bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of some aromatic polyimides
Authors: Butt M. Saeed , Akhter Zareen , Bolte Michael , Siddiqi Humaira Masood , Nawaz Haq , Zafar‐uz‐Zaman M. 
Published: July 2009

AbstractThe diamine 2‐methyl‐1,3‐bis(4‐aminophenyloxy)benzene was prepared via a nucleophilic substitution reaction and was characterized with Fourier transform infrared, elemental analysis, and 1H‐ and 13C‐NMR spectroscopy. The prepared diamine was also characterized with single‐crystal analysis. The geometric parameters of C19H18N2O2 were in the usual ranges. The dihedral angles between the central phenyl ring and the two terminal aromatic rings were 88.9 and 91.6°. The crystal structure was stabilized by NH···N hydrogen bonds. The diamine was then polymerized with 3,3′,4,4′‐benzophenone tetracarboxylic acid dianhydride, 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride, 3,4,9,10‐perylenetetracarboxylic acid dianhydride, and pyromellitic dianhydride by either a one‐step solution polymerization reaction or a two‐step procedure. These polymers had inherent viscosities ranging from 0.61 to 0.85 dL/gm. Some of the polymers were soluble in most common organic solvents even at room temperature, and some were soluble on heating. The degradation temperatures of the resultant polymers fell in the range of 260–500°C in nitrogen (with only 10% weight loss). The specific heat capacity at 200°C ranged from 1.0 to 2.21 J g−1 K−1. The temperatures at which the maximum degradation of the polymer occurred ranged from 510 to 610°C. The glass‐transition temperatures of the polyimides ranged from 182 to 191°C. The activation energy and enthalpy of the polyimides ranged from 44.44 to 73.91 kJ/mol and from 42.58 to 72.08 kJ/mol K, respectively. The moisture absorption was found in the range of 0.23–0.71%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis, characterization, and property evaluations of copolymers of diamantyl methacrylate with methyl methacrylate
Authors: Sinkel Carsten , Agarwal Seema , Fokina Natalie A. , Schreiner Peter R. 
Published: July 2009

AbstractThis work reports the homo‐ and copolymerization behavior of previously unknown 4‐diamantyl methacrylate (DMA) with vinyl comonomers like methyl methacrylate (MMA); the starting monomer DMA was synthesized in our laboratory using 4‐diamantanol and methacryloyl chloride. The structures of the homo‐ and copolymers were analyzed using NMR techniques. DMA was found to be more reactive than MMA during copolymerization. The reactivity ratios as determined by the Kelen‐Tüdos method are rMMA = 0.58 and rDMA = 1.75. The incorporation of a few mol % of diamantyl units into the PMMA backbone led to a significant increase in its thermal stability and glass transition temperature. The polymers with 15 and 42 mol % of DMA units in the copolymers showed increased Tg values of 126°C and 172°C, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Gold‐Loaded Carbon Nanoparticles from Poly(vinyl alcohol)‐b‐poly(acrylonitrile) Non‐Shell‐Cross‐Linked Micelles
Authors: Bryaskova Rayna , Willet Nicolas , Duwez Anne‐Sophie , Debuigne Antoine , Lepot Laurent , Gilbert Bernard , Jérôme Christine , Jérôme Robert , Detrembleur Christophe 
Published: July 2009

AbstractHerein we show that a new amphiphilic poly(vinyl alcohol)‐b‐poly(acrylonitrile) block copolymer dispersed in water can be easily loaded with gold nanoparticles by addition of chlorauric acid followed by reduction by sodium borohydride. After deposition of the so‐loaded micelles onto a silicon wafer, followed by an appropriate thermal treatment, the poly(acrylonitrile) core of the micelles is carbonized, while the poly(vinyl alcohol) shell is completely decomposed and volatilized, leading to gold encapsulated in carbon nanoparticles. The morphology of the micelles is maintained during thermal treatment without requiring shell‐cross‐linking of the micelles prior to pyrolysis.
Pharmacokinetics of caffeic acid phenethyl ester and its catechol‐ring fluorinated derivative following intravenous administration to rats
Authors: Wang Xinyu , Pang Jihai , Maffucci Jacqueline A. , Pade Devendra S. , Newman Robert A. , Kerwin Sean M. , Bowman Phillip D. , Stavchansky Salomon 
Published: June 2009

AbstractThe pharmacokinetic profiles of caffeic acid phenethyl ester (CAPE) and its catechol‐ring fluorinated derivative (FCAPE) were determined in rats after intravenous administration of 5, 10 or 20 mg/kg for CAPE and 20 mg/kg for FCAPE, respectively. The plasma concentrations of CAPE and FCAPE were measured using a validated liquid chromatography tandem mass spectrometric method. The pharmacokinetic parameters were estimated using non compartmental analysis (NCA) and biexponential fit. The results showed that the area under the plasma concentration‐time curve for CAPE treatment increased in a proportion greater than the increase in dose from 5 to 20 mg/kg of CAPE. Total body clearance values for CAPE ranged from 42.1 to 172 ml/min/kg (NCA) and decreased with the increasing dose of CAPE. Similarly, the volume of distribution values for CAPE ranged from 1555 to 5209 ml/kg, decreasing with increasing dose. The elimination half‐life for CAPE ranged from 21.2 to 26.7 min and was independent of dose. That FCAPE was distributed extensively into rat tissues and eliminated rapidly was indicated by a high value of volume of distribution and similar short elimination half‐life as that of CAPE. Copyright © 2009 John Wiley & Sons, Ltd.
Tissue distribution of the novel DPP‐4 inhibitor BI 1356 is dominated by saturable binding to its target in rats
Authors: Fuchs Holger , Binder Rudolf , Greischel Andreas 
Published: June 2009

AbstractBI 1356 (INN: linagliptin) is an inhibitor of dipeptidyl peptidase‐4 (DPP‐4). This study investigated whether saturable binding of BI 1356 to its target DPP‐4 occurs in tissues and whether drug accumulation occurs at these sites in vivo. In order to test these hypotheses, the tissue distribution of BI 1356 was determined in wild‐type and DPP‐4 deficient rats at different dose levels by means of whole body autoradiography and measurement of tissue radioactivity concentrations after single i.v. dosing of [14C]‐radio labeled BI 1356. The accumulation behavior of drug‐related radioactivity in tissues was further explored in an oral repeat dose study. Tissue levels of [14C]BI 1356 related radioactivity were markedly lower in all investigated tissues of the DPP‐4 deficient rats and the difference of the dose‐dependent increase of radioactivity tissue levels between both rat strains indicates that tissue distribution at low doses of BI 1356 is dominated by binding of BI 1356 to DPP‐4 in tissues. As the binding to DPP‐4 is strong but reversible, the tissue binding results in a long terminal half‐life in several tissues including plasma. The binding capacity to DPP‐4 is, however, limited. In the rat, saturation of DPP‐4 binding is suggested at an intravenous dose above 0.01–0.1 mg/kg [14C]BI 1356. As the DPP‐4 binding capacity is saturated already at low doses, accumulation of BI 1356 in tissues is unlikely, despite the long persistence of low amounts in the body. Copyright © 2009 John Wiley & Sons, Ltd.
Artemisinin–a possible CYP2B6 probe substrate?
Authors: Asimus Sara , Ashton Michael 
Published: June 2009

AbstractAim. To comparein vitrometabolism rates for artemisinin and the CYP2B6 substrates, bupropion, propofol and efavirenz in human liver microsomes.Methods. Rate constants of artemisinin, bupropion, propofol and efavirenz metabolism by human liver microsomes from a panel of 12 donors, with different levels of CYP2B6 activity, were estimated in WinNonlin. Correlations between the metabolic rate constant for artemisinin and the other CYP2B6 substrates were examined.Results. Artemisinin and propofol depletion data in human liver microsomes were described by first order kinetic models. For bupropion and efavirenz, metabolite formation data were incorporated in the model. Rate constants varied considerably for all substrates. There was a high degree of correlation of rate constants between substrates (r⩾0.87,p<0.001).Conclusions. The rate ofin vitrometabolism of artemisinin was correlated significantly to that of bupropion, propofol and efavirenz, suggesting artemisinin to be a potential alternative marker to assess CYP2B6 activity. Further studies characterizing the metabolic fate of artemisinin are needed in order to evaluate its utility as anin vitroandin vivoCYP2B6 probe substrate, since CYP2B6 might not be the only CYP isoform involved in the depletion of artemisinin. Copyright © 2009 John Wiley & Sons, Ltd.
Evaluation of the effect of intravenous volume expanders upon the volume of distribution of gentamicin in septic neonates
Authors: Sherwin Catherine M. T. , Kostan Esther , Broadbent Roland S. , Medlicott Natalie J. , Reith David M. 
Published: June 2009

AbstractSepsis has been reported to increase the volume of distribution of gentamicin in neonates. To determine whether this was caused by the use of intravenous volume expanders a retrospective nested case–control study was performed comparing confirmed septic neonates with non‐septic controls. Data were collected on intravenous administration of 0.45% saline/10% dextrose, 0.45% saline/5% dextrose, 0.9% normal saline, red blood cells, platelets, immunoglobulin (Intragam P) and albumin. A population pharmacokinetic analysis was performed using NONMEM for 116 neonates (29 confirmed septic) from which 363 gentamicin serum concentrations were available. The final covariate model was CL=0.097×(current weight/2)1.3×(postnatal age/7)0.29 and V=1.07×(current weight/2)0.8+(confirmed sepsis)×0.13. The gentamicin volume of distribution was not significantly influenced by the cumulative intravenous volume expanders. The principal covariates that affected the gentamicin volume of distribution were current body weight and confirmed sepsis. Copyright © 2009 John Wiley & Sons, Ltd.
Changes in synaptic efficacy and seizure susceptibility in rat brain slices following extremely low‐frequency electromagnetic field exposure
Authors: Varró Petra , Szemerszky Renáta , Bárdos György , Világi Ildikó 
Published: July 2009

AbstractThe effects of electromagnetic fields (EMFs) on living organisms are recently a focus of scientific interest, as they may influence everyday life in several ways. Although the neural effects of EMFs have been subject to a considerable number of investigations, the results are difficult to compare since dissimilar exposure protocols have been applied on different preparations or animals. In the present series of experiments, whole rats or excised rat brain slices were exposed to a reference level‐intensity (250–500 µT, 50 Hz) EMF in order to examine the effects on the synaptic efficacy in the central nervous system. Electrophysiological investigation was carried out ex vivo, on neocortical and hippocampal slices; basic synaptic functions, short‐ and long‐term plasticity and seizure susceptibility were tested. The most pronounced effect was a decrease in basic synaptic activity in slices treated directly ex vivo observed as a diminution in amplitude of evoked potentials. On the other hand, following whole‐body exposure an enhanced short‐ and long‐term synaptic facilitation in hippocampal slices and increased seizure susceptibility in neocortical slices was also observed. However, these effects seem to be transient. We can conclude that ELF‐EMF exposure exerts significant effects on synaptic activity, but the overall changes may strongly depend on the synaptic structure and neuronal network of the affected region together with the specific spatial parameters and constancy of EMF. Bioelectromagnetics 30:631–640, 2009. © 2009 Wiley‐Liss, Inc.
Tragfähigkeit von randnahen Kopfbolzen bei der Versagensart seitlicher Betonausbruch
Authors: Hofmann Jan , Eligehausen Rolf 
Published: June 2009

AbstractKopfbolzen, die sehr nahe am Bauteilrand verankert werden, können infolge seitlichen Betonausbruchs versagen. Bei dieser Versagensart kommt es zu einem Abplatzen des Betons auf der Seitenfläche des Bauteils. Die Berechnung der Tragfähigkeit erfolgt dabei mit dem CC‐Verfahren.Numerische und experimentelle Untersuchungen zeigen, dass der bisherige Berechnungsansatz konservative Ergebnisse liefert. Um den Einfluss einzelner Parameter auf die Tragfähigkeit zu bestimmen, wurden Versuche verschiedener Autoren ausgewertet und ergänzende numerische Untersuchungen durchgeführt. Diese zeigen, dass– der kritische Randabstand von 3.c1 auf 2.c1 reduziert werden kann.– der Einfluss des Randabstandes geringer als bisher angenommen ist.– der Einfluss der Betondruckfestigkeit unterschätzt wird.– der Einfluss direkt nebeneinander liegender Kopfbolzen nicht berücksichtigt wird. Um wirtschaftlichere Ergebnisse für die Tragfähigkeit von randnahen Kopfbolzen zu erhalten wird ein modifizierter Berechnungsansatz aufgezeigt, der die Versuchsergebnisse und numerischen Berechnungen gut abbildet. Dieser Ansatz findet Eingang in die neue europäische Bemessungsnorm 'Design of Fasteners for Use in Concrete' und ermöglicht damit eine genauere Berechnung von Kopfbolzenverankerungen nahe am Bauteilrand für die Versagensart Blow Out.Load Bearing Capacity of Headed Studs in Case of Blow Out Failure ModeHeaded studs placed near to the edge of a concrete member can fail because of blow out. In case of this failure mode the concrete spalls at the lateral surface of the concrete member. The failure load can be calculated by the Concrete capacity method (CCmethod).Numerical and experimental investigation show that the CC‐method leads to conservative results. To determine the influence parameters on the load bearing capacity the tests of different authors are evaluated and advanced numerical simulations are carried out. The evaluation shows that– the critical edge can be reduced to two times the edge distance.– the influence of the edge distance is smaller than assumed.– the influence of the concrete compressive strength is underestimated.– the influence of headed stud placed sided by side is not considered. To get more economic results relating the load capacity of headed studs at the edge a modification of the CC‐Method is proposed. This modified CC‐method corresponds quite well with the test results as well as with the results of the numerical simulations. The proposed design equation will be included in the European design guide 'Design of Fasteners for Use in Concrete'.
Rissbildung und Zugtragverhalten von mit Fasern verstärktem Stahlbeton am Beispiel ultrahochfesten Betons
Authors: Leutbecher Torsten , Fehling Ekkehard 
Published: June 2009

AbstractWegen des Problems möglicher Inhomogenitäten der Faserverteilung/‐ orientierung ist der Einsatz von Fasern als alleinige Bewehrung im konstruktiven Ingenieurbau auf wenige Anwendungsgebiete beschränkt (z. B. Aufnahme von Zwangbeanspruchungen). Unter Zugbeanspruchung lässt sich zudem mit den in der Praxis für normalfeste Betone gebräuchlichen Fasergehalten nach der Erstrissbildung kaum ein verfestigendes Verhalten erzielen. Kombiniert man jedoch Stabstahlbewehrung und Faserbewehrung zu einem stahlfaserverstärkten Stahlbeton, so addieren sich die Vorteile beider Verbundwerkstoffe gleichermaßen. Besonders bei erhöhten Anforderungen an die Rissbreite (Größenordnung: unter 0, 1 mm) kann durch gemischte Bewehrung aus Stabstahl und Fasern eine wesentliche Verbesserung gegenüber Stahlbeton erzielt werden. Im Teil 1 dieses Beitrags wurden die für das Verständnis der unterschiedlichen Wirkungsweisen der beiden Bewehrungselemente “Stabstahl” und “Fasern” erforderlichen mechanischen Zusammenhänge dargestellt. Im Teil 2 erfolgt eine Überprüfung der abgeleiteten Beziehungen anhand experimenteller Untersuchungen an gemischt bewehrten Zugelementen aus ultrahochfestem Beton (UHPC). Für UHPC erreicht die Thematik besondere Aktualität, da aus Gründen der Duktilität der Einsatz von Fasen bei diesen Betonen die Regel ist. Der Nachweis der Begrenzung der Rissbreite bei kombinierter Bewehrung wird zudem an zwei Rechenbeispielen veranschaulicht.Crack Formation and Tensile Behaviour of Concrete Members Reinforced with Rebars and Fibres exemplified by Ultra‐High‐Performance Concrete. Part 2: Experimental Investigations and Examples of ApplicationDue to the problem of possible inhomogeneities of fibre distribution/orientation the use of fibres as sole reinforcement is limited in engineering practice to few applications (e. g. coverage of stresses due to constraints). In addition, it is hardly possible to obtain strain hardening after first crack formation with fibre contents commonly used for normal strength concretes. However, if steel fibre reinforcement is used in combination with bar reinforcement, the advantages of both components are additive in the composite material. Especially for enhanced requirements concerning the crack width (order of magnitude: 0.1 mm), with combined reinforcement of rebars and fibres an essential improvement compared to reinforced concrete can be achieved. In part 1 of this contribution the mechanical relationships required for the understanding of the different behaviours of the two reinforcing elements “rebars” and “fibres” have been presented. In part 2 the derived relationships are validated on the basis of experimental investigations on tensile members with combined reinforcement made of ultra‐high‐performance concrete (UHPC). For UHPC the topic is of special interest, because fibres are added to these concretes generally to improve ductility. The crack width control with combined reinforcement is furthermore illustrated by means of two examples.
Verstärkung einer denkmalgeschützten Tonnenschale mit Textilbeton
Authors: Schladitz Frank , Lorenz Enrico , Jesse Frank , Curbach Manfred 
Published: June 2009

AbstractBei dem Umbau der Ingenieurschule Zwickau in ein Finanzamt wurde eine über 100 Jahre alte Stahlbetondachkonstruktion mit Textilbeton verstärkt. Im Vergleich mit anderen Verstärkungsmöglichkeiten konnte nur eine Textilbetonverstärkung den Anforderungen des Denkmal‐ und Brandschutzes, des Architekten sowie des Bauherrn gerecht werden und die statischen Forderung erfüllen. Die Textilbetonschicht, aus Feinbeton und textiler Bewehrung, wurde mit Gesamtdicken von nur 1,0 bis 1,5 cm aufgetragen.
Modelling Tree Roots in Mixed Forest Stands by Inhomogeneous Marked Gibbs Point Processes
Authors: Eckel Stefanie , Fleischer Frank , Grabarnik Pavel , Kazda Marian , Särkkä Aila , Schmidt Volker 
Published: July 2009

AbstractThe aim of the paper is to apply point processes to root data modelling. We propose a new approach to parametric inference when the data are inhomogeneous replicated marked point patterns. We generalize Geyer's saturation point process to a model, which combines inhomogeneity, marks and interaction between the marked points. Furthermore, the inhomogeneity influences the definition of the neighbourhood of points. Using the maximum pseudolikelihood method, this model is then fitted to root data from mixed stands of Norway spruce (Picea abies(L.)Karst.) and European beech (Fagus sylvatica L.) to quantify the degree of root aggregation in such mixed stands. According to the analysis there is no evidence that the two root systems are not independent.
Development of predictive quantitative retention–activity relationship models of alkaloids by mixed micellar liquid chromatography
Authors: Chen Yu , Wu Li‐ping , Chen Cong , Ye Li‐ming 
Published: July 2009

AbstractThe mixed micellar liquid chromatography is a mode that uses mixed micellar system of Brij35/SDS (85 : 15) as a mobile phase under adequate experimental conditions, can simulate the resting membrane potential and the conformation of the long hydrophilic polyoxyethylene chains remains unchanged. In this article, the applications of biopartitioning micellar chromatography, using mixed micellar system to describe and estimate bioactivities of alkaloids, has been focused. The BMCBrij35/SDS‐QRAR models of half‐life time, volume of distribution, plasma clearance and area under concentration–time curve were obtained using Brij35‐SDS retention data. The aim is to take a look at the capability of the mixed micellar liquid chromatography model to describe and/or estimate the bioactivity of alkaloids. Copyright © 2009 John Wiley & Sons, Ltd.
Enhanced interferon‐β production by CHO cells through elevated osmolality and reduced culture temperature
Authors: Han Young Kue , Koo Tai Young , Lee Gyun Min 
Published: July 2009

AbstractFor efficient production of native interferon‐β (IFN‐β) in recombinant CHO cell culture, the IFN‐β molecular aggregation that occurs during culture needs to be minimized. To do so, we investigated the effect of hyperosmolality and hypothermia on IFN‐β production and molecular aggregation in rCHO cell culture. Both hyperosmolality (470 mOsm/kg) and hypothermia (32°C) increased specific native INF‐β productivity qIFN‐β. Furthermore, they decreased the IFN‐β molecular aggregation, although severe IFN‐β molecular aggregation could not be avoided in the later phase of culture. To overcome growth suppression at hyperosmolality and hypothermia, cells were cultivated in a biphasic mode. Cells were first cultivated at 310 mOsm/kg and 37°C for 2 days to rapidly obtain a reasonably high cell concentration. The temperature and osmolality were then shifted to 32°C and 470 mOsm/kg, respectively, to achieve high qIFN‐β and reduced IFN‐β molecular aggregation. Due to the enhanced qIFN‐β and delayed molecular aggregation, the highest native IFN‐β concentration achieved on day 6 was 18.03 ± 0.61 mg/L, which was 5.30–fold higher than that in a control batch culture (310 mOsm/kg and 37°C). Taken together, a combination of hyperosmolality and hypothermia in a biphasic culture is a useful strategy for improved native IFN‐β production from rCHO cells. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Precisely Programmed and Robust 2D Streptavidin Nanoarrays by Using Periodical Nanometer‐Scale Wells Embedded in DNA Origami Assembly
Authors: Kuzuya Akinori , Kimura Mayumi , Numajiri Kentaro , Koshi Naohiro , Ohnishi Toshiyuki , Okada Fuminori , Komiyama Makoto 
Published: June 2009

AbstractA new punched DNA origami assembly with periodic nanometer‐scale wells has been successfully designed and constructed. Through the attachment of two biotins at the two edges of each well, just one streptavidin (SA) tetramer (d=5 nm) was size‐selectively captured in each 6.8×12×2.0 nm well; this allowed formation of a 28 nm‐period SA nanoarray of individual molecules. The position of SA capture can be fully controlled by placement of biotins in the nanoarray well. Moreover, construction of a 2D nanoarray of individual SA tetramers through selective positioning of SA tetramers in any desired wells in a complex of such punched origami motifs is also possible. The stability of the SA captured by this fixation strategy (DNA wells and two biotin linkers) was directly compared on the same molecule with the stability of SA captured with other possible strategies that do not employ wells or two linkers. In this way, the robustness of this means of fixation was clearly established.