bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pseudostationary Pulsed Laser Polymerization: A Simple Method for the Direct Determination of Axial Dispersion as Occurring in Size Exclusion Chromatography
Authors: Kornherr Andreas , Olaj Oskar Friedrich , Schnöll‐Bitai Irene , Zifferer Gerhard 
Published: May 2003

AbstractTheoretical distribution curves were calculated for several values of pulse separation t0 and concentrations of initiating radicals ρ formed by each pulse for both types of termination (disproportionation and combination). The absolute and relative peak widths of the additional peaks for the number, molar mass, and hyperdistribution were determined and compared. In all cases, the peak widths of these different distributions became the same with increasing values of C = ktρt0 and/or L0 = kp[M]t0, with [M] = monomer concentration and kt and kp are the rate constants of termination and propagation, respectively. This is similar to the behavior of Poisson distributions if only the degrees of polymerization are fairly high (P̄n ≥ 50). The analogy is further supported by the finding that under the same conditions the peak widths themselves approach the theoretical ones for Poisson distributions. Thus, the fulfilment of these two criteria suggests that the various peaks in multimodal distributions should be treated in the same formal way as Poissonian peaks although they clearly originate from a superposition of adjacent Poissonian peaks of different amplitude and, on the whole have a peak width somewhat in excess of the theoretical one of true Poisson peaks of the same P̄n. The point of inflection can be used as a measure of L0 without reservation only if the first criterion is not fulfilled. The influence of axial dispersion on the location of the extrema was calculated by use of standard deviations σad,k (0.05 and 0.025) to give “experimental curves” for which a pronounced increase in the absolute and relative peak widths was observed. Based on an assumed additivity of the peak variances, a simple procedure was tested for the direct determination of σad,k. The accuracy increased with increasing peak chain lengths and C values for those values determined from the first peak. The values determined from the second peak in the chain length region between 400–700 were closest to the input value.The points of inflection on the low and high molecular weight side of the additional first three peaks are given as a function of the peak maximum. The lower and upper lines were calculated with Equation (11) and (12), respectively.imageThe points of inflection on the low and high molecular weight side of the additional first three peaks are given as a function of the peak maximum. The lower and upper lines were calculated with Equation (11) and (12), respectively.
Die γ2‐Phase und ihre Effekte auf die Eigenschaften heterogener Mehrstoffaluminiumbronzen
Authors: Benkißer G. , Ladewig C. , Rühl I. 
Published: May 2003

AbstractIn diesem Bericht werden die Effekte der chemischen Zusammensetzung und der Herstellung und Verarbeitung auf das Gefüge und einige Eigenschaften heterogener Mehrstoffaluminiumbronzen dargestellt. Insbesondere werden die Entstehung und die Erscheinungsformen der γ2‐ Phase in den Gefügen und die Beziehungen zwischen den Gefügen und den Eigenschaften der Legierungen beschrieben.
Verschleißbeständige MMC mit in situ Karbiden
Authors: Wewers B. , Berns H. 
Published: May 2003

AbstractVerschleißbeständige Hartverbundwerkstoffe bestehen aus einem Verbund von Hartpartikeln, die in einer weicheren Metallmatrix eingebettet sind. Die Hartpartikel tragen zur Erhöhung des Verschleißwiderstandes bei, die Matrix liefert die notwendige Unterstützung und Duktilität. Die Wirksamkeit der Hartpartikel hängt neben ihrer Verteilung und ihrem Volumengehalt in der Matrix von ihrer Härte und Größe ab. Die Auswahl an kommerziell erhältlichen wirksamen Hartpartikeln ist zum Einen begrenzt und zum Anderen ist ihr Preis im Vergleich zum Preis des Matrixpulvers um ein Vielfaches höher. Aus diesem Grund war es das Ziel der vorliegenden Arbeit, die Auswahl an kostengünstigen wirksamen Hartpartikeln zu erweitern. Es wird ein neues pulvermetallurgisches Herstellungsverfahren vorgestellt, bei dem nicht Hartstoffpulver, sondern handelsübliche Ferrolegierungspulver mit und ohne Zugabe von Kohlenstoff mit verschiedenen härtbaren Stahlmatrixpulvern gemischt und anschließend heiß isostatisch gepresst (HIP) werden. Während des HIP‐Prozesses bildet sich durch die Diffusion von C in die Ferropartikel in situ ein Stahlmatrix‐ Karbid‐Verbundwerkstoff. Die durchgeführten Untersuchungen zeigen, dass in tribologisch hoch aber mechanisch, bzw. thermozyklisch gering beanspruchten Werkzeugen die Werkstoffneuentwicklung ein interessantes und kostengünstiges Potential bietet.
Improved fatigue resistance of pseudo‐elastic NiTi alloys by thermo‐mechanical treatment
Authors: Hornbogen E. , Heckmann A. 
Published: May 2003

AbstractShape memory alloys are susceptible to two types of fatigue in addition to classical fatigue: 1. Pseudo‐elastic fatigue leads to an increase in the slope of the pseudo‐elastic plateau and final loss of pseudo‐elasticity 2. A change in transformation temperature. Usually the martensite temperature is lowered with the number of cycles until final loss of transformability. This paper describes measures to improve stability against both types of fatigue. Such methods are simple ageing in order to achieve precipitation in austenite, and thermo‐mechanical treatments such as ausforming that introduce lattice defects into austenite, which transforms subsequently into martensite. Another method consists in the introduction of defects into martensite by marforming plus subsequent ageing. This ageing treatment has two purposes. It increases the classical strength and restores the β‐phase from residual martensite and consequently it recreates transformability. It is shown that the last mentioned method leads to the greatest effect in respect to stabilisation against both types of fatigue. An additional effect of these treatments is a transition of localised to more homogeneous strain. Its relevance for fatigue resistance is still under investigation.
Shear Creep Deformation of the Super Alloy Single Crystal CMSX‐4 at High Temperatures and Low Stresses
Authors: Kamaraj M. , Serin K. , Kolbe M. , Neuking K. , Eggeler G. 
Published: May 2003

AbstractIn the present paper we investigate the shear creep behavior of the single crystal super alloy CMSX‐4 at temperatures between 950 and 1100 °C and shear stresses ranging from 80 to 155 MPa. A double shear creep test technique is used to study the shear creep behavior of four specific macroscopic crystallographic shear systems defined by a specific crystallographic shear plane and a specific crystallographic shear direction (systems investigated: {001}<110>, {100}<010>, {011}<01‐1>, and {111}<01‐1>). The shear creep behavior is analyzed in terms of the shape of individual creep curves and in terms of the stress and the temperature dependence of the secondary shear creep rate. Individual creep curves are generally characterized by a pronounced primary creep range where creep rates decrease by up to three orders of magnitude. A sharp creep rate minimum is not observed. The secondary creep range starts at shear stresses of the order of 0.02 and is followed by a secondary creep range which extends over shear strain ranges of the order of 0.1. No pronounced increase of shear creep rate in the later stages of creep is observed. Norton plots yield power law stress exponents ranging from 5.5 to 9.7. The temperature dependence of the secondary creep rate is of an Arrhenius type and apparent activation energies between 549 and 690 kJ/mol were found. There is a clear influence of crystallography on shear creep rates, which vary between different macroscopic crystallographic shear systems; this effect decreases with increasing temperature. The shear creep results obtained in the present study are discussed in the light of results from uniaxial testing and in the light of underlying microscopic deformation processes.
Analysis of spray formed tool steels
Authors: Schulz A. , Matthaei‐Schulz E. , Spangel S. , Vetters H. , Mayr P. 
Published: May 2003

AbstractThe technique of atomising liquid metal and compacting the micro‐droplets to a billet on a rotating support combines advantages from cast, wrought and powder metallurgical materials. A production rate of several tons per hour requires precisely controlled processing routines. Important process parameters based on processing, manufacturing and application of spray formed material are now developed by fundamental investigations established in projects focused in a special co‐operative research program (SFB 372) at the University of Bremen which is funded by the Deutsche Forschungsgemeinschaft (DFG). By this method advanced alloys of high hardness can be formed without inhomogeneities like segregations and pores in the center of the ingot. By example of tool steels the influence of spray forming on microstructure and homogeneity of the elemental distribution is shown.
Deposition and heat treatment of CuAlNi shape memory thin films
Authors: Wu X. , Kutschej K. , Kneissl A. C. 
Published: May 2003

AbstractCuAlNi thin films were fabricated by magnetron sputtering process. After heat treatment, the thin films presented a shape memory effect. Calowear method was used to measure the thickness of the thin films. SEM, XRD and TEM were used to characterize the thin films. The phase transformation in the thin films was examined by DSC. The deposition rate increased with increasing sputtering power and decreased with increasing Ar pressure. Compared to the composition of the target, both the content of Al and the content of Ni increased a little. The sputtering conditions had little influence on the content of Ni. The content of Al varied slightly with sputtering power, while decreased with increasing Ar pressure. The deposited thin films were columnar. The grain size was very fine. The phases were α‐Cu and α2. After heat treatment at 800 oC/ 60 min + 300 oC/ 60 min in vacuum, CuAlNi shape memory thin films were obtained. The phase in the heat‐treated thin films was β1’ martensite. Martensite transformation was observed and a two‐way shape memory effect could be shown.
Ein einfacher Festigkeitsversuch für Scheiben aus spröden Werkstoffen
Authors: Danzer R. , Börger A. , Supancic P. , Ruiz Villanueva M. A. 
Published: May 2003

AbstractDer 4‐Kugel Versuch ist eine einfache Möglichkeit zur Festigkeitsprüfung von Scheiben aus spröden Werkstoffen. Eine scheibenförmige Probe wird an einer Deckfläche an drei Punkten gelagert und an der gegenüberliegenden Deckfläche mittig belastet. Die Lagerung und die Lasteinleitung wird durch kugelförmige Teile realisiert. Die Vorrichtung weist eine dreizählige Symmetrie auf. In dieser Arbeit wird die Vorrichtung zur Prüfung von Aluminiumoxidproben verwendet. Dabei wird die Größe der Proben, das Dicken zu Durchmesserverhältnis und die Auflagersituation der Proben systematisch verändert. Es war möglich, die numerischen Berechnungen zur Ermittlung der maximalen Spannung in den Scheiben durch Bruchexperimente zu bestätigen. Dabei mußte das Weibullverhalten der Keramik berücksichtigt werden.Vorzüge des 4‐Kugelversuchs liegen vor allem in der großen Toleranz des Verfahrens gegenüber kleinen Abweichungen der tatsächlichen von der idealen Testgeometrie, der Möglichkeit, leicht verbogene Scheiben und damit auch unbearbeitete Sinterkörper zu testen, der geringen Reibung und dem großen Potential, auch besonders kleine Proben zu prüfen. Als Nachteil ist im Vergleich zur herkömmlichen Biegeprüfung von Balken vor allem die aufwendigere Auswertung der Ergebnisse anzuführen.
Auswirkungen von statischen Langzeitglühungen auf Gefüge und mechanische Eigenschaften einer γ‐TiAl Basislegierung
Authors: Beschliesser M. , Jeglitsch F. , Kestler H. , Clemens H. 
Published: May 2003

AbstractIn dieser Arbeit werden die Ergebnisse von statischen Langzeitglühungen (700 °C bzw. 800 °C bis zu 10.000 Stunden an Luft) anhand eines volllamellaren Gefüges (Designed Fully Lamellar, DFL) der pulvermetallurgisch hergestellten Ti‐46.5Al‐4(Cr,Nb,Ta,B) Legierung dargestellt. Das Ziel dieser Arbeit ist es, mögliche Gefügeveränderungen und deren Auswirkungen auf die mechanischen Eigenschaften der γ‐TiAl Basislegierung als Funktion der Auslagerungstemperatur und ‐zeit zu beschreiben und mit thermodynamischen Berechnungen zu vergleichen. Mit Hilfe der thermodynamischen Berechnungen mittels der Software ThermoCalc ist es möglich, für eine gegebene Legierung Phasenanteile und Zusammensetzung der konstituierenden Phasen im Gleichgewicht zu berechnen. Nach sehr langen Auslagerungszeiten kann davon ausgegangen werden, dass Menge und Art der konstituierenden Phasen der untersuchten Legierung einen Gleichgewichtswert angenommen haben. Daneben wurden, ebenfalls in Abhängigkeit der Auslagerungstemperatur und ‐zeit, die mechanischen Eigenschaften im Zugversuch bei Raumtemperatur und bei 700 °C in Vakuum ermittelt.
Microstructural characterization of INCOLOY alloy MA 956
Authors: Hupalo M. F. , Terada M. , Kliauga A. M. , Padilha A. F. 
Published: May 2003

AbstractOxide dispersion strengthened (ODS) ferritic materials obtained by mechanical alloying (MA) display particular microstructure and texture. In this paper a microstructural characterization of an INCOLOY MA 956 alloy in the recrystallized (zone annealed) condition is presented. The alloy exhibits a highly anisotropic microstructure, consisting of elongated grains with a high grain aspect ratio (GAR). The alloy also exhibited strong crystallographic texture. The crystallographic direction <111> was approximately parallel to the extrusion direction of the material. The yttria particles, added to the starting powders, react with aluminum and oxygen present in the system during thermomechanical processing and form mixed (Y,Al) oxides. The analysis of extracted particles showed that the majority of yttrium‐aluminum oxides were tetragonal (Y3Al5O12) and orthorhombic (AlYO3). Quantitative analysis using TEM micrographs showed two classes of dispersoid sizes.
Tribokorrosionsverhalten von mehrphasigen Bronzen
Authors: Tikana L. , Dago L. G. , Heßing C. 
Published: May 2003

AbstractDie Tribokorrosion ist bei erosionsgefährdeten Bauteilen eine Erscheinung, die dann auftreten kann, wenn das Zwischen‐ bzw. Umgebungsmedium chemisch reaktiv ist. Das ist insbesondere der Fall, wenn der Werkstoff in den entsprechenden Medien passiviert. Die vom Werkstoff gebildete Passivschicht, die einen Korrosionsschutz gewährt, wird bei der tribologischen Beanspruchung abgetragen und nach erneuter Bildung immer wieder zerstört.Mehrphasige Bronzen des Typs Cu‐Al‐Ni‐Fe werden im Bereich der Meerestechnik, der Offshoretechnik und der chemischen Industrie eingesetzt. Sie können als Schiffspropeller‐, Turbinenschaufel‐ und Strömungsleitungswerkstoff der Erosion ausgesetzt sein. In der vorliegenden Arbeit wird das Tribokorrosionsverhalten dieser mehrphasigen Bronzen am Beispiel der Legierung CuAl10Ni5Fe5 untersucht. Das allgemeine Korrosionsverhalten des gewählten Werkstoffes in Laugen und Meerwasser ist in der Regel gut. Ist aber der Korrosionsbeanspruchung eine tribologische überlagert, so kann es zu Tribokorrosion kommen. Die Legierung wurde in den o.g. Medien einer Kavitationsbeanspruchung unterzogen und die auftretenden Mechanismen untersucht. Dabei zeigte sich, dass je besser das Passivierungsverhalten war, um so tribokorrosionsanfälliger war der Werkstoff.
Kerbformoptimierung ohne FEM: Ein einfacher Weg, um Kerbspannungen abzubauen
Authors: Mattheck C. , Scherrer M. , Tesari I. , Kraft O. 
Published: May 2003

AbstractEine analytische Vorgehensweise zur Bauteiloptimierung wird vorgestellt, die ohne FEM‐Einsatz auskommt. Es ergeben sich deutliche Kerbspannungsreduktionen bei minimalem Aufwand.
Prescription and non‐prescription analgesic use among the US adult population: results from the third National Health and Nutrition Examination Survey (NHANES III)
Authors: Paulose‐Ram Ryne , Hirsch Rosemarie , Dillon Charles , Losonczy Katalin , Cooper Michael , Ostchega Yechiam 
Published: May 2003

AbstractPurposeTo estimate prescription and non‐prescription analgesic use in a nationally representative sample of US adults.MethodsData collected during the third National Health and Nutrition Examination Survey (1988–1994), for persons 17 years and older were analyzed (n = 20 050). During the household interview, respondents reported use, in the last month, of prescription and non‐prescription analgesics.ResultsAn estimated 147 million adults reported monthly analgesic use, Prescription analgesic use was 9% while non‐prescription use was 76%. Females were more likely than males to use prescription (11 vs. 7%, p < 0.001) and non‐prescription (81 vs. 71%, p < 0.001) analgesics. Across race–ethnicity groups, males (∼8%) and females (11–13%) had similar age‐adjusted prescription analgesic use. Non‐prescription analgesic use was higher among non‐Hispanic whites than non‐Hispanic blacks and Mexican–Americans for males (76 vs. 53% (p < 0.001) and 59% (p < 0.001), respectively) and females (85 vs. 68% (p < 0.001) and 71% (p < 0.001), respectively). With increasing age, prescription analgesic use increased whereas non‐prescription use decreased. Approximately 30% of adults used multiple analgesics during a 1‐month period. This was more common among females (35%) than males (25%, p < 0.001) and among younger (17–44 years, 33%) rather than older age groups (45+ years, 26%, p < 0.001).ConclusionsAnalgesic use among US adults is extremely high, specifically of non‐prescription analgesics. Given this, health care providers and consumers should be aware of potential adverse effects and monitor use closely. Published in 2002 by John Wiley & Sons, Ltd.
Trends in prescribing for heart failure in Dutch primary care from 1996 to 2000
Authors: Pont Lisa G. , Sturkenboom Miriam C. J. M. , van Gilst Wiek H. , Denig Petra , Haaijer‐Ruskamp Flora M. 
Published: May 2003

AbstractPurposeThe aim of this study is to explore trends in primary care prescribing for chronic heart failure (CHF) over a 5‐year period (1996–2000).MethodsThis study consisted of repeated cross‐sectional surveys in a dynamic cohort from the Integrated Primary Care Information (IPCI) primary care database. The cohort comprised all patients aged ≥55 years with a CHF diagnosis and prescribed a cardiovascular medication during the study period. The point prevalence per calendar year was determined for each of the main drug groups used to treat CHF.ResultsThe study population consisted of 3121 CHF patients. Small increases were seen in the percentage of CHF patients prescribed spironolactone (4.6%, 95% CI: 2.3–6.9%), β‐blockers (6.1%, 95% CI: 2.6–9.5%) and angiotensin II antagonists (6.8%, 95% CI: 5.1–8.6%) during the study period, while the prescribing of digoxin decreased (−4.4%, 95% CI: −8.2 to −0.7). Prescribing of diuretics (difference: −0.7% 95% CI: −2.7–4.2) and ACE inhibitors (difference: 4.0% 95% CI: −0.1–8.2%) remained unchanged.ConclusionsPrescription of some drug groups for CHF increased. However, given the new scientific evidence that has emerged in past 15 years regarding CHF pharmacotherapy, the changes observed were less than expected. Copyright © 2003 John Wiley & Sons, Ltd.
Impact of cisapride label changes on codispensing of contraindicated medications
Authors: Guo Jeff Jianfei , Curkendall Suellen , Jones Judith K. , Fife Daniel , Goehring Earl , She Dewei 
Published: May 2003

AbstractObjectiveTo quantify the impact of the first three label changes and ‘Dear Doctor’ letters as sole interventions, sent to prescribers and pharmacists, on the prescribing and dispensing of cisapride and contraindicated drugs.MethodsUsing a managed care claims database, a total of 38 757 patients with cisapride prescriptions (July 1993– December 1998) were selected. An interrupted time series analysis and an exponentially weighted moving average analysis (EWMA) were conducted to determine whether there were changes in the proportion of contraindicated codispensings following each intervention.Results3.6% of cisapride dispensings overlapped with contraindicated drug dispensings. Beginning in 1994, the overlapped proportions declined slowly from 4.5% ending at 3.2% in 1998. The interrupted time series analysis showed that there was a statistically significant abrupt permanent decrease in the proportion of contraindicated dispensing following the June 1998 label change (coefficient −1.0094, p = 0.045), meaning that the proportion of contraindicated dispensing dropped nearly one percentage point after the third intervention. The 1995 label changes did not have statistically significant effects. The EWMA analysis showed that the proportion of contraindicated dispensings was lower than 3 standard deviations below average during the period after the June 1998 intervention, with no significant effects following the two earlier interventions.ConclusionsThe June 1998 cisapride label change and accompanying ‘Dear Doctor’ letter had a downward impact on the proportion of dispensing of contraindicated drugs with cisapride. The other two label changes did not have independent significant impacts. Copyright © 2003 John Wiley & Sons, Ltd.
Liver function testing in patients on HMG‐CoA reductase inhibitors
Authors: Andrade Susan E. , Donahue James G. , Chan K. Arnold , Watson Douglas J. , Platt Richard 
Published: May 2003

AbstractPurposeThe Food and Drug Administration currently requires the labeling of HMG‐CoA reductase inhibitors to recommend liver function tests (LFTs) before the start of therapy and at various intervals during therapy, depending on the specific agent. We sought to determine the frequency and patterns of LFT screening in patients receiving HMG‐CoA reductase inhibitors.MethodsA retrospective study was conducted at a staff‐model health maintenance organization among 4178 new users of HMG‐CoA reductase inhibitors during the period 1 January 1991 through 31 December 1996. The number and proportions of HMG‐CoA reductase inhibitor therapy courses with baseline LFTs (within 180 days prior to dispensing), follow‐up LFTs and LFT abnormalities were calculated.ResultsFor the initial HMG‐CoA reductase inhibitor dispensed, 1947 patients (47%) had at least one screening LFT at baseline and 3063 (73%) had at least one follow‐up LFT. Twenty‐seven (0.9%) patients with at least one follow‐up LFT performed had a level greater than 3 times the upper limit of normal. In a random sample of 100 discontinued patients, none discontinued due to elevated LFTs or liver disease.ConclusionsA large proportion of patients dispensed HMG‐CoA reductase inhibitors in this managed care setting did not have baseline and follow‐up LFTs performed. Modest LFT abnormalities were common among users of HMG‐CoA reductase inhibitors; however, in this population, serious abnormalities were rare. Copyright © 2003 John Wiley & Sons, Ltd.