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  • 1
    Language: English
    In: Surgical and Radiologic Anatomy, 2011, Vol.33(2), pp.123-128
    Description: Byline: Afshin Teymoortash (1), Stella Hamzei (1), Tobias Murthum (1), Behfar Eivazi (1), Ingo Kureck (2), Jochen A. Werner (1) Keywords: Temporal bone; Radiological anatomy; Computed tomography; Digital volume tomography; Visualization Abstract: Purpose The aim of the present study was to analyze the diagnostic value of some temporal bone structures, e.g., ossicular chain, with digital volume tomography (DVT) compared with computed tomography (CT). Methods Radiological imaging for presentation structures of the temporal bone were performed by DVT and CT. Axial and coronal scans in vitro examinations were performed in 38 human temporal bones. 43 structures were defined. The frequency of visualization of these anatomic structures were studied and statistically analyzed. Results In the present study there was a higher significance of identified structures in DVT. In 15 (34.9%) temporal bone specimens defined structures were found equally in DVT and CT scans of axial images and 12 (27.9%) of coronal images. However, 9 structures (20.1%) of axial scans and 5 structures (11.6%) of coronal scans could be identified statistically significantly (P 〈 0.05) more often in DVT than in CT. Conclusion Anatomical structures of the temporal bone can be identified in higher significance in DVT than in CT scans. Author Affiliation: (1) Department of Otolaryngology, Head and Neck Surgery, Philipp University of Marburg, Deutschhausstr. 3, 35037, Marburg, Germany (2) Department of Neuroradiology, Philipp University of Marburg, Marburg, Germany Article History: Registration Date: 05/08/2010 Received Date: 14/09/2009 Accepted Date: 05/08/2010 Online Date: 13/08/2010
    Keywords: Temporal bone ; Radiological anatomy ; Computed tomography ; Digital volume tomography ; Visualization
    ISSN: 0930-1038
    E-ISSN: 1279-8517
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  • 2
    Language: English
    In: Science of the Total Environment, 01 April 2013, Vol.449, pp.63-70
    Description: Increasing arsenic concentrations in freshwater ecosystems is of global concern. Processes affecting arsenic fluxes in catchments are known. These processes are in turn controlled by the underlying geology and air pollution history. In contrast to the knowledge on catchment processes less is known about the hydrochemical processes controlling the fixation/remobilization of arsenic within lakes and artificial reservoirs. Consequently, we examined a reservoir system in the Ore Mts. (Germany) regarding its sink and source potentials affecting arsenic fluxes. This area was faced with heavy deposition inputs from coal burning based acid rain until the beginning of the 1990s. Hereafter concentrations of sulfate and nitrate in runoff waters decreased, whereas dissolved organic carbon (DOC) concentrations are still increasing. Along with this, arsenic concentrations in the water discharge from the catchments increase. Our results reveal that the sediments of the investigated reservoir system contain high inventories of arsenic in association with ferric and organic phases. A nitrate deficit dependent arsenic release is suggested. It is indicated that arsenic release from the reservoir sediments may be controlled by water nitrate concentration, which in turn is dependent on the nitrate concentration in the runoff water from the catchment. ► We examine increasing dissolved arsenic in water reservoirs. ► Arsenic release from sediments was controlled by decreasing water nitrate concentration. ► Basin sediment arsenic was found in ferric and humic matter. ► A long term trend of arsenic in water is negatively related to nitrate.
    Keywords: Arsenic Fluxes ; Iron ; Metalloid ; Nitrate ; Sediments ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 3
    Language: English
    In: Science, March 15, 2013, Vol.339(6125), p.1298(5)
    Description: Silicatein-[alpha] is responsible for the biomineralization of silicates in sponges. We used silicatein-[alpha] to guide the serf-assembly of calcite "spicules" similar to the spicules of the calcareous sponge Sycon sp. The self-assembled spicules, 10 to 300 micrometers ([micro]m) in length and 5 to 10 [micro]m in diameter, are composed of aligned calcite nanocrystals. The spicules are initially amorphous but transform into calcite within months, exhibiting unusual growth along [100]. They scatter x-rays like twinned calcite crystals. Whereas natural spicules evidence brittle failure, the synthetic spicules show an elastic response, which greatly enhances bending strength. This remarkable feature is linked to a high protein content. With nano-thermogravimetric analysis, we measured the organic content of a single spicule to be 10 to 16%. In addition, the spicules exhibit waveguiding properties even when they are bent. 10.1126/science.1216260
    Keywords: Carbonates -- Analysis ; Calcite Crystals -- Analysis
    ISSN: 0036-8075
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  • 4
    In: Environmental Science: Processes & Impacts, 2013, Vol.15(12), pp.2297-2303
    Description: Metal and metalloid mobilization processes within seepage water are of major concern in a range of water reservoir systems. The mobilization process of arsenic and heavy metals within a dam and sediments of a drinking water reservoir was investigated. Principle component analysis (PCA) on time series data of seepage water showed a clear positive correlation of arsenic with iron and DOC (dissolved organic carbon), and a negative correlation with nitrate due to respiratory processes. A relationship of reductive metal and metalloid mobilization with respiration of old carbon was shown. The system is influenced by sediment layers as well as a recent DOC input from degraded ombrotrophic peatbogs in the catchment area. The isotopic composition ( 12 C, 13 C and 14 C) of DOC is altered along the path from basin to seepage water, but no significant changes in structural parameters (LC-OCD-OND, FT-IR) could be seen. DIC (dissolved inorganic carbon) in seepage water partly originates from respiratory processes, and a higher relationship of it with sediment carbon than with the DOC inventory of infiltrating water was found. This study revealed the interaction of respiratory processes with metal and metalloid mobilization in sediment water flows. In contrast to the presumption that emerging DOC via respiratory processes mainly controls arsenic and metal mobilization it could be shown that the presence of aged carbon compounds is essential. The findings emphasize the importance of aged organic carbon for DOC, DIC, arsenic and metal turnover.
    Keywords: Sediment Pollution ; Arsenic ; Water Reservoirs ; Dissolved Inorganic Carbon ; Respiration ; Organic Carbon ; Dissolved Organic Carbon ; Seepages ; Metabolism ; Metals ; Arsenic ; Water Flow ; Respiration ; Organic Carbon ; Time Series Analysis ; Sediments ; Rare Earth Elements ; Carbon ; Dissolved Organic Carbon ; Seepages ; Drinking Water ; Reservoirs ; Iron ; Metals ; Arsenic ; Carbon ; Respiration ; Organic Carbon ; Flow Discharge ; Seepage ; Reservoirs ; Sediments ; Metals ; Arsenic ; Carbon ; Respiration ; Organic Carbon ; Flow Discharge ; Seepage ; Reservoirs ; Sediments ; Renewable Resources-Water ; Water Treatment and Distribution ; Water Resources and Supplies ; Characteristics, Behavior and Fate;
    ISSN: 2050-7887
    E-ISSN: 2050-7895
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  • 5
    Language: English
    In: Journal of Biological Chemistry, 10/10/1997, Vol.272(41), pp.25474-25482
    Description: The biosynthesis of gallic acid was studied in cultures of the fungus Phycomyces blakesleeanus and in leaves of the tree Rhus typhina. Fungal cultures were grown with [1-13C]glucose or with a mixture of unlabeled glucose and [U-13C6]glucose. Young leaves of R. typhina were kept in an incubation chamber and were supplied with a solution containing a mixture of unlabeled glucose and [U-13C6]glucose via the leaf stem. Isotope distributions in isolated gallic acid and aromatic amino acids were analyzed by one-dimensional 1H and 13C NMR spectroscopy. A quantitative analysis of the complex isotopomer composition of metabolites was obtained by deconvolution of the 13C13C coupling multiplets using numerical simulation methods. This approach required the accurate analysis of heavy isotope chemical shift effects in a variety of different isotopomers and the analysis of long range 13C13C coupling constants. The resulting isotopomer patterns were interpreted using a retrobiosynthetic approach based on a comparison between the isotopomer patterns of gallic acid and tyrosine. The data show that both in the fungus and in the plant all carbon atoms of gallic acid are biosynthetically equivalent to carbon atoms of shikimate. Notably, the carboxylic group of gallic acid is derived from the carboxylic group of an early intermediate of the shikimate pathway and not from the side chain of phenylalanine or tyrosine. It follows that the committed precursor of gallic acid is an intermediate of the shikimate pathway prior to prephenate or arogenate, most probably 5-dehydroshikimate. A formation of gallic acid via phenylalanine, the lignin precursor, caffeic acid, or 3,4, 5-trihydroxycinnamic acid can be ruled out as major pathways in the fungus and in young leaves of R. typhina. The incorporation of uniformly 13C-labeled glucose followed by quantitative NMR analysis of isotopomer patterns is suggested as a general method for biosynthetic studies. As shown by the plant experiment, this approach is also applicable to systems with low incorporation rates.
    Keywords: Chemistry ; Anatomy & Physiology;
    ISSN: 0021-9258
    E-ISSN: 1083-351X
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  • 6
    Language: English
    In: International Journal of Hydrogen Energy, 05 June 2014, Vol.39(17), pp.9447-9456
    Description: One of the main goals for improvement of high-temperature polymer electrolyte fuel cells (HT-PEFCs) is the increase of the fuel cell performance under different operating conditions. We investigated the correlation between operating conditions and structural changes in the electrodes by means of in-situ through-plane synchrotron X-ray radiography. From the radiographs it is possible to clearly distinguish between the electrode crack structure beneath the ribs and beneath the channels of the flow field. We present a statistical method to analyze these crack structures. For this purpose a ‘radar’ method was developed in order to obtain the width of the cracks at many different locations and the distribution of crack widths. We found a different behavior of cracks located beneath the ribs and beneath the channels and an influence of the operating conditions on local regions of the crack structure.
    Keywords: Ht-Pefc ; Electrode Crack Structure ; Crack Width ; Synchrotron X-Ray Radiography ; Engineering
    ISSN: 0360-3199
    E-ISSN: 1879-3487
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  • 7
    In: Journal of the American Chemical Society, June 17, 1992, Vol.114(13), p.5048(7)
    Description: Ultraviolet irradiation of 4-acetoxy-6-((E)-2-phenylethenyl)-2H-pyran-2-one resulted in the (2pi + 2pi) dimers rel-(1R,6S,7S,8S)-5-acetoxy-7-phenyl-8- (4-acetoxy-2-oxo-2H-pyran-6-yl)-1-((E)-2-phenylethenyl)-2-oxabicyclo-(4.2.0) octa-4-en-3-one and r-1,t-3-bis(4-acetoxy-2-oxo-2H-pyran-6-yl)-c-2,t-4- diphenylcyclobutane. This dichotomy is the result of the complexes crystal topology which consists of two topochemically relevant reaction centers possessing two monomers about the inversion center. On the other hand, 4-acetoxy-6-((E)-2-phenylethenyl)-2H-1,5-oxazin-2-one exhibited photostability and gave off monomer fluorescence emissions.
    Keywords: Electrons -- Research ; Ketones -- Research ; Molecular Structure -- Research
    ISSN: 0002-7863
    E-ISSN: 15205126
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  • 8
    In: Analytical Chemistry, Sept 15, 1998, Vol.70(18), p.3892(6)
    Keywords: Optical Detectors -- Design And Construction ; Chemical Detectors -- Design And Construction ; Luminescence -- Measurement
    ISSN: 0003-2700
    E-ISSN: 15206882
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  • 9
    Language: English
    In: Water, Air, & Soil Pollution, 2017, Vol.228(8), pp.1-16
    Description: Arsenic concentrations in a drinking water reservoir system in the Eastern Ore mountains (Osterzgebirge, Germany) were observed over a 17-year period. The region experienced an environmental change during the past 20 years with decreasing acid, sulphur and nitrogen deposition and a recovering vitality of forested catchment sites. An increase of the arsenic content in the reservoir waters during that change was observed. This was caused by a diminished nitrate supply leading to lower redox potential in the sediments favouring sediment arsenic release. The recent annual cycle in the Altenberg reservoir water arsenic concentration was found to be independent from artificial aeration of the hypoxic hypolimnion during the summer stratification. However, we found a strong seasonal dependent change in water As concentration, with a maximum in autumn and a minimum in spring. The low productive system is driven by peat derived organic matter. For the recent arsenic catchment yield coherencies to dissolved organic carbon export and runoff intensity were found, indicating rising arsenic loads due to climate-related soil organic matter destabilization. Thus, in the reservoir system, both dry and wet climate conditions can increase the water As concentrations due to an internal arsenic release and a catchment arsenic import.
    Keywords: Acidification recovery ; Arsenic fluxes ; DOC ; Global change ; Nitrate ; Precipitation extremes
    ISSN: 0049-6979
    E-ISSN: 1573-2932
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  • 10
    Language: English
    In: International Journal of Hydrogen Energy, 09 July 2013, Vol.38(20), pp.8448-8460
    Description: A novel, realistic 3D model is developed describing the microstructure of non-woven GDL in PEMFC which consists of strongly curved and non-overlapping fibers. The model is constructed by a two-stage procedure. First we introduce a system of random fibers, where the locations of their midpoints are modeled by a 3D Poisson point process and the fibers themselves by random 3D polygonal tracks which represent single fibers in terms of multivariate time series. Secondly, we transform the random fiber system into a system of non-overlapping fibers using an iterative method leaned on the so-called force-biased algorithm. The model is validated by comparing transport-relevant characteristics computed for experimental 3D synchrotron data, and for realizations sampled from the stochastic microstructure model. Finally, we suggest a model for the spatial distribution of PTFE, a wet-proofing agent often used in non-woven GDL, and combine this PTFE model with our new microstructure model for non-woven GDL.
    Keywords: Fiber-Based Material ; Stochastic Modeling ; Vectorial Autoregression ; Non-Woven ; Ptfe ; Synchrotron Tomography ; Engineering
    ISSN: 0360-3199
    E-ISSN: 1879-3487
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