bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface modification of nylon 6 films treated with an He/O2 atmospheric pressure plasma jet
Authors: Gao Zhiqiang , Sun Jie , Peng Shujing , Yao Lan , Qiu Yiping
Published: December 2010

To investigate the effect of the gas composition of the plasma treatment on the surface modification of an atmospheric pressure plasma jet (APPJ), nylon 6 films were treated with APPJ with pure helium (He), He + 1% oxygen (O2), and He + 2% O2, respectively. Atomic force microscopy showed increased surface roughness, whereas X‐ray photoelectron spectroscopy revealed increased oxygen contents after the plasma treatments. The plasma‐treated samples had lower water contact angles and higher T‐peel strengths than the control. The addition of a small amount of O2 to the He plasma increased the effectiveness of the plasma treatment in the polymer surface modification in terms of surface roughness, surface oxygen content, etching rate, water contact angle, and bonding strength. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
The effects of different silane crosslinking approaches on composites of polyethylene blends and wood flour
Authors: Clemons Craig M. , Sabo Ronald C. , Hirth Kolby C.
Published: December 2010

Though silane chemistry has been used to crosslink unfilled polyethylene for many years, such crosslinking has only been recently applied to wood plastic composites to improve properties such as creep resistance. However, the presence of wood significantly changes the silane chemistry and a greater understanding is necessary for optimal processing and performance. We investigated three different approaches of adding silane and peroxide during reactive extrusion of wood‐plastic composites were investigated and compared to their unfilled counterparts. Up to 2 grams of a 20:1 solution of vinyltrimethoxysilane and dicumyl peroxide by weight were added per 100 grams of plastic. Low density polyethylene, high density polyethylene, and a blend of the two were investigated as matrices in composites containing approximately 25% wood flour. The unfilled plastics crosslinked efficiently and little premature crosslinking occurred during processing. Though only modest improvements in tensile strengths were found in unfilled plastics, the notched Izod impact energy of unfilled HDPE improved nearly 600% when crosslinked. Unlike the unfilled plastics, most of the crosslinking of the composites occurred during processing. This resulted in high viscosities and processing difficulties, negating some of the advantages of a separate crosslinking step and limiting the amount of crosslinking possible. Some reinforcement of the plastics by the wood flour was achieved when sufficient crosslinking solution was added. Adding crosslinking solution also and greatly increased reverse‐notched impact energies. The differences between the approaches for preparing the crosslinked composites appeared to largely be a matter of efficiency in terms of the amount of crosslinking solution required to affect processing and performance. The most efficient approach was a two‐step procedure where the silane was first grafted to the plastic and then wood flour was compounded with the grafted silane in a second step. Published 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Flow behavior in a corotating twin‐screw extruder of pure polymers and blends: Characterization by fluorescence monitoring technique
Authors: Fang Haixia , Mighri Frej , Ajji Abdellah , Cassagnau Philippe , Elkoun Said
Published: December 2010

The objective of this work was to investigate the flow behavior of pure polymers and blends, especially miscible polymer/polymer systems, in a corotating twin‐screw extruder (TSE) using an online fluorescence monitoring device. An immiscible blend was also studied for the sake of comparison. The fluorescence signal was obtained by using synthesized fluorescence tracers added to the melt at very low concentrations. These tracers consisted of two styrene‐maleic anhydride copolymers (SMA) labeled with anthracene. The investigated blends were SMA8 (8 wt % of MA in SMA)/polystyrene (PS), SMA14 (14 wt % of MA in SMA)/styrene acrylonitrile copolymer (SAN), and poly(methyl methacrylate) (PMMA)/ethyl acrylate‐methyl methacrylate copolymer (PMMAEA). The residence time distribution (RTD), the mean residence time (t), the dimensionless variance (σθ2), the Peclet number (Pe) and the fluorescence peak intensity distribution of pure polymers and binary polymer systems were investigated and interpreted in terms of polymers rheological properties. It was observed that polymers presenting higher viscosity or higher pressure showed longer residence time. A difference in behavior was also observed for the RTD of miscible and immiscible blends. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Crystallinity of polyamide 6 staple fibers in the felt structure under simulated paper machine conditions
Authors: Hakala Tomi , Harlin Ali
Published: December 2010

Polyamide 6 (PA6) is used in staple fibers and yarns in paper machine press felts due to its good mechanical properties. The crystalline modifications (α and γ forms) and the degree of crystallinity of PA6 can change under stress (compression) and heat (friction), which are present during mechanical dewatering (nip). Here, we investigate the effects of the molecular weight and crystallinity of a polymer on the mechanical properties of PA6 staple fibers such as wear resistance and compaction. The experimental part involves the ageing of felt specimens in a wet pressing simulator. The properties of the felt (air permeability), and the durability and branching of the staple fiber are examined as functions of the wear of a press felt and the crystallinity of the polymer. The changes that take place in the PA6 polymer are investigated using several techniques, and their connection with the properties of a new or aged press felt is discussed. The results indicate that the increase in molecular weight has a beneficial effect on the material's mechanical properties, and our observations also support previous studies on the crystallinity and branching of PA6. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Microwave‐assisted synthesis of polyglycerol from glycerol carbonate
Authors: Iaych Kamal , Dumarçay Stéphane , Fredon Emmanuel , Gérardin Christine , Lemor Alain , Gérardin Philippe
Published: December 2010

Microwave irradiation of glycerol carbonate allows formation of glycidol, which readily polymerizes to form polyglycerol under mild conditions comparatively to the classical polyetherification reaction involving high temperature and basic conditions. Analysis of the crude reactional mixture indicated the presence of low‐molecular weight oligomers constituted mainly of di, tri, and tetraglycerols with small quantities of higher molecular weights oligomers. Molecular size distribution was relatively similar to that of polyglycerols obtained under basic condition, even if these latter contained slightly higher amounts of high‐molecular weight oligomers. Structure of oligomers differs slightly according to the conditions of polymerization, and polyglycerols are obtained under microwave activation containing higher contents of cyclic isomers, whereas polyglycerols obtained under basic conditions contain more ramified isomers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Effect of compounding sequence on the morphology of organoclay‐filled PA6/PP/MAPP blends
Authors: Wang Li , Guo Zhao‐Xia , Yu Jian
Published: December 2010

Four types of compounding sequences were utilized to prepare organoclay‐filled polyamide 6 (PA6)/polypropylene (PP)/maleic anhydride grafted PP (MAPP) blends. The amount of PA6 molecules grafted to MAPP during in situ compatibilization reaction and the distribution ratio of organoclay in the continuous phase and interface zone were determined quantitatively. The relationship among dispersion and distribution states of organoclay, the amount of PA6 grafted to MAPP as well as the deformation, breakup and coalescence of dispersed droplets was elucidated to interpret the difference in phase morphology. Crystallization behavior and dynamic mechanical properties were also investigated and correlated with the morphology of the materials. It has been shown that the PA6/organoclay masterbatch approach results in the smallest average domain size because of the best organoclay dispersion, the highest amounts of PA6 grafted to MAPP, and organoclay at the interface, which efficiently stabilizes the droplets and prevents coalescence of the droplets. The material prepared by this approach has the biggest improvement in dynamic storage modulus. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Star‐shape poly(acrylic acid)‐composed glass‐ionomer cements: Effects of MW and arm number on mechanical properties
Authors: Zhao Jun , Weng Yiming , Xie Dong
Published: December 2010

This study reports the synthesis and characterization of the star‐shape poly(acrylic acid)s with different arm numbers and molecular weight (MW)s. The effects of arm number and initiator concentration on the atom‐transfer radical polymerization reaction kinetics and solution viscosity were studied. The effects of MW and arm number on mechanical properties were evaluated. The results showed that both arm number and MW had significant impacts on the polymerization kinetics, solution viscosity, mechanical strengths, and wear‐resistance. Decreasing arm number and increasing initiator concentration increased the reaction rate. Increasing arm number and initiator concentration decreased the solution viscosity. Decreasing arm number and increasing MW increased mechanical strengths and wear‐resistance. Within the limitations of this study, the experimental cement was 28% in compressive strength, 48% in compressive modulus, 39% in diametral tensile strength, 60% in flexural strength, and 62% in Knoop hardness higher but 19% in fracture toughness lower than commercial Fuji II LC cement. The abrasion and attrition of the experimental cement were only 1.3% and 9.5% of Fuji II LC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Inverted emulsion polymerization route to polyaniline‐3D nanofiber network using sulfonated‐p‐cresol as novel dopant
Authors: Saravanan Chandrasekar , Palaniappan Srinivasan , Akhila Valaboju , Madhavendra Sunkara Sakunthala , Bangal Prakriti Ranjan
Published: December 2010

Sulfonated‐p‐cresol (SPC) was used as novel dopant for the first time in the synthesis of polyaniline in 3D nanofiber networks (PANI‐3D). Polyaniline in 3D nanofiber network was prepared using organic solvent soluble benzoyl peroxide as oxidizing agent in presence of SPC and sodium lauryl sulfate (SLS) surfactant via inverted emulsion polymerization pathway. The influence of synthesis conditions such as the concentration of the reactants, stirring/static condition, and temperature etc., on the properties and formation of polyaniline nanofiber network were investigated. Polyaniline in 3D nanofiber network with 40–160 nm (diameter), high yield (134 wt % with respect to aniline used), and reasonably good conductivity (0.1 S/cm) was obtained in 24 h time. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Antifungal activity of chitosan against Fusarium oxysporum f. sp. cubense
Authors: Al‐Hetar M. Y. , Zainal Abidin M. A. , Sariah M. , Wong M. Y.
Published: December 2010

The in vitro antifungal activity of chitosan against Fusarium oxysporum f. sp. cubense Race 4 (FocR4) the causal agent of banana wilt was investigated. Chitosan at all concentrations tested reduced the hyphal growth of FocR4 on potato dextrose agar media and recording maximum inhibition of 76.36% at 8 mg/mL. The inhibitory effect was found to increase as chitosan concentration increases. The 50% effective concentration value was estimated by probit analysis, and it was 1.4 mg/mL. Chitosan was more effective in potato dextrose broth where it completely inhibited the mycelial growth of FocR4 at all concentrations tested. Chitosan inhibited the sporulation of FocR4 by a maximum of 96.53% at 8 mg/mL chitosan, and 100% inhibition for spore germination was recorded at all concentrations tested. Chitosan at concentrations of more than 1.6 mg/mL was also found to induce morphological changes in FocR4 characterized by agglomeration of hyphae, abnormal shapes, vesicles, or empty cells devoid of cytoplasm in the mycelia. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Novel amphiphilic dextran copolymers nanoparticles for delivery of doxorubicin
Authors: Gao Hongxia , Li Mingjun , Wu Yan
Published: December 2010

In this work, a novel biodegradable amphiphilic copolymer based on dextran and 1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphoethanolamine (DPPE) was successfully prepared. The amphiphilic copolymer may self‐assemble into polymeric micelles in an aqueous solution. Fluorescence spectroscopy, dynamic light scattering (DLS), and a transmission electron microscope (TEM) method confirmed the formation of copolymeric micelles. To estimate the feasibility as novel drug carriers, doxorubicin (DOX) was incorporated into polymeric nanoparticles. The DOX‐loaded nanoparticles exhibited greater antitumor effect than free DOX for HeLa celles, suggesting that the dextran/DPPE nanoparticles have great potential as a tumor targeting drug carrier. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
UV aging resistance properties of PBO fiber coated with nano‐ZnO hybrid sizing
Authors: Zhang Chun‐Hua , Huang Yu‐Dong , Yuan Wen‐Jing , Zhang Jian‐Nan
Published: December 2010

In this article, we focus on the ultraviolet (UV) shielding efficiency for poly(p‐phenylene‐2,6‐benzobisoxazole) (PBO) fiber with zinc oxide (ZnO) nanoparticle/epoxy hybrid coating. ZnO nano particles were initially functionalized with silicon coupling agent for improving their dispersion and surface reactivity, and then they were hybridized with epoxy resin by grafting on the ZnO nano particles. The hybrid reactions have been indicated by means of Fourier transform infrared spectrometer (FT‐IR). Its UV light shielding effect of the hybrid coating on PBO fiber properties has been studied using ultraviolet spectrum, tensile test, atomic force microscopy (AFM), and X‐ray photoelectron spectroscopy (XPS). Results showed that the surface topographic, the surface polymer structure, and the tensile strength of coated PBO fiber were less declined than that of uncoated fiber by UV light. From these results, the nano‐ZnO hybrid sizing had good UV‐aging shielding efficiency for PBO fiber. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Improvement of the photostabilization of PVC films in the presence of 2N‐salicylidene‐5‐(substituted)‐1,3, 4‐thiadiazole
Authors: Yousif Emad , Salih Nadia , Salimon Jumat
Published: December 2010

The photostabilization of poly(vinyl chloride) (PVC) films by 2N‐salicylidene‐5‐(substituted)‐1,3,4‐thiadiazole compounds was investigated. The PVC films containing concentration of complexes 0.5% by weight were produced by the casting method from tetrahydrofuran (THF) solvent. The photostabilization activities of these compounds were determined by monitoring the carbonyl, polyene, and hydroxyl indices with irradiation time. The changes in viscosity average molecular weight of PVC with irradiation time were also tracked (using THF as a solvent). The quantum yield of the chain scission (ϕcs) of these complexes in PVC films was evaluated and found to range between 4.72 × 10−8 and 8.99 × 10−8. Results obtained showed that the rate of photostabilization of PVC in the presence of the additive followed the trend:

According to the experimental results obtained, several mechanisms were suggested depending on the structure of the additive. Among them, UV absorption, peroxide decomposer, and radical scavenger for photostabilizer mechanisms were suggested. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Preparation and biodegradation of hydroxyl terminated poly(fumaric acid‐co‐diethylene glycol) and its segmented polyurethane
Authors: Yang Qun , Shao Fen‐Juan , Lu Da‐Nian , Kimura Yoshiharu
Published: December 2010

Hydroxyl terminated poly(fumaric acid‐co‐diethylene glycol), poly(FA‐co‐DEG) was prepared by melt polycondensation. The resultant unsaturated aliphatic polyester was characterized by Fourier transform infrared (FTIR) spectroscopy, hydroxyl value, acid value, and intrinsic viscosity. Its enzymatic degradation and crosslinking behavior as well as the effect of crosslinking degree on enzymatic degradation were also investigated. The crosslinking degree and reduction of carbon–carbon double bonds revealed excellent self‐crosslinking nature of poly(FA‐co‐DEG) at high temperature. The results of enzymatic degradation showed that poly(FA‐co‐DEG) has excellent biodegradability and that the biodegradation can be controlled by the crosslinking degree. Polyurethane was prepared by the reaction of poly(FA‐co‐DEG), 2,4‐toluene diisocyanate (TDI), and 1,4‐butanediol (BD). It was found that the biodegradation of the obtained polyurethane was slower than that of the original unsaturated aliphatic polyester poly(FA‐co‐DEG). The peeling strength of the polyurethane was very high, supporting better adhesion property with enhanced crosslinking. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Properties of polystyrene/organically modified layered double hydroxide nanocomposites synthesized by solvent blending method
Authors: Sahu Balakrushna , Pugazhenthi G.
Published: December 2010

In this work, organically modified layered double hydroxides (OLDHs) were prepared and used to make exfoliated polystyrene (PS) nanocomposites by solvent blending method. First, Mg‐Al, Co‐Al, Ni‐Al, Cu‐Al, Cu‐Fe, and Cu‐Cr LDHs were synthesized by coprecipitation method at constant pH using their nitrate salts. The organically modified LDHs (OLDHs) were synthesized using sodium dodecyl sulfate (SDS). Then, PS nanocomposites containing 5 wt % of the above modified LDHs were developed by solvent blending method. The structural and thermal properties of LDHs and their corresponding nanocomposites were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), FTIR spectroscopy, and thermogravimetric analysis (TGA). The formation of exfoliated PS/OLDH nanocomposites is demonstrated by XRD and TEM analysis. TEM analysis also confirms the nanoscale dispersion of the LDH layers in the PS matrix. The presence of sulfate groups in the modified LDHs is confirmed by FTIR spectroscopy. The entire PS/OLDH nanocomposites exhibit enhanced thermal stability relative to pure PS. When 50% weight loss is selected as point of comparison, the decomposition temperature of the nanocomposites is about 5–13°C higher than that of pure PS. Water uptake of the PS nanocomposites is found to be less when compared to pure PS. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis, Structural Characterization, and Reactivity of Group 4 Metallacarboranes Bearing the Ligand [H2C(C5Me4)(C2B9H10)]3−
Authors: Liu Dongmei , Shen Hao , Wang Yaorong , Cai Yuepeng , Xie Zuowei
Published: December 2010

A new organic–inorganic hybrid ligand H2C(C5Me4H)(C2B10H11) (2) has been prepared. A selective deboration reaction with piperidine in ethanol resulted in the isolation of [Me3NH][H2C(C5Me4H)(C2B9H11)] (3). An amine‐elimination reaction of 3 with [Zr(NMe2)4] produced a neutral metal‐amide complex [η5:η5‐H2C(C5Me4)(C2B9H10)]Zr(NMe2)(NHMe2) (4). The double‐ring‐opening reaction of 4 with tetrahydrofuran (THF) afforded [η5:η5‐H2C(C5Me4)(C2B9H10)]Zr (OCH2CH2CH2CH2)2N(CH3)2 (5). Treatment of the trianionic salt of 3 with [MCl4(thf)2] gave complexes [{η5:η5‐H2C(C5Me4)(C2B9H10)}M(μ‐Cl)2][Li(thf)2] (M=Zr (6), Hf (7)). Reaction of 6 with LiCH2TMS generated the ionic species [{η5:η5‐H2C(C5Me4)(C2B9H10)}Zr(CH2TMS)2][Li(thf)3] (9). Interaction of complex 6 with KCH2(NMe2)‐o‐C6H4 led to the formation of the neutral metal alkyl complex [η5:η5‐H2C(C5Me4)(C2B9H10)]Zr[σ:σ‐CH2(NMe2)‐o‐C6H4] (10). All complexes have been fully characterized by various spectroscopic techniques and elemental analyses. Some were further confirmed by single‐crystal X‐ray analyses.
Zum Einfluss baulicher Randbedingungen auf das dynamische Verhalten von WIB‐Eisenbahnbrücken
Authors: Rauert Tim , Bigelow Hetty , Hoffmeister Benno , Feldmann Markus , Patz Rüdiger , Lippert Peter
Published: December 2010

Die Weiterentwicklung des europäischen Eisenbahnnetzes ist unter anderem durch den vermehrten Einsatz von Hochgeschwindigkeitszügen und eine signifikante Anhebung der Betriebsgeschwindigkeiten gekennzeichnet. Um die Auswirkungen von Zugbeanspruchungen auf Eisenbahnbrücken im Rahmen einer dynamischen Bemessung hinreichend genau vorhersagen zu können, ist die Kenntnis der wesentlichen dynamischen Systemeigenschaften erforderlich. Nur so können bemessungsrelevante Resonanzeffekte, die bei hohen Geschwindigkeiten grundsätzlich nicht auszuschließen sind, rechnerisch auf zuverlässige Weise erfasst werden. Messungen insbesondere an WIB‐Überbauten zeigen jedoch, dass eine realistische rechnerische Abschätzung von Brückeneigenfrequenzen schwierig ist. Tatsächliche und rechnerische Werte weichen in vielen Fällen erheblich voneinander ab. Als ursächlich wird hierfür unter anderem eine unzureichende Berücksichtigung baulicher Randbedingungen angesehen, die teilweise erheblichen Einfluss auf die Steifigkeits‐ und Dämpfungseigenschaften der Brücke haben. Der erste Teil des Beitrags führte in die Problematik ein und präsentierte Ergebnisse aus Messuntersuchungen an WIB‐Brücken. Im vorliegenden zweiten Teil des Beitrags wird nun auf Grundlage numerischer Studien gezeigt, wie sich bauliche Randbedingungen auf das dynamische Verhalten von WIB‐Überbauten auswirken. Abschließend werden die Untersuchungsergebnisse dazu genutzt, Vorschläge für eine genauere dynamische Bemessung abzuleiten.

On the influence of constructional elements on the dynamic behaviour of filler beam railway bridges. Enhancements of the European railway system are amongst other things mainly characterized by increased usage of high speed trains and significantly raised operating speeds. To predict effects of train loading on railway bridges for a dynamic design adequately, knowledge of the system’s significant dynamic characteristics is required. Only this ensures that resonance effects, which generally cannot be screened out for high speeds, can be covered analytically by reliable values. Measurements especially carried out on filler beam bridges have shown though that a realistic estimation of eigenfrequencies of bridges is difficult. Actual values and measured ones differ significantly in many cases. In particular non‐consideration of structural constraints is seen as reason for this, given that they have an immense effect on a bridge’s stiffness and damping characteristics. The first part of the contribution gave a brief survey on the dynamics of high‐speed railway bridges. Furthermore results from measurements on filler beam railway decks were presented. In this second part of the contribution the influence of particular constructional elements on the dynamic behaviour of filler beam bridges is investigated, supported by numerical studies. Finally the main outcomes are discussed and proposals for an improved dynamic bridge design are made.
Konrad Zuse und die Baustatik — Zur Formierung der Computerstatik (Teil 2)
Authors: Kurrer Karl‐Eugen
Published: December 2010

Konrad Zuse verallgemeinerte das 1934 mit seiner Studienarbeit am Beispiel der statisch unbestimmten Analyse entwickelte programmförmige Rechenschemata 1936 zum “Verfahren des Rechenplanes oder Programms” (Konrad Zuse). Von 1936 bis 1941 entfaltete er dieses Verfahren in erster Linie für die Bau‐ und Flugzeugstatik. Diese numerischen Rechenpläne bildeten eine wesentliche Seite der historisch‐logischen Entwicklung von Zuses programmgesteuerten Rechenautomaten Z1 (1938) und Z3 (1941). Mit den numerischen Rechenplänen ist auch die erste Stufe der Initialphase der Computerstatik benannt. Ihre zweite Stufe hebt mit Zuses Plankalkül an (1942—1949) — der ersten “Plattform für Softwareentwicklung” (Peter Jan Pahl ) — in dessen Zentrum sein allgemeines Konzept des Rechnens steht, das Zuse aus dem Kalkül‐Begriff der Mathematik entwickelt und das Zahlenrechnen als Sonderfall enthält. Die beiden Stufen werden im Folgenden eingehend dargestellt und durch eine exemplarische Skizze der um 1950 einsetzenden Konstituierungsphase der Computerstatik abgerundet.

Konrad Zuse and the theory of structures — on the formation of computational mechanics (part 2). It was in 1936 that Konrad Zuse generalised the program‐type calculation scheme, which he had developed in his student project of 1934 using the example of the statically indeterminate analysis, to form the ”computing plan or program method” (Konrad Zuse). Between 1936 and 1941 he continued to develop this method, in the first place for structural and aviation engineering. These numerical computing plans formed one fundamental element in the historico‐logical evolution of Zuse’s program‐controlled automatic computers Z1 (1938) and Z3 (1941). The numerical computing plans also mark the first step in the initial phase of computational mechanics. The second step (1942—1949) began with Zuse’s ”Plankalkül” (Calculus of Programs) — the first ”software development platform” (Peter Jan Pahl) —, the heart of which is his general calculation concept, which Zuse developed from the formal system concept of mathematics and which contains numerical computation as a special case. Both of these steps are presented in detail below and rounded off with an illustrative outline of the constitution phase of computational mechanics which began around 1950.
Geschichtliche Entwicklung und aktuelle Praxis der Probebelastung — Teil 2: Entwicklung von Normen und heutige Anwendung
Authors: Bolle Guido , Schacht Gregor , Marx Steffen
Published: December 2010

Im Zuge des massenhaften Einsatzes von Probebelastungen im 19. und zu Beginn des 20. Jahrhunderts zeigte sich die Notwendigkeit, deren Planung, Durchführung und Auswertung durch allgemeine Richtlinien und Normen zu stützen.

Im Beitrag wird das Ringen um erste zaghafte Festlegungen beschrieben, die im Laufe der Jahre immer konkreter zu einer verwendbaren Handlungsgrundlage ausgearbeitet wurden. Unter Kritikern blieb jedoch immer die Frage über die Sicherheit und vor allem die Aussagekraft von Belastungsversuchen auf der Grundlage der verwendeten Bewertungskriterien offen.

Mit der Weiterentwicklung der Berechnungsverfahren auch durch den Einsatz von Computertechnik wurden Probebelastungen von Neubauten ab den 1970‐er Jahren entbehrlich. Für auffällig gewordene bestehende Tragwerke stellt die Probebelastung jedoch auch heute noch eine — und manchmal die einzige — Methode zum Nachweis einer ausreichenden Tragfähigkeit dar. Die hierfür angewendete moderne Belastungs‐ und Messtechnologie bietet jedoch im Unterschied zur traditionellen Vorgehensweise ein hohes Maß an Sicherheit und Informationsgewinn.

Historical Development and current practise of load tests in situ — Part 2: Development of standards and current practise. Because of the large demand and use of load testing in the 19th and at the beginning of the 20th century, there was the necessity to standardise the planning, execution and analysis in general guidelines and codes.

This article describes the struggling and first tentative specification, which were more and more specified to an useful basis in the following years. The used criterions for the assessment have often been a reason for critics on the value and the safety of loading tests.

The further development of calculation methods especially the computer technology made the load testing of new structures superfluous in the 1970s. But for existing structures loading tests are today often a — and sometimes the only — method to proof a sufficient load bearing capacity. The today used modern loading‐ and measuring technology provides, in contrast to the traditional method, a high degree of safety and structural information.
Ingenieurwissenschaftliche Untersuchungen an der Hagia Sophia in Istanbul — Teil 2: Zum Tragverhalten
Authors: Duppel Christoph
Published: December 2010

Die Hagia Sophia in Istanbul, eines der bau‐ und kulturgeschichtlich wichtigsten und ingenieurmäßig bemerkenswertesten Bauwerke der letzten 1500 Jahre, war im Rahmen des DFG‐Projektes “Ingenieurwissenschaftliche Untersuchungen an der Hauptkuppel und den Hauptpfeilern der Hagia Sophia in Istanbul” [1] Gegenstand umfänglicher Forschungstätigkeit, erst zum Konstruktionsgefüge, dann zum Tragverhalten.

Ein optimierter Einsatz zerstörungsfreier, geophysikalischer Untersuchungsmethoden ermöglichte erstmals eine umfassende Aussage zum Bestand und inneren Zustand der tragenden Bauteile, wie sie sich über die Jahrhunderte und mehrere Teileinstürze hinweg bis zum heutigen Tag entwickelt haben. Hierüber wurde im ersten Teil dieses Beitrages berichtet [15].

Der sich nun anschließende zweite Teil beschäftigt sich mit dem Tragverhalten der Hagia Sophia. Ausgehend von grundsätzlichen Überlegungen zum Lastfluss in Pendentifkuppeln werden die erarbeiteten neuen Kenntnisse über die Bauwerksstruktur in ihrer statischen Bedeutung bewertet, den bisherigen Berechnungsgrundlagen vergleichend gegenübergestellt und im Rahmen eigener Studien zum Lastfluss und Tragverhalten unter statischer Belastung eingesetzt. Hinsichtlich der Frage der Erdbebengefährdung wird ein Ausblick auf ein Anschlussprojekt gegeben, welches — auf den erzielten Forschungsergebnissen aufbauend — die dynamische Analyse der Hagia Sophia zum Inhalt hat.

Engineering Studies on the Hagia Sophia in Istanbul — Part 2: On the Structural Behavior. The Hagia Sophia in Istanbul, which is one of the most important and remarkable buildings of the past 1500 years from the point of view of architectural and cultural history as well as from a civil‐engineering perspective, has been the object of extensive research — first, regarding its structure and then, its structural behavior as the subject of the DFG Project ”Engineering Studies of the Main Dome and Main Pillars of the Hagia Sophia in Istanbul”.

The optimized use of non‐destructive, geo‐physical methods of examination allowed, for the first time, making comprehensive statements on the existing structure and the internal condition of the structural parts as they have developed over the centuries and through several partial collapses to this day. A report on this can be found in the first part of my article.

This second part focuses on the structural behavior of the Hagia Sophia. Departing from fundamental deliberations on load flow in pendentive domes, the importance of the new findings about the structural characteristics for structural behavior is evaluated, compared to the bases for calculation used before, and used in the context of studies on load flow and structural behavior under a structural load. With regard to the issue of earthquake risk, an outlook is provided on a follow‐up project that will focus on a dynamic analysis of the Hagia Sophia, based on these research results.
Für Nietzsche konstruiert — ein Dach‐ und Fassadentragwerk ausgeschnitten aus Brettsperrholz
Authors: Trautz Martin
Published: December 2010

Die Dach‐ und Fassadenkonstruktion des Nietzsche‐Dokumentationszentrum (NDZ) in Naumburg/Saale ist eine unkonventionelle Anwendung des neuartigen Werkstoffes Brettsperrholz in der Form, dass sämtliche Fassaden‐ und Dachtragwerksteile als fugenlos zusammenhängende und abgewinkelte Rahmenschenkel aus dem Plattenwerkstoff ausgeschnitten wurden. Die Rahmenteile sind im Bereich des geschlossenen Daches im Grundriss versetzt zueinander angeordnet und über die Dachplatte aus Brettsperrholz, die als elastisches Verbindungselement fungiert, miteinander verbunden. Auf diese Weise entsteht eine außergewöhnliche Konstruktion, die Sehgewohnheiten widerspricht und eine Architektur prägt, die in dieser Weise Bezug auf den Philosophen und seinen kritisch hinterfragenden Geist nimmt.

Designed for Nietzsche — A Roof‐ and Facade‐Structure Cut Out from Cross‐Laminated Timber‐Plates. The structure of the roof and the facade of the Nietzsche‐Documentation‐Centre in Naumburg/Saale, a small town in the heart of Germany where the philosopher Friedrich Nietzsche spent a major part of his life, is an unconventional application of cross‐laminated‐timber‐plates. It consists of frame elements cut out from the wooden plate‐material similar to puzzle‐parts sawed out from plywood with a jigsaw. All parts were produced that way and put together with a roofing plate also made from cross‐laminated‐timber, which works as an elastic longitudinal hinge‐element. The structure is a rather unconventional one and refers to the critical and non conformal ideas of the well‐known philosopher Friedrich Nietzsche.
At the crossroads of differentiation and proliferation: Precise control of cell‐cycle changes by multiple signaling pathways in Drosophila follicle cells
Authors: Klusza Stephen , Deng Wu‐Min
Published: December 2010

Here, we discuss the findings to date about genes and pathways required for regulation of somatic follicle‐cell proliferation and differentiation during Drosophila oogenesis and demonstrate how loss of these genes contributes to the tumorigenic potential of mutant cells. Follicle cells undergo cell‐fate determination through stepwise activation of multiple signaling pathways, including the Notch, Hedgehog, Wingless, janus kinase/STAT, and JNK pathways. In addition, changes in DNA replication and cellular growth depend on the spatial and temporal activation of the mitotic cycle‐endocycle and endocycle‐gene amplification cell‐cycle switches and insulin‐dependent monitoring of cellular health; systemic loss of these pathways contributes to loss of controlled cellular proliferation, loss of differentiation/growth, and aberrant cell polarity in follicle cells. We also highlight the effects of the neoplastic and Hippo pathways on the cell cycle and cellular proliferation in promoting normal development and conclude that lack of coordination of multiple signaling pathways promotes conditions favorable for tumorigenesis.
Carbohydrate synthesis by disaccharide phosphorylases: Reactions, catalytic mechanisms and application in the glycosciences
Authors: Luley‐Goedl Christiane , Nidetzky Bernd
Published: December 2010

Disaccharide phosphorylases are glycosyltransferases (EC 2.4.1.α) of specialized carbohydrate metabolism in microorganisms. They catalyze glycosyl transfer to phosphate using a disaccharide as donor substrate. Phosphorylases for the conversion of naturally abundant disaccharides including sucrose, maltose, α,α‐trehalose, cellobiose, chitobiose, and laminaribiose have been described. Structurally, these disaccharide phosphorylases are often closely related to glycoside hydrolases and transglycosidases. Mechanistically, they are categorized according the stereochemical course of the reaction catalyzed, whereby the anomeric configuration of the disaccharide donor substrate may be retained or inverted in the sugar 1‐phosphate product. Glycosyl transfer with inversion is thought to occur through a single displacement‐like catalytic mechanism, exemplified by the reaction coordinate of cellobiose/chitobiose phosphorylase. Reaction via configurational retention takes place through the double displacement‐like mechanism employed by sucrose phosphorylase. Retaining α,α‐trehalose phosphorylase (from fungi) utilizes a different catalytic strategy, perhaps best described by a direct displacement mechanism, to achieve stereochemical control in an overall retentive transformation. Disaccharide phosphorylases have recently attracted renewed interest as catalysts for synthesis of glycosides to be applied as food additives and cosmetic ingredients. Relevant examples are lacto‐N‐biose and glucosylglycerol whose enzymatic production was achieved on multikilogram scale. Protein engineering of phosphorylases is currently pursued in different laboratories with the aim of broadening the donor and acceptor substrate specificities of naturally existing enzyme forms, to eventually generate a toolbox of new catalysts for glycoside synthesis.
Biofilm research using calorimetry – a marriage made in heaven?
Authors: Buchholz Friederike , Harms Hauke , Maskow Thomas
Published: December 2010

Aggregated bacteria growing on a surface, so‐called biofilms, play an important role in technical processes like wastewater treatment, bioremediation, or bioprocessing. In contrast, problems arise when biofilm growth results in undesired processes that may cause huge financial losses, e.g., clogged pipes, microbially influenced corrosion or pathogenic contamination. For observation purposes and to develop efficient control strategies, real‐time monitoring tools for biofilms are required. Among the large variety of tools used in biofilm research, calorimetry is rarely applied, even though many characteristics qualify it for biofilm investigation and monitoring. Calorimetric measurements are non‐invasive and non‐destructive, and can be applied to nearly any kind of samples (including heterogeneous or turbid solutions) without the need of special sample preparation. Online and real‐time data acquisition reduces the labor and facilitates high‐throughput measurements. The following article is meant to introduce and promote calorimetry as a future tool in biofilm research. It attempts an assessment of common, existent monitoring tools and specifically addresses the potential of calorimetry in this field.
A rapid and highly sensitive UPLC–QTOF MS method for quantitative evaluation of Nardostachys jatamansi using Nardin as the marker
Authors: Mallavadhani Uppuluri Venkata , Panigrahi Reba , Pattnaik Banita
Published: December 2010

Nardostachys jatamansi DC. is a highly reputed Medhya and Nootropic (Learning and Memory) Ayurvedic medicinal plant. Its use as herbal medicine singly and as an ingredient of multi‐herbal formulations is fast increasing. In order to authenticate and evaluate it quantitatively, its standardization is highly warranted with respect to a reliable marker. In this connection a rapid and highly sensitive UPLC‐QTOF MS method has been developed. The analysis was carried out on an Acquity BEH C18 column with gradient elution of methanol–water and 3 mm ammonium acetate using QTOF mass detector in negative ionization mode. The method was validated over a concentration range of 9.76–156.25 ng/mL nardin. The calibration curve is linear with the correlation coefficient (r) and coefficient of determination (R2) were 0.9997 and 0.9995 respectively. The LOD and LOQ were 3.050 and 9.277 ng/mL respectively. The recovery of nardin in the range 96.36–111.13% achieved from spiked samples was consistent and reproducible. The inter‐day and intra‐day assay precision of the analytes over the entire concentration range was less than 5%. The developed method required only 4 min for chromatography to authenticate and quantify the marker, viz. nardin in N. jatamansi samples, in addition to the sample preparation time. Copyright © 2010 John Wiley & Sons, Ltd.
Quantitative liquid chromatography tandem mass spectrometry analysis of macromolecules using signature peptides in biological fluids
Authors: Halquist Matthew S. , Thomas Karnes H.
Published: December 2010

Targeted protein quantification using peptide surrogates has increasingly become important to the validation of biomarker candidates and development of protein therapeutics. These approaches have been proposed and employed as alternatives to immunoassays in biological fluids. Technological advances over the last 20 years in biochemistry and mass spectrometry have prompted the use of peptides as surrogates to quantify enzyme digested proteins using triple quadrupole mass spectrometers. Multiple sample preparation processes are often incorporated to achieve quantification of target proteins using these signature peptides. This review article focuses on these processes or hyphenated techniques for quantification of proteins with peptide surrogates. The most recent advances and strategies involved with hyphenated techniques are discussed. Copyright © 2010 John Wiley & Sons, Ltd.
Simultaneous quantification of twelve active components in Yiqing granule by ultra‐performance liquid chromatography: application to quality control study
Authors: Chen Juan , Yang Yang , Shi Yan‐Ping
Published: December 2010

An ultra‐performance liquid chromatography (UPLC) method coupled with photodiode array (PDA) detection has been developed and validated for simultaneous quantification of 12 active components (berberine, palmatine, jatrorrhizine, aloe‐emodin, rhein, emodin, chrysophanol, physcion, baicalin, baicalein, wogonoside and wogonin) in Yiqing granule. Optimum separation were achieved on a C18 column (50 × 2.1 mm i.d., 1.7 µm particle) through a 7.5 min gradient delivery of a mixture of A (acetonitrile) and B (0.1% aqueous phosphoric acid containing 1.8 mmol/L sodium dodecyl sulfonate and 10% acetonitrile, v/v) at a flow rate of 0.3 mL/min at 30°C. Because of the different UV characteristics of these components, three detection wavelengths were used for quantitative analysis. All of the analytes showed good linearity (r of >0.999). The method was validated for repeatability, precision, stability, accuracy and selectivity. The validated method was applied to quality control of Yiqing granule from different production batches. Copyright © 2010 John Wiley & Sons, Ltd.
Green consumer behaviour: an experimental analysis of willingness to pay for remanufactured products
Authors: Michaud Céline , Llerena Daniel
Published: December 2010

Products' end‐of‐life management has recently become a critical business issue. One of the possible end‐of‐life strategies is remanufacturing, which can provide competitive advantages through material and energy savings. Beyond industrial organization challenges, there is a question about the interest of developing a green marketing strategy for remanufactured products. Indeed, remanufactured products can be considered as green products since their industrial process has environmental benefits. Our paper asks whether consumers are willing to pay for remanufactured products, especially when they are informed that these products are ‘green’. We use experimental auctions to elicit consumers' WTP for specific characteristics of remanufactured products. Our study indicates that consumers tend to value the remanufactured product less than the conventional one unless they are informed about their respective environmental impacts. We find no evidence that consumers are willing to pay a premium for the green (i.e. remanufactured) product. However, providing environmental information to consumers has an effect on their WTP for the conventional product: they generally decrease significantly their WTP for the conventional (and thus most polluting) product. Copyright © 2010 John Wiley & Sons, Ltd and ERP Environment.
Structural Analysis of CYP101C1 from Novosphingobium aromaticivorans DSM12444
Authors: Ma Ming , Bell Stephen G. , Yang Wen , Hao Yiming , Rees Nicholas H. , Bartlam Mark , Zhou Weihong , Wong Luet‐Lok , Rao Zihe
Published: December 2010

CYP101C1 from Novosphingobium aromaticivorans DSM12444 is a homologue of CYP101D1 and CYP101D2 enzymes from the same bacterium and CYP101A1 from Pseudomonas putida. CYP101C1 does not bind camphor but is capable of binding and hydroxylating ionone derivatives including α‐ and β‐ionone and β‐damascone. The activity of CYP101C1 was highest with β‐damascone (kcat=86 s−1) but α‐ionone oxidation was the most regioselective (98 % at C3). The crystal structures of hexane‐2,5‐diol‐ and β‐ionone‐bound CYP101C1 have been solved; both have open conformations and the hexanediol‐bound form has a clear access channel from the heme to the bulk solvent. The entrance of this channel is blocked when β‐ionone binds to the enzyme. The heme moiety of CYP101C1 is in a significantly different environment compared to the other structurally characterised CYP101 enzymes. The likely ferredoxin binding site on the proximal face of CYP101C1 has a different topology but a similar overall positive charge compared to CYP101D1 and CYP101D2, all of which accept electrons from the ArR/Arx class I electron transfer system.
Chemoenzymatic Synthesis of Fluorescent and Colored Polyesters
Authors: Navarra Cristina , Marzorati Mattia , Danieli Bruno , Riva Sergio
Published: December 2010

A simple chemoenzymatic strategy for the synthesis of colored and fluorescent poly(ε‐caprolactone) esters has been developed. The procedure involves first the reaction of a functionalized primary amine with ε‐caprolactone, to give an amide with a terminal primary hydroxy group, followed by an enzymatic ring‐opening polymerization catalyzed by Novozym 435. The proposed method is easy to handle and is suitable for the incorporation of different amines, as it shown for the yellow compound N‐deacetylthiocolchicine and the fluorescent amines 4‐(2‐aminoethylamino)‐7‐(N,N‐dimethylsulfamoyl)benzofurazan and dansylcadaverine. A similar strategy is considered for the synthesis of poly(ε‐caprolactone) esters, employing alcohols as initiators of the reaction. In this case, an intermediate ester carrying a terminal primary hydroxy group cannot be isolated and the reaction forms directly the desired polymers.
Crystallographic Analysis of Metal‐Ion Binding to Human Ubiquitin
Authors: Arnesano Fabio , Belviso Benny Danilo , Caliandro Rocco , Falini Giuseppe , Fermani Simona , Natile Giovanni , Siliqi Dritan
Published: December 2010

The metal‐binding ability of human ubiquitin (hUb) towards a selection of biologically relevant metal ions and complexes has been probed. Different techniques have been used to obtain crystals suitable for crystallographic analysis. In the first type of experiments, crystals of hUb have been soaked in solutions containing copper(II) acetate and two metallodrugs, Zeise salt (K[PtCl3(η2‐C2H4)]⋅H2O) and cisplatin (cis‐[PtCl2(NH3)2]). The Zeise salt is used in a test for hepatitis, whereas cisplatin is one of the most powerful anticancer drugs in clinical use. The Zeise salt readily reacts with hUb crystals to afford an adduct with three platinum residues per protein molecule, Pt3–hUb. In contrast, copper(II) acetate and cisplatin were found to be unreactive for contact times up to one hour and to cause degradation of the hUb crystals for longer times. In the second type of experiments, hUb was cocrystallized with a solution of copper(II) or zinc(II) acetate or cisplatin. Zinc(II) acetate gives, at low metal‐to‐protein molar ratios (8:1), crystals containing one metal ion per three molecules of protein, Zn–hUb3 (already reported in previous work), whereas at high metal‐to‐protein ratios (70:1) gives crystals containing three ZnII ions per protein molecule, Zn3–hUb. In contrast, once again, copper(II) acetate and cisplatin, even at low metal‐to‐protein ratios, do not give crystalline material. In the soaking experiment, the Zeise anion leads to simultaneous platination of His68, Met1, and Lys6. Present and previous results of cocrystallization experiments performed with ZnII and other Group 12 metal ions allow a comprehensive understanding of the metal‐ion binding properties of hUb with His68 as the main anchoring site, followed by Met1 and carboxylic groups of Glu16, Glu18, Glu64, Asp21, and Asp32, to be reached. In the case of platinum, Lys6 can also be a binding site. The amount of bound metal ion, with respect to that of the protein, appears to be a relevant parameter influencing crystal packing.