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  • Springer  (45)
  • Institute of Physics  (40)
  • 1
    Electronic Resource
    Electronic Resource
    The Relation Between Trabecular Bone Strength and Bone Mineral Density Assessed by Dual Photon and Dual Energy X-Ray Absorptiometry in the Proximal Tibia (1996)
    Springer
    Calcified tissue international 59 (1996), S. 311-314 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Trabecular bone strength — Bone mineral density — Proximal tibia.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. The feasibility of two noninvasive methods [dual photon absorptiometry (DPA) and dual energy X-ray absorptiometry (DXA)] for prediction in vivo of local variations of trabecular bone strength within the proximal tibia was evaluated in 14 cadaveric knees. Trabecular bone strength was measured using an osteopenetrometer and from destructive compression tests performed on bone cylinders, thus measuring the penetration strength and ultimate strength in the medial, lateral, and central part of the tibial bone specimens. Linear regression analysis showed significant relations between BMD measured by DPA (r2= 72%) or DXA (r2= 73%) and ultimate strength. Even closer relations between BMD (DPA: r2= 80%, DXA r2= 81%) and penetration strength of trabecular bone were found. We conclude that DPA and DXA are suitable methods for evaluation in vivo of local variations in trabecular bone strength within the proximal tibia, and could easily be performed preoperatively before insertion of total knee arthroplasty.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900131
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  • 2
    Electronic Resource
    Electronic Resource
    Hydrocarbon synthesis over sulfide catalysts. Break-down of the Anderson-Schulz-Flory distribution (1995)
    Springer
    Topics in catalysis 2 (1995), S. 207-221 
    Details
    ISSN: 1572-9028
    Keywords: hydrocarbon synthesis ; methanation ; ethanation ; sulfide catalysts ; hydrocarbon distribution ; Anderson-Schulz-Flory distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of hydrocarbon synthesis over sulfide-based catalysts was studied. It appears that the formation of methane follows another reaction path than that of higher hydrocarbons. This might explain the very high selectivities for ethane and propane as compared with conventional Fischer-Tropsch catalysts. Reference is made to testing of the catalysts at industrial conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01491968
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  • 3
    Electronic Resource
    Electronic Resource
    Enzymatic activity in the activated-sludge floc matrix (1995)
    Springer
    Applied microbiology and biotechnology 43 (1995), S. 755-761 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The enzymatic activity of activated sludge was investigated with special emphasis on the localization of the enzymes in the sludge floc matrix. Activated sludge from an advanced activated-sludge treatment plant, performing biological N and P removal, was used. An enzymatic fingerprint was established using a panel of six different enzymes. The fingerprint revealed peptidase as the most dominating specific enzyme tested. By monitoring sludge bulk enzymatic activity over a 3-month period using fluorescein diacetate as an enzyme substrate, considerable variations in activity were observed even over short periods (a few days). The variation in esterase activity was to some extent correlated to the presence of humic compounds in the sludge, but not to the sludge protein content. Comparison of full sludge enzyme activity to the activity of a batch-grown sludge culture indicated that enzymes accumulated in sludge flocs. A large proportion of the exoenzymes were immobilized in the sludge by adsorption in the extracellular polymeric substances (EPS) matrix. This was demonstrated by extraction of EPS from the activated sludge using cation exchange. Contemporary to the release of EPS a very large fraction of the exoenzymes was released into the water. This showed that the exoenzymes should be considered to be an integrated part of the EPS matrix rather than as direct indicators of the microbial activity or biomass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00164784
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  • 4
    Electronic Resource
    Electronic Resource
    Enzymatic activity in the activated-sludge floc matrix (1995)
    Springer
    Applied microbiology and biotechnology 43 (1995), S. 755-761 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The enzymatic activity of activated sludge was investigated with special emphasis on the localization of the enzymes in the sludge floc matrix. Activated sludge from an advanced activated-sludge treatment plant, performing biological N and P removal, was used. An enzymatic fingerprint was established using a panel of six different enzymes. The fingerprint revealed peptidase as the most dominating specific enzyme tested. By monitoring sludge bulk enzymatic activity over a 3-month period using fluorescein diacetate as an enzyme substrate, considerable variations in activity were observed even over short periods (a few days). The variation in esterase activity was to some extent correlated to the presence of humic compounds in the sludge, but not to the sludge protein content. Comparison of full sludge enzyme activity to the activity of a batch-grown sludge culture indicated that enzymes accumulated in sludge flocs. A large proportion of the exoenzymes were immobilized in the sludge by adsorption in the extracellular polymeric substances (EPS) matrix. This was demonstrated by extraction of EPS from the activated sludge using cation exchange. Contemporary to the release of EPS a very large fraction of the exoenzymes was released into the water. This showed that the exoenzymes should be considered to be an integrated part of the EPS matrix rather than as direct indicators of the microbial activity or biomass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00164784
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  • 5
    Electronic Resource
    Electronic Resource
    Changes in the composition of extracellular polymeric substances in activated sludge during anaerobic storage (1996)
    Springer
    Applied microbiology and biotechnology 44 (1996), S. 823-830 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Changes in the chemical composition of organic compounds in total activated sludge, activated sludge extracellular polymeric substances (EPS), and sludge bulk water during anaerobic storage (12 days) were studied. The background for the study was that anaerobic storage of activated sludge, which often takes place at wastewater treatment plants before dewatering, causes a deterioration of the dewaterability. The reasons are not known at present, but may be related to changes in exopolymer composition of the flocs. The results showed that a fast decrease in total sludge protein and carbohydrate took place within 3 days of anaerobic storage as a result of degradation processes, which accounted for approximately 20% of the organic fraction. The amount of uronic acids and humic compounds remained almost constant in the sludge. The EPS were extracted from the floc matrix using a cationexchange resin. In the EPS matrix a similar initial (2–3 days) degradation of proteins and carbohydrate took place, whereas the content of DNA and uronic acids showed minor changes. The extractability of humic compounds increased during the first 3 days of storage. No changes in extractability of the carbohydrate were observed. A fraction of the EPS protein was found to be difficult to extract but was observed to be degraded during the anaerobic storage. The EPS composition was further characterized by high-performance size-exclusion chromatography analysis obtained by on-line UV detection and post-column detection of proteins, carbohydrates, humic compounds and DNA. Four fractions of polysaccharides were found, of which only one was responsible for the decrease in the carbohydrate content observed with storage time. The fraction was presumably of low molecular mass. Humic compounds and volatile fatty acids (acetate and propionate) were released to the bulk water from the flocs during the storage. A possible mechanism to explain the reduced dewaterability developed during anaerobic storage, partly because of the observed changes in EPS, is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00178625
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  • 6
    Electronic Resource
    Electronic Resource
    Changes in the composition of extracellular polymeric substances in activated sludge during anaerobic storage (1996)
    Springer
    Applied microbiology and biotechnology 44 (1996), S. 823-830 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Changes in the chemical composition of organic compounds in total activated sludge, activated sludge extracellular polymeric substances (EPS), and sludge bulk water during anaerobic storage (12 days) were studied. The background for the study was that anaerobic storage of activated sludge, which often takes place at wastewater treatment plants before dewatering, causes a deterioration of the dewaterability. The reasons are not known at present, but may be related to changes in exopolymer composition of the flocs. The results showed that a fast decrease in total sludge protein and carbohydrate took place within 3 days of anaerobic storage as a result of degradation processes, which accounted for approximately 20% of the organic fraction. The amount of uronic acids and humic compounds remained almost constant in the sludge. The EPS were extracted from the floc matrix using a cation-exchange resin. In the EPS matrix a similar initial (2–3 days) degradation of proteins and carbohydrate took place, whereas the content of DNA and uronic acids showed minor changes. The extractability of humic compounds increased during the first 3 days of storage. No changes in extractability of the carbohydrate were observed. A fraction of the EPS protein was found to be difficult to extract but was observed to be degraded during the anaerobic storage. The EPS composition was further characterized by high-performance size-exclusion chromatography analysis obtained by on-line UV detection and post-column detection of proteins, carbohydrates, humic compounds and DNA. Four fractions of polysaccharides were found, of which only one was responsible for the decrease in the carbohydrate content observed with storage time. The fraction was presumably of low molecular mass. Humic compounds and volatile fatty acids (acetate and propionate) were released to the bulk water from the flocs during the storage. A possible mechanism to explain the reduced dewaterability developed during anaerobic storage, partly because of the observed changes in EPS, is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00178625
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  • 7
    Electronic Resource
    Electronic Resource
    Digital voltage vector control with adaptive parameter tuning (1990)
    Springer
    Electrical engineering 74 (1990), S. 69-77 
    Details
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Dieser Artikel beschreibt ein vollständiges digitales Steuerungssystem für Standard-Induktionsmotoren. Ein neues Wechselrichter-Spannungsvektor-Steuerungssystem für Hochfrequenzschaltung und ein prädiktives Frequenz-Spannungs-Steuerungssystem, das den Bedarf von Tacho-Rückmeldung eliminiert, ist entwickelt worden. Außerdem wurde ein selbsteinstellendes Parameteranpassungsverfahren entwickelt. Dieses Verfahren nimmt Rücksicht auf die große Variation der elektrischen Parameter verschiedener Fabrikate von Standard-Induktionsmotoren. Für Überwachungszwecke sind Schaltschutz, Minimierung des Schaltverlustes und anwendungsspezifische integrierte Schaltungen vielfach benutzt worden. Die stationären und dynamischen Verhältnisse der Antriebe werden dokumentiert und durch Simulationen verglichen.
    Notes: Contents This paper describes a completely digital control system for standard induction motors. A new inverter voltage vector control system for high frequency switching has been designed, and a predictive frequency-voltage control system that eliminates the need of tacho feedback has been developed. In addition, an adaptive parameter tuning method has been developed. This method takes the large variation in electrical parameters of standard induction motors of different manufactures into account. For control purposes, switch protection and switch loss minimizing, custom designed application specific integrated circuits have been used extensively. Steady-state and dynamic performances of the drive are documented and compared to simulations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01573233
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of geochemical conditions on fate of organic compounds in groundwater (1996)
    Springer
    Environmental geology 27 (1996), S. 335-346 
    Details
    ISSN: 1432-0495
    Keywords: Organic compounds ; Groundwater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract In situ microcosms were successfully used to study the degradation of a range of organic compounds in two pristine aquifers, one aerobic (Vejen) and one anaerobic (Villa Farm). Degradation and sorption behavior in the laboratory column microcosms packed with Villa Farm sediment was very similar to that in the in situ microcosms. However, when the columns were packed with quartz and equilibrated with aerated Villa Farm groundwater, behavior mirrored that at Vejen, indicating that oxygen rather than sediment or groundwater composition was the critical parameter. The aromatic and polyaromatic compounds (benzene, toluene,o-xylene, naphthalene) degraded under aerobic conditions only. The organochlorine compounds (trichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane, 1,4-dichlorobenzene and 1,2-dichlorobenzene) showed little or no sign of degradation either aerobically or anaerobically. Interpretation of the data was complicated by strong sorption to the Villa Farm sediment but tetrachloromethane, nitrobenzene, ando-nitrophenol appeared to degrade under anaerobic conditions only. Phenol degraded rapidly under both sets of conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00766703
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  • 9
    Electronic Resource
    Electronic Resource
    Reagents for photoaffinity labeling. I. Photobinding efficiency of aryl azido-, diazocyclopentadienyl-and ethyl diazomalonyl-derivatives of 9-aminoacridine (1983)
    Springer
    Cellular and molecular life sciences 39 (1983), S. 1063-1072 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A method for the comparison of photoaffinity labeling probes has been developed and tested with model reagents containing 5 different photoprobes attached to 9-acridinylamino groups through hexamethylenoxy or hexamethylenamino linkers. The fluorescence properties of the acridine part of the reagents were employed for detection of the labels. The merits and disadvantages of the different photoprobes are discussed. The photoreaction of the reagents with proteins (bovine serum albumin and histones), RNA (ribosomal), and DNA (calf thymus) were studied in order to compare the efficiency and suitability of aryl azido and diazo photoprobes. By using Pyrex-filtered light (λ〉300 nm), it was observed that the reagents derived from 4-azidobenzoyl-(a), 4-azido-2-nitrophenyl- (b), or 2-diazopentadienylcarbonyl- (c) are the most efficient, labeling bovine serum albumin in yields of 22%, 9% and 9%, respectively, with relative rates of 0.25∶0.06∶1. The acridines containing photoprobesa, b andc were shown to function as photoaffinity labeling reagents of the histones in chromatin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01943115
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  • 10
    Electronic Resource
    Electronic Resource
    Prevention of enteral radiocesium absorption by hexacyanoferrates(II) in piglets (1988)
    Springer
    Cellular and molecular life sciences 44 (1988), S. 502-504 
    Details
    ISSN: 1420-9071
    Keywords: Hexacyanoferrate(II) ; 134Cs ; cesium absorption ; biological half-life ; piglet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The efficacy of different hexacyanoferrates(II) in preventing the enteral absorption of134Cs was studied in piglets. As compared to the controls, oral application of134Cs together with KFe[Fe(CN)6], NH4Fe[Fe(CN)6], or Fe4[Fe(CN)6]3 resulted in a strong reduction of the134Cs-uptake by more than 97%. The decrease in enteral absorption depends on the dose of administered hexacyanoferrate(II), whereas differences between the compounds under study were small. The biological half-life of134Cs in non-hexacyanoferrate(II) treated piglets was 21.6±3.3 days (mean±SD).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01958927
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