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  • 1
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    Corrosion inhibition of carbon and low alloy steels in sulphuric acid solutions by 2-mercaptopyrimidine derivatives (1993)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 44 (1993), S. 264-268 
    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: Inhibierung der Korrosion von Kohlenstoffstahl und niedriglegierten Stählen in Schwefelsäure durch 2-mercaptopyrimidinderivateVerschiedene Derivate von 2-mercaptopyrimidin mit -OH, -SH, -NH2 oder -CH3 als Substituenten wurden als Inhibitoren der Korrosion von Armco-Eisen und niedriglegierten Stählen in 1 m Schwefelsäure untersucht. Die Versuchsdauer betrug 6 h, die Temperatur lag zwischen 60 und 90°C. Der Verlauf der Korrosionsgeschwindigkeit in Abhängigkeit von der Zeit wurde durch Polarisationswiderstandsmessungen und analytische Bestimmung des gelösten Eisen verfolgt. Von den untersuchten Derivaten zeigten 2-mercaptopyrimidin, 2,4-dimercaptopyrimidin und 2-mercapto-4-methylpyrimidin die beste Wirkung, wobei im Fall von Armco-Eisen Hemmwerte von 98% bei 90°C erreicht wurden. Die Anwesenheit von Chrom und Molybdän im Stahl beeinflußt die Wirksamkeit der Pyrimidinderivate ungünstig und verringert den Hemmwert bei 90°C.Auf der Grundlage der Molekülstruktur der untersuchten Substanzen wird versuchsweise eine Erklärung für den Wirkungsmechanismus gegeben.
    Notes: Several derivatives of 2-mercaptopyrimidine (containing -OH, -SH, -NH2 or -CH3 substituents) have been studied as corrosion inhibitors of ARMCO iron and low alloy steels in 1 M sulphuric acid solutions. Tests have been conducted during 6 h in the temperature interval between 60 and 90°C. The trends of the corrosion rates as a function of time have been determined by polarisation resistance measurements and analytical determinations of dissolved iron. 2-mercaptopyrimidine, 2,4-dimercaptopyrimidine and 2-mercap-to-4-methylpyrimidine showed the most satisfactory action, reaching efficiencies of 98% on ARMCO iron at 90°C. The presence of Cr and Mo in the alloys exerted a negative influence on the efficiency of pyrimidine derivatives, by diminishing their action at 90°C.A tentative interpretation of the action mechanisms of the additives has been given on the basis of their molecular characteristics.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19930440604
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  • 2
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    Corrosion in solar heating systems. II. Corrosion behaviour of AA 6351 in water/glycol solutions (1987)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 38 (1987), S. 83-88 
    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: Korrosion in Solarheizungssystemen. II. Korrosionsverhalten von AA 6351 in Wasser/Glykol-LösungenBei der vorliegenden Untersuchung wurde das Korrosionsverhalten der als Werkstoffe für Solarabsorberplatten verwendeten Metalle ermittelt. Dazu wurde die Korrosionsbeständigkeit von AA 6351 (1% Si, 0,6% Mg, 0,3% Mn, Rest Al) in nichtinhibierten Wärmeträgerflüssigkeiten wie Ethylen- und Propylenglykol/Wasser-Gemischen untersucht. Zur Langzeitprüfung wurden die Proben 60 Tage lang in reinen, mit Chlorid verunreinigten oder teilweise zersetzten Glykol/Wasser-Lösungen exponiert (80°C). Die Zersetzung der Wärmeträgerflüssigkeiten, die unter Praxisbedingungen saure Produkte liefern, wurde simuliert, indem die Ethylen- und Propylenglykol/Wasser-Gemische in Kontakt mit Kupfer 30 Tage am Sieden gehalten wurden.In Glykol/Wasser-Gemischen führten Chloride in niedrigen Konzentrationen (200 ppm) zu einer Beschleunigung der Korrosion von Aluminium um mehr als eine Größenordnung; in teilweise zersetzten Lösungen mit 143 oder 86 ppm Kupfer-II-Ionen war die Korrosion im Vergleich zu den reinen Lösungen um mehr als 2 Größenordnungen verstärkt.Bei den gravimetrischen Untersuchungen wurde teilweise Lochkorrosion beobachtet; die Stärke dieser Korrosion wurde aufgrund der größten und der mittleren Lochtiefe, der Lochdichte und der mittleren Lochgröße beurteilt.Der Einfluß der Wärmeübergangs auf die Korrosion der Al-Legierung und das Kontaktbad Kupfer/AA 6351 wurde gravimetrisch und elektrochemisch ermittelt. Danach wird durch den Wärmeübergang durch Aluminium das Lochkorrosionspotential des Metalls beträchtlich erhöht. Im Falle des Kontaktpaars Aluminium/Kupfer führte der Wärmeübergang zu verstärkter Kontaktkorrosion des Aluminiums, und zwar auch dann, wenn der Wärmeübergang durch das Kupfer erfolgte.Die Korrosionsgeschwindigkeiten des Aluminiums unter Kontaktkorrosionsbedingungen wurden aus den mittleren galvanischen Strömen berechnet; ihr Beitrag zur gesamten gravimetrisch ermittelten Korrosion war aber gering. Dieser Umstand ist ein Indiz dafür, daß in Lösungen mit geringer Leitfähigkeit die Gefahr des Kontakts zwischen verschiedenen Metallen nicht durch den Kontakt selbst bedingt ist, sondern vor allem dadurch, daß sich das edlere Metall in der gleichen Lösung wie das Aluminium befindet.
    Notes: A research was carried out in order to investigate the corrosion behaviour of the metals most commonly used as construction materials for solar absorber plates.With this view, an attempt was made to test the corrosion resistance of the aluminium alloy AA 6351 (nominal composition: 1% Si, 0.6% Mg, 0.3% Mn, the balance Al) towards common uninhibited heat transfer fluids, such as ethylene and propylene glycol/water mixtures.Long time gravimetric tests consisted in up to 60 day exposures of the aluminium specimens to pure, chloride-polluted, or degraded glycol/water solutions, at the temperature of 80°C. The degradation into acidic products, experienced by heat transfer liquids in service, was simulated by keeping the ethylene and propylene glycol/water solutions at their boiling temperature for 30 days, in contact with copper.In glycol/water solutions the presence of chlorides at low concentration (200 ppm) caused the aluminium corrosion rates to increase by more than one order of magnitude, while in degraded solutions, containing 143 or 86 ppm cupric ions, corrosion rates higher than two order of magnitude with respect to pure solutions were obtained.During the gravimetric tests, pitting corrosion was observed in some cases and its extent was rated by evaluating the deepest and the average metal penetration, the pit density and the average pit size.The influence of heat transfer on the alloy AA 6351 corrosion and on the couple copper/AA 6351 efficiency was evaluated by gravimetric and electrochemical tests. Heat transfer through aluminium was found to significantly increase the aluminium alloy pitting potential. On the contrary, it stimulated the aluminium galvanic corrosion, when applied on either aluminium or copper.Under galvanic coupling conditions, the aluminium corrosion rates calculated from the average galvanic currents were a very little contribution to the gravimetric corrosion rates. This demonstrates that in low conductive solutions the risk of matching such dissimilar metals as copper and aluminium does not reside in the galvanic contact itself, but mainly in the mere presence of the noblest metal in the same solution where aluminium is immersed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19870380206
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  • 3
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    Corrosion in solar heating systems. I. Copper behaviour in water/glycol solutions (1986)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 37 (1986), S. 479-484 
    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: Korrosion in Solarheizungssystemen. I. Verhalten von Kupfer in Wasser/Glycol-GemischenEs wurde ein Forschungszentrum entwickelt, um das Korrosionsverhalten metallischer Werkstoffe zu untersuchen, die üblicherweise in Solarheizungsanlagen verwendet werden.Diese Arbeit enthält die experimentellen Ergebnisse über den Korrosionswiderstand von Kupfer in Ethylen- und Propylen-Glycol/Wasser-Gemischen (1:1 in Vol.-Anteilen), wie sie üblicherweise als Wärmetransportmedium benutzt werden. Es wurden langzeitige gravimetrische Tests an Elektrolytkupfer bei 80°C durchgeführt, auch in Glykol/Wasser-Gemischen, die vorher auf diese Temperatur erhitzt oder durch 200 ppm Chlorid verunreinigt worden waren.Die chemische Zusammensetzung, die Halbleitereigenschaften sowie die Morphologie wurden durch Feinstrukturuntersuchungen, Pulsphotopotentialmessungen und mit dem Rasterelektronenmikroskop untersucht.Der Einfluß des Wärmedurchgangs auf die Kupferkorrosion und den Elementstrom der Kombination Kupfer/6351 Aluminium wurde durch elektrochemische Messungen verfolgt.Die folgenden Ergebnisse wurden erhalten: - Ethylen- und Propylen-Glycol/Wasser-Gemische haben eine geringe Aggressivität. Dennoch erhöhen Chloride, sowie eine teilweise Zersetzung des Glycols durch hohe Temperatur die Aggressivität erheblich. Unter allen experimentellen Bedingungen waren die Korrosionsraten des Kupfers in Ethylenglycollösungen höher als in Propylenglycollösungen.- In chloridfreien Medien stimuliert ein Wärmedurchgang die kathodische Reaktion der Kupferkorrosion.- Eine Elementbildung zwischen Kupfer und Aluminium führt zu einer Lochkorrosion des Aluminiums. Die Lochkorrosion wird durch Wärmetransport und Gegenwart von Chlorid in der Lösung beschleunigt, besonders in Ethylenglycol.
    Notes: A research programme has been developed in order to investigate the corrosion behaviour of metallic materials commonly used in solar heating systems.This paper presents the results of an experimental study on copper corrosion resistance in ethylene and propylene glycol/water solutions (1:1 by volume) constituting the most common bases of heat transfer fluids. Long time gravimetric tests were carried out on electrolytic copper at 80°C, even in glycol/water solutions previously degraded at their boiling temperature or polluted with 200 ppm chlorides.Chemical compositions, semiconducting properties and morphological characteristics of all surface products were investigated by X-ray diffraction analysis, pulse photopotential technique and SEM observations, respectively. Heat transfer effects on copper corrosion and copper/6351 aluminium alloy couple efficiency were evaluated by electrochemical tests.The following results were obtained:- Ethylene and propylene glycol/water solutions are low corrosive media. Nevertheless, chloride pollution and/or high temperature degradation of glycols markedly increase their aggressivity. Under all the experimental conditions, copper corrosion rates are higher in ethylene than propylene glycol solutions.- In chloride-free solutions, heat transfer stimulates the cathodic reaction of the copper corrosion process.- Galvanic contact between copper and aluminium alloy always causes pitting corrosion on aluminium electrodes. The severity of the pitting attack is enhanced by the presence of heat transfer conditions on copper and/or chloride ions in the solutions, particularly in ethylene glycol.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19860370902
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  • 4
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    Inhibition of localized attack on the aluminium alloy AA 6351 in glycol/water solutions (1989)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 40 (1989), S. 393-398 
    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: Inhibierung des örtlichen Angriffs der Aluminiumlegierung AA 6351 in Glykol-Wasser-LösungenEine frühere Untersuchung hatte gezeigt, daß bei Einwirkung gebrauchter (teilweise zersetzter) Lösungen von Propylenglykol in Wasser (1:1 Vol., 80°C, 60 d) oder von kochenden Lösungen von Propylenglykol in Wasser (30 d) die Aluminiumlegierung AA 6351 (Richtanalyse: 1% Si, 0,6% Mg, 0,3% Mn, Rest Al) örtlich stark angegriffen wird.Bei der vorliegenden Untersuchung wurde die Zersetzung dadurch erzeugt, daß die Propylenglykol/Wasser-Lösung in Kontakt mit der Legierung AA 6351 30 Tage lang am Sieden gehalten wurde. Der beobachtete örtliche Angriff ist hauptsächlich durch Kupferionen bedingt, die bei der Auflösung der Aluminiumlegierung (0,07% Cu) entstehen und bei der Abscheidung auf dem Aluminium als punktförmige kathodische Bereiche fungieren.Mit der vorliegenden Untersuchung sollte festgestellt werden, ob es möglich ist, die Lochkorrosionsbeständigkeit der Legierung AA 6351 durch Zugabe von Inhibitoren zur Lösung zu verbessern. Verwendet wurden dazu zwei anorganische Salze (Natriummolybdat und Natriumwolframat) sowie zwei Pyridinderivate (2-Aminopyrimidin und 2-Hydroxypyrimidin), deren Wirksamkeit mit kurzzeitigen elektrochemischen Versuchen (galvanische Kopplung und Aufnahme von Polarisationskurven) sowie durch Langzeitversuche unter die Lochkorrosion fördernden Bedingungen ermittelt wurde.Aufgrund der Ergebnisse hemmen die anorganischen Salze und 2-Aminopyrimidin die örtliche Korrosion sowohl in teilweise zersetzten Lösungen bei 80°C als auch in reiner kochender Lösung während ziemlich langer Zeiträume.Die Kurzzeitversuche lassen vermuten, daß die beiden anorganischen Salze die elektrochemischen Prozesse sowohl auf der Legierungsoberfläche als auch an den durch Ausscheidung von Kupfer entstandenen kathodischen Bereichen verzögern, während die Wirksamkeit des 2-Aminopyrimidins seiner Fähigkeit zur Komplexbildung mit gelösten Kupferionen zuzuschreiben ist, die auf diese Weise stabil gelöst bleiben, 2-Hydroxypyrimidin hemmt den örtlichen Angriff von AA 6351 nicht.
    Notes: A previous study had shown that exposure to degraded propylene glycol(PG)/water solution (1:1 in volume) at 80°C for 60 days or to boiling PG/water solution for 30 days induce remarkable localized attack on aluminium alloy AA 6351 (nominal composition: 1% Si, 0.6% Mg, 0.3% Mn, balance Al).In the present work degradation of the solution was achieved by holding the PG/water solution at its boiling temperature for 30 days in contact with AA 6351.The observed localized attack was mainly attributed to the action of copper ions dissolved from the aluminium alloy (copper content = 0.07%) and then deposited as small spots acting as efficient cathodic areas.The objective of this work was to examine the feasibility of enhancing pitting resistance of AA 6351 by adding suitable inhibitors to the solutions. The compounds used were two inorganic salts: sodium molybdate and sodium tungstate and two derivatives of pyrimidine: 2-aminopyrimidine (2AP) and 2-hydroxypyrimidine (2HP). The inhibiting efficiencies of these substances were tested by both short-time electrochemical tests (galvanic coupling tests and polarization curves) and long-time immersions under experimental conditions causing the localized attack. Molybdate, tungstate and, to some extent, also 2AP efficiently inhibit AA 6351 localized corrosion in degraded solutions at 80°C and in pure boiling solutions, for long exposure periods.The short-time electrochemical tests suggest that molybdate and tungstate are able to retard the electrochemical processes occurring on both the aluminium alloy and the small copper cathodic area produced by copper deposition. On the other hand, the 2AP efficiency is attributed to some complexing capability of this pyrimidine derivative towards dissolved copper ions, that are stabilized in solution. 2HP does not prevent AA 6351 localized attack.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19890400607
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    Dithio-oxamide as inhibitor of Copper corrosion in chloride solutions at various ph values (1991)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 42 (1991), S. 421-427 
    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: Dithiooxamid als Inhibitor der Korrosion von Kupfer in Chloridlösungen mit unterschiedlichen pH-WertenUntersucht werden die inhibierenden Eigenschaften von Dithiooxamid bei der Korrosion von Kupfer in chloridhaltigen Medien verschiedener pH-Werte. Die Versuchslösungen (0.1 M Natriumchlorid in Britton-Robinson-Puffer) wurden auf pH 3, 5, 7 und 9 eingestellt. Die Inhibitorkonzentration betrug 10-3 M.Die inhibierende Wirkung von Dithiooxamid wurde nach einer Versuchsdauer von 20 Tagen bei 30°C ermittelt. Dabei wurden zur Klärung des Inhibierungsmechanismus sowohl Gleichstromversuche (Polarisationskurven und voltammetrische Versuche) als auch Wechselstromversuche (elektrochemische Impedanzspektroskopie, EIS) durchgeführt.Die Ergebnisse zeigen, daß die Hemmwirkung des Dithiooxamids bei pH 5 und 7 ihr Maximum erreicht, daß jedoch auch bei pH 3 der Korrosionsprozess noch verzögert werden kann. Im Gegensatz dazu wird bei pH 9 der Korrosionprozeß stimuliert. Im pH-Bereich 3 bis 7 dürfte der Inhibitor einen Schutzfilm (Cu(II) DTOA-Salz) bilden; dieses Salz ist wahrscheinlich das Ergebnis eines zweistufigen Prozesses, bei dem Cu(I)DTOA als Zwischenprodukt auftritt. Die EIS-Analyse deutet darauf hin, daß das Verhalten von Kupfer in Chloridlösungen mit dem Modell der partiell blockierten Elektrode beschrieben werden kann. Aufgrund dieser Analyse ist anzunehmen, daß der bei pH 3 und 7 auf dem Kupfer entstehende DTOA-Film weniger porös ist als die Kupferoxid- oder Kupfer-I-chloridfilme, die sonst in inhibierten Lösungen entstehen, so daß der DTOA-Film den Stofftransport stark behindern dürfte.
    Notes: This paper investigates the inhibiting properties of dithiooxamide (DTOA) towards copper corrosion in chloride media at different pH values. The aggressive solutions were prepared by dissolving 0.1 M sodium chloride in a Britton Robinson buffer, adjusted at the pH values of 3, 5, 7 and 9. The inhibitor was tested at the concentration of 10-3 M.The inhibiting efficiency of DTOA was evaluated after 20 days of immersion in the solutions at the temperature of 30°C. Both dc (polarization curves and voltammetric tests) and ac (electrochemical impedance spectroscopy, EIS) electrochemical tests were performed to elucidate the inhibition process.The results indicate that DTOA affords its best inhibiting efficiency at pH 5 and 7, but even at pH 3 it can retard the corrosion process. On the contrary, at pH 9 it stimulates the corrosion process. Between pH 3 and 7, the additive is reputed to form a protective film of Cu(II)DTOA salt, which is formed through a two step oxidative process, probably involving Cu(I)DTOA as an intermediate. The EIS analysis indicates that in chloride solutions copper fits a model of a partially blocked electrode. This analysis suggests that at pH 3 and 7 the film produced on copper by DTOA has a lower porosity than that of the oxide or cuprous chloride films formed in non inhibited solutions, thus hindering the mass transport through the layer.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19910420806
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    Corrosion behaviour of the aluminium alloy AA 6351 in glycol/water solutions degraded at elevated temperature (1988)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 39 (1988), S. 379-384 
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    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: Korrosionsverhalten der Aluminiumlegierung AA 6351 in bei höheren Temperaturen abgebauten Glykol/Wasser-LösungenEin Forschungsprogramm wurde aufgestellt, um das Korrosionsverhalten der in Solarkollektrosystemen vorwiegend verwendeten Metalle zu ermitteln. Die üblichen Wärmeträssigkeiten, wie wäßrige Glykollösungen, sind wenig aggressiv, solange sie nicht verschmutzt oder durch Einwirkung höherer Temperaturen zersetzt wurden.Die vorliegende Arbeit behandelt das Korrosionsverhalten der Aluminiumlegierung 6351 (Richtanalyse (%) 1 Si, 0,6 Mg, 0,3 Mn, Rest Al) in Ethylenglykol/- oder Propylenglykol/Wasser-Lösungen (1:1 Vol.) nach Abbau bei 108°C in Kontakt mit der als Katalysator der oxidativen Zersetzung von Glykol wirkenden Legierung AA 6351.Die in dieser Lösung bei 80°C und einer Versuchsdauer von 60 Tagen durchgeführten Untersuchungen haben gezeigt, daß durch den thermischen Abbau die Geschwindigkeit der ebenmäßigen Korrosion erhöht wird und außerdem beträchtliche Lochkorrosion auftritt. Die Lochkorrosion kann vor allem der Wirkung der Kupferionen zugeschrieben werden, die bei der Auflösung des Aluminiums entstehen und in der Lösung mittels Atomadsorptionsspektroskopie nachgewiesen werden können.In Zusammenhang mit den Abbauversuchen wurden auch Versuche in gepufferter Ethylenglykol/Wasser-Lösung (pH 4) bei 80°C durchgeführt, wobei der Lösung gezielt Säuren zugesetzt wurden, die bei der oxidativen Zersetzung von Glykol entstehen (Oxal-, Glykol-, Essig- und Ameisensäure); die Konzentrationen betrugen 10-3 oder 10-2 M.In diesen Lösungen wurde das Korrosionsverhalten von AA 6351 30 Tage lang untersucht, wobei die Gewichtsverluste und der Polarisationswiderstand gemessen und nach zwei Stunden bzw. 30 Tagen Polarisationskurven aufgenommen wurden.Nur Oxalsäure und 10-2 M Glykolsäure führten dabei zu einer Erhöhung der Korrosionsgeschwindigkeit, das jedoch nur in der Anfangszeit der Versuche. Sobald in Lösungen mit diesen Säuren Deckschichten entstanden waren, boten diese sehr guten Schutz.Das Verhalten von AA 6351 in Lösungen mit Oxal- und Glykolsäure ist demnach damit zu erklären, daß keine unlöslichen Aluminiumsalze der organischen Säuren entstehen, sondern vielmehr ein Oxidfilm mit spezifischer Dichte und hohem Schutzvermögen.
    Notes: A research programme has been developed to characterize the corrosion behaviour of the metals most widely used in solar collector systems.Common heat transfer fluids such as glycol/water solutions show a low aggressivity, unless pollution or high temperature exposure (degradation) occur.This paper deals with the study of the corrosion behaviour of the aluminium alloy 6351 (nominal composition: 1% Si, 0.6%Mg, 0.3% Mn, the balance Al) in ethylene or propylene glycol (EG or PG)/water solutions (1:1 in volume) degraded at 108°C in contact with AA 6351 as glycol oxidative degradation catalyzer.The tests in degraded solutions, performed at 80°C over a period of 60 days, showed that degradation causes an increase in the uniform corrosion rates and a remarkable pitting attack.Pitting corrosion has been mainly attributed to the action of copper ions dissolved from the aluminium alloy and detected in the solutions by atomic adsorption analysis.In conjunction with the degradation studies, tests were also performed at 80°C in buffered PG/water solutions (pH 4) containing the acids reported to be produced during the process of glycol oxidative degradation (oxalic, glycolic, acetic and formic acids), at the concentrations 10-3 or 10-2 M.In these solutions the corrosion behaviour of AA 6351 was investigated over a period of 30 days by measuring the gravimetric corrosion rates and the polarization resistance values and by recording the polarization curves after 2 h or 30 days of immersion.Only oxalic acid and 10-2 M glycolic acid significantly increased the AA 6351 corrosion rates, but only in the first period of immersion. On the contrary, when the surface films were formed in the solutions of these acids, they afforded the highest protectivity.The analogous behaviour of AA 6351 in oxalic and glycolic solutions has not been attributed to the formation of an insoluble aluminium salt film with the organic anions, but rather to the growth of an oxide film with peculiar characteristics of thickness and protectivity.
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    URL: http://dx.doi.org/10.1002/maco.19880390805
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    Innate lymphoid cells regulate CD4+ T-cell responses to intestinal commensal bacteria (2013)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2013-05-24
    Description: Innate lymphoid cells (ILCs) are a recently characterized family of immune cells that have critical roles in cytokine-mediated regulation of intestinal epithelial cell barrier integrity. Alterations in ILC responses are associated with multiple chronic human diseases, including inflammatory bowel disease, implicating a role for ILCs in disease pathogenesis. Owing to an inability to target ILCs selectively, experimental studies assessing ILC function have predominantly used mice lacking adaptive immune cells. However, in lymphocyte-sufficient hosts ILCs are vastly outnumbered by CD4(+) T cells, which express similar profiles of effector cytokines. Therefore, the function of ILCs in the presence of adaptive immunity and their potential to influence adaptive immune cell responses remain unknown. To test this, we used genetic or antibody-mediated depletion strategies to target murine ILCs in the presence of an adaptive immune system. We show that loss of retinoic-acid-receptor-related orphan receptor-gammat-positive (RORgammat(+)) ILCs was associated with dysregulated adaptive immune cell responses against commensal bacteria and low-grade systemic inflammation. Remarkably, ILC-mediated regulation of adaptive immune cells occurred independently of interleukin (IL)-17A, IL-22 or IL-23. Genome-wide transcriptional profiling and functional analyses revealed that RORgammat(+) ILCs express major histocompatibility complex class II (MHCII) and can process and present antigen. However, rather than inducing T-cell proliferation, ILCs acted to limit commensal bacteria-specific CD4(+) T-cell responses. Consistent with this, selective deletion of MHCII in murine RORgammat(+) ILCs resulted in dysregulated commensal bacteria-dependent CD4(+) T-cell responses that promoted spontaneous intestinal inflammation. These data identify that ILCs maintain intestinal homeostasis through MHCII-dependent interactions with CD4(+) T cells that limit pathological adaptive immune cell responses to commensal bacteria.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3699860/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3699860/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hepworth, Matthew R -- Monticelli, Laurel A -- Fung, Thomas C -- Ziegler, Carly G K -- Grunberg, Stephanie -- Sinha, Rohini -- Mantegazza, Adriana R -- Ma, Hak-Ling -- Crawford, Alison -- Angelosanto, Jill M -- Wherry, E John -- Koni, Pandelakis A -- Bushman, Frederic D -- Elson, Charles O -- Eberl, Gerard -- Artis, David -- Sonnenberg, Gregory F -- 2-P30 CA016520/CA/NCI NIH HHS/ -- AI061570/AI/NIAID NIH HHS/ -- AI074878/AI/NIAID NIH HHS/ -- AI087990/AI/NIAID NIH HHS/ -- AI095466/AI/NIAID NIH HHS/ -- AI095608/AI/NIAID NIH HHS/ -- AI095776/AI/NIAID NIH HHS/ -- AI097333/AI/NIAID NIH HHS/ -- AI102942/AI/NIAID NIH HHS/ -- DK071176/DK/NIDDK NIH HHS/ -- DP5 OD012116/OD/NIH HHS/ -- DP5OD012116/OD/NIH HHS/ -- P01 DK071176/DK/NIDDK NIH HHS/ -- P30 DK050306/DK/NIDDK NIH HHS/ -- P30DK50306/DK/NIDDK NIH HHS/ -- R01 AI061570/AI/NIAID NIH HHS/ -- R01 AI074878/AI/NIAID NIH HHS/ -- R01 AI095466/AI/NIAID NIH HHS/ -- R01 AI097333/AI/NIAID NIH HHS/ -- R01 AI102942/AI/NIAID NIH HHS/ -- R21 AI083480/AI/NIAID NIH HHS/ -- R21 AI087990/AI/NIAID NIH HHS/ -- T32 AI007532/AI/NIAID NIH HHS/ -- T32 AI055428/AI/NIAID NIH HHS/ -- T32-AI055428/AI/NIAID NIH HHS/ -- U01 AI095608/AI/NIAID NIH HHS/ -- England -- Nature. 2013 Jun 6;498(7452):113-7. doi: 10.1038/nature12240. Epub 2013 May 22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Gastroenterology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23698371" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigen Presentation/immunology ; Bacteria/*immunology ; CD4-Positive T-Lymphocytes/cytology/*immunology/pathology ; Cell Proliferation ; Histocompatibility Antigens Class II/immunology/metabolism ; Humans ; Immunity, Innate/*immunology ; Inflammation/pathology ; Interleukin-17/metabolism ; Interleukin-23/metabolism ; Interleukins/metabolism ; Intestines/*immunology/*microbiology/pathology ; Mice ; Mice, Inbred C57BL ; Mice, Transgenic ; Nuclear Receptor Subfamily 1, Group F, Member 3/metabolism ; *Symbiosis
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 8
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    Friedreich's ataxia: autosomal recessive disease caused by an intronic GAA triplet repeat expansion (1996)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1996-03-08
    Description: Friedreich's ataxia (FRDA) is an autosomal recessive, degenerative disease that involves the central and peripheral nervous systems and the heart. A gene, X25, was identified in the critical region for the FRDA locus on chromosome 9q13. This gene encodes a 210-amino acid protein, frataxin, that has homologs in distant species such as Caenorhabditis elegans and yeast. A few FRDA patients were found to have point mutations in X25, but the majority were homozygous for an unstable GAA trinucleotide expansion in the first X25 intron.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Campuzano, V -- Montermini, L -- Molto, M D -- Pianese, L -- Cossee, M -- Cavalcanti, F -- Monros, E -- Rodius, F -- Duclos, F -- Monticelli, A -- Zara, F -- Canizares, J -- Koutnikova, H -- Bidichandani, S I -- Gellera, C -- Brice, A -- Trouillas, P -- De Michele, G -- Filla, A -- De Frutos, R -- Palau, F -- Patel, P I -- Di Donato, S -- Mandel, J L -- Cocozza, S -- Koenig, M -- Pandolfo, M -- 722/Telethon/Italy -- NS34192/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1996 Mar 8;271(5254):1423-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department de Genetica, University of Valencia, Spain.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8596916" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Amino Acid Sequence ; Base Sequence ; Chromosomes, Human, Pair 9/*genetics ; DNA Primers ; Female ; Friedreich Ataxia/*genetics ; Genes, Recessive ; Heterozygote ; Humans ; *Introns ; *Iron-Binding Proteins ; Male ; Molecular Sequence Data ; Pedigree ; Point Mutation ; Polymerase Chain Reaction ; Proteins/chemistry/*genetics ; Sequence Alignment ; *Trinucleotide Repeats
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 9
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    Innate lymphoid cells promote anatomical containment of lymphoid-resident commensal bacteria (2012)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2012-06-08
    Description: The mammalian intestinal tract is colonized by trillions of beneficial commensal bacteria that are anatomically restricted to specific niches. However, the mechanisms that regulate anatomical containment remain unclear. Here, we show that interleukin-22 (IL-22)-producing innate lymphoid cells (ILCs) are present in intestinal tissues of healthy mammals. Depletion of ILCs resulted in peripheral dissemination of commensal bacteria and systemic inflammation, which was prevented by administration of IL-22. Disseminating bacteria were identified as Alcaligenes species originating from host lymphoid tissues. Alcaligenes was sufficient to promote systemic inflammation after ILC depletion in mice, and Alcaligenes-specific systemic immune responses were associated with Crohn's disease and progressive hepatitis C virus infection in patients. Collectively, these data indicate that ILCs regulate selective containment of lymphoid-resident bacteria to prevent systemic inflammation associated with chronic diseases.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3659421/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3659421/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sonnenberg, Gregory F -- Monticelli, Laurel A -- Alenghat, Theresa -- Fung, Thomas C -- Hutnick, Natalie A -- Kunisawa, Jun -- Shibata, Naoko -- Grunberg, Stephanie -- Sinha, Rohini -- Zahm, Adam M -- Tardif, Melanie R -- Sathaliyawala, Taheri -- Kubota, Masaru -- Farber, Donna L -- Collman, Ronald G -- Shaked, Abraham -- Fouser, Lynette A -- Weiner, David B -- Tessier, Philippe A -- Friedman, Joshua R -- Kiyono, Hiroshi -- Bushman, Frederic D -- Chang, Kyong-Mi -- Artis, David -- 2-P30 CA016520/CA/NCI NIH HHS/ -- AI061570/AI/NIAID NIH HHS/ -- AI074878/AI/NIAID NIH HHS/ -- AI083480/AI/NIAID NIH HHS/ -- AI087990/AI/NIAID NIH HHS/ -- AI095466/AI/NIAID NIH HHS/ -- AI095608/AI/NIAID NIH HHS/ -- AI47619/AI/NIAID NIH HHS/ -- K08 DK093784/DK/NIDDK NIH HHS/ -- K08-DK093784/DK/NIDDK NIH HHS/ -- P30 AI 045008/AI/NIAID NIH HHS/ -- P30DK50306/DK/NIDDK NIH HHS/ -- R01 AI061570/AI/NIAID NIH HHS/ -- R01 AI074878/AI/NIAID NIH HHS/ -- R01 AI095466/AI/NIAID NIH HHS/ -- R01 AI102942/AI/NIAID NIH HHS/ -- R21 AI083480/AI/NIAID NIH HHS/ -- R21 AI087990/AI/NIAID NIH HHS/ -- T32 AI007532/AI/NIAID NIH HHS/ -- T32 AI055428/AI/NIAID NIH HHS/ -- T32 RR007063/RR/NCRR NIH HHS/ -- T32-AI007532/AI/NIAID NIH HHS/ -- T32-AI055428/AI/NIAID NIH HHS/ -- T32-RR007063/RR/NCRR NIH HHS/ -- U01 AI095608/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 2012 Jun 8;336(6086):1321-5. doi: 10.1126/science.1222551. Epub 2012 Jun 6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22674331" target="_blank"〉PubMed〈/a〉
    Keywords: Adult ; Alcaligenes/immunology/isolation & purification/*physiology ; Animals ; Bacterial Translocation ; Crohn Disease/immunology/microbiology ; Hepatitis C, Chronic/immunology/microbiology ; Humans ; Immunity, Innate ; Inflammation ; Interleukins/administration & dosage/biosynthesis/*immunology ; Intestines/*immunology/microbiology ; Leukocyte L1 Antigen Complex/metabolism ; Liver/microbiology ; Lymph Nodes/immunology ; Lymphocytes/*immunology ; Lymphoid Tissue/*immunology/*microbiology ; Macaca mulatta ; Mice ; Mice, Inbred C57BL ; Middle Aged ; Spleen/microbiology ; Young Adult
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 10
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    Coinfection. Virus-helminth coinfection reveals a microbiota-independent mechanism of immunomodulation (2014)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2014-08-02
    Description: The mammalian intestine is colonized by beneficial commensal bacteria and is a site of infection by pathogens, including helminth parasites. Helminths induce potent immunomodulatory effects, but whether these effects are mediated by direct regulation of host immunity or indirectly through eliciting changes in the microbiota is unknown. We tested this in the context of virus-helminth coinfection. Helminth coinfection resulted in impaired antiviral immunity and was associated with changes in the microbiota and STAT6-dependent helminth-induced alternative activation of macrophages. Notably, helminth-induced impairment of antiviral immunity was evident in germ-free mice, but neutralization of Ym1, a chitinase-like molecule that is associated with alternatively activated macrophages, could partially restore antiviral immunity. These data indicate that helminth-induced immunomodulation occurs independently of changes in the microbiota but is dependent on Ym1.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4548887/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4548887/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Osborne, Lisa C -- Monticelli, Laurel A -- Nice, Timothy J -- Sutherland, Tara E -- Siracusa, Mark C -- Hepworth, Matthew R -- Tomov, Vesselin T -- Kobuley, Dmytro -- Tran, Sara V -- Bittinger, Kyle -- Bailey, Aubrey G -- Laughlin, Alice L -- Boucher, Jean-Luc -- Wherry, E John -- Bushman, Frederic D -- Allen, Judith E -- Virgin, Herbert W -- Artis, David -- 095831/Wellcome Trust/United Kingdom -- 2-P30 CA016520/CA/NCI NIH HHS/ -- 5T32A100716334/PHS HHS/ -- AI061570/AI/NIAID NIH HHS/ -- AI074878/AI/NIAID NIH HHS/ -- AI082630/AI/NIAID NIH HHS/ -- AI083022/AI/NIAID NIH HHS/ -- AI087990/AI/NIAID NIH HHS/ -- AI095466/AI/NIAID NIH HHS/ -- AI095608/AI/NIAID NIH HHS/ -- AI097333/AI/NIAID NIH HHS/ -- AI102942/AI/NIAID NIH HHS/ -- AI106697/AI/NIAID NIH HHS/ -- F32 AI085828/AI/NIAID NIH HHS/ -- F32-AI085828/AI/NIAID NIH HHS/ -- HHSN272201300006C/PHS HHS/ -- K08 DK097301/DK/NIDDK NIH HHS/ -- K08-DK097301/DK/NIDDK NIH HHS/ -- MR/J001929/1/Medical Research Council/United Kingdom -- P01 AI106697/AI/NIAID NIH HHS/ -- P30-AI045008/AI/NIAID NIH HHS/ -- P30-DK050306/DK/NIDDK NIH HHS/ -- R01 AI 084887/AI/NIAID NIH HHS/ -- R01 AI061570/AI/NIAID NIH HHS/ -- R01 AI074878/AI/NIAID NIH HHS/ -- R01 AI095466/AI/NIAID NIH HHS/ -- R01 AI097333/AI/NIAID NIH HHS/ -- R01 AI102942/AI/NIAID NIH HHS/ -- R21 AI087990/AI/NIAID NIH HHS/ -- T32-AI007532/AI/NIAID NIH HHS/ -- U01 AI095608/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 2014 Aug 1;345(6196):578-82. doi: 10.1126/science.1256942. Epub 2014 Jul 17.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. Institute for Immunology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. ; Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA. ; Institute of Immunology and Infection Research, Centre for Immunity, Infection and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, UK. ; Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. Institute for Immunology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. Department of Medicine, Division of Gastroenterology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. ; Department of Medicine, Division of Gastroenterology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. ; Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. ; Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Universite Paris Descartes, Paris, France. ; Institute for Immunology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. ; Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. Institute for Immunology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. dartis@mail.med.upenn.edu.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25082704" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; CD8-Positive T-Lymphocytes/immunology ; Caliciviridae Infections/*immunology ; Coinfection/*immunology/microbiology/parasitology ; Gastroenteritis/*immunology/virology ; Germ-Free Life ; *Immunomodulation ; Intestines/immunology/microbiology/virology ; Lectins/*immunology ; Macrophage Activation ; Macrophages/immunology ; Mice ; Mice, Inbred C57BL ; Microbiota/*immunology ; Norovirus/*immunology ; Trichinella/*immunology ; Trichinellosis/*immunology ; beta-N-Acetylhexosaminidases/*immunology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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