bluuebunny/crossref_metadata_2025_split huggingface dataset:
A study on the curing kinetics of epoxycyclohexyl polyhedral oligomeric silsesquioxanes and hydrogenated carboxylated nitrile rubber by dynamic differential scanning calorimetry
Authors: Liu Qing , Ren Wentan , Zhang Yong , Zhang Yinxi 
Published: September 2011

AbstractA new organic–inorganic hybrid material was prepared through reactive blending of hydrogenated carboxylated nitrile rubber (HXNBR) with epoxycyclohexyl polyhedral oligomeric silsesquioxanes (epoxycyclohexyl POSS). The structure of the composite was characterized by Fourier transform infrared spectroscopy (FTIR) and solid‐state 13C Nuclear Magnetic Resonance spectra (solid‐state 13C‐NMR). The differential scanning calorimetry (DSC) at different heating rates was conducted to investigate the curing kinetics. A single overall curing process by an nth‐order function (1 − α)n was considered, and multiple‐heating‐rate models (Kissinger, Flynn–Wall–Ozawa, and Crane methods) and the single‐heating‐rate model were employed. The apparent activation energy (Ea) obtained showed dependence on the POSS content and the heating rate (β). The overall reaction order n was practically constant and close to 1. The isoconversion Flynn–Wall–Ozawa method was also performed and fit well in the study. With the single‐heating‐rate model, the average Ea for the compound with a certain POSS content, 66.90–104.13 kJ/mol was greater than that obtained with Kissinger and Flynn–Wall–Ozawa methods. Furthermore, the calculated reaction rate (dα/dt) versus temperature curves fit with the experimental data. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Impact, thermal, and morphological properties of functionalized rubber toughened‐poly(ethylene terephthalate) nanocomposites
Authors: Lim S. R. , Chow W.S. 
Published: September 2011

AbstractIn this study, poly(ethylene terephthalate)/organo‐montmorillonite (PET/OMMT) nanocomposites were melt‐compounded using twin screw extruder followed by injection molding. Maleic anhydride grafted styrene‐ethylene/butylene‐styrene (SEBS‐g‐MAH) was used to improve the impact properties of the PET/OMMT nanocomposites. The notched and un‐notched impact strength of PET/OMMT nanocomposites increased at about 2.5 times and 5.5 times by the addition of 5 wt % of SEBS‐g‐MAH. Atomic force microscopy (AFM) scans were taken from the polished surface of both PET/OMMT and SEBS‐g‐MAH toughened PET/OMMT nanocomposites. The addition of SEBS‐g‐MAH altered the phase structure and clay dispersion in PET matrix. It was found that some of the OMMT silicate layers were encapsulated by SEBS‐g‐MAH. Further, the addition of SEBS‐g‐MAH decreased the degree of crystallinity of the PET/OMMT nanocomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis and Cytotoxicity Evaluation of Novel Podophyllotoxin Derivatives
Authors: Chengniu Wang , Zhonghua Wu , Yu Zhao , Chunyan Ni , Xiaodong Zhao , Li Zhu 
Published: September 2011

AbstractSeven benzylamino derivatives of podophyllotoxin 8a–8g were synthesized and their chemical structures were confirmed by IR, 1H‐NMR, 13C‐NMR and ESI‐MS spectral analyses. Their abilities to inhibit the growth of cancer cells A549, HCT‐116 and HepG2, were investigated by MTT assay. Compound 8b possessed the highest cytotoxicity on cancer cell lines with average IC50 values of 3.8 µM. All we synthetic compounds were cytotoxic against three cancer cell lines at the micromolar range, indicating podophyllotoxin derivatives with structural modification of benzylamino possess potent antitumor activity.
Steroid/Triterpenoid Functional Molecules based on “Click Chemistry”
Authors: Hu J. , Lu J. R. , Ju Y. 
Published: September 2011

AbstractThis Focus Review highlights the design and synthesis of various functional molecules based on steroid/triterpenoid as building blocks through the copper‐catalyzed azide–alkyne cycloaddition (CuAAC) “click” reaction, as well as their applications in bioactivity, recognition, and assembly. This method shows great promise to allow us to develop novel molecules with characteristic functions using the CuAAC “click” reaction.
Reactions under the Click Chemistry Philosophy Employed in Supramolecular and Mechanostereochemical Systems
Authors: Fahrenbach Albert C. , Stoddart J. Fraser 
Published: September 2011

AbstractSupramolecular chemistry and mechanostereochemistry have been major beneficiaries of the concepts and reactions pioneered under the “click chemistry” philosophy. The success of the copper(I) 1,3‐dipolar cycloaddition between azides and alkynes, resulting in the triazole ring has inspired the application of other emerging click reactions, for example, Diels–Alder cycloadditions, thiol–ene/yne chemistry, and nitrile N‐oxide cycloadditions, towards the creation of advanced functional supramolecular and mechanostereochemical systems. In this Focus Review, recent advances in the use of click chemistry in these fields are highlighted.
Applying Small Molecule Microarrays and Resulting Affinity Probe Cocktails for Proteome Profiling of Mammalian Cell Lysates
Authors: Shi Haibin , Uttamchandani Mahesh , Yao Shao Q. 
Published: September 2011

AbstractSmall molecule microarrays (SMMs) are proving to be increasingly important tools for assessing protein–ligand interactions, as well as in screening for enzyme substrates and inhibitors, in a high‐throughput manner. We previously described an SMM‐facilitated screening strategy for the rapid identification of probes against γ‐secretase, an aspartic protease. In this article, we extend upon this work with an expanded library of hydroxyethylamine‐derived inhibitors which non‐exclusively target aspartic proteases. Our library is diversified across P2, P1, P1’, and P2’ positions. Accordingly, 86 new inhibitors are synthesized using a combinatorial, solid‐phase synthetic approach, bringing the total library size to 284‐biotinylated compounds, which were arrayed onto avidin slides. In order to elucidate enzymatic activity and profiles within complex biological samples, screening is performed using fluorescently‐labeled mammalian cell lysates. This yielded reproducible profiles or binding fingerprints that correspond with interactions from aspartic proteases or accessory proteins as well as other interacting targets that were present in the sample. The brightest microarray hits were converted to affinity‐based probes (AfBPs) using convenient, 1‐step “click” chemistry with benzophenone from the relevant building blocks. Pull‐down/mass spectrometric analysis with these probes (individuals or cocktail) yielded putative protein targets that include well‐known aspartic proteases, such as cathepsin D which is a clear marker for breast cancer cell lines, T47D. Many other hits were also identified, which may be secondary or tertiary interactors of aspartic proteases, or yet unreported off‐targets of the hydroxyethylamine pharmacophore. Our work herein thus provides a candidate list of biomarkers for further investigations. Taken together, this SMM‐facilitated strategy for the discovery of new AfBPs should provide a useful tool for high‐throughput development of novel small molecule probes and the identification of new aspartic proteases as well as related biomarkers in the future.
Analyse des Trag‐ und Verformungsverhaltens einer Gruppe geokunststoffummantelter Säulen im Großversuch
Authors: Raithel Marc , Werner Sandra , Küster Volker , Alexiew Dimiter 
Published: September 2011

AbstractDas Gründungssystem “Geokunststoffummantelte Säulen“ (auch GEC Geotextile Encased Columns genannt) für Erdbauwerke auf gering tragfähigen Böden ist in Deutschland nach seiner Einführung vor ca. 15 Jahren mittlerweile Stand der Technik. Die aktuellen Empfehlungen für Bewehrungen aus Geokunststoffen (EBGEO 2010) der DGGT enthalten sowohl die entsprechenden Berechnungs‐ und Bemessungsverfahren als auch konstruktive und technologische Hinweise. Die praktischen Erfahrungen zeigen jedoch zunehmend, dass gegenüber der Berechnung noch Tragreserven vorliegen. Mittels eines Großversuchs sollten die Grenzzustände und Systemgrenzen weiter untersucht werden. Es wird auf die ersten wichtigsten Ergebnisse und Auswertungen eingegangen sowie mögliche modifizierte Vorgehensweisen bei der Systemberechnung tendenziell aufgezeigt.Analysis of bearing behaviour and deformations of geotextile encased columns in a large‐scale test. The foundation system Geotextile Encased Columns (GEC) for embankments on soft subsoil started in Germany about 15 years ago and has become state‐of‐the‐art. The recent German Code for design of geosynthetic reinforced soil systems (EBGEO 2010) of the German Geotechnical Society comprises design and dimensioning procedures and provides useful recommendations regarding concepts and construction as well. Based on the permanently increasing practical experience, it seems that the system has higher bearing resources than formally calculated. A 1 : 1 field test was designed “on the edge” in order to provoke a limit state of the system and to identify its “upper limits”. The most important first test results are shown, evaluated and commented and possible tendencies for modifications regarding some design and calculation aspects are explained.
Textilbetonverstärkte Stahlbetonstützen
Authors: Ortlepp Regine , Schladitz Frank , Curbach Manfred 
Published: September 2011

AbstractNachdem Untersuchungen an Stützenköpfen unterschiedlicher Geometrie gezeigt haben, dass mit textilbewehrtem Beton eine beachtliche Verstärkungswirkung von Stützen erzielt werden kann, ging es darum, die Gültigkeit der hierfür entwickelten Rechenmodelle an Großversuchen zu überprüfen. Zur Berechnung stahlbewehrter Stützen mit realistischen Bauteilabmessungen wurde hierzu das anhand von kleinteiligen Versuchen an unbewehrten Betonstützen entwickelte Modell weiterentwickelt. Die Vorhersagegenauigkeit wurde anhand von drei Stahlbetonstützen mit rundem Querschnitt experimentell untersucht. Die Tragfähigkeit der mit Textilbeton verstärkten Stützen nahm im Vergleich zur Referenzstütze deutlich zu. Die Versuchsergebnisse zeigen, dass die erreichbaren Traglasten mit dem weiterentwickelten Umschnürungsmodell sehr gut abgeschätzt werden können. Neben einer Steigerung der Tragfähigkeit ergibt sich durch die textilbewehrte Verstärkung eine Verbesserung des Vorankündigungsverhaltens. Insgesamt wurde eine große Duktilität der verstärkten Stützen erreicht.TRC strengthened RC ColumnsAfter research on differently shaped column heads has shown the considerable strengthening effect of textile reinforced concrete (TRC), we aimed to verify the validation of the developed calculation models in large scale tests. The model, which was developed on the basis of plain concrete columns in small scale experiments, was therefore enhanced. How accurate the predictions of the model for reinforced large scale columns were was examined by large scale testings at three reinforced concrete columns with round cross sections. The bearing capacity of the TRC strengthened columns increased considerably in comparison with the reference's. The achieved ultimate loads had been estimated very well by the developed confinement model. Besides an increase of the ultimate load the textile reinforcement also led to a considerably improved prior warning behaviour. During the load increase fine and later well visible and, homogeneously distributed cracks occurred. All in all we have reached a high ductility of the reinforced columns.
Plastische Berechnungsverfahren: Formeln und Diagramme für Rechteckplatten
Authors: Friedrich Richard 
Published: September 2011

AbstractDie neuen Normen erlauben, auch bei der Ermittlung der Schnittgrößen – wie schon bei der Querschnittsbemessung – das plastische Verhalten des Stahlbetons zu berücksichtigen. Dabei unterscheidet man zwischen kinematischen und statischen Verfahren zur Bestimmung oberer und unterer Schranken der Tragfähigkeit. Nach einer einführenden Darstellung der statischen Berechnungen im elastischen und im plastischen Bereich werden Formeln und – beispielhaft – Diagramme für vier‐, drei‐ und zweiseitig gelagerte Rechteckplatten unter Gleichlast angegeben. Zum Einsatz kommt die Bruchlinientheorie, ein kinematisches plastisches Verfahren, das bei gut gewählten Bruchfiguren ausreichend sichere Ergebnisse liefert. Es folgen Berechnungsbeispiele für Platten und Hinweise auf weitere Einsatzmöglichkeiten der Schnittgrößenermittlung im plastischen Bereich.Plastic analysis and design: Formulas and diagrams for rectangular slabsThe new codes allow to determine the sectional efforts taking into consideration the plastic behaviour of reinforced concrete – as for the design of cross sections. The kinematic and the static procedures give upper and lower bounds of the load carrying capacity. After an introductory presentation of the static treatment in the elastic and in the plastic domain, formulas and – exemplary – diagrams for rectangular slabs with supports on four, three and two sides under uniformly distributed loads are presented. The yield‐line method, a kinematic plastic procedure is utilized, which gives sufficient safe results – with well selected fail geometries. Numerical examples for various slabs and references to other possibilities of obtaining sectional efforts in the plastic domain complete the paper.
The significant rectal neoplasm and mucosectomy by transanal endoscopic microsurgery (Br J Surg 2011; 98: 1342–1344)
Authors: Barendse R M , Fockens P , Bemelman W A , de Graaf E J R , Dekker E 
Published: September 2011

Abstract
The Editors welcome topical correspondence from readers relating to articles published in the Journal. Responses should be sent electronically via the BJS website (http://www.bjs.co.uk). All letters will be reviewed and, if approved, appear on the website. A selection of these will be edited and published in the Journal. Letters must be no more than 250 words in length.
Activity, Stability, and Degradation Mechanisms of Dealloyed PtCu3 and PtCo3 Nanoparticle Fuel Cell Catalysts
Authors: Hasché Frédéric , Oezaslan Mehtap , Strasser Peter 
Published: September 2011

AbstractA key challenge in today’s fuel cell research is the understanding and maintaining the durability of the structure and performance of initially highly active Pt fuel cell electrocatalysts, such as dealloyed Pt or Pt monolayer catalysts. Here, we present a comparative long‐term stability and activity study of supported dealloyed PtCu3 and PtCo3 nanoparticle fuel cell catalysts for the oxygen reduction reaction (ORR) and benchmark them to a commercial Pt catalyst. PtCu3 and PtCo3 were subjected to two distinctly different voltage cycling tests: the “lifetime” regime [10 000 cycles, 0.5–1.0 V vs. RHE (reversible hydrogen electrode), 50 mV s−1] and the corrosive “start‐up” regime (2000 cycles, 0.5–1.5 V vs. RHE, 50 mV s−1). Our results highlight significant activity and stability benefits of dealloyed PtCu3 and PtCo3 for the ORR compared with those of pure Pt. In particular, after testing in the “lifetime” regime, the Pt‐surface‐area‐based activity of the Pt alloy catalysts is still two times higher than that of pure Pt. From our electrochemical, morphological, and compositional results, we provide a general picture of the temporal sequence of dominant degradation mechanisms of a Pt alloy catalyst during its life cycle.
Stereoselective Synthesis of Trisubstituted Olefins by a Directed Allylic Substitution Strategy
Authors: Schmidt Yvonne , Breit Bernhard 
Published: September 2011

AbstractNew methodology for the stereoselective synthesis of trisubstituted olefins is presented. The use of ortho‐diphenylphosphanyl benzoate (o‐DPPB) as a directing leaving group for copper‐mediated allylic substitution with Grignard reagents allowed for the stereoselective construction of a wide range of E olefins, without the need for an adjacent electron‐withdrawing group. Our modular three‐step approach toward trisubstituted alkenes commenced with geminal α‐methylene aldehydes. Addition of an organometallic reagent and introduction of the o‐DPPB group by esterification was followed by the o‐DPPB‐directed copper‐mediated allylic substitution with a Grignard reagent to furnish stereodefined trisubstituted olefins. Additionally, incorporation of a stereocenter from the chiral pool allowed the preparation of an enantiomerically pure olefin that bore three alkyl substituents in high E/Z selectivity.
Negishi Cross‐Coupling Reactions Catalyzed by an Aminophosphine‐Based Nickel System: A Reliable and General Applicable Reaction Protocol for the High‐Yielding Synthesis of Biaryls
Authors: Gerber Roman , Frech Christian M. 
Published: September 2011

AbstractTreatment of NMP solutions of NiCl2 with 1,1′,1′′‐(phosphanetriyl)tripiperidine (≈2.05 equiv), dissolved in THF, in air at 25 °C forms a highly active catalytic system for the cross‐coupling of a large variety of electronically activated, non‐activated, deactivated, and ortho‐substituted, heterocyclic, and functionalized aryl bromides and aryl chlorides with diarylzinc reagents. Very high levels of conversion and yields were obtained within 2 h at 60 °C in the presence of only 0.1 mol % of catalyst (based on nickel) and thus at catalyst loadings far lower than typically reported for nickel‐catalyzed versions of the Negishi reaction. Various aryl halides—which may contain trifluoromethyl groups, fluorides, or other functional groups such as acetals, ketones, ethers, esters, lactones, amides, imines, anilines, alkenes, pyridines, quinolines, and pyrimidines—were successfully converted into the corresponding biaryls. Electronic and steric variations are tolerated in both reaction partners. Experimental observations indicate that a molecular (NiI/NiIII) mechanism is operative.
Surface‐Modified Protein Microspheres Capture Amyloid‐β and Inhibit its Aggregation and Toxicity
Authors: Richman Michal , Wilk Sarah , Skirtenko Natalia , Perelman Alex , Rahimipour Shai 
Published: September 2011

AbstractThe biocompatible and biodegradable properties of protein microspheres and the recent advances in their preparation have generated considerable interest of utilizing these core‐shell structures for drug delivery and diagnostic applications. However, effective targeting of protein microspheres to desirable cells or loci still remains a challenge. Here, we describe for the first time a facile one‐pot sonochemical approach for covalent modification of protein microspheres made from serum albumin; the surface of which is covalently decorated with a short recognition peptide to target amyloid‐β (Aβ) as the main pathogenic protein in Alzheimer’s disease (AD). The microspheres were characterized for their morphology, size, and entrapment efficacy by electron microscopy, dynamic light scattering and confocal microscopy. Fluorescence‐activated cell‐sorting analysis and Thioflavin‐T binding assay demonstrated that the conjugated microspheres bind with high affinity and selectivity to Aβ, sequester it from the medium and reduce its aggregation. Upon incubation with Aβ, the microspheres induced formation of amorphous aggregates on their surface with no apparent fibrillar structure. Moreover, the microspheres directly reduced the Aβ‐induced toxicity toward neuron like PC12 cells. The conjugated microspheres are smaller than unmodified microspheres and remained stable throughout the incubation under physiological conditions.
A Combined Far‐Infrared Spectroscopic and Electrochemical Approach for the Study of Iron–Sulfur Proteins
Authors: El Khoury Youssef , Hellwig Petra 
Published: September 2011

AbstractHerein, we present the development of a far‐infrared spectroscopic approach for studying metalloenzyme active sites in a redox‐dependent manner. An electrochemical cell with 5 mm path and based on silicon windows was found to be appropriate for the measurement of aqueous solutions down to 200 cm−1. The cell was probed with the infrared redox signature of the metal–ligand vibrations of different iron–sulfur proteins. Each FeS cluster type was found to show a specific spectral signature. As a common feature, a downshift of the frequency of the FeS vibrations was seen upon reduction, in line with the increase of the FeS bond. This downshift was found to be fully reversible. Electrochemically induced FTIR difference spectroscopy in the far infrared is now possible, opening new perspectives on the understanding of metalloproteins in function of the redox state.
Characterization of transgenic mice expressing cancer‐associated variants of human NOTCH1
Authors: Berquam‐Vrieze Katherine E. , Swing Deborah A. , Tessarollo Lino , Dupuy Adam J. 
Published: September 2011

AbstractThe Notch1 receptor plays a critical role in cell fate decisions during development. Activation of Notch signaling has been implicated in several types of cancer, particularly T‐cell acute lymphoblastic leukemia (T‐ALL). Consequently, several transgenic mouse strains have been made to study the role of Notch1 in T‐ALL. However, the existing Notch1 transgenic lines mimic a translocation event found in only ∼ 1% of T‐ALL cases. Here we describe three novel NOTCH1 transgenic mouse strains that have Cre‐inducible expression of the entire human NOTCH1 locus, each possessing a common mutation found in T‐ALL. Unlike existing Notch1 transgenic strains, these NOTCH1 transgenic strains express full‐length receptors from anendogenous human promoter that should be susceptible to a number of Notch antagonists that have recently been developed. These strains will allow researchers to modulate Notch signaling to study bothnormal development and cancer biology. genesis 50:112–118, 2012. © 2011 Wiley Periodicals, Inc.
M cells expressing the complement C5a receptor are efficient targets for mucosal vaccine delivery
Authors: Kim Sae‐Hae , Jung Dae‐Im , Yang In‐Young , Kim Ju , Lee Kyung‐Yeol , Nochi Tomonori , Kiyono Hiroshi , Jang Yong‐Suk 
Published: September 2011

AbstractIn the mucosal immune system, M cells are known as specialized epithelial cells that take up luminal antigens, although the receptors on M cells and the mechanism of antigen uptake into M cells are not well‐understood. Here, we report the expression of the complement C5a receptor (C5aR) on the apical surface of M cells.C5armRNA expression in co‐cultured Caco‐2 human M‐like cells was six‐fold higher than in mono‐cultured cells. C5aR expression was detected together with glycoprotein 2, an M‐cell‐specific protein, on the apical surface of M‐like cells and mouse Peyer's patch M cells. Interestingly, after oral administration ofYersinia enterocoliticawhich expresses outer membrane protein H (OmpH) that is homologous to the Skp α1 domain ofEscherichia coli, a ligand of C5aR, dense clustering and phosphorylation of C5aR were detected in M cells. Finally, targeted antigen delivery to M cells using C5aR as a receptor was achieved using the OmpH α1 ofY. enterocoliticasuch that the induction of ligand‐conjugated antigen‐specific immune responses was confirmed in mice after oral immunization of the OmpH β1α1‐conjugated antigen. Collectively, we identified C5aR expression on M cells and suggest that C5aR could be used as a target receptor for mucosal antigen delivery.
A New Series of Nanoporous Ionic Crystals Based on Polyoxometalates – Synthesis, Crystal Structures, and Adsorption Properties
Authors: Han Xiaohui , Xu Lin , Li Fengyan , Jiang Ning 
Published: September 2011

AbstractBased on polyoxometalate cluster anions and macrocations, KH2[Cr3O(OOCCH3)6(H2O)3][α‐GeMo12O40]·10H2O (1), K1.5H1.5[Cr3O(OOCCH3)6(H2O)3][α‐GeW12O40]·9.5H2O (2), NaH2[Cr3O(OOCCH3)6(H2O)3]3[α‐P2W18O62]·32H2O (3), and Na3[Cr3O(OOCCH3)6(H2O)3]3[α‐As2W18O62]·34H2O (4) have been prepared by a conventional method and characterized by single‐crystal X‐ray diffraction, IR and UV/Vis spectroscopy, elemental analysis, thermogravimetric analysis (TGA) and powder X‐ray diffraction (PXRD). In addition, the gas adsorption properties of these four compounds for methanol and ethanol have been investigated. The adsorption studies display an apparent difference between methanol and ethanol vapor adsorption and demonstrate that such microporous materials could be applied as new molecular sieves for selective sorption from a mixture of C1 and C2 alcohols.