bluuebunny/crossref_metadata_2025_split huggingface dataset:
Methoden zur mechanischen Charakterisierung von modifizierten Implantatoberflächen in der Orthopädischen Chirurgie
Authors: Fritsche A. , Haenle M. , Mittelmeier W. , Neumann H.‐G. , Heidenau F. , Fulda G. , Bader R. 
Published: September 2008

AbstractDerzeit müssen in den ersten 10 Jahren nach Implantation durchschnittlich etwa 10 % aller Hüft‐ und Knieendoprothesen ausgetauscht werden. Eine Revision ist meist infolge aseptischer oder septischer Lockerung der Implantate erforderlich. Zur verbesserten Osteointegration werden Implantate für die Orthopädische Chirurgie heute zunehmend beschichtet. Beschichtungen müssen biokompatibel sein und hohen mechanischen Anforderungen gerecht werden. Hierbei spielen die Haftfestigkeit und die Abriebbeständigkeit der Schichten eine Schlüsselrolle. In der vorliegenden Arbeit werden Methoden zur experimentellen Bestimmung dieser Parameter mittels verschiedener Verfahren exemplarisch an zwei innovativen Implantatbeschichtungen (TiN und TiO2‐Cu) vorgestellt. Zur Ermittlung der Haftfestigkeit wurden unterschiedliche, standardisierte Verfahren verwendet. Dazu zählten der Dornbiegeversuch, die Ritzprüfung und der Stirnzugversuch. Die Abriebbeständigkeit wurde in einem speziellen Prüfstand nach 1,5 Mio Lastzyklen ermittelt. Die Untersuchungen zeigten, dass die beiden getesteten TiN‐ und TiO2‐Cu‐Schichten haftfest und abriebbeständig waren. Mit den genannten Verfahren lassen sich die Haftfestigkeit und die Abriebbeständigkeit von bioaktiven, verschleißmindernden oder anti‐allergenen Oberflächenbeschichtungen für Endoprothesen zuverlässig bestimmen.
Flussmittelfreies Hartlöten unter reaktiver Prozessgasatmosphäre – ein alternatives Verfahren zum Fügen von Aluminiumwerkstoffen
Authors: Bach Fr.‐W. , Möhwald K. , Holländer U. , Tiemann S. 
Published: September 2008

AbstractDas Fügen von Aluminiumwerkstoffen ist aufgrund der hohen Sauerstoffaffinität des Aluminiums nach wie vor eine Herausforderung. Insbesondere die Wirtschaftlichkeit des Verfahrens sowie der Verzicht auf Flussmittel beim Schutzgasofenlöten stehen derzeit im Vordergrund aktueller Forschungsvorhaben. Die gezielte Zumischung reaktiver Gase zur inerten Prozessgasatmosphäre bietet eine geeignete Möglichkeit, Aluminiumwerkstoffe flussmittelfrei zu löten. Unter Einsatz von Chlorwasserstoff soll eine Aktivierung der Lot‐ und Werkstückoberfläche ermöglicht werden, die eine Zerstörung der Oxidschichten einleiten soll. Des Weiteren kommt das stark reduzierende Gas Silan zum Einsatz, dass die Schutzgasatmosphäre gezielt von Sauerstoff‐ und Wasserrückständen befreit. Anhand eines geeigneten Ofenlötprozesses sollen sowohl reduzierende als auch aktivierende Zusätze in Kombination eingesetzt und auf ihren Einfluss auf die verwendeten Gasmischungen und Werkstoffe getestet werden [1–5].
Verbundschmieden hybrider Stahl‐Aluminium Bauteile
Authors: Behrens B.‐A. , Holz F. 
Published: September 2008

AbstractIn Zeiten steigender Energiepreise kommt dem Leichtbau in der Automobilindustrie eine besondere Rolle zu. Die Herstellung hybrider Bauteile mittels Massivumformung stellt dabei eine Erfolg versprechende Methode dar, einbaufertige Funktionsteile in wenigen Prozessschritten ressourcenschonend herzustellen. Bei der Kombination von Stahl und Aluminium als hybrides Werkstoffsystem ist die Erwärmung der Bauteile eine besondere Herausforderung, da der Stahl bei einer Temperatur von mindestens 900 °C umgeformt wird, während das Aluminium eine Temperatur von 500 °C nicht überschreiten sollte. Für diese inhomogene Temperaturverteilung werden Erwärmungsmöglichkeiten aufgezeigt.
Kinematik und Spanungsformen beim Zirkularfräsen
Authors: Denkena B. , de Leon L. , Dege J.H. 
Published: September 2008

AbstractEine Alternative zur konventionellen Bohrbearbeitung mit Spiralbohrern ist das Zirkularfräsen, auch Orbitalbohren genannt. Hierbei bewegt sich ein Schaftfräswerkzeug auf einer helixförmigen Bahn in das Werkstück und erzeugt so die Bohrung. Im Rahmen dieser Arbeit wird zunächst die Kinematik beim Zirkularfräsen und anschließend die sich aus den Eingriffsbedingungen ergebenden Spanungsformen beschrieben. Für die Ermittlung der Spanungsform werden zwei Ansätze zur Berechnung der drehwinkelabhängigen axialen Schnitttiefe miteinander verglichen. Eine darauf basierende Berechnung des zerspanten Volumens an Axial‐ und Tangentialschneide zeigt, dass das Volumenverhältnis nur vom Verhältnis von Werkzeug‐ zu Bohrungsdurchmesser abhängt.
Identifying personality traits to enhance trust between organisations: an experimental approach
Authors: Fahr René , Irlenbusch Bernd 
Published: September 2008

AbstractWe investigate an experimental representatives' trust game which resembles trust relationships between representatives of organisations. Personality traits of subjects are elicited by a personality questionnaire (Cattell's 16 PF‐R) which is well established in personnel psychology. For the first time, personality traits are linked to actually observed behaviour in a trust game. Detailed personality profiles are derived and it is shown that they differ significantly between behavioural types. Individuals with low scores in anxiety turn out to be particularly qualified for enhancing trust between organisations. Copyright © 2008 John Wiley & Sons, Ltd.
Oxidation products of polyunsaturated fatty acids in infant formulas compared to human milk – A preliminary study
Authors: Michalski Marie‐Caroline , Calzada Catherine , Makino Asami , Michaud Sabine , Guichardant Michel 
Published: September 2008

AbstractInformation about lipid oxidation in fresh and stored human milk compared with infant formulas is scarce. We aimed to assess n‐6 and n‐3 PUFA oxidation in these milks by measuring the 4‐hydroxynonenal (4‐HNE) and 4‐hydroxyhexenal (4‐HHE) content. Human milk samples (n = 4), obtained from volunteer mothers, were analyzed fresh and after 1 wk at 4°C or 24 h at 18°C. Vitamin E and malondialdehyde (MDA) were measured by HPLC and fatty acid profile by GC. The 4‐HHE and 4‐HNE contents were measured by GC‐MS. Infant formulas (n = 10) were tested; their fat droplet size was measured by laser light scattering and observed by confocal laser scanning microscopy. Human milk samples contained 31.0 ± 6.3 g/L of lipids and 1.14 ± 0.26 mg/L of vitamin E. Fat droplets were smaller in infant formulas than reported in human milk. The (4‐HHE/n‐3 PUFA) ratio was 0.19 ± 0.01 μg/g in fresh human milk (unchanged after storage) versus 3.6 ± 3.1 μg/g in dissolved powder formulas and 4.3 ± 3.8 μg/g in liquid formula. (4‐HNE/n‐6 PUFA) was 0.004 ± 0.000 μg/g in fresh milk (0.03 ± 0.01 μg/g after storage) versus 1.1 ± 1.0 μg/g in dissolved powder formulas and 0.2 ± 0.3 μg/g in liquid formula. Infant formulas also contained more MDA than human milk. n‐3 PUFA were more prone to oxidation than n‐6 PUFA. Whether threshold levels of 4‐HHE and 4‐HNE would be of health concern should be elucidated.
Pyrrolizidine alkaloids in honey: Risk analysis by gas chromatography‐mass spectrometry
Authors: Kempf Michael , Beuerle Till , Bühringer Manuela , Denner Martina , Trost Daniela , von der Ohe Katharina , Bhavanam Vijaya B. R. , Schreier Peter 
Published: September 2008

AbstractRecently, contamination of honey with pyrrolizidine alkaloids (PA) has been reported as potential health risk. Therefore, it was of interest to develop a reliable tool for selective and quantitative determination of PA in honey. Sample preparation of the novel method comprises strong cation exchange SPE (SCX‐SPE), followed by two reduction steps using zinc and LiAlH4, as well as subsequent silylation. During this procedure the separated PA are converted into the necin backbone, the common structural feature of PA toxicity, which is analyzed by GC‐MS in the SIM mode. The procedure was validated using PA from extracts of Senecio vernalis as well as authentic PA standards including their corresponding N‐oxides. The PA content of honey samples was quantified with heliotrine as internal standard. The method was applied to generate a dataset in order to evaluate the potential risk of PA contamination especially for retail honeys available on the German/European market. No selection criteria in terms of floral or geographical origin were applied on the samples before analysis. In total, 216 commercially available floral honey samples were analyzed. Among them 19 samples contained PA, in the range of 0.019–0.120 μg/g, calculated as retronecine equivalents. The reported method facilitates the selective determination of PA without the need to identify each individual PA independently. The PA contamination of honey is expressed in terms of a single sum parameter and no background information such as foraged plants and pollen analysis is necessary. The LOQ is 0.01 ppm with a S/N of 7:1.
Resolving an apparent discrepancy between theory and experiment: spin–spin coupling constants for FCCF
Authors: Del Bene Janet E. , Provasi Patricio F. , Alkorta Ibon , Elguero José 
Published: September 2008

AbstractAb initio equation of motion coupled cluster singles and doubles (EOM–CCSD) and second‐order polarization propagator approximation (SOPPA) calculations have been performed to evaluate spin–spin coupling constants for FCCF (difluoroethyne). The computed EOM‐CCSD value of 3J(FF) obtained at the experimental geometry of this molecule supports the previously reported experimental value of 2.1 Hz, thereby resolving an apparent discrepancy between theory and experiment. This coupling constant exhibits a strong dependence on the CC and CF distances, and its small positive value results from a sensitive balance of paramagnetic spin‐orbit (PSO) and spin‐dipole (SD) terms. The three other unique FCCF coupling constants 1J(CC), 1J(CF), and 2J(CF) have also been reported and compared with experimental data. While 1J(CF) is in agreement with experiment, the computed value of 2J(CF) is larger than our estimate of the experimental coupling constant. Copyright © 2008 John Wiley & Sons, Ltd.
Multi‐frequency improved constant amplitude pulses for broadband inversion
Authors: Brown Douglas 
Published: September 2008

AbstractOptimization of constant amplitude broadband inversion pulses for maximum inversion over a range of multiple fields yields more regular pulses with better tolerance to B1 errors than those optimized for a single field. These multi‐frequency improved constant amplitude (MICA) pulses as constructed for 13C broadband inversion give best results for HMQC and especially HSQC type experiments. Most of the advantages of MICA pulses versus other inversion pulses in these experiments can be attributed to their relatively short durations. Linearly truncated versions of these pulses do not offer any advantage over MICA pulses for these applications. MICA inversion pulses can also be used for decoupling and a 13C decoupling example gives twice the decoupling bandwidth as the GARP1 sequence at the same power level with no appreciable increase in decoupling sidebands. Copyright © 2008 John Wiley & Sons, Ltd.
Layer‐specific anatomical, physiological and functional MRI of the retina
Authors: Duong Timothy Q. , Pardue Machelle T. , Thulé Peter M. , Olson Darin E. , Cheng Haiying , Nair Govind , Li Yingxia , Kim Moon , Zhang Xiaodong , Shen Qiang 
Published: September 2008

AbstractMost retinal imaging has been performed using optical techniques. This paper reviews alternative retinal imaging methods based on MRI performed with spatial resolution sufficient to resolve multiple well‐defined retinal layers. The development of these MRI technologies to study retinal anatomy, physiology (blood flow, blood volume, and oxygenation) and function, and their applications to the study of normal retinas, retinal degeneration and diabetic retinopathy in animal models are discussed. Although the spatiotemporal resolution of MRI is poorer than that of optical imaging techniques, it is unhampered by media opacity and can thus image all retinal and pararetinal structures, and has the potential to provide multiple unique clinically relevant data in a single setting and could thus complement existing retinal imaging techniques. In turn, the highly structured retina with well‐defined layers is an excellent model for advancing emerging high‐resolution anatomical, physiological and functional MRI technologies. Copyright © 2008 John Wiley & Sons, Ltd.
Second trimester amniotic fluid annexin A5 levels and subsequent development of intrauterine growth restriction
Authors: Dundar Ozgur , Yoruk Pınar , Tutuncu Levent , Muhcu Murat , Ipcioglu Osman , Ergur Ali Rustu , Mungen Ercument 
Published: September 2008

AbstractObjectiveThe purpose of this study was to investigate the levels of annexin A5 in second trimester amniotic fluid, and evaluate its correlation with subsequent development of intrauterine growth restriction (IUGR).MethodA total of 264 women undergoing mid‐trimester amniocentesis between January 2007 and December 2007 were enrolled for the study. Amniocentesis was performed for routine indications. After delivery, outcome data were obtained.ResultsMaternal age, frequency of nulliparity, fetal sex and gestational week at amniocentesis were similar between groups. As expected, prevalence of smoking was higher in IUGR developing mothers. Significant positive correlations were present between annexin A5 levels and gestational age at amniocentesis (P = 0.02) and maternal age (P = 0.01). Linear regression analysis revealed that annexin A5 levels were positively correlated with patient's age. Smoking women had significantly lower annexin A5 levels in the mid‐trimester amniotic fluid (9.9 ± 2.3 and 10.7 ± 1.3 ng/mL, P = 0.01). Logistic regression analysis demonstrated that after controlling for gestational age at amniocentesis, smoking, maternal age, and maternal hypertension, annexin A5 was not significantly associated with IUGR (P = 0.07).ConclusionAmniotic fluid annexin A5 levels in the mid‐trimester are not associated with IUGR at birth after controlling for maternal smoking and other confounders. Copyright © 2008 John Wiley & Sons, Ltd.
Application of transcervical hysterofetoscopy and cord blood collection at first trimester termination of pregnancy for fetal abnormalities
Authors: Chan B. C. , Hui P. W. , Leung W. C. , Leung K. Y. , Pun T. C. , Lee C. P. 
Published: September 2008

AbstractObjectiveTo examine the applicability of hysterofetoscopy and cord blood collection at first trimester termination of pregnancy for fetal abnormalities.MethodsFrom 2004 to 2007, transcervical hysterofetoscopy was performed in seven patients at the same operation setting of surgical termination of pregnancy. The findings were compared with prenatal diagnosis. Feasibility of cord blood collection was also examined.ResultsOut of these seven patients, six of them had prenatal ultrasound diagnosis of cystic hygroma. All of them had chromosomal abnormalities. Subcutaneous oedema was confirmed by hysterofetoscopy with good view. Another pregnancy was complicated by homozygous alpha thalassaemia and the diagnosis was confirmed by electrophoresis of fetal haemoglobin collected from umbilical cord vessel. Cord blood collection was also attempted in two other patients yielding fetal blood with minimal maternal contamination.ConclusionTranscervical hysterofetoscopy is a feasible tool in confirming external fetal structural abnormalities before surgical termination of pregnancy. It can be performed under either general anaesthesia or conscious sedation. Umbilical cord blood collection can facilitate confirmation of genetic diseases. It may also allow the potential of isolating fetal mesenchymal stem cell in first trimester. Copyright © 2008 John Wiley & Sons, Ltd.
Effects of organically modified clay loading on rate and extent of cure in an epoxy nanocomposite system
Authors: Ingram Sharon E , Pethrick Richard A , Liggat John J 
Published: September 2008

AbstractBACKGROUND: Cloisite 30B was added to diglycidyl ether of bisphenol F and cured with diaminodiphenylsulfone to investigate how the organoclay influenced the extent of cure.RESULTS: A substantial increase in the extent of cure was found with the addition of Cloisite 30B, when lower cure temperatures were employed. Cloisite 30B at 2 wt% resulted in a 40 °C increase in glass transition temperature and an increase in the magnitude of the bending modulus even though a high level of intercalated material was detected.CONCLUSIONS: It was observed that the addition of Cloisite 30B to the epoxy system increased the level of cure in the polymer, and was particularly prominent at low cure temperatures. Copyright © 2008 Society of Chemical Industry
A gel‐free MS‐based quantitative proteomic approach accurately measures cytochrome P450 protein concentrations in human liver microsomes
Authors: Wang Michael Zhuo , Wu Judy Qiju , Dennison Jennifer B. , Bridges Arlene S. , Hall Stephen D. , Kornbluth Sally , Tidwell Richard R. , Smith Philip C. , Voyksner Robert D. , Paine Mary F. , Hall James Edwin 
Published: September 2008

AbstractThe human cytochrome P450 (P450) superfamily consists of membrane‐bound proteins that metabolize a myriad of xenobiotics and endogenous compounds. Quantification of P450 expression in various tissues under normal and induced conditions has an important role in drug safety and efficacy. Conventional immunoquantification methods have poor dynamic range, low throughput, and a limited number of specific antibodies. Recent advances in MS‐based quantitative proteomics enable absolute protein quantification in a complex biological mixture. We have developed a gel‐free MS‐based protein quantification strategy to quantify CYP3A enzymes in human liver microsomes (HLM). Recombinant protein‐derived proteotypic peptides and synthetic stable isotope‐labeled proteotypic peptides were used as calibration standards and internal standards, respectively. The lower limit of quantification was ˜20 fmol P450. In two separate panels of HLM examined (n= 11 andn= 22), CYP3A, CYP3A4 and CYP3A5 concentrations were determined reproducibly (CV ≤27%). The MS‐based method strongly correlated with the immunoquantification method (r2≥0.87) and marker activities (r2≥0.88), including testosterone 6β‐hydroxylation (CYP3A), midazolam 1′‐hydroxylation (CYP3A), itraconazole 6‐hydroxylation (CYP3A4) and CYP3A5‐mediated vincristine M1 formation (CYP3A5). Taken together, our MS‐based method provides a specific, sensitive and reliable means of P450 protein quantification and should facilitate P450 characterization during drug development, especially when specific substrates and/or antibodies are unavailable.
2D‐ and 3D‐microstructured biodegradable polyester resins
Authors: Vaida Cristian , Mela Petra , Keul Helmut , Möller Martin 
Published: September 2008

AbstractBiodegradable polyester resins were prepared via photo crosslinking of functional polyesters obtained by copolymerization of ε‐caprolactone and the functional cyclic esters γ‐acryloyloxy‐ε‐caprolactone (ACL) and γ‐methacryloyloxy‐ε‐caprolactone (MCL). The cyclic esters were prepared via Baeyer‐Villiger oxidation of the corresponding 4‐acyloyloxy‐cyclohexanone derivatives. Copolymers with different content of either acryloyloxy or methacryloyloxy functional groups were prepared via catalyzed ring‐opening polymerization (ROP) of γ‐acyloyloxy‐ε‐caprolactones and ε‐caprolactone using Al(OiPr)3 as catalyst and initiator. 2D‐ and 3D‐micropatterning of the copolymers was performed via UV‐crosslinking of polymer films on a suitable substrate and by UV replica molding on both rigid and elastic masters, showing the processability of these novel functional polyesters and their potential as substrates for biomedical devices. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6789–6800, 2008
Synthesis and characterization of polycholesteryl methacrylate–polyhydroxyethyl methyacrylate block copolymers
Authors: Zhou Yuxiang , Kasi Rajeswari M. 
Published: September 2008

AbstractWe report the synthesis and characterization of a series of novel diblock copolymers, poly(cholesteryl methacrylate‐b‐2‐hydroxyethyl methacrylate) (PCMA‐b‐PHEMA). Monomers, cholesteryl methacrylate (CMA) and 2‐(trimethylsiloxy)ethyl methacrylate (HEMA‐TMS), were prepared from methyacryloyl chloride and 2‐hydroxyethyl methacrylate, respectively. Homopolymers of CMA, PCMA, with well‐defined molecular weights and polydispersity indices (PDI), were prepared by reversible addition fragmentation and chain transfer (RAFT) method. Precursor diblock copolymers, PCMA‐b‐P(HEMA‐TMS), were synthesized using PCMA as macromolecular chain transfer agent and monomer, HEMA‐TMS. Product diblock copolymers, PCMA‐b‐PHEMA, were prepared by deprotecting trimethylsilyl units in the precursor diblock copolymers using acid catalysts. Detailed molecular characterization of the precursor diblock copolymers, PCMA‐b‐P(HEMA‐TMS), and the product diblock copolymers, PCMA‐b‐PHEMA, confirmed the composition and structure of these polymers. This versatile synthetic strategy can be used to prepare new amphiphilic block copolymers with cholesterol in one block and hydrogen‐bonding moieties in the second block. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6801–6809, 2008
Alternating copolymerization of cyclohexene oxide and carbon dioxide catalyzed by noncyclopentadienyl rare‐earth metal bis(alkyl) complexes
Authors: Zhang Zhichao , Cui Dongmei , Liu Xinli 
Published: September 2008

AbstractThe syntheses of several dialkyl complexes based on rare‐earth metal were described. Three β‐diimine compounds with varying N‐aryl substituents (HL1=(2‐CH3O(C6H4))NC(CH3)CHC(CH3)NH(2‐CH3O(C6H4)), HL2 = (2,4,6‐(CH3)3 (C6H2))NC(CH3)CHC(CH3)NH(2,4,6‐(CH3)3(C6H2)), HL3 = PhNC(CH3)CH(CH3) NHPh) were treated with Ln(CH2SiMe3)3(THF)2 to give dialkyl complexes L1Ln (CH2SiMe3)2 (Ln = Y (1a), Lu (1b), Sc (1c)), L2Ln(CH2SiMe3)2(THF) (Ln = Y (2a), Lu (2b)), and L3Lu(CH2SiMe3)2(THF) (3). All these complexes were applied to the copolymerization of cyclohexene oxide (CHO) and carbon dioxide as single‐component catalysts. Systematic investigation revealed that the central metal with larger radii and less steric bulkiness were beneficial for the copolymerization of CHO and CO2. Thus, methoxy‐modified β‐diiminato yttrium bis(alkyl) complex 1a, L1Y(CH2SiMe3)2, was identified as the optimal catalyst, which converted CHO and CO2 to polycarbonate with a TOF of 47.4 h−1 in 1,4‐dioxane under a 15 bar of CO2 atmosphere (Tp=130 °C), representing the highest catalytic activity achieved by rare‐earth metal catalyst. The resultant copolymer contained high carbonate linkages (>99%) with molar mass up to 1.9 × 104 as well as narrow molar mass distribution (Mw/Mn = 1.7). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6810–6818, 2008