bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of nanosilica reinforced waterborne silylated polyether adhesive with high shear strength
Authors: Zhang Yang , You Bo , Huang Huang , Zhou Shuxue , Wu Limin , Sharma Anupama 
Published: May 2008

AbstractWaterborne adhesives are extremely environment‐friendly but unfortunately deficient in mechanical properties. In this article, nanosilica, stemming from tetraethyl orthosilicate (TEOS), silica sol, and/or fumed silica powder, was employed to reinforce the waterborne silylated polyether adhesives. Effects of TEOS content, silica sol content, and the type and content of fumed silica on the shear strength of the adhesive were investigated using a scanning electronic microscope and an electronic instron tester and the strengthening mechanisms of different silica source were discussed. All the shear strengths of silylated polyether adhesives first increased and then decreased as TEOS content, silica sol content or fumed silica content increased. Colloidal silica particles was less efficient than fumed silica particles for reinforcing the polyether adhesive but can increase the shear strength of hydrophobic fumed silica embedded adhesive. Comparing the adhesives with the hydrophilic fumed silica (HS‐5) or the extremely hydrophobic fumed silica (TS‐720), the adhesive with moderate hydrophobic fumed silica (TS‐610) had the highest shear strength. The maximal shear strength of 2.5 MPa was achieved when TEOS, silica sol, and fumed silica were combined. It seemed that TEOS, silica sol, and fumed silica played crosslinking (with polyether chain), dispersing (for fumed silica), and reinforcing roles on waterborne adhesive, respectively. This reinforcing mechanism opened a new way to fabricate waterborne adhesives (or coatings) with high performances. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effects of loading rate and thickness on mixed‐mode I/II fracture toughness of thermoset epoxy resin
Authors: Kanchanomai C. , Rattananon S. 
Published: May 2008

AbstractThe influences of loading rate and thickness on fracture behavior and mechanism of thermoset epoxy resin with polyamine hardener under mixed‐mode (mode I/II) loading have been studied at low thickness and low loading rate (LTLL), as well as high thickness and high loading rate (HTHL). Under the variation of mixed‐mode loading from mode I to mode II, fracture toughness of HTHL specimens were under plane‐strain condition. For LTLL specimens, the fracture toughness at dominated mode I loading was under plane‐stress condition, whereas those at dominated mode II loading were under plane‐strain condition. The stretched zone due to the principal stress in the normal direction to the crack plane as well as shear lips due to the Poisson contraction in the thickness direction were the main characteristic of the fracture surface of LTLL specimen tested at pure mode I loading. On the other hand, the mirror‐like fracture surface was observed for the HTHL specimen tested at pure mode I loading. Under pure mode II loading, the aligned stretched zone due to the maximum shear stress was the main characteristic of the fracture surface of LTLL specimen, whereas irregular appearance of the stretched zone was observed for the HTHL specimen. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Melt reaction of zein with glyoxal to improve tensile strength and reduce solubility
Authors: Kruger Woods Kristen , Selling Gordon W. 
Published: May 2008

AbstractGlyoxal, in the presence of base, has been used to crosslink zein in a melt process involving reaction in a melt state combined with compression molding. The resulting zein articles had improved tensile strength, increasing from 34.3 to 40.6 MPa, when the amount of glyoxal was 6% by zein weight. Reduced solubility in solvents, such as acetic acid, was achieved with glyoxal amounts as low as 1%. Derivitization of zein by glyoxal required the presence of base. As little as 0.00019 mmol of NaOH per gram of zein when using 6% glyoxal gave reduced solubility. Other bases such as KOH and Ca(OH)2 also gave reduced solubility. However, these bases did not yield improvements in tensile strength. Decreases in melt temperature and processing time caused a corresponding decrease in tensile strength, but had little effect on solubility. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Plasma treatment for enhancing mechanical and thermal properties of biodegradable PVA/starch blends
Authors: Yang Sung‐Yeng , Huang Chi‐Yuan 
Published: May 2008

AbstractTwo series of biodegradaable polyvinyl alcohol (PVA)/starch blends, i.e., PVA with/without plasma treatment (PP/P series), were produced by single‐screw extruder. The influences of plasma pretreatment and PVA content on the tensile properties, thermal behaviors, melt flow index, and biodegradability of blends were investigated. PVA pretreated by plasma (PPVA) reacted with glycerol was found not only to mechanically strengthen the PPVA/starch blend but also to improve the compatibility of PPVA and starch. Compared with PVA/starch blends, the melt flow indices of PPVA/starch blends were improved significantly by 200–300% and their tensile strength also increased two‐to‐three‐fold. Thermogravimetry analysis (TGA) showed that the thermal stability of PPVA/starch (85/300g) blend was better than PVA/starch blend at processing temperature and outperformed than PVA and starch at high temperature. Both the PPVA/starch and PVA/starch blends finished biodegradation within 9–10 weeks in soil burial tests. The esterification reaction of PPVA and glycerol was characterized by FTIR spectroscopic measurement and TGA test. The morphologic evolutions of the blend during biodegradation were investigated carefully by scanning electron microscope (SEM) imaging. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effect of sonolysis on kinetics and physicochemical properties of treated chitosan
Authors: Li Jin , Cai Jun , Fan Lihong 
Published: May 2008

AbstractLow molecular weight chitosan with weight‐average molecular weight from 161 to 22,000Da were obtained by sonolysis. Optimal conditions for sonolysis were described. The influence of sonolysis condition and the molecular parameters of initial chitosan on the degradation rate and degradation rate constant were investigated in detail. Weight‐average molecular weight (Mw) and molecular weight dispersion (Mw/Mn) of samples were measured by gel permeation chromatography. The structure of degraded chitosan were characterized by Fourier transform infrared, X‐ray diffraction, and electrospray ionization mass spectrometry. For a given sonolysis time, the decrease in molecular weight has been found to be greatest at lowest reaction temperature and lowest chitosan concentration. Molecular weight of samples decreased exponentially with increasing sonication time at early stages. The action mode of ultrasound on the splitting of molecular chain of chitosan has been discussed. The degree of deacetylation of the main hydrolysis products almost unchanged compared with the initial chitosan. The decrease of molecular weight led to transformation of crystal structure but the chemical structures of residues were not modified. Ultrasonic treatment on chitosan is an alternative, safe method to prepare chitosan having different molecular weights, which are more suitable for biomedical and food applications. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Influence of nanoclay on urea‐formaldehyde resins for wood adhesives and its model
Authors: Lei Hong , Du Guanben , Pizzi Antonio , Celzard A. 
Published: May 2008

AbstractThe addition of small percentages of Na+‐montmorillonite (NaMMT) nanoclay appears to improve considerably the performance of thermosetting urea‐formaldehyde (UF) resins used as adhesives for plywood and for wood particleboard. X‐ray diffraction (XRD) studies indicated that NaMMT loses the periodic atomic structure when mixed in small proportions in the acid‐curing environment characteristic of the curing of UF resins. This can be interpreted as becoming exfoliated under such conditions. The partly crystalline structure of the ordered zones of the UF resins is maintained but at a slightly lower level. Differential scanning calorimetry (DSC) indicated that NaMMT has an accelerating effect on the curing of the UF resin. It also appears to lead to a more controlled rate of crosslinking implying a more regular hardened network. The influence of NaMMT addition was particularly noted in plywood by the increase in water resistance of the UF‐bonded panel. In the case of wood particleboard even the dry internal bond strength of the panel, a direct indication of the performance of the resin, improved with small additions of NaMMT. A hypothesis and model of the reasons why such improvement to the performance of UF resins by addition of nanoclay should occur has been presented. This is based on the application of percolation theory to the networking capability of the clay nanoplatelets. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Rhodium‐Catalyzed Asymmetric Addition of Terminal Alkynes to Diarylphosphinylallenes
Authors: Nishimura Takahiro , Guo Xun‐Xiang , Hayashi Tamio 
Published: May 2008

AbstractThe presence of an acid was found to be essential in the rhodium‐catalyzed asymmetric addition of terminal alkynes to diarylphosphinylallenes giving exo‐enynes in high yields with high regio‐ and enantioselectivity. The stereochemical outcome is determined at the protonolysis of the π‐allylrhodium(I) intermediate involved in the catalytic cycle.
Easily Accessible C2‐Symmetric Chiral Bicyclo[3.3.0] Dienes as Ligands for Rhodium‐Catalyzed Asymmetric 1,4‐Addition
Authors: Feng Chen‐Guo , Wang Zhi‐Qian , Tian Ping , Xu Ming‐Hua , Lin Guo‐Qiang 
Published: May 2008

AbstractThe synthesis of a new type of C2‐symmetric chiral diene ligands with a nonbridged bicyclic [3.3.0] backbone was successfully introduced. Using highly efficient lipase‐catalyzed transesterification and Suzuki‐coupling strategies, a broad family of enantiopure 3,6‐disubstituted bicyclo[3.3.0] dienes with different electronic and steric properties could be easily prepared. The application of these new diene ligands in the Rh‐catalyzed asymmetric 1,4‐addition of arylboronic acids to α,β‐unsaturated carbonyl compounds have been examined, and excellent enantioselectivities (up to 98 % ee) as well as good yields are achieved under very mild reaction conditions at room temperature.
Monopilegründungen von Offshore‐Windenergieanlagen – Zum Einfluss einer veränderlichen zyklischen Lastangriffsrichtung
Authors: Dührkop Jan , Grabe Jürgen 
Published: May 2008

AbstractDie zyklische Horizontalbelastung von Offshore‐Monopiles für Windenergieanlagen stellt seit einigen Jahren eine sehr große Herausforderung an die Fachplaner dar, da derzeit kein abgesicherter Bemessungsansatz verfügbar ist. Die in Forschung und Entwicklung eingesetzten Methoden und Verfahren, wie Finite‐Elemente‐Analysen oder Modellversuche, fokussieren sich im ersten Ansatz auf eindirektionale Schwellbeanspruchung. Die in diesem Beitrag dargestellten Modellversuche zeigen jedoch, dass eine geringfügige Veränderung der Lastangriffsrichtung zu Pfahlkopfverschiebungen führt, die diejenigen eines eindirektional belasteten Pfahls um ein Vielfaches übersteigen. Der Pfahl arbeitet sich zyklisch auf einem Weg des geringsten Widerstands durch den Versuchsboden. Der Pfahl driftet aus der Hauptbelastungsrichtung heraus.
Injizieren von Spanngliedern mit nachträglichem Verbund mit Einpressmörtel – Ein Erfahrungsbericht
Authors: Gutsch Alex‐W. 
Published: May 2008

AbstractEine hohe Qualität des Injizierens von Spanngliedern in Vorspannsystemen ist für die Dauerhaftigkeit von Spannbetonbauteilen mit nachträglichem Verbund besonders wichtig. Schäden an Bauwerken und Spannbetonkonstruktionen zeigen, dass in manchen Fällen teilweise oder sogar vollständig unverfüllte Spannglieder die Ursache für teure Sanierungsmaßnahmen sind. Dies ist einer der Gründe dafür, dass die Herstellung des Einpressmörtels auf der Baustelle und der Einpressvorgang in die Spannkanäle selbst seit ca. sechs Jahren in Deutschland durch eine unabhängige Überwachungsstelle fremdüberwacht werden müssen.In diesem Beitrag sollen die Erfahrungen der ersten sechs Jahre der Fremdüberwachung vorgestellt werden. Basierend auf den gewonnenen Erkenntnissen werden weiterhin Empfehlungen gegeben, wie die Herstellung und das Injizieren des Einpressmörtels in die Spannkanäle noch verbessert werden kann, um die Qualität der Einpressarbeiten insgesamt zu sichern und in der Zukunft sichere und dauerhafte Spannbetonbauwerke mit nachträglichem Verbund erstellen zu können.
Beitrag zur Berechnung der Durchbiegung von Stahlbetonbauteilen und Kritik an der ÖNORM B 4700
Authors: Schäfer Friedrich , Taheri Zia 
Published: May 2008

AbstractIm Folgenden wird eine Berechnung der Durchbiegung des Stahlbetons angegeben. Diese unterscheidet sich gegenüber früheren Durchbiegungsberechnungen der ÖNORM B4700 – Stahlbetontragwerke (EUROCODE‐nahe Berechnung, Bemessung und konstruktive Durchbildung) – und ÖNORM B4200/8 dadurch, dass unter anderem Versuchsresultate berücksichtigt und die Vorgänge wirklichkeitsnah erfasst werden.Die nach den oben genannten ÖNORMEN berechneten und überhöhten Tragwerke in Österreich sind nach Jahrzehnten noch überhöht. Dies kann unter anderem als Indiz für eine falsche Durchbiegungsberechnung angesehen werden.Es wird daher empfohlen, die in der ÖNORM B4700 – Stahlbetontragwerke – angegebene Berechnungsmethode der Durchbiegung des Stahlbetons erstens aus der Norm zu entfernen, da diese, wie wir zeigen werden, nicht richtig ist; zweitens sich wie in der DIN 1045 auf eine Angabe der Schlankheiten zu beschränken und eventuell die Durchbiegung nach den hier angegebenen Überlegungen zu berechnen und drittens diese dem Bauingenieur zu überlassen und auf diese Weise auch die Qualen der Bauingenieure zu beenden.Da die Normen auch den Stand der Technik darstellen und eingehalten werden müssen, stellt dies zusätzlich ein rechtliches Problem dar.Wie gezeigt wird, beinhaltet die angegebene Methode der Berechnung der Durchbiegung in der ÖNORM B4700 schon im Ansatz schwere Gedankenfehler und falsche Voraussetzungen.
Über den Bodendruck erdgelagerter Behälter
Authors: Rosemeier Gustav‐Erich 
Published: May 2008

AbstractEs werden Probleme bodengelagerter Behälter behandelt, deren Unterbauten schalenförmig ausgebildet sind. Die physikalischen Bodeneigenschaften sollen dabei denen eines elastischen Halbraums entsprechen, wobei Randkorrekturen bei den Bodenpressungen berücksichtigt werden.
15N cyclotides by whole plant labeling
Authors: Mylne Joshua S. , Craik David J. 
Published: May 2008

AbstractCyclotides are 28–37 amino acid peptides incorporating three disulfide bonds and a cyclic backbone. Their cyclic and knotted topology renders them immune to denaturation by heat or organic solvents and highly resistant to proteolysis. They have a range of interesting and potentially useful pharmaceutical properties and have been proposed as scaffolds within which peptides with drug activities can be stabilized for delivery. Some members of the family also have agricultural applications deriving from their potent insecticidal activity. Labeling peptides with the NMR‐active and stable 15N isotope facilitates a range of studies by NMR, including structural and dynamics studies and their use as tracers. However, owing to their head‐to‐tail cyclized peptide backbone labeled cyclotides are not amenable to conventional recombinant labeling strategies. We have developed an approach to overcome this limitation by growing the cyclotide‐bearing plant Oldenlandia affinis on nitrogen‐free agar media supplemented with 15N salts and obtaining complete labeling at no detriment to plant biomass. We purified the insecticidal cyclotides kalata B1 and kalata B2 as examples and provide heteronuclear single quantum coherence (HSQC) NMR spectra for each. This method of labeling cyclotides involves only a fraction of the cost of uniform labeling by solid‐phase peptide synthesis. © 2008 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 90: 575–580, 2008.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Erratum: Solvent subset selection for polymorph screening
Authors: Allesø Morten , Rantanen Jukka , Aaltonen Jaakko , Cornett Claus , van den Berg Frans 
Published: May 2008

AbstractThe above article (DOI: 10.1002/cem.1107) was published online on 21 January 2008. An error was subsequently identified. Figures 2a, 2b and 2c should appear as below.The print publication will incorporate the amendment identified by this erratum notice.
Au‐Catalyzed Tandem Cyclization/[1,2]‐Alkyl Migration Reaction of Epoxy Alkynes: Synthesis of Spiropyranones
Authors: Shu Xing‐Zhong , Liu Xue‐Yuan , Ji Ke‐Gong , Xiao Hui‐Quan , Liang Yong‐Min 
Published: May 2008

AbstractA novel gold‐catalyzed tandem cyclization/[1,2]‐alkyl migration process of epoxy alkynes to spiropyranones has been discovered. From this process, the construction of adjacent multiple stereocenters with a new quaternary carbon atom is achieved. The gold‐catalyzed domino process is stereospecific with respect to the migrating carbon atom. A type of unusual CC bond cleavage of epoxide systems has also been discovered, which can lead to the formation of two Z alkenes and a carbonyl functional group in one step with excellent stereoselectivity. Furthermore, this efficient domino process could be achieved in the presence of the simplest and least expensive gold catalyst [NaAuCl4]⋅2 H2O with a low catalyst loading.
Rare‐Earth Metal Alkyl and Hydride Complexes Supported by a Linked Anilido–cyclopentadienyl Ligand: Synthesis, Structure, and Reactivity
Authors: Robert Dominique , Voth Peter , Spaniol Thomas P. , Okuda Jun 
Published: May 2008

AbstractTrimethylsilylmethyl complexes of the type [Ln(η5‐C5Me4CH2SiMe2NC6H4R‐4‐κN)(CH2SiMe3)(thf)n] containing a dianionic ligand [C5Me4CH2SiMe2NC6H4R‐4]2– with a para‐substituted anilido group and a CH2SiMe2 link were prepared. The yttrium complex [Y(η5‐C5Me4CH2SiMe2NPh‐κN)(CH2SiMe3)(thf)2] (2a) reacts with H2 to generate the corresponding dimeric hydride [Y(η5‐C5Me4CH2SiMe2NPh‐κN)(μ‐H)(thf)]2 (5a). Pyridine inserts into the Y–H bond in a 1,2‐fashion to afford the stable 2‐hydropyridyl complex [Y(η5‐C5Me4CH2SiMe2NPh‐κN)(η1‐NC5H6)(py)2] (6a). Upon reaction with tBuC≡CH, protonolysis takes place to give the dimeric alkynyl complex [Y(η5‐C5Me4CH2SiMe2NPh‐κN)(μ‐C≡CtBu)(thf)]2 (7a).(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Fabrication and Electrochemical Behavior of Hemoglobin Modified Carbon Ionic Liquid Electrode
Authors: Sun Wei , Gao Ruifang , Li Xiaoqing , Wang Dandan , Yang Maoxia , Jiao Kui 
Published: May 2008

AbstractA new hemoglobin (Hb) and room temperature ionic liquid modified carbon paste electrode was constructed by mixing Hb with 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIMPF6) and graphite powder together. The Hb modified carbon ionic liquid electrode (Hb‐CILE) was further characterized by FT‐IR spectra, scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Hb in the carbon ionic liquid electrode remained its natural structure and showed good direct electrochemical behaviors. A pair of well‐defined quasireversible redox peaks appeared with the apparent standard potential (E′) as −0.334 (vs. SCE) in pH 7.0 phosphate buffer solution (PBS). The electrochemical parameters such as the electron transfer number (n), the electron transfer coefficient (α) and the heterogeneous electron transfer kinetic constant (ks) of the electrode reaction were calculated with the results as 1.2, 0.465 and 0.434 s−1, respectively. The fabricated Hb‐CILE exhibited excellent electrocatalytic activity to the reduction of H2O2. The calibration range for H2O2 quantitation was between 8.0×10−6 mol/L and 2.8×10−4 mol/L with the linear regression equation as Iss (μA)=0.12 C (μmol/L)+0.73 (n=18, γ=0.997) and the detection limit as 1.0×10−6 mol/L (3σ). The apparent Michaelis–Menten constant (KMapp) of Hb in the modified electrode was estimated to be 1.103 mmol/L. The surface of this electrochemical sensor can be renewed by a simple polishing step and showed good reproducibility.
Semi‐active multi‐step predictive control of structures using MR dampers
Authors: Xu Long‐He , Li Zhong‐Xian 
Published: May 2008

AbstractA semi‐active multi‐step predictive control (SAMPC) system with magnetorheological (MR) dampers is developed to reduce the seismic responses of structures. This system can predict the next multi‐step responses of structure according to the current state and has a function of self‐compensation for time delay that occurred in real application. To study the performance of the proposed control algorithm for addressing time delay and reducing the seismic responses, a numerical example of an 11‐story structure with MR dampers is presented. Comparison with the uncontrolled structure indicates that both the peak and the norm values of structural responses are all clearly reduced when the predictive length l⩽10 and the delayed time step d⩽20 are selected, and the SAMPC strategy can guarantee the stability of the controlled structure and reduce the effects of time delay on controlled responses to a certain extent. A performance comparison is also made between the SAMPC strategy and the passive‐off and passive‐on methods; results indicate that this SAMPC system is more effective than the two passive methods in reducing structural responses subjected to earthquakes. Copyright © 2008 John Wiley & Sons, Ltd.
Biological importance of a polymorphic CA sequence within intron 1 of the epidermal growth factor receptor gene (EGFR) in high grade central osteosarcomas
Authors: Kersting Christian , Agelopoulos Konstantin , Schmidt Hartmut , Korsching Eberhard , August Christian , Gosheger Georg , Dirksen Uta , Juergens Heribert , Winkelmann Wilfried , Brandt Burkhard , Bielack Stefan , Buerger Horst , Gebert Carsten 
Published: May 2008

AbstractExpression of EGFR in high grade osteosarcomas has been observed to be correlated with an improved prognosis. Yet, the underlying mechanism remained unclear since amplifications of EGFR have rarely been described. Recently, the length of a polymorphic CA repeat located at a 5′‐regulatory sequence in the intron 1 of the EGFR gene (SSR I) has been shown to be associated with its basal transcriptional activity. We therefore determined the allelic length of CA SSR‐I in 219 cases of high grade osteosarcoma and correlated the results with EGFR expression in 34 cases, the presence of amplifications within the CA SSR‐I repeat in 59 cases, and clinical follow‐up. Our results confirm that in osteosarcoma patients short alleles are more frequent than longer ones, 16 CA repeats being the most frequent. The allele composition differed significantly from the one recently described in a healthy control population (P < 0.01). Short alleles tended to be associated with increased expression of EGFR. Amplifications of the EGFR gene were seen in 13.5% of cases. Significant correlations between allele length composition and neoadjuvant chemotherapy response or long term clinical outcome could not be established. While we were able to show that high frequency of EGFR expression in osteosarcomas is associated with predominantly short alleles of EGFR‐CA SSR I, persisting shortcomings in the correspondence with clinical data point toward the existence of additional, putatively more important transcription control mechanisms for EGFR in osteosarcomas which might account for the good prognostic value of EGFR expression. © 2008 Wiley‐Liss, Inc.