting in growth of single crystal layers of TiC and alumina throughout the coating. However, when deposited on the r-surface the alumina layers generally grow unevenly. No pores are observed within the alumina layers, while a small number of pores are found at the interfaces below the TiC layers. The TiC and alumina layers grow epitaxially on the c- and a-surface substrates. On the r-surface, epitaxy is present only at some rare locations. The TiC layers were oxidized in situ for 2min in CO(2)/H(2) prior to the alumina layer deposition. For all three samples chemical analyses show that the whole TiC layer is oxidized. On the c- and a-surfaces the TiC layer was oxidized to an fcc TiCO phase. On the r-surface the oxidation stage resulted in a transformation of the initially deposited fcc TiC to a monoclinic TiCO phase, which appears to be a modified TiO structure with a high carbon content.
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| 6. |
- Cheng, Kimberley, et al.
(författare)
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Rapana thomasiana hemocyanin (RtH): Comparison of the two isoforms, RtH1 and RtH2, at 19 angstrom 16 angstrom resolution
- 2006
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Ingår i: Micron. - : Elsevier BV. - 0968-4328 .- 1878-4291. ; 37:6, s. 566-576
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Forskningsöversikt (refereegranskat)abstract
- Three-dimensional (3D) reconstructions of the two 8.4 MDa Rapana thomasiana hemocyanin isoforms, RtH1 and RtH2, have been obtained by cryoelectron microscopy of molecules embedded in vitreous ice and single particle image processing. The final 3D structures of the RtH1 and RtH2 didecamers at 19 angstrom and 16 angstrom resolution, respectively, are very similar to earlier reconstructions of gastropodan hemocyanins, revealing structural features such as the obliquely oriented subunits, the five- and two-fold symmetrical axes. Three new interactions are defined; two of them connecting the arch and the wall while the third is formed between the collar and the wall. The collar-wall connection and one of the arch-wall connections are positioned between two individual subunit dimers, while the second arch-wall connection is located between two subunits within the subunit dimer. All three interactions establish connections to the first tier of the wall. Furthermore, for each interaction we have allocated two first tier functional units most likely involved in forming the connections. (
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| 7. |
- Chinga-Carrasco, Gary, et al.
(författare)
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Micro-structural characterisation of homogeneous and layered MFC nano-composites
- 2013
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Ingår i: Micron. - : Elsevier BV. - 0968-4328 .- 1878-4291. ; 44:1, s. 331-338
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Tidskriftsartikel (refereegranskat)abstract
- The complementary capabilities of various characterisation methods for micro-structural assessment are demonstrated. The assessed structures were composed of unbleached microfibrillated cellulose (MFC) in combination with bleached and 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) pre-treated MFC materials. The biodegradable nano-composites were thus characterised in detail, including laser profilometry, scanning electron microscopy (SEM) in high and low vacuum modes, and field-emission SEM. The distribution of the unbleached MFC materials was assessed by staining the unbleached MFC with osmium tetroxide (OsO4), which reacts with CC double bonds encountered in lignin. In addition, some properties of the MFC nano-composite films were tested, i.e. tensile properties, water wettability and oxygen permeability. In general, the group of characteristics of the nano-composite MFC films was better than the properties of the films made of the neat MFC qualities. This indicates that mixing complementary MFC qualities could give synergetic effects that are not exploited completely when using the MFC qualities separately. The study thus confirms the suitability of unbleached MFC materials as a component in multilayer structures, for example biodegradable packaging applications.
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| 8. |
- Chinga-Carrasco, Gary
(författare)
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Optical methods for the quantification of the fibrillation degree of bleached MFC materials
- 2013
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Ingår i: Micron. - : Elsevier BV. - 0968-4328 .- 1878-4291. ; 48, s. 42-48
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the suitability of optical devices for quantification of the fibrillation degree of bleached microfibrillated cellulose (MFC) materials has been assessed. The techniques for optical assessment include optical scanner, UV-vis spectrophotometry, turbidity, quantification of the fiber fraction and a camera system for dynamic measurements. The results show that the assessed optical devices are most adequate for quantification of the light transmittance of bleached MFC materials. Such quantification yields an estimation of the fibrillation degree. Films made of poorly fibrillated materials are opaque, while films made of highly fibrillated materials containing a major fraction of nanofibrils are translucent, with light transmittance larger than 90%. Finally, the concept of using images acquired with a CCD camera system, for estimating the fibrillation degree in dynamic conditions was exemplified. Such systems are most interesting as this will widen the applicability of optical methods for quantification of fibrillation degree online in production lines, which is expected to appear in the years to come.
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| 9. |
- Chinga-Carrasco, Gary, et al.
(författare)
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The effect of residual fibres on the micro-topography of cellulose nanopaper
- 2014
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Ingår i: Micron. - : Elsevier BV. - 0968-4328 .- 1878-4291. ; 56, s. 80-84
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Tidskriftsartikel (refereegranskat)abstract
- Nanopaper is a new material concept composed of nanocellulose, which has been proposed for a series of applications. Recently, the surface of nanopapers has also been emphasized as an important structure to control. This is due to the potential of nanopaper structures as a substrate for printing functionality, which could expand the applicability of nanopaper as a functionalized biomaterial. In this study, we demonstrate how the roughness of nanopaper is affected by the fraction of residual fibres that were not fibrillated into nanofibrils after a homogenization procedure. The topography and morphology were assessed with laser profilometry, atomic force microscopy and scanning (transmission) electron microscopy. The results show a linear correlation between the estimated fraction of residual fibres and the roughness of the assessed nanopapers. Furthermore, the fraction of residual fibres can be reduced by fractionating the nanocellulose, which is demonstrated in the present work. Such knowledge will be valuable for designing nanopaper surfaces with specific structural characteristics.
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| 10. |
- Estradé, S., et al.
(författare)
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Distinguishing the core from the shell in MnOx/MnOy and FeOx/MnOx core/shell nanoparticles through quantitative electron energy loss spectroscopy (EELS) analysis
- 2012
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Ingår i: Micron. - : Elsevier BV. - 0968-4328 .- 1878-4291. ; 43:1, s. 30-36
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Forskningsöversikt (refereegranskat)abstract
- The structural and chemical characterization of inverted bi-magnetic MnOx(antiferromagnetic)/MnOy(ferrimagnetic) and FeOx(soft-ferrimagnetic)/MnOx(hard-ferrimagnetic) core/shell nanoparticles has been carried out by means of scanning transmission electron microscopy with electron energy loss spectroscopy analysis, (S)TEM-EELS. Quantitative EELS was applied to assess the local composition of the nanoparticles by evaluating the local Mn oxidation state based on the Mn L-3/L-2 peak intensity ratio and the Mn L-3 peak onset. The analysis allows to unambiguously distinguish the core from the shell and to determine the nature of the involved manganese oxides in both cases. The results evidence that the structure of the nanoparticles is, in fact, more complex than the one designed by the synthesis parameters.
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| 11. |
- Gamelas, José A. F., et al.
(författare)
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On the morphology of cellulose nanofibrils obtained by TEMPO-mediated oxidation and mechanical treatment
- 2015
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Ingår i: Micron. - : Elsevier BV. - 0968-4328 .- 1878-4291. ; 72, s. 28-33
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Tidskriftsartikel (refereegranskat)abstract
- The morphological properties of cellulose nanofibrils obtained from eucalyptus pulp fibres were assessed. Two samples were produced with the same chemical treatment (NaClO/NaBr/TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidation), but distinct mechanical treatment intensities during homogenization. It was shown that the nanofibrils production yield increases with the mechanical energy. The effect of mechanical treatment on the yield was confirmed by laser profilometry of air-dried nanocellulose films. However, no significant differences were detected regarding the nanofibrils width as measured by atomic force microscopy (AFM) of air-dried films. On the other hand, differences in size were found either by laser diffraction spectroscopy or by dynamic light scattering (DLS) of the cellulose nanofibrils suspensions as a consequence of the differences in the length distribution of both samples. The nanofibrils length of the more nanofibrillated sample was calculated based on the width measured by AFM and the hydrodynamic diameter obtained by DLS. A length value of ca. 600. nm was estimated. The DLS hydrodynamic diameter, as an equivalent spherical diameter, was used to estimate the nanofibrils length assuming a cylinder with the same volume and with the diameter (width) assessed by AFM. A simple method is thus proposed to evaluate the cellulose nanofibrils length combining microscopy and light scattering methods.
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| 12. |
- Hamngren Blomqvist, Charlotte, 1984, et al.
(författare)
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Interconnectivity imaged in three dimensions : Nano-particulate silica-hydrogel structure revealed using electron tomography
- 2017
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Ingår i: Micron. - : Elsevier BV. - 0968-4328 .- 1878-4291. ; 100, s. 91-105
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Tidskriftsartikel (refereegranskat)abstract
- We have used Electron Tomography (ET) to reveal the detailed three-dimensional structure of particulate hydrogels, a material category common in e.g. controlled release, food science, battery and biomedical applications. A full understanding of the transport properties of these gels requires knowledge about the pore structure and in particular the interconnectivity in three dimensions, since the transport takes the path of lowest resistance. The image series for ET were recorded using High-Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM). We have studied three different particulate silica hydrogels based on primary particles with sizes ranging from 3.6 nm to 22 nm and with pore-size averages from 18 nm to 310 nm. Here, we highlight the nanostructure of the particle network and the interpenetrating pore network in two and three dimensions. The interconnectivity and distribution of width of the porous channels were obtained from the three-dimensional tomography studies while they cannot unambiguously be obtained from the two-dimensional data. Using ET, we compared the interconnectivity and accessible pore volume fraction as a function of pore size, based on direct images on the nanoscale of three different hydrogels. From this comparison, it was clear that the finest of the gels differentiated from the other two. Despite the almost identical flow properties of the two finer gels, they showed large differences concerning the accessible pore volume fraction for probes corresponding to their (two-dimensional) mean pore size. Using 2D pore size data, the finest gel provided an accessible pore volume fraction of over 90%, but for the other two gels the equivalent was only 10–20%. However, all the gels provided an accessible pore volume fraction of 30–40% when taking the third dimension into account.
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| 13. |
- Härmark, Johan, et al.
(författare)
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Shell thickness determination of polymer-shelled microbubbles using transmission electron microscopy
- 2016
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Ingår i: Micron. - : Elsevier. - 0968-4328 .- 1878-4291. ; 85, s. 39-43
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Tidskriftsartikel (refereegranskat)abstract
- Intravenously injected microbubbles (MBs) can be utilized as ultrasound contrast agent (CA) resulting in enhanced image quality. A novel CA, consisting of air filled MBs stabilized with a shell of polyvinyl alcohol (PVA) has been developed. These spherical MBs have been decorated with superparamagnetic iron oxide nanoparticles (SPIONs) in order to serve as both ultrasound and magnetic resonance imaging (MRI) CA. In this study, a mathematical model was introduced that determined the shell thickness of two types of SPIONs decorated MBs (Type A and Type B). The shell thickness of MBs is important to determine, as it affects the acoustical properties. In order to investigate the shell thickness, thin sections of plastic embedded MBs were prepared and imaged using transmission electron microscopy (TEM). However, the sections were cut at random distances from the MB center, which affected the observed shell thickness. Hence, the model determined the average shell thickness of the MBs from corrected mean values of the outer and inner radii observed in the TEM sections. The model was validated using simulated slices of MBs with known shell thickness and radius. The average shell thickness of Type A and Type B MBs were 651nm and 637nm, respectively.
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| 14. |
- Kahl, Sören, et al.
(författare)
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In Situ EBSD During Tensile Test of Aluminum AA3003 Sheet
- 2014
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Ingår i: Micron. - : Elsevier. - 0968-4328 .- 1878-4291. ; 58, s. 15-24
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Tidskriftsartikel (refereegranskat)abstract
- Miniature tensile-test specimens of soft-annealed, weakly textured AA3003 aluminum sheet in 0.9 mm thickness were deformed until fracture inside a scanning electron microscope. Tensile strength measured by the miniature tensile test stage agreed well with the tensile strength by regular tensile testing. Strain over the microscope field of view was determined from changes in positions of constituent particles. Slip lines were visible in secondary electron images already at 0.3% strain; activity from secondary slip systems became apparent at 2% strain. Orientation rotation behavior of the tensile load axis with respect to the crystallographic axes agreed well with previously reported trends for other aluminum alloys. Start of the fracture and tensile crack propagation were documented in secondary electron images. The region of fracture nucleation included and was surrounded by many grains that possessed high Schmid factors at zero strain. Crystal lattice rotation angles in the grains surrounding the initial fracture zone were higher than average while rotations inside the initial fracture zone were lower than average for strains from zero to 31%. The orientation rotation behavior of the tensile load axes of the grains around the fracture zone deviated from the average behavior in this material.
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| 15. |
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| 16. |
- Nilsson, Harriet, et al.
(författare)
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Collection and X-ray microanalysis of airway surface liquid in the mouse using ion exchange beads.
- 2004
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Ingår i: Micron. - : Elsevier BV. - 0968-4328 .- 1878-4291. ; 35:8, s. 701-5
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Tidskriftsartikel (refereegranskat)abstract
- The airway surface liquid (ASL) is a thin layer of liquid covering the airway epithelium. The ionic composition of the ASL is assumed to be important for airway function and may be altered in diseases such as cystic fibrosis and exercise-induced asthma. A method for collection of ASL is presented in which the fluid is collected using small dextran ion-exchange beads. The beads are equilibrated with the ASL in a humidity chamber, collected under silicon oil, dried and analyzed by X-ray microanalysis. Analysis of standard beads prepared by exposure to different salt solutions shows that linear calibration lines can be obtained, but that beads absorb different elements to a different extent. The results show that the ASL in mice is hypotonic, and that the mucus component of the ASL has an elemental composition that is different from that of the periciliary fluid.
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| 17. |
- Petersson, Christoffer, 1973-, et al.
(författare)
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Assessing the interaction between Helicobacter pylori and human neutrophils by freeze-fracture replica labeling
- 2005
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Ingår i: Micron. - : Elsevier BV. - 0968-4328 .- 1878-4291. ; 36:6, s. 558-562
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Tidskriftsartikel (refereegranskat)abstract
- We recently introduced a freeze-fracture replica labeling method adapted to studies of bacterial envelopes. This report describes a further development of this detergent-digested freeze-fracture replica labeling technique, thus more exactly the conception of this explicit methodology for visualization of bacteria-host cell interactions. Our experimental model employs human neutrophils and the gastric pathogenic bacterium Helicobacter pylori. The phagocytic process performed by the neutrophils represents a crucial element of the host defense system against invading microorganisms, and by so doing, it allows direct observation of the interplay between bacteria and host cells at an ultrastructural level. The here launched methodology can be used as a tool to investigate the events taking place between pathogenic microbes and phagocytes, as well as for pinpoint targeting of other cell-cell communications in the field of cell biology. © 2005 Elsevier Ltd. All rights reserved.
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| 18. |
- Zachrisson, Jan, 1980-, et al.
(författare)
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A new EBSD based methodology for the quantitative characterisation of microstructures formed by displacive fcc–bcc transformations
- 2013
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Ingår i: Micron. - : Elsevier BV. - 0968-4328 .- 1878-4291. ; 45:February, s. 45-54
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Tidskriftsartikel (refereegranskat)abstract
- This work is concerned with a new methodology that can be used to quantify the degree to which grains in the microstructure are aligned in the form of packets. The methodology is based on a crystallographic definition of the term packet which is used to deduce the theoretically ideal misorientations of intra-packet grain boundaries. A misorientation distribution obtained from extensive EBSD mapping can thus be split into intra- and inter-packet misorientations and the corresponding fractions can be determined by integration. The theoretical framework of the methodology is explained and a step-by-step description of the procedure is given. Results from a trace analysis are provided to justify the assumptions made regarding habit plane and examples are included showing how the grain boundary network can be split into two separate parts, one for lath boundaries and the other for packet boundaries. Moreover, example weld metal microstructures along with the corresponding misorientation distributions as well as quantitative values of the microstructures are presented.
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| 19. |
- Leek, Håkan, et al.
(författare)
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Pilocarpine treatment of xerostomia in head and neck patients
- 2002
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Ingår i: Micron. - 0968-4328. ; 33:2, s. 153-155
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Forskningsöversikt (refereegranskat)abstract
- We studied the effect of pilocarpine hydrochloride, a parasympathicomimewtic agent, on major salivary gland output and subjective responses in 40 patients with salivary hypofunction. Pilocarpine increased salivary output or gave significant symptomatic relief in 21 of the 40 patients. The women fared better than the men. Side effects were uncommon, were generally mild, and caused no treatment interruption. These results indicate that pilocarpine is effective in relieving the signs and symptoms of postradiation xerostomia. (C) 2001 Elsevier Science Ltd. All rights reserved.
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| 20. |
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| 21. |
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| 22. |
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| 23. |
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| 24. |
- Ciancio, Regina, 1978, et al.
(författare)
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Electron backscattering diffraction and X-ray diffraction studies of interface relationships in Sr3Ru2O7/Sr2RuO4 eutectic crystals
- 2011
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Ingår i: Micron. - : Elsevier BV. - 0968-4328. ; 42:4, s. 324-329
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Tidskriftsartikel (refereegranskat)abstract
- Sr3Ru2O7/Sr2RuO4 eutectic system is investigated by electron backscattering diffraction (EBSD) and X-ray diffraction (XRD). The eutectic growth enables the solidification of the two phases in an ordered lamellar pattern extending along the growth direction, namely the b-axis direction. The eutectic material thus provides in the a-c plane two distinct interfaces having different microstructures with respect to the growth direction. Our analysis shows that, across the inplane c-axis direction (characterized by a poor lattice matching), the b-axis orientation is not constant at the individual interfaces, showing an orientation spread of about 5 degrees. However, across the in-plane a-axis direction (characterized by a good lattice matching), the b-axis orientation does not change within a few tenths of degree (about 0.25 degrees). Such information at nanoscale is also verified on a macroscopic level by standard XRD investigation.
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| 25. |
- Palmquist, Anders, 1977, et al.
(författare)
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A technique for evaluating bone ingrowth into 3D printed, porous Ti6Al4V implants accurately using X-ray micro-computed tomography and histomorphometry.
- 2017
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Ingår i: Micron. - : Elsevier BV. - 0968-4328. ; 94, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the application of X-ray micro-computed tomography (micro-CT) to accurately evaluate bone formation within 3D printed, porous Ti6Al4V implants manufactured using Electron Beam Melting (EBM), retrieved after six months of healing in sheep femur and tibia. All samples were scanned twice (i.e., before and after resin embedding), using fast, low-resolution scans (Skyscan 1172; Bruker micro-CT, Kontich, Belgium), and were analysed by 2D and 3D morphometry. The main questions posed were: (i) Can low resolution, fast scans provide morphometric data of bone formed inside (and around) metal implants with a complex, open-pore architecture?, (ii) Can micro-CT be used to accurately quantify both the bone area (BA) and bone-implant contact (BIC)?, (iii) What degree of error is introduced in the quantitative data by varying the threshold values?, and (iv) Does resin embedding influence the accuracy of the analysis? To validate the accuracy of micro-CT measurements, each data set was correlated with a corresponding centrally cut histological section. The results show that quantitative histomorphometry corresponds strongly with 3D measurements made by micro-CT, where a high correlation exists between the two techniques for bone area/volume measurements around and inside the porous network. On the contrary, the direct bone-implant contact is challenging to estimate accurately or reproducibly. Large errors may be introduced in micro-CT measurements when segmentation is performed without calibrating the data set against a corresponding histological section. Generally, the bone area measurement is strongly influenced by the lower threshold limit, while the upper threshold limit has little or no effect. Resin embedding does not compromise the accuracy of micro-CT measurements, although there is a change in the contrast distributions and optimisation of the threshold ranges is required.
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| 26. |
- Shah, Furqan A.
(författare)
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The many facets of micropetrosis-Magnesium whitlockite deposition in bisphosphonate-exposed human alveolar bone with osteolytic metastasis
- 2023
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Ingår i: Micron. - : Elsevier BV. - 0968-4328. ; 168
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Tidskriftsartikel (refereegranskat)abstract
- The lacuno-canalicular space of apoptotic osteocytes eventually becomes mineralised in vivo. This condition is known as micropetrosis and is a fundamental characteristic of ageing bone. Increased prevalence of such hypermineralised osteocyte lacunae is viewed as a structural marker of impaired bone function - both me-chanical and biological. Within the lacuno-canalicular space, mineralised apoptotic debris typically occurs as micrometre-sized, spherical nodules of magnesium-rich, carbonated apatite. Moreover, characteristically facetted, rhomboidal nodules of magnesium whitlockite [Mg-whitlockite; Ca18Mg2(HPO4)2(PO4)12] have been reported in human alveolar bone exposed to the bisphosphonate alendronate. This work provides supporting evidence for Mg-whitlockite formation in the alveolar bone of a 70-year-old male exposed to the bisphosphonate zoledronic acid to suppress osteolytic changes in skeletal metastasis. Backscattered electron scanning electron microscopy (BSE-SEM) revealed spherical and rhomboidal nodules within the lacuno-canalicular space. A variant of spherical nodules exhibited a fuzzy surface layer comprising radially extending acicular crystallites. The rhomboidal nodules ranged between-200 nm to-2.4 mu m across the widest dimension (652 +/- 331 nm). Micro-Raman spectroscopy and energy dispersive X-ray spectroscopy confirmed that rhomboidal nodules are compo-sitionally distinct from spherical nodules, exhibiting higher Mg content and lower Ca/P ratio. Formation of Mg-whitlockite within osteocyte lacunae is multifactorial in nature and suggests altered bone biomineralisation. Nevertheless, the underlying mechanism(s) and sequence of events remain poorly understood and warrant further investigation. The possibility to discriminate between carbonated apatite and Mg-whitlockite nodules within osteocyte lacunae, based on particle morphology, attests to the diagnostic potential of BSE-SEM with or without additional analyses of material composition.
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| 27. |
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| 28. |
- Yuvaraj, Jothi Kumar, et al.
(författare)
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Diversity of olfactory structures: A comparative study of antennal sensilla in Trichoptera and Lepidoptera
- 2018
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Ingår i: Micron. - : Elsevier BV. - 0968-4328. ; 111, s. 9-18
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Tidskriftsartikel (refereegranskat)abstract
- The antenna is the main sensory organ of insects, housing different types of sensilla dedicated to detect chemicalcues, motion, humidity and temperature. Sensilla are divided into different types based on their wall structureand morphology. Among the olfactory sensilla, there is an enormous variation in the numbers and morphologicaltypes present in different insect taxa. The reasons for this variation remain obscure, though there may be acorrelation between sensillum morphology and the characteristics of the stimulus that the olfactory sensoryneurons inside the sensillum detect. Here, we report the first comparative analysis of the morphology and ultrastructureof sensilla from Rhyacophila nubila (Rhyacophilidae: Trichoptera) and three species of Lepidoptera,Eriocrania semipurpurella (Eriocraniidae), Lampronia capitella (Prodoxidae), and Bicyclus anynana (Nymphalidae),which use different chemical types of pheromones. Our results, together with a thorough literature review,suggest a shift in major types of olfactory sensilla, from a high proportion of sensilla placodea or auricillica inTrichoptera and the most basal moth lineages (including Eriocraniidae), respectively, to sensilla trichodea in themore derived Lepidoptera (including Prodoxidae and the Ditrysia clade), which parallels the change in the typesof sex pheromones used.
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