bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wasserstoffversprödungsanfälligkeit hochfester Werkstoffzustände Teil 1: Wasserstoffversprödungsanfälligkeit aus metallkundlicher Sicht
Authors: Kloos K. H. , Beyer St. 
Published: May 2005

AbstractNach den Ausführungen in 2.1 und 2.2 können hoch‐ und höchstfeste Vergütungszustände sowie einsatzgehärtete und einsatzvergütete Werkstoffzustande hinsichtlich ihrer Wasserstoffversprödungsanfälligkeit nach rein metallkundlicher Sicht ähnlich beurteilt werden:

Wasserstoffinduzierte interkristalline Brüche scheinen nur in Anwesenheit von Korngrenzenverunreinigungen aufzutreten.
Die Wasserstoffversprödungsanfälligkeit ist am höchsten im Bereich der dritten Anlaßstufe, wo zunehmende ε‐Karbidauflösung auf den Subkorngrenzen und anwachsende Karbidfilmbelegung auf den Lattengrenzen des Massivmartensits und den ehemaligen Austenitkorngrenzen stattfindet. Für übliche Einsatzstähle ist dies im allgemeinen der Anlaßtemperaturbereich zwischen 200–400 °C. In diesem Bereich durfte das Gefüge gemäß 2.1 zum überwiegenden Teil reversible Fallen enthalten. Die reversiblen Fallen werden einerseits durch die gelösten Korngrenzenverunreinigungen (P, N, S, usw.) repra. für Wasserstoff bildet. Das bedeutet, daß Wasserstoffanreicherungsmechanismen hier besonders wirksam werden können und insbesondere unter Zugbeanspruchung ortlich kritische Wasserstoffkonzentrationen schneller erreicht werden.
Legierungselemente können sowohl den Versprödungsgrad einer Anlaßversprödung als auch den Temperaturbereich der Versprödungsanfälligkeit maßgeblich beeinflussen. Da eine deutliche Korrelation zwischen dem Temperaturbereich einer Anlaßversprödung – auch wenn diese nur latent vorhanden ist – und der Wasser‐ stoffversprödungsanfälligkeit besteht, ist es insbesondere bei Vergütungsstahlen mit Elementen wie Mo oder Ni, die Vorgänge der dritten Anlaßstufe zu höheren Anlaßtemperaturen verschieben können, moglich, daß auch die Wasserstoffversprödungsanfälligkeit bis zu Anlaßtemperaturen von 450–500 °C bestehen bleibt.
Quecksilberporosimetriemessungen an durch Druckwasserstrahlen beanspruchten Betonproben
Authors: Momber A. 
Published: May 2005

AbstractDer Beitrag beschreibt das Verhalten von Zementstein und Betonen bei der Beanspruchung durch Flüssigkeisstrahlen hoher Geschwindigkeit. Mittels Quecksilberporosimetriemessungen und Korngrößenanalysen wird festgestellt, daß der Versagensvorgang bruchmechanisch orientiert ist und daß das Verhalten deutlich durch die Zuschlagstoffkörner beeinflußt wird.
Long‐term Creep Behavior of austenitic steel S‐590 (X 40 CoCrNi 20 20)
Authors: Bürgel R. 
Published: May 2005

AbstractTypical data from discontinuous long‐term stress rupture tests were adapted for a differentiated creep analysis. A test series of more than 2000 000 h (23 years) single test time was available for austenitic steel S‐590. This alloy was formerly used for high temperature applications. Various factors influence the creep behavior and cause anomalies from classical three‐stage creep division. These phenomena are: microstructural instability, early creep damage (cavitation, microcracks) and corrosion. Typical features of diffusion creep were not observed. The procedure used in this examination and the principal findings can be applied to other high temperature materials.
Bewertung von Oberflächenrissen mit Methoden des plastischen Versagens
Authors: Keller H. P. 
Published: May 2005

AbstractUntersuchungen an Flachzugproben und Behältern aus Vergütungs‐ und Feinkornbaustählen mit etwa halbelliptischen Oberflächenrissen haben gezeigt. Daß die Versagensspannung nach Verfahren des plastischen Versagens konservativ ermittelt wird. Während sie nach dem Ansatz von Harrison und dem Fließkriterium von Mises – unabhängig von der Rißtiefe – im Mintel um etwa 10% unterschätzt wird, bewerten die anderen untersuchten Verfahren (Mattheck, Chell) deutlich konservativer. Der Grad der Unterschätzung wächst von etwa 30 bzw. 40% bei mittleren Rißtiefen bis zu 70% bei tiefen Rissen. Für einseitigen Wasserstoffangriff auf der Rißausgangsseite ergaben sich i.a. die gleichen konservativen Bewertungen wie bei Luftumgebung.Die Untersuchung hat weiterhin gezeigt, Daß die Versagensspannung von Fluchzugproben unter Luft‐ und Wasserstoff‐Atmosphäre mit etwa konstanter Rißtiefe mit guter Genauigkeit berechnet werden kann, wenn im Restquerschnitt der Mittelwert zwischen Streckgrenze und Zugfestigkeit als Fließspannung angesetzt wird.Es ist für ähnliche Bauteile zu erwarten, daß die erarbeiteten Ergebnisse auf Werkstoffe mit vergleichbaren Rißzähigkeits‐ und Festigkeitseigenschaften übertragbar sind.
Degradation and regeneration of the cross‐linking agent azo‐t‐butane
Authors: Shaw Timothy J. , Jones Brian A. 
Published: May 2005

AbstractThe ability of commercially available azo‐t‐butun (ATB) to facilitate immobilization of polysiloxane stationary phases in capillary columns deteriorates upon storage. Aged ATB produces columns with high bleed, solute retention shifts, erratic immobilization efficiency, and high activity. This deterioration is accelerated in the presence of light, suggesting free radical processes are involved. The loss of certain lowlevel impurities, which act as free radical transfer agents or radical sinks, may be responsible for the performance change. Regeneration can often temporarily be accomplished using platinum catalyzed reduction with trichlorosilane. The addition of small amounts of toluene or other radical transfer agents to aged ATB moderates the cross‐linking process, allowing the reproducible production of columns with good immobilization efficiency, excellent intertness, low thermal bleed, and proper polarity.
Parkinsonian features of eight pathologically diagnosed cases of diffuse lewy body disease
Authors: Louis Elan D. , Goldman James E. , Powers James M. , Fahn Stanley 
Published: May 2005

AbstractPremortem diagnosis of diffuse Lewy body disease (DLBD) is difficult, and knowledge of the parkinsonian features of DLBD might facilitate the diagnosis. In this study, we compared the parkinsonian syndrome of DLBD and Parkinson's disease (PD). We retrospectively reviewed the charts of Columbia‐Presbyterian Medical Center (CPMC) Brain Bank cases (1989–1993) with pathologically diagnosed DLBD or PD, and the literature on the parkinsonian features in DLBD patients presenting with parkinsonism. Parkinsonism accompanied or preceded cognitive/psychiatric changes in most CPMC cases (DLBD 100%, PD 88%). DLBD had an earlier mean age of onset than PD did (57 versus 64 years), a similar male: female ratio (1.7:1 versus 1.9:1), and similar mean disease duration (12–13 years). Cognitive/psychiatric changes were less frequent in PD than in DLBD (65 versus 100%) (p = 0.025). Rest tremor was specifically mentioned in 29% of DLBD versus 56% of PD (p = 0.10). Bradykinesia was less common in PD (56% versus 86%) (p = 0.05). All those with PD responded to L‐Dopa, as did all those with DLBD who received L‐Dopa. In conclusion, there are subtle differences between PD and DLBD in age of onset, frequency of cognitive/psychiatric changes, bradykinesia, and rest tremor. However, even when taken together, these cannot be used to distinguish these entities.
Intramolecular motion and reorientational barriers in 9‐fluorenone, 4‐methyl‐9‐fluorenone and 4,5‐dimethyl‐9‐fluorenone
Authors: Wilson Nancy K. 
Published: May 2005

AbstractCarbon‐13 nuclear magnetic resonance spin‐lattice relaxation times and nuclear Overhauser enhancements were measured as functions of temperature for the hydrogen‐bearing carbons in 9‐fluorenone, 4‐methyl‐9‐fluorenone and 4,5‐dimethyl‐9‐fluorenone. Reorientational diffusion constants were obtained from the dipolar T1 values. Isotropic overall molecular motion was assumed, and the methyl group rotation was separated from the overall molecular reorientation by the method of Woessner. Arrhenius plots of the dependence of the rotation rates on temperature provided values of the energy barriers for molecular reorientation and methyl group rotation. The energy barriers for molecular reorientation are essentially the same: 9‐fluorenone 11.8 ± 0.5 kJ mol−1, 4‐methyl‐9‐fluorenone 11.9 ± 0.5 kJ mol−1 and 4,5‐dimethyl‐9‐fluorenone 11.7 ± 0.2 kJ mol−1. The barriers to methyl group rotation are 4‐methyl‐9‐fluorenone 7.8 ± 0.9 kJ mol−1 and 4,5‐dimethyl‐9‐fluorenone 11.0 ± 0.5 kJ mol−1. Thus the bay methyl‐methyl steric interaction in 4,5‐dimethyl‐9‐fluorenone increases the methyl rotational barrier by 3.2 kJ mol−1.
A Study of steric and electronic effects in some methane‐ and dimethane‐sulphonanilides by 13C NMR spectroscopy
Authors: Hasan Misbah Ul , Asrof Ali Sk. 
Published: May 2005

AbstractThe steric and electronic interactions in several methanesulphonanilides and dimethane‐sulphonanilides have been examined on the basis of their 13C NMR chemical shifts. In aromatic amines there is evidence of nitrogen electron pair donation into the aromatic ring. However, the substitution of a methanesulphonyl group on nitrogen, as in N‐phenylmethanesulphonamide, causes a decrease in this resonance interaction. The chemical shifts of ortho‐ and para‐carbons therefore move downfield in comparison with the corresponding amines. Substitution of the aromatic ring at the para position by electron‐withdra wing and electron‐donating groups affects the resonance process. The substitution of methyl groups either at nitrogen or at the ortho positions causes severe steric inhibition of resonance, which is clearly reflected in the chemical shifts of these compounds. The chemical shifts in several dimiethane‐sulphonanilides have also been examined and compared with the shifts in the corresponding methanesulphonanilides. The observed differences are explained in terms of steric, mesomeric and inductive interactions in these molecules. The preferred conformations of these compounds in solution are also postulated on the basis of their chemical shifts.
Effect of nitrogen substituents on CN rotational barriers in enamine derivatives
Authors: Azzaro Marcel , Geribaldi Serge , Videau Bruno 
Published: May 2005

AbstractRates of rotation around the CN bond in a series of ten N,N‐disubstituted 3‐amino‐5,5‐dimethylcyclohex‐2‐enones were determined from total NMR line shape analysis. Linear correlations are shown to exist between Δ and parameters describing the inductive and steric effects of N‐alkyl substituents. The substituent effects on the barriers seem to occur mainly through a change in the potential energy of non‐bonded interactions between the nitrogen substituents and the hydrogen atoms in the ortho position to the amino group.
15N, 1H and 13C NMR. A study of the complexation of binuclear lanthanide(III)‐silver(I) shift or relaxation reagents with substrates containing multiply bonded nitrogen
Authors: Audit M. , Davoust D. , Goasdoue N. , Platzer N. 
Published: May 2005

AbstractBinuclear lanthanide(III)‐silver(I) β‐diketonate chelates are effective NMR shift and relaxation reagents for substrates containing one or two multiply bonded nitrogen atoms, despite the fact that some of the substrates are able to react with lanthanide chelates alone. The silver cation is bonded to the nitrogen—nitrogen or nitrogen—carbon multiple bond. The lanthanide(III) chelate tetrakis anion is held in proximity to the substrate, without delocalization of spin density from the lanthanide to the studied nuclei (15N, 13C, 1H) of the substrate. Greater spectral simplification is achieved with a binuclear shift reagent than with a single lanthanide chelate in two ways. First, the complexation ability of the π electron pair may be greater than that of the heteroatom lone pair when that of the latter is lowered owing to steric (azobenzene, trans‐aldimine derivatives) or conjugative effects (benzonitrile is similar in this respect to heteroaryl substrates in which the heteroatom is devoid of basicity). Second, resolution may be far better preserved in cases where very strong binding to the lanthanide chelates results in extensive broadening of the NMR signals (imidazole, thiazole and oxazole derivatives).
Carbon‐13 NMR spectra of adamantane carboxylic acids and diamantane mono‐ and di‐carboxylic acids and esters
Authors: Hájek Milan , Vodička LuděK , Trška Petr , Sklenář Vladimír 
Published: May 2005

AbstractThe 13C NMR chemical shifts of 17 adamantane and diamantane mono‐ and di‐carboxylic acids and methyl esters have been measured in CDCl3, and D2O. The assignment of the chemical shifts was verified using an additivity rule and the lanthanide shift technique.
1H and 13C NMR spectra of the rotational isomers of N‐hydroxymethylamides and derivatives
Authors: Gate E. N. , Hooper D. L. , Stevens M. F. G. , Threadgill M. D. , Vaughan K. 
Published: May 2005

AbstractA series of N‐hydroxymethylamides, RCONR′CH2OH, and their O‐methyl and O‐acetyl derivatives, have been studied by 13C and 1H magnetic resonance spectroscopy. Signals have been assigned to the E‐ and Z‐isomers on the basis of the analysis of the fully coupled spectra, and by comparison of the chemical shifts with those of model compounds. The introduction of the hydroxy, alkoxy or acetoxy groups at the α‐position of the N‐alkyl moiety causes a significant shift in the equilibrium towards the E‐rotamer compared with the unsubstituted N‐alkylamide. The predominant effect in determining the E: Z ratio appears to be the steric interaction between the carbonyl oxygen and the α‐oxygen in the alkyl moiety; intramolecular hydrogen bonding does not play a significant role in determining the rotamer populations of these molecules.
NMR of carboxylic‐17O in amino acids
Authors: Steinschneider A. , Valentine B. , Burgar M. I. , Fiat D. 
Published: May 2005

Abstract17O NMR studies were conducted on the α‐COOH groups of the amino acids Val, Leu, Ile, His and Pro and on the γ‐COOH group of Glu. Limit chemical shifts, downfield from external water, were 249‐257 ppm in aqueous solution at low pH, and 234–243 ppm in HSO3F. The relative nuclear screening order for α‐COOH 17O between pH ‐1 and 13 and in HSO3F was usually Pro>Leu>His>Val>Ile, reflecting on interactions with the side chain. Concomitant with ionization in aqueous solution, the α‐ and γ‐COOH resonances were displaced to lower field, by 13–18 aid 24 ppm, respectively, presumably owing to overriding effects of the bond order‐charge density term in the paramagnetic contribution toward nuclear shielding. Titration with alkali above neutrality resulted in 2–4 ppm upfield shifts related to deprotonation of the α‐NH3+ group. T2 relaxation times were inversely related to the molecular weight. Line widths of amino acid 17O‐COOH resonances near neutrality were between 280 and 525 Hz, corresponding to T2 relaxation times between 0.6 and 1.1 ms. Titration from acidic to neutral pH increased T2 by up to 1.7‐fold. T1 measured for 17O‐Gly and γ‐17O‐Glu changed in parallel with T2. This was attributed to decreasing rotational correlation times, τc, in line with expected changes in the nuclear quadrupole coupling constant. τc values calculated from 17O relaxation in solutions near neutrality (zwitterion predominant) were in good agreement with τη, expected from solution properties and with the assumption of isotropic rotation. T2 decreased when the pH was increased above neutrality, partly owing to increasing solution viscosity.
NMR studies in the heterocyclic series xxv—13C NMR spectra of some azole dicyanomethylides
Authors: Begtrup Mikael , Elguero José , Díez‐Barra Enrique , Pardo Carmen 
Published: May 2005

AbstractChemical shifts and coupling constants are reported for seven azole derivatives (imidazoles, triazoles and their benzo derivatives), their quaternary salts and the corresponding dicyanomethylides. The assignment of the heterocyclic carbons is based on couplings with the N‐methyl group. Compared with neutral azoles the quaternary salts show irregular effects for the chemical shifts. On the other hand, the 13C chemical shifts of dicyanomethylides are similar to those of N‐methyl quaternary salts.
Carbon‐13 NMR spectra of anthraquinone‐derived dyes
Authors: Rubin I. B. , Buchanan M. V. 
Published: May 2005

AbstractThe 13C NMR spectra of six anthraquinone‐derived dyes, namely benzanthrone, 1‐(methylamino)anthraquinone, 1,4‐di‐p‐toluidinoanthraquinone, 1,4‐diamino‐2,3‐dihydroanthraquinone, 1,4‐diaminoanthraquinone and dibenzochrysenedione, have been measured. The chemical shift assignments were achieved by elucidation of the coupling patterns of the fully coupled spectra and by comparison with the chemical shifts of other anthraquinone derivatives and other model compounds. One‐ and three‐bond carbon‐hydrogen coupling constants are also reported.
15N NMR studies of the tautomeric equilibrium of some 1‐hydroxybenzotriazoles
Authors: Schilf W. , Stefaniak L. , Witanowski M. , Webb G. A. 
Published: May 2005

AbstractBy means of 15N NMR shielding measurements it is possible to obtain quantitative results on tautomeric equilibria for N‐hydroxybenzotriazole and its 4‐ and 6‐mononitro derivatives. For the unsubstituted compound the position of the tautomeric equilibrium is found to depend on the pKa value of the solvent. Intramolecular hydrogen bonding appears to be responsible for an increase in the proportion of the N‐oxide form present in the equilibrium mixture of the 4‐mononitro compound.
31P spin‐sattice relaxation times of tertiary aryl phosphines and their iridium(I) and gold(I) complexes
Authors: Jans‐Bürli S. , Pregosin P. S. 
Published: May 2005

Abstract31P spin‐lattice relaxation times, T1, and 31P‐1H NOE values, η, for CDCl3, solutions of the compounds P(C6H4‐p‐X)3, [IrCl(CO){P(C6H4‐p‐X)3}2] (X = H, CH3, F, Cl, OCH3) and [AuCl{P(C6H4‐p‐X)3}] (X = H, OCH3) are reported. For the uncoordinated tertiary phosphines T1 = 26–28 s, except for X = OCH3 for which T1 = 14 s. For the iridium(I) complexes T1 falls in the range 4.4–8.7 s, whereas for the gold(I) compounds the values are 15.7 and 11.3 s for X = H and OCH3, respectively. The data are discussed in terms of the differing relaxation mechanisms within each class of compound. The unusually low T1 values observed when X = OCH3 is attributed to a relatively large change in the dipole‐dipole contribution to T1, such that T1 (dipole‐dipole) decreases.
Selective heteronuclear chemical shift correlation without soft pulses
Authors: Delsuc M. A. , Guittet E. , Lallemand J. Y. 
Published: May 2005

AbstractThe elucidation of 1H‐13C connectivities is one of the most powerful NMR tools for the determination of unknown structures, and a new one‐dimensional correlation technique is presented, based on a modified INEPT sequence. Omission of the first two 180° refocusing pulses and randomization of the mixing delay realize addition of a 13C bearing the selected 1H. This technique avoids resorting to the acquisition time and data storage consuming two‐dimensional approaches, and does not require any selective pulse or decoupling.
Non‐quaternary suppression with flip‐back: A useful technique for high‐resolution NMR of solids
Authors: Harris Robin K. , Kenwright Alan M. , Packer Kenneth J. 
Published: May 2005

AbstractA modification to the well‐established non‐quaternary suppression pulse sequence used in high‐resolution solid‐state NMR is proposed which allows the inclusion of a ‘flip‐back’ pulse. The utility of such a sequence is demonstrated by spectra obtained using the standard and modified NQS sequences for a glycidyl ether derivative.
1H and 13C NMR spectra of (Z)‐N‐(o‐hydroxy‐benzylidene)‐p‐x‐phenylamine N‐oxides and (Z)‐N‐(2‐hydroxy‐1‐naphthylmethylene)‐p‐X‐phenylamine N‐oxides
Authors: Arumugam N. , Manisankar P. , Sivasubramanian S. , Wilson D. A. 
Published: May 2005

AbstractSubstituent effects on the 1H and 13C chemical shifts of (Z)‐N‐(o‐hydroxybenzylidene)‐p‐X‐phenylamine N‐oxides [(Z)‐α‐(o‐hydroxyphenyl)‐N‐p‐X‐phenyl nitrones] and (Z)‐N‐(2‐hydroxy‐1‐naphthylmethylene)‐p‐X‐phenylamine N‐oxides [(Z)‐α‐(2‐hydroxy‐1‐naphthyl)‐N‐p‐X‐phenyl nitrones] have been obtained. A combination of SFDOR and NOE methods was necessary for complete assignment of signals in the naphthalene series. Correlations have been found between the chemical shifts of various protons and carbons and Hammett o‐ parameters and Swain and Lupton F and R parameters. With both series of compounds a fixed conformation, due to intramolecular hydrogen bonding, is observed which affects the polarity of the nitrone group compared with that in α,N‐diphenyl nitrone. Reduced through‐resonance between aryl rings via the nitrone function was found. This may be attributed to the α‐aryl ring and the nitrone group being held out of coplanarity by the hydrogen bond.
Carbon‐13 chemical shift assignment of some organophosphorus compounds. Part 3. Diaryl‐, dialkoxy‐ and dihalo‐(alkylamido or arylamido) phosphorus derivatives with general formula Y2P(X)NHR
Authors: Al‐rawi Jasim M. A. , Ayed Naceur 
Published: May 2005

AbstractCarbon‐13 chemical shifts and PC coupling constants of fifteen compounds containing the amine moiety and with the general formula Y2P(X)NHR are reported (Y=Cl, C2H5O, C6H5; Y2 = OCH2CH2O 1,2‐dioxybenzene: X = S, Se or O: R = Et, n‐Pr, n‐Bu, i‐Pr, t‐Bu, Ph, C6H11). The effects of sulphurization and selenization on J(PC) and on chemical shifts were verified.
Nitrogen and oxygen nuclear quadrupole and nuclear magnetic resonance spectroscopic study of NO bonding in pyridine 1‐oxides
Authors: Woyciesjes Peter M. , Janes Nathan , Ganapathy S. , Hiyama Yukio , Brown Theodore L. , Oldfield Eric 
Published: May 2005

Abstract14N nuclear quadrupole resonance (NQR) spectra of the NO functional group in a series of 4‐substituted pyridine 1‐oxides (R = H, CH3, C6H5, OCH3, OCH2C6H5, Cl, CN, NO2) and the natural abundance 17O NQR and nuclear magnetic resonance (NMR) solution spectra of a number of selected systems were obtained. The orientations of the principal axes of the 14N electric field gradient tensor (efg) in the NO group were determined using a Townes‐Dailey treatment of the NQR results, combined with a 13C cross‐polarization magic‐angle sample‐spinning NMR line shape analysis of carbons bonded directly to nitrogen. The major principal axis (Z) is coincident with the NO bond. The orientation of the principal (Z) axis of the 17O efg tensor also lies along the N‐O bond, as determined by Townes‐Dailey analysis. The NO π‐bond orders show considerable sensitivity to the nature of the para‐substituent, ranging from 0.17 to 0.31. 17O and 15N NMR chemical shifts parallel these changes in π‐bond order.
Computer simulation of lanthanide induced shifts (LIS) in bifunctional substrates. Geometry of europium‐quinone complexes
Authors: Aversa M. C. , Giannetto P. , Saija A. 
Published: May 2005

AbstractBy observing the shifts of the 1H NMR signals of 1,4‐benzoquinones induced by Eu(fod)3, and simulating them with the aid of a novel computer program TWOCEN, it has been shown that the two carbonyl groups of 1,4‐toluquinone and 2,6‐dimethyl‐1,4‐benzoquinone compete in the Eu coordination. The metal binds at two sites on both the carbonyl groups, with 4‐CO having a greater complexing ability with respect to 1‐CO, in line with steric and electronic considerations.
Carbon NMR spectra of conjugated nitrones
Authors: Moskal Janusz , Milart Piotr 
Published: May 2005

Abstract13C NMR spectra of some bifunctional nitrones containing the aldonitrone functionality as part of the hetero‐1,3‐diene system have been determined, and interpreted for the chemical shifts and coupling constants. The steric structures and long‐range substituent effects on the heteroene carbon resonances are discussed.
Carbon‐13 NMR studies on catechol, phenol and benzene derivatives of biological relevance
Authors: Lai Adolfo , Monduzzi Maura , Saba Giuseppe 
Published: May 2005

AbstractSome biologically relevant derivatives of catechol, phenol and benzene were studied by 13C NMR spectroscopy. The 13C chemical shifts of the aromatic ring are discussed in terms of the polarizing ability of the substituents.