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  • 1
    Language: English
    In: Biomacromolecules, 13 July 2015, Vol.16(7), pp.1938-47
    Description: The periodontium is the set of tissues responsible for tooth anchorage, and consists of interconnected layers of mineralized and unmineralized tissues (bone, ligament and cementum). The ligament-cementum interface is a particularly elegant example of biological control of mineralization and the controlling factors are poorly understood. Here we use a tissue-based in vitro model of mineralization, in which sections of demineralized mouse jaw remineralize with the same selectivity as found in vivo, to probe the molecular mechanism of control over collagen mineralization in the periodontium. Removal or enzymatic cleavage of noncollagenous proteins have very similar effects: a reduction in the rate of remineralization that is much more drastic in cementum than in dentin. The periodontal ligament does not mineralize within experimental parameters even after protein removal/digestion. Dephosphorylation results in a slight reduction in mineralization in dentin and cementum. Understanding the mechanisms controlling selective mineralization in the periodontium will help elucidate the molecular factors controlling collagen biomienralization, and provide inspiration for the development of scaffolds for regeneration of hard-soft tissue interfaces.
    Keywords: Calcification, Physiologic ; Collagen -- Metabolism ; Dental Cementum -- Physiology ; Dentin -- Physiology ; Extracellular Matrix Proteins -- Metabolism ; Periodontium -- Physiology
    ISSN: 15257797
    E-ISSN: 1526-4602
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  • 2
    Language: English
    In: Journal of Applied Physics, 15 April 2011, Vol.109(8)
    Description: In this paper various methods for studying p-n junctions in thin film solar cells are applied with the aim to localize and investigate defects on a microscopic scale. Different electron and ion beam characterization methods are introduced to determine the p-n junction position using two different examples from crystalline silicon on glass thin film technology. In a first example, planview and cross section electron beam induced current measurements revealed that oxygen rich columnar growth at textured substrates strongly disturbs the p-n junction. In a second example, diffusion from glass substrate is identified by ToF-SIMS to influence the electrical and structural characteristics of the thin Si layer resulting in a modified p-n junction. A model describing the formation of both defect structures is introduced.
    Keywords: Articles
    ISSN: 0021-8979
    E-ISSN: 1089-7550
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  • 3
    Language: English
    In: Journal of Applied Physics, 28 January 2013, Vol.113(4)
    Description: It had been shown already earlier by X-ray microanalysis that, in positions of defect-induced junction breakdown in industrial multicrystalline (mc) silicon solar cells, iron-containing precipitates may exist. However, the nature of these precipitates was unknown so far. Here, in such positions, scanning transmission electron microscopy was performed after defect-controlled focused ion beam preparation. First of all, the defect site was localized by microscopic reverse-bias electroluminescence imaging. The high accuracy of following FIB target preparation (〈0.1  μ m necessary) was obtained by both, electron beam-induced current imaging and secondary electron material contrast observation during the slice-by-slice milling of the TEM specimen. By nano-beam electron diffraction (NBED) and energy dispersive spectroscopy, the iron-containing precipitates were identified as α-type FeSi 2 needles, about 30 nm in diameter and several μ m in length. The FeSi 2 needles show preferential orientation relationships to the silicon matrix and are located in terraced large-angle grain boundaries. Elaborate nano-beam electron diffraction investigation of the FeSi 2 revealed orientation relationships of the precipitate to the silicon, which confirm earlier investigations on monocrystalline material. A model explaining the defect-induced breakdown mechanism due to rod-like α-FeSi 2 precipitates is presented.
    Keywords: Articles
    ISSN: 0021-8979
    E-ISSN: 1089-7550
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  • 4
    Language: English
    In: Forest Ecology and Management, Nov 15, 2013, Vol.308, p.76(14)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.foreco.2013.07.043 Byline: A. Lausch, M. Heurich, D. Gordalla, H.-J. Dobner, S. Gwillym-Margianto, C. Salbach Abstract: acents The study aimed to predict outbreak potential of bark beetle based on detection different vitality stages of spruce. acents Hyperspectral data are able to detect changes in biochemical-biophysical vegetation characteristics in spruce forest. acents Important spectral information for derivation vitality status of spruce are 450-890nm. acents We found a classification accuracy of 64.04% between C3 - infestation 2010 and C5 - healthy. acents Hyperspectral data with grain of 4m contain relevant information to estimate differences in vitality of spruce than 7m.
    Keywords: Remote Sensing -- Methods ; Bark Beetles -- Methods ; Agricultural Pests -- Methods
    ISSN: 0378-1127
    Source: Cengage Learning, Inc.
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  • 5
    Language: English
    In: Ecological Modelling, Jan 10, 2015, Vol.295, p.5(13)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ecolmodel.2014.09.018 Byline: Angela Lausch, Andreas Schmidt, Lutz Tischendorf Abstract: * Data mining are the only way to extract knowledge from complex and large data. * Environmental research is an interdisciplinary research. * Therefore classical data mining approaches are sectoral and insufficient. * Linked open data is a new approach for extract knowledge in interdisciplinary data. Author Affiliation: Department of Computational Landscape Ecology, Helmholtz Centre for Environmental Research - UFZ, Permoserstr, 15/D-04318, Leipzig, Germany
    Keywords: Data Mining
    ISSN: 0304-3800
    Source: Cengage Learning, Inc.
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  • 6
    In: Journal of Applied Microbiology, June 2014, Vol.116(6), pp.1521-1530
    Description: To purchase or authenticate to the full-text of this article, please visit this link: http://onlinelibrary.wiley.com/doi/10.1111/jam.12492/abstract Byline: V. Lausch, P. Hermann, M. Laue, N. Bannert Keywords: detection; electron microscopy; tip-enhanced Raman spectroscopy; rapid methods Abstract Aims Successive application of negative staining transmission electron microscopy (TEM) and tip-enhanced Raman spectroscopy (TERS) is a new correlative approach that could be used to rapidly and specifically detect and identify single pathogens including bioterrorism-relevant viruses in complex samples. Our objective is to evaluate the TERS-compatibility of commonly used electron microscopy (EM) grids (sample supports), chemicals and negative staining techniques and, if required, to devise appropriate alternatives. Methods and Results While phosphortungstic acid (PTA) is suitable as a heavy metal stain, uranyl acetate, paraformaldehyde in HEPES buffer and alcian blue are unsuitable due to their relatively high Raman scattering. Moreover, the low thermal stability of the carbon-coated pioloform film on copper grids (pioloform grids) negates their utilization. The silicon in the cantilever of the silver-coated atomic force microscope tip used to record TERS spectra suggested that Si-based grids might be employed as alternatives. From all evaluated Si-based TEM grids, the silicon nitride (SiN) grid was found to be best suited, with almost no background Raman signals in the relevant spectral range, a low surface roughness and good particle adhesion properties that could be further improved by glow discharge. Conclusions Charged SiN grids have excellent particle adhesion properties. The use of these grids in combination with PTA for contrast in the TEM is suitable for subsequent analysis by TERS. Significance and Impact of the Study The study reports fundamental modifications and optimizations of the negative staining EM method that allows a combination with near-field Raman spectroscopy to acquire a spectroscopic signature from nanoscale biological structures. This should facilitate a more precise diagnosis of single viral particles and other micro-organisms previously localized and visualized in the TEM.
    Keywords: Detection ; Electron Microscopy ; Tip‐Enhanced Raman Spectroscopy ; Rapid Methods
    ISSN: 1364-5072
    E-ISSN: 1365-2672
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  • 7
    Language: English
    In: Advanced Functional Materials, 18 October 2013, Vol.23(39), pp.4906-4912
    Description: Collagen biomineralization is a complex process and the controlling factors at the molecular level are still not well understood. A particularly high level of spatial control over collagen mineralization is evident in the anchorage of teeth to the jawbone by the periodontal ligament. Here, unmineralized ligament collagen fibrils become mineralized at an extremely sharp mineralization front in the root of the tooth. A model of collagen biomineralization based on demineralized cryosections of mouse molars in the bone socket is presented. When exposed to metastable calcium and phosphate‐containing solutions, mineral re‐deposits selectively into the natively mineralized tissues with high fidelity, demonstrating that the extracellular matrix retains sufficient information to control the rate of mineralization at the tissue level. While solutions of simulated bodily fluid produce amorphous calcium phosphate within the tissue section, a more highly supersaturated solution stabilized with polyaspartic acid produces oriented, crystalline calcium phosphate with diffraction patterns consistent with hydroxyapatite. The model thus replicates both spatial control of mineral deposition, as well as the matrix‐mineral relationships of natively mineralized collagen fibrils, and can be used to elucidate roles of specific biomolecules in the highly controlled process of collagen biomineralization. This knowledge will be critical in the design of collagen‐based scaffolds for tissue engineering of hard‐soft tissue interfaces. is presented, based on deposition of mineral from metastable calcium and phosphate‐containing solutions into demineralized sections of mouse periodontal tissues. Mineral deposits selectively into natively mineralized tissues of the tooth root with high fidelity, mimicking the pattern of mineralization in vivo, and demonstrating that the extracellular matrix of these tissues retains sufficient information to control collagen mineralization.
    Keywords: Biomineralization ; Biomimetics ; Hydroxyapatite ; Composite Materials ; Connective Tissues
    ISSN: 1616-301X
    E-ISSN: 1616-3028
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  • 8
    Language: English
    In: Gait & Posture, September 2013, Vol.38(4), pp.843-846
    Description: The foot posture index (FPI) is a commonly used method to quantify standing foot posture. No normative data have, however, been presented to establish the range of a normal difference and asymmetrical differences between FPI score in the right foot and in the left foot. The purpose of the present study was to establish normative values for the difference between the FPI scores across the two feet. Among 930 healthy adults, FPI score was quantified in both feet. Difference between the two feet was calculated as FPI score on the right foot minus the FPI score on the left foot. Based on a normal distribution of the differences, asymmetry was defined as values below or above one standard deviation (SD) from the mean. Severe asymmetry was below and above ±2 SD from the mean. Normal difference was defined as the range between ±1 SD. A reference range for normal difference in FPI score between left foot and right foot was −2 to +2. Asymmetry scores ranged from −2 to −4 and +2 to +4, while severe asymmetry was 〈−4 and 〉4. Normative values for the difference between FPI scores in right foot and left foot have been presented from a large sample of healthy adults. These normative values can be used to identify a normal difference or an asymmetrical difference in foot posture across feet in one individual.
    Keywords: Asymmetry ; Foot Posture Index ; Normative Values ; Foot ; Medicine ; Anatomy & Physiology
    ISSN: 0966-6362
    E-ISSN: 1879-2219
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  • 9
    Language: English
    In: Forest Ecology and Management, 2011, Vol.261(2), pp.233-245
    Description: ▶ infestation over an 18-year study period goes through different phases. ▶ The spread of the is affected by a complex interplay between active population factors and habitat factors with varying degrees of importance at individual phases. ▶ The importance of individual habitat variables and the combinations of these variables vary to different extents. ▶ There are no monocausal correlations between individual habitat factors and the spread of the over the entire eighteen years model period. The relationship between abiotic and biotic factors and the spread of the European spruce bark beetle, (L.), was investigated at a landscape level over a model period of 18 years in the Bavarian Forest National Park in Germany. Deadwood areas – where – caused tree mortality of 100% – were photographed annually using Color-infrared aerial photography and digitally recorded in vector form. Thirty-two static and dynamic habitat variables were quantitatively determined using spatial pattern analysis and geostatistics from 1990 to 2007 at the landscape scale. The importance of the presence of deadwood areas for thirty-two habitat variables for the occurrence of the bark beetle was quantitatively recorded using an Ecological Niche Factor Analysis (ENFA). It was shown over a long model period that the intensity of the bark beetle infestation went through different phases over the 18-year study period. No mono-causal correlations could be found between individual habitat factors and the spread of the bark beetle over the entire model period. On the one hand, these findings underline the complexity of the system, on the other hand, this could be interpreted as a possible explanation for conclusions drawn by previous studies that differ from each other. The importance of individual habitat variables and the combinations of variables varied to different extents within these phases. An examination of the cumulative importance of the habitat demonstrated that the biological structural variables such as the distance from the site of the previous year's infestation, the area and the perimeter of the infested areas from the previous year are of great importance for the incidence of the bark beetle, but not across all years. Of equal significance for assessing the size of the area and the distance of the deadwood areas from the sites of the previous year's infestation are the size of the areas, the perimeter of the deadwood areas and the proximity index. An evaluation of the stages of forest succession showed that cumulatively, a short distance between the infested areas and the forest areas with conifers in the early stages of growth was an equally important habitat factor from 1990 to 2007. By quantitatively recording habitat factors that are significant for the spread of the bark beetle it may help predict areas that are at risk and thus to develop suitable management strategies to minimise or stop the spread and the effect of the bark beetle.
    Keywords: Bark Beetle ; Ecological Niche Factor Analysis (Enfa) ; Environmental Factors ; Infestations ; Ips Typographus (L.) ; Landscape Level ; Outbreak Risk ; Forestry ; Biology
    ISSN: 0378-1127
    E-ISSN: 1872-7042
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  • 10
    Language: English
    In: Journal of Applied Physics, 21 November 2013, Vol.114(19)
    Description: In this contribution, a new method to determine the crystal orientation with the example of chemical treated silicon wafers by means of optical microscopy has been demonstrated. The introduced procedure represents an easy method to obtain all relevant parameters to describe the crystal structure of the investigated material, i.e., the crystal grain orientation and the grain boundary character. The chemical treatment is a standard mono-texture for solar cells, well known in the solar industry. In general, this concept can also be applied to other crystalline materials, i.e., GaAs, SiC, etc., the only thing that needs to be adjusted is the texturing method to reveal specific crystal planes and the calculation model. In conclusion, an application of this method is shown with the example of the defect classification of recombination active defects in mc-Si solar cell. The introduced method demonstrates a simple and quick opportunity to improve the crystallization process and the quality of electronic devices by means of an optical microscope and a chemical treatment of the material.
    Keywords: Articles
    ISSN: 0021-8979
    E-ISSN: 1089-7550
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