Library

X
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  (11)
  • Arene complexes  (2)
  • Carboxylation efficiency  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Changes in photosynthetic capacity, carboxylation efficiency, and CO2 compensation point associated with midday stomatal closure and midday depression of net CO2 exchange of leaves of Quercus suber (1984)
    Springer
    Planta 162 (1984), S. 193-203 
    Details
    ISSN: 1432-2048
    Keywords: Carboxylation efficiency ; Compensation point (CO2) ; Photosynthesis (temperature, humidity) ; Quercus ; Sclerophyll
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The carbon-dioxide response of photosynthesis of leaves of Quercus suber, a sclerophyllous species of the European Mediterranean region, was studied as a function of time of day at the end of the summer dry season in the natural habitat. To examine the response experimentally, a “standard” time course for temperature and humidity, which resembled natural conditions, was imposed on the leaves, and the CO2 pressure external to the leaves on subsequent days was varied. The particular temperature and humidity conditions chosen were those which elicited a strong stomatal closure at midday and the simultaneous depression of net CO2 uptake. Midday depression of CO2 uptake is the result of i) a decrease in CO2-saturated photosynthetic capacity after light saturation is reached in the early morning, ii) a decrease in the initial slope of the CO2 response curve (carboxylation efficiency), and iii) a substantial increase in the CO2 compensation point caused by an increase in leaf temperature and a decrease in humidity. As a consequence of the changes in photosynthesis, the internal leaf CO2 pressure remained essentially constant despite stomatal closure. The effects on capacity, slope, and compensation point were reversed by lowering the temperature and increasing the humidity in the afternoon. Constant internal CO2 may aid in minimizing photoinhibition during stomatal closure at midday. The results are discussed in terms of possible temperature, humidity, and hormonal effects on photosynthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397440
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Density functional calculations of the structures and bond energies of Cr(CO)6 and (η6-C6H6) Cr(CO)2(CX) (X=O, S) complexes (1995)
    Springer
    Theoretical chemistry accounts 91 (1995), S. 157-167 
    Details
    ISSN: 1432-2234
    Keywords: Density functional theory ; Metal-ligand bond energies ; Chromium ; Arene complexes ; Chalcocarbonyls
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Quantum chemical calculations based on density functional theory have been performed on Cr(CO)6, (η6-C6H6)Cr(CO)3 and (η6-C6H6)Cr(CO)2(CS) at the local and nonlocal level of theory using different functionals. Good agreement is obtained with experiment for both optimized geometries and metal-ligand binding energies. In particular, a comparison of metal-arene bond energies calculated for the (η6-C6H6)Cr(CO)3 and (η6-C6H6)Cr(CO)2(CS) complexes correlates well with kinetic data demonstrating that substitution of one CO group by CS leads to an important labilizing effect of this bond, which may be primarily attributed to a larger π-backbonding charge transfer to the CS ligand as compared with CO.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01114983
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Effects of temperature at constant air dew point on leaf carboxylation efficiency and CO2 compensation point of different leaf types (1985)
    Springer
    Planta 166 (1985), S. 81-88 
    Details
    ISSN: 1432-2048
    Keywords: Carboxylation efficiency ; Compensation point (CO2) ; Photosynthesis (temperature, humidity) ; Sclerophyll ; Transpiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of temperature on photosynthesis at constant water-vapor pressure in the air was investigated using two sclerophyll species, Arbutus unedo and Quercus suber, and one mesophytic species, Spinacia oleracea. Photosynthesis and transpiration were measured over a range of temperatures, 20–39° C. The external concentration of CO2 was varied from 340 μbar to near CO2 compensation. The initial slope (carboxylation efficiency, CE) of the photosynthetic response to intercellular CO2 concentration, the CO2 compensation point (Γ), and the extrapolated rate of CO2 released into CO2-free air (R i) were calculated. At an external CO2 concentration of 320–340 μbar CO2, photosynthesis decreased with temperature in all species. The effect of temperature on Γ was similar in all species. While CE in S. oleracea changed little with temperature, CE decreased by 50% in Q. suber as temperature increased from 25 to 34° C. Arbutus unedo also exhibited a decrease in CE at higher temperatures but not as marked as Q. suber. The absolut value of R i increased with temperature in S. oleracea, while changing little or decreasing in the sclerophylls. Variations in Γ and R i of the sclerophyll species are not consistent with greater increase of respiration with temperature in the light in these species compared with S. oleracea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397389
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Density functional calculations of the structures and bond energies of Cr(CO)6 and (η6-C6H6)Cr(CO)2(CX) (X=O, S) complexes (1995)
    Springer
    Theoretica chimica acta 91 (1995), S. 157-167 
    Details
    ISSN: 0040-5744
    Keywords: Key words: Density functional theory ; Metal-ligand bond energies ; Chromium ; Arene complexes ; Chalcocarbonyls
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  Quantum chemical calculations based on density functional theory have been performed on Cr(CO)6, (η6-C6H6)Cr(CO)3 and (η6-C6H6)Cr(CO)2(CS) at the local and nonlocal level of theory using different functionals. Good agreement is obtained with experiment for both optimized geometries and metal–ligand binding energies. In particular, a comparison of metal–arene bond energies calculated for the (η6-C6H6)Cr(CO)3 and (η6-C6H6)Cr(CO)2(CS) complexes correlates well with kinetic data demonstrating that substitution of one CO group by CS leads to an important labilizing effect of this bond, which may be primarily attributed to a larger π-backbonding charge transfer to the CS ligand as compared with CO.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01114983
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Das Verhalten rostfreier Stahlgußlegierungen unter gleichzeitiger mechanischer und korrosiver Belastung (1980)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 11 (1980), S. 244-258 
    Details
    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: Behaviour of stainless cast alloys under combined mechanical and corrosive attackIn media with 3000 mg B/1 (as boric acid, H3BO3) and varying chloride contents down to 1 mg Cl-/1 13%-Cr-steels show pitting. Under constant load cracks appear simultaneously. As can be expected, 17%-Cr-steels are more resistant and duplex ferritic austenitic steels exhibit no corrosion cracking in 3% NaCl-solution even after 10 000 hrs. Generally, corrosion resistance improves with increasing contents of ferrite forming elements. Corrosion cracks are interpreted in termes of anodic stress corrosion cracking. Notch impact bending tests with hydrogen charged specimens show that deformability is reduced.
    Notes: 13%-Cr-Stähle zeigen in Lösungen mit 3000 mg B/1 (als Borsäure, H3BO3) und unterschiedlichen Chloridgehalten Lochkorrosion bis herab zu Konzentrationen von 1 mg Cl-/1. Bei mechanischer Zugbeanspruchung treten gleichzeitig Risse auf. 17%-Cr-Stähle sind erwartungsgemäß beständiger und ferritisch-austenitische Stähle zeigen in 3% NaCl-Lösung auch im 10 000 h-Versuch keine Korrosionsrisse. Generell steigt die Beständigkeit mit zunehmendem Anteil an ferritbildenden Elementen. Die Korrosionsrisse werden als anodische Spannungsrißkorrosion interpretiert. Kerbschlagbiegeversuche mit wasserstoffbeladenen Proben ergeben eine Abnahme des Verformungsvermögens.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19800110707
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Die Inhibition von KühlkreisläufenVorgetragen am 214. DECHEMA-Kolloquium am 28. November 1974. (1975)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 26 (1975), S. 192-199 
    Details
    ISSN: 0947-5117
    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: The inhibition of cooling systemsThe choice of an efficient corrosion inhibitor has to take in account the type of the cooling system, the materials used as well as the specific operating conditions, for instance - very low or very high velocities of the cooling water- heat transfer- the inhibitor may be asked to have some lubricating properties- vibrations, that can cause cavitation or fatigue corrosion- interaction between the corrosion inhibitor and other electrochemical systems of corrosion protection (cathodic protection).In numerous applications it is necessary to improve the inhibition by an addition of other effective substances (like dispersants, hardness stabilizers, mixture of inhibitors with selective protection properties).
    Notes: Die Auswahl eines Kühlwasserinhibitors richtet sich nach der Art des Kühlsystems und der darin verwendeten Werkstoffe sowie nach den spezifischen Beanspruchungen, so z. B.- extrem hohe oder niedrige Strömungsgeschwindigkeiten des Kühlmediums,- hohe Wärmebelastung der zu Kühlenden Metallwand,- Reibungsvorgänge, wobei der Inhibitor zusätzlich eine Schmierfunktion ausüben muß,- Vibrationen, die zu Kavitationserscheinungen oder zur Werkstoffermüdung führen Können,- Wechselwirkungen des Inhibitors mit anderen elektrochemischen Schutzverfahren (z. B. lokaler kathodischer Schutz von hochbeanspruchten Zonen des Kühlsystems).In zahlreichen Fällen ist es zudem notwendig, die Wirksamkeit der Inhibierung durch den Zusatz von weiteren Wirkstoffen zu unterstützen (Dispergiermittel, Härtestabilisatoren, Gemische von Inhibitoren mit selektiver Schutzwirkung).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19750260304
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Prüfung und Auswahl von KavitationsinhibitorenVortrag, gehalten an der Università di Ferrara anläßlich des 4. Europäischen Symposiums über Korrosionsinhibitoren, September 1975. (1976)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 27 (1976), S. 425-431 
    Details
    ISSN: 0947-5117
    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: Testing and Selecting Cavitation InhibitorsAn investigation has been made into possibility of using electrochemical procedures as well as the gravimetrical method for testing cavitation inhibitors. The relation between the structure of the inhibitor, the nature and form of the cavitation attack and the mechanism of destruction was also examined. This work was performed with a group of conventional cooling water inhibitors and some pyridine compounds.It was shown that electrochemical investigations are less suitable for enabling inhibitors to be selected for high cavitation intensities, because electrochemical losses amount to only a relatively small part of the total loss of material. Nevertheless they are indispensable as a supplement to magnetostrictive investigations for appraising the overall performance of an inhibitor, because it has been found that a good cavitation inhibitor does not always achieve the same success against electrochemical corrosion.Furthermore it was demonstrated that interface inhibitors generally yield better results than membrane inhibitors or passivators. The protection afforded by interface inhibitors depends on their structure, the chain length and in the case of the pyridine components investigated the nature and position of the substituents in the pyridine ring.
    Notes: Es wurde untersucht, ob für die Erprobung von Kavitationsinhibitoren neben der gravimetrischen Methode auch elektrochemische Prüfverfahren eingesetzt werden können. Es wurde ferner der Zusammenhang zwischen Struktur des Inhibitors, Art und Form des Kavitationsangriffes und Mechanismus der Zerstörung untersucht. Diese Arbeit wurde mit einer Gruppe herkömmlicher Kühlwasserinhibitoren sowie mit einigen Pyridinverbindungen durchgeführt.Wie es sich zeigte, sind elektrochemische Untersuchungen weniger geeignet, eine Inhibitorauswahl bei hohen Kavitationsintensitäten zu ermöglichen, da die elektrochemische Metallauflösung nur einen relativ kleinen Teil des gesamten Abtrags ausmacht. Sie sind aber als Ergänzung zu magnetostriktiven Untersuchungen für die Beurteilung des Gesamtverhaltens eines Inhibitors unbedingt notwendig, da es sich gezeigt hat, daß nicht immer ein guter Kavitationsinhibitor mit demselben Erfolg gegen elektrochemische Korrosion eingesetzt werden kann.Wie sich außerdem herausstellte, liefern Grenzflächeninhibitoren in der Norm bessere Resultate als Membraneninhibitoren oder Passivinhibitoren. Bei den Grenzflächeninhibitoren ist die Schutzwirkung von der Struktur des Inhibitors abhängig, wobei insbesondere Kettenlänge und - bei den untersuchten Pyridinverbindungen - Art und Stellung der Substituenten eine wichtige Rolle spielen.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19760270606
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Einfluß von Schutzfremdströmen auf die Wirkung von KühlwasserinhibitorenVorgetragen auf der „Woche der Korrosion“ des Wissenschaftlichen Vereins für Maschinenbau, Budapest 14. -18. Oktober 1974 (1974)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 25 (1974), S. 734-739 
    Details
    ISSN: 0947-5117
    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: The influence of imposed protection currents on the efficiency of inhibitors for cooling watersIn case where the cathodic protection of a cooling system is not feasible a combination of cathodic protection and inhibition may be of advantage. The authors have studied the potential influence of a direct current on the efficiency of an inhibitor; during the experimental work they have used a current intensity corresponding to the maximum intensity of the protection current used in practice. Using potentiokinetic methods they have found that the number of inhibitors which may be used in such conditions is rather small. In the case of inhibitors based on nitrites or amines the protecting efficiency is rather reduced after some hundred hours' operation under direct current, and in some case even a corrosion stimulation has been experienced. Inhibitors based on chromates and anticorrosion oil emulsions exhibit improved electrochemical stability, though, in the case of oils emulsion breaking must be taken into account after relatively short durations of operation.
    Notes: In Fällen, wo der kathodische Schutz eines Kühlsystems schwer durchführbar ist, erweist sich eine Kombination von kathodischem Schutz und Inhibierung als vorteilhaft. Die Verfasser untersuchten mögliche Einflüsse von Gleichstrom auf die Wirksamkeit von Inhibitoren; bei diesen Versuchen arbeiteten sie mit einer Stromstärke, welche der maximalen in der Praxis verwendeten Schutzstromstärke entsprach. Mit Hilfe von potentiokinetischen Methoden wurde gefunden, daß die zahl der unter diesen Bedingungen verwendbaren Inhibitoren sehr klein ist. Im Falle von Inhibitoren auf Basis von Nitriten oder Aminen verringert sich schon nach einigen Stunden Gleichstromeinwirkung die Schutzwirkung und in manchen Fällen zeigt sich sogar eine stimulierende Wirkung. Die Inhibitoren auf Basis von Chromaten oder Korrosionsschutzölemulsionen sind hingegen elektrochemisch gut beständig im Falle der Öle ist jedoch damit zu rechnen, daß die Emulsion schon nach verhältnismäßig kurzer Betriebsdauer bricht.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19740251007
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Lochfraß- und Kontaktkorrosion an magnesiumumhülten Spaltstoffelementen (1968)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 19 (1968), S. 895-900 
    Details
    ISSN: 0947-5117
    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: Pitting and contact corrosion in magnesium-canned fuel rodsWhen nuclear fuel elements  -  containing Mg, graphite and Zircaloy  -  are stored in water there is the danger of contact corrosion of Mg in contact wit graphite; in partcular when cholorides are present (even in traces) there exists the danger of pitting corrosion. Only at pH values 〉 11,5 a bydroxide layer is formed which yields a certain protection. The pitting potential in alkaline waters is shifted to more negative values with incrasing chloride contents; this displacement can be prevented by inhiitors. Most efficient is the addition of sodium carbonate which gives rise to the formation of a protective hydromagnesite layer.
    Notes: Bei Lagerung verbrauchter Brennstoffelemente  -  Werkstoffe Mg, Graphit, Zircaloy  -  in Wasser besteht die Gefahr der Kontaktkorrosion von Mg bei Kontakt mit Graphit; besonders bei Anwesenheit von Chloriden besteht Lochfraßgefahr. Erst bei pH Werten 〉 11,5 entsteht eine Hydroxidschicht, die einen gewissen Schutz bewirkt. Das Lochfraßpotential im alkalischen Wasser verschiebt sich mit zunehmendem Chloridgebalt stark in den Bereich negativer Werte, was durch Inhibitoren verhindert werden kann. Am günstigsten ist Zusatz von Natriumcarbonat, das zur Bildung eines Schutzfilms aus Hydromagnesit führt.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19680191010
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Die Inhibierung der Korrosion in industriellen Kühlsystemen (1979)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 30 (1979), S. 713-722 
    Details
    ISSN: 0947-5117
    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
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19790301007
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...