ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Polymer and Materials Science  (14)
  • Semi-arid shrubs  (2)
  • Wiley-Blackwell  (14)
  • Springer  (2)
  • American Association for the Advancement of Science
  • American Physical Society
Collection
Publisher
  • Wiley-Blackwell  (14)
  • Springer  (2)
  • American Association for the Advancement of Science
  • American Physical Society
  • 1
    ISSN: 1432-1939
    Keywords: Browsing responses ; Semi-arid shrubs ; Nonstructural carbohydrate accumulation ; Regrowth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nonstructural carbohydrate allocation patterns in response to different frequencies of simulated browsing (leaf and twig removal) were studied in the following semi-arid shrubs: Osteospermum sinuatum, a dwarf deciduous shrub, Pteronia pallens, a dwarf evergreen shrub, and Ruschia spinosa, a dwarf leaf-succulent shrub. Simulated browsing at all frequencies resulted in the elevation, or had no effect, on total nonstructural carbohydrate (TNC) concentrations of O. sinuatum plant parts, and resulted in the decrease in TNC concentrations of R. spinosa plant parts. The responses of P. pallens were intermediate with elevations as well as declines in TNC concentrations of plant parts measured in response to various clipping frequencies. At the low frequency of simulated browsing (every 26 weeks) elevations in plant TNC content were measured in the two non-succulent shrubs O. sinuatum and P. pallens. It was concluded that the overcompensation with respect to TNC accumulation observed in the two non-succulent species represents one of the ways in which excess photosynthate is utilized by browsed shrubs with a limited regiowth potential. Simulated browsing was the least detrimental with respect to biomass production to the non-succulent O. sinuatum and P. pallens, and most injurious to the leaf-succulent shrub, R. spinosa. The observed TNC allocation patterns could not adequately explain the variation among species in the production of new growth and it was concluded that some factor(s) other than the carbon resource was limiting regrowth.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-1939
    Keywords: Induced defence ; Clipping ; Semi-arid shrubs ; Herbivore-deterrents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Allocation of carbon to chemical defences has often been suggested to be a direct response to browsing or grazing by herbivores. This study quantitatively compares total polyphenol and tannin production in response to simulated browsing of three karoo shrubs in order to test this induced defence hypothesis. The three species studied responded to browsing either by rapid regrowth or by increasing polyphenol production in the remaining tissues. The patterns did not follow any phylogenetic relationships but were weakly associated with the palatability of each species. The highly palatable deciduous species Osteospermum sinuatum, which is capable of rapid regrowth, showed no or very low levels of constitutive and browsing-induced total polyphenols, condensed tannins and protein-precipitating tannins. The evergreen sclerophyllous species Pteronia pallens showed a limited regrowth capacity and had intermediate levels of polyphenols, while the evergreen succulent species Ruschia spinosa showed almost no regrowth over the study period. R. spinosa contained the highest constitutive and browsing-induced levels of polyphenols, condensed tannins and protein-precipitating tannins. In two of the species more than one anti-herbivore defence feature co-occur. P. pallens foliage contains both hepatotoxins and polyphenols while R. spinosa has both structural (spines) and chemical defences. Responses of karoo shrubs to simulated browsing are interpreted as the result of passive alterations in plant chemistry rather than as an active defence response to herbivores.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 26 (1995), S. 27-31 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Stahlbleche wurden mittles Gleichstrom-Magnetron-Sputtern mit Titannitrid beschichtet. Durch Variation des Stickstoffdurchflusses konnten Schichten mit unterschiedlicher chemischer Zusammensetzung erhalten werden. Die Schichten wurden mittels Gimmentladungsspektroskopie und einer naßchemischen Methode quantitativ analysiert. Für die naßchemische Analyse wurden die Schichten vom Substrat getrennt, aufgeschlossen und nachfolgend die Elemente Titan mittels Atomabsorptionsspektroskopie und Stickstoff nach Kjeldahl bestimmt. Die Analysenergebnisse zeigen signifikante Unterschiede zwischen den beiden Verfahren, die durch die unterschiedlichen verwendeten Standards verursacht werden. So ergibt die GDOS-Analyse im Vergleich zur naßchemischen Analyse für unterstöchiometrische TiNx-Schichten (x 〈 1) zu niedrige Stickstoffgehalte und für etwa stöchiometrische Schichten (x ≈ 1) zu hohe. Aufgrund der Standards kann geschlossen werden, daß die naßchemische Analyse mit einem geringeren systematischen Fehler behaftet ist. Sie ist aber in der Handhabbarkeit der GDOS-Analyse weit unterlegen und eignet sich damit besser für die Kalibration von speziellen Proben, die nachfolgend bei der GDOS-Analyse als Standard eingesetzt werden können.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Surface engineering of light weight materials with ion- and plasma-assisted methodsIncreasing applications of light weight materials are expected in the future. Pursuing this trend surface engineering of these materials - especially ion- and plasma-assisted methods - swill be of increasing interest to enhance their wear and corrosion resistance. In a research co-operation some promising methods were examined on different aluminium and titanium alloys to assess their potential to increase the surface properties. Among these were magnetron sputtering of chromium nitride, ion beam assisted deposition of Cr/CrN and Al/A2O3 layers, ion implantation and ion beam assisted nitriding. Compared to the steel substrates the assessment of the mechanical properties such as the critical load of the scratch test of the coated light weight materials is different. Furthermore, it could be shown that both spherical section and glow discharge optical spectroscopy are useful methods to characterize the near-surface zone influenced by ion implantation.
    Notes: Es ist zu erwarten, daß die Anwendungsbreite von Leichtmetall-legierungen in Zukunft noch steigen wird. Mit diesem Trend werden auch oberflächentechnische Methoden - insbesondere ionen- und plasmaunterstützte Verfahren - gefragt sein, um den Verschleiß- und Korrosionswiderstand der Oberflächen zu verbessern. Im Rahmen eines Verbundprojektes wurden verschiedene aussichtsreiche Verfahren untersucht, um ihr Potential zur Verbesserung der Oberflächeneigenschaften von Aluminium- und Titanlegierungen einschätzen zu können. Hierunter befanden sich das Magnetronsputtern von Chromnitrid, die ionenstrahluntersützte Abscheidung von Cr/CrN- und Al/A2O3Schichten, die Ionenimplantation und das Ionenstrahlnitrieren. Im Vergleich mit beschichteten Stahlsubstraten ergeben sich Unterschiede bei der Einschätzung wichtiger mechanischer Eigenschaften, wie der im Ritztest ermittelten kritischen Last. Weiterhin konnte gezeigt werden daß sowohl der Kalottenschliff als auch die Glimmentladungspektroskopie gut geeignet sind, die durch Ionenimplantation beeinflußte Randzone zu charakterisieren.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 29 (1998), S. 525-536 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Temperature of cutting tools by thin filmsDuring the cutting process, cutting tools are exposed to complex mechanical, thermal, dynamic and tribological loads. Especially in the case of dry machining the demands on cutting tools are very high. Dry machining becomes more and more interesting because of tightened up ecolaws and increased costs for the handling of coolants. Due to a renunciation on coolants the cutting tools need to be modified to the process of dry machining. Thereby modern plasma and ion based surface technologies can be used to deposit a thin film adopting the functions of coolants, e.g. cooling and lubricating.In this research project several coating types, e.g. titanium and chromium based coatings, where developed and characterized regarding their mechanical, tribological and thermal properties. For the research, four partners collaborated permuting all steps of surface and coatings design. Materials Science Institute (WW), Aachen University of Technology, performed the development of PVD coatings and the thermophysical characterization by thermal wave analysis. Surface modifications of uncoated and coated tools by ion beam assisted deposition were carried out at Stiftung Institut für Werkstofftechnik (IWT), Bremen. To determine the cutting properties of coated tools, practical tests were performed at Laboratory for Machine Tools and Production Engineering (WZL), Aachen University of Technology.
    Notes: Zerspanwerkzeuge sind während ihres Einsatzes einem komplexen und schwer zu erfassenden Beanspruchungskollektiv ausgesetzt. Dieses wird besonders durch die aus ökonomischen und ökologischen Gründen angestrebte Trockenzerspanung beeinflußt. Der vollständige Verzicht auf Kühlschmierstoffe bedeutet aus technologischer Sicht, daß Werkzeuge, Schneidstoffe und Zerspanoperationen auf die Bedingungen der Trockenzerspanung umgestellt werden müssen. Dabei bieten moderne ionen-und plasmagestütze Oberflächentechnologien insofern einen Lösungsansatz, daß durch Beschichtungen bzw. Oberflächenmodifikationen wichtige Aufgaben der Kühlschmiermittel durch den beschichteten Schneidstoff selbst übernommen werden können. Dies sind vor allem der Ersatz von Schmierung und Kühlung.Für den Bereich der Trockenzerspanung wurden im Rahmen eines Verbundvorhabens u.a Titanbasisschichten sowie Chrombasisschichten entwickelt und hinsichtlich der physikalischen Eigenschaften untersucht. Durch die enge Zusammenarbeit der beteiligten Forschungsstellen konnte das jeweils vorhandene Erfahrungspotential vollständig in die Schichtsystementwicklung einfließen. Diese umfaßte alle iterativen Schritte des Schichtmodifikation, begleitende Schichtanalytik bis hin zum Praxistest. So war beispielsweise das Lehr- und Forschungsgebiet Werkstoffwissenschaften der RWTH Aachen für die Schichtentwicklung sowie fü die thermophysikalische Charakterisierung der Schichten zuständig. Die Stiftung Institut für Werkstofftechnik, Bremen, führte eine Optimierung der Interfaces und der Hartstoffschichten mittels ionenstrahlgestützter Beschichtungsverfahren durch. So konnte das Substrat vor bzw. die Hartstoffschicht nach der Beschichtung an den Anwendungsfall angepaßt werden. Die Untersuchung hinsichtlich der Praxistauglichkeit der beschichteten Schneidstoffe erfolgte am Werkzeugmaschinenlabor der RWTH Aachen durch entsprechende Zerspanversuche.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 24 (1993), S. 125-130 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: HSS-Zerspanwerkzeuge wurden mittels Magnetron-Sputtern mit TiN beschichtet unter Variation der Sputterparameter Druck, Leistung und Bias-Spannung. Untersucht wurde der Zusammenhang zwischen den grundlegenden Schichteigenschaften Eigenspannung, Härte und Morphologie und dem Verhalten gegen tribologische Beanspruchung mittels Modellverschleißversuchen und Zerspanversuchen von Mumetall. Sowohl die Schichtmorphologie als auch die Eigenspannungen wurden durch die Parameter-variation verändert, um optimale Beschichtungsbedingungen ableiten zu können. Die tribologischen Untersuchungen zeigen, daß die Beschichtungsparameter und die Schichtdicke den Verschleißwiderstand maßgeblich beeinflussen können. Dabei führen die Modellverschleiß- und Zerspanergebnisse zu qualitativ gleichen Aussagen, so daß eine aussagekräftige Simulation des Werkzeugverschleißes als Test für weitere modifizierte Schichten verwendet werden kann.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 39 (1990), S. 2419-2441 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dielectric techniques have been implemented to study aqueous colloidal suspensions. A four electrode cell was used in two configurations; the first, a sweep of frequencies using a sequence of standard single frequency null-balance measurements, and the second relying on the dielectric response to a Fourier synthesized pseudo random white noise (FSPN) with measurements performed using correlation techniques in the time domain. Single frequency measurements, which take on the order of 5-10 min per spectrum, were performed on polymer latex standards of varying size, latex concentration, and electrolyte concentration and were extended from 0.02 to over 500 kHz. It was found that the central relaxation frequency fc was inversely propotional to the square of the particle size, consistent with previous experimental results. Experiments were performed at different particle concentration and ionic strengths, and the magnitude and breadth of the dielectric dispersion was analyzed in terms of current theories. The distribution of relaxation times was found to be in general qualitative agreement with those predicted by some existing theories. The results indicate that a wide range of conditions exist in terms of latex concentration and ionic environment where the rapid and accurate measurement of polymer latex particle size and size distribution is feasible. FSPN measurements, which take on the order of seconds, were shown to be accurate over a moderate frequency range for model electrical network studies but were only partially successful for aqueous suspensions of latex because of high frequency limitations in the electronics. Experimental details and difficulties concerning the application of this technique are discussed.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 51 (1979), S. 679-679 
    ISSN: 0009-286X
    Keywords: Abwasserabgabengesetz ; Höchstwertkontrolle ; verteilungsfreie Statistik ; Aussagequantifizierung ; Einleiter-Schichtung ; Selbstüberwachung ; Höchstwertneugestaltung ; ordnungsrechtliche Grenzwerte ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...