bluuebunny/crossref_metadata_2025_split huggingface dataset:
The impact of cupric ion on thermo‐oxidative degradation of chitosan
Authors: Ou Chun‐Yan , Li Si‐Dong , Yang Lei , Li Cheng‐Peng , Hong Peng‐Zhi , She Xiao‐Dong 
Published: April 2010

AbstractThe thermal degradation of chitosan and chitosan–cupric ion compounds in air was studied using thermogravimetric and differential thermal analyses in the temperature range 30–600 °C. The impact of cupric ion on the thermo‐oxidative degradation of chitosan was investigated. Fourier transform infrared and X‐ray diffraction analyses were utilized to determine the microstructure of the chitosan–cupric ion compounds. Kinetic parameters such as activation energy, pre‐exponential factor, Gibbs energy, and enthalpy and entropy of activation were determined using the Coats–Redfern equation. The results show that the thermo‐oxidative degradation of chitosan and chitosan–cupric ion compounds is a two‐stage reaction. The impact of cupric ion on the thermo‐oxidative degradation of chitosan is significant, and all thermodynamic parameters indicate that the thermo‐oxidative degradation of chitosan and chitosan–cupric ion compounds is a non‐spontaneous process and proceeds via a mechanism involving nucleation and growth, with an Avrami–Erofeev function (A4) with the integral form [−ln(1 − α)]4. Copyright © 2010 Society of Chemical Industry
Differential effects of phe19 and phe20 on fibril formation by amyloidogenic peptide Aβ16–22 (Ac‐KLVFFAE‐NH2)
Authors: Inouye Hideyo , Gleason Katherine A. , Zhang Dong , Decatur Sean M. , Kirschner Daniel A. 
Published: April 2010

AbstractThe sequence KLVFFAE (Aβ16–22) in Alzheimer's β‐amyloid is thought to be a core β‐structure that could act as a template for folding other parts of the polypeptide or molecules into fibrillar assemblies rich in β‐sheet. To elucidate the mechanism of the initial folding process, we undertook combined X‐ray fiber/powder diffraction and infrared (IR) spectroscopy to analyze lyophilized Aβ16–22 and solubilized/dried peptide containing nitrile probes at F19 and/or F20. Solubilized/dried wild‐type (WT) Aβ16–22 and the peptide containing cyanophenylalanine at F19 (19CN) or at F20 (20CN) gave fiber patterns consistent with slab‐like β‐crystallites that were cylindrically averaged around the axis parallel to the polypeptide chain direction. The WT and 19CN assemblies showed 30‐Å period arrays arising from the stacking of the slabs along the peptide chain direction, whereas the 20CN assemblies lacked any such stacking. The electron density projection along the peptide chain direction indicated similar side‐chain dispositions for WT and 20CN, but not for 19CN. These X‐ray results and modeling imply that in the assembly of WT Aβ16–22 the F19 side chain is localized within the intersheet space and is involved in hydrophobic contact with amino acids across the intersheet space, whereas the F20 side chain localized near the slab surface is less important for the intersheet interaction, but involved in slab stacking. IR observations for the same peptides in dilute solution showed a greater degree of hydrogen bonding for the nitrile groups in 20CN than in 19CN, supporting this interpretation. Proteins 2010. © 2010 Wiley‐Liss, Inc.
Distance‐dependent classification of amino acids by information theory
Authors: Pape Susanne , Hoffgaard Franziska , Hamacher Kay 
Published: April 2010

AbstractReduced amino acid alphabets are useful to understand molecular evolution as they reveal basal, shared properties of amino acids, which the structures and functions of proteins rely on. Several previous studies derived such reduced alphabets and linked them to the origin of life and biotechnological applications. However, all this previous work presupposes that only direct contacts of amino acids in native protein structures are relevant. We show in this work, using information–theoretical measures, that an appropriate alphabet reduction scheme is in fact a function of the maximum distance amino acids interact at. Although for small distances our results agree with previous ones, we show how long‐range interactions change the overall picture and prompt for a revised understanding of the protein design process. Proteins 2010. © 2010 Wiley‐Liss, Inc.
Computational alanine scanning with linear scaling semiempirical quantum mechanical methods
Authors: Diller David J. , Humblet Christine , Zhang Xiaohua , Westerhoff Lance M. 
Published: April 2010

AbstractAlanine scanning is a powerful experimental tool for understanding the key interactions in protein–protein interfaces. Linear scaling semiempirical quantum mechanical calculations are now sufficiently fast and robust to allow meaningful calculations on large systems such as proteins, RNA and DNA. In particular, they have proven useful in understanding protein–ligand interactions. Here we ask the question: can these linear scaling quantum mechanical methods developed for protein–ligand scoring be useful for computational alanine scanning? To answer this question, we assembled 15 protein–protein complexes with available crystal structures and sufficient alanine scanning data. In all, the data set contains ΔΔGs for 400 single point alanine mutations of these 15 complexes. We show that with only one adjusted parameter the quantum mechanics‐based methods outperform both buried accessible surface area and a potential of mean force and compare favorably to a variety of published empirical methods. Finally, we closely examined the outliers in the data set and discuss some of the challenges that arise from this examination. Proteins 2010. © 2010 Wiley‐Liss, Inc.
Cross‐resistance, mode of inheritance and stability of resistance to emamectin inSpodoptera litura(Lepidoptera: Noctuidae)
Authors: Shad Sarfraz Ali , Sayyed Ali H , Saleem Mushtaq A 
Published: April 2010

AbstractBACKGROUND:Spodoptera litura(F.) is a cosmopolitan pest that has developed resistance to several insecticides. The aim of the present study was to establish whether an emamectin‐selected (Ema‐SEL) population could render cross‐resistance to other insecticides, and to investigate the genetics of resistance.RESULTS:Bioassays at G1gave resistance ratios (RRs) of 80‐, 2980‐, 3050‐ and 2800‐fold for emamectin, abamectin, indoxacarb and acetamiprid, respectively, compared with a laboratory susceptible population Lab‐PK. After three rounds of selection, resistance to emamectin in Ema‐SEL increased significantly, with RRs of 730‐fold and 13‐fold compared with the Lab‐PK and unselected (UNSEL) population respectively. Further studies revealed that three generations were required for a tenfold increase in resistance to emamectin. Resistance to abamectin, indoxacarb, acetamiprid and emamectin in UNSEL declined significantly compared with the field population at G1. Furthermore, selection with emamectin reduced resistance to abamectin, indoxacarb and acetamiprid on a par with UNSEL. Crosses between Ema‐SEL and Lab‐PK indicated autosomal and incomplete dominance of resistance. A direct test of a monogenic model and Land's method suggested that resistance to emamectin was controlled by more than one locus.CONCLUSION:Instability of resistance and lack of cross‐resistance to other insecticides suggest that insecticides with different modes of action should be recommended to reduce emamectin selection pressure. Copyright © 2010 Society of Chemical Industry
The depsipeptide method for solid‐phase synthesis of difficult peptides
Authors: Coin Irene 
Published: April 2010

AbstractAfter about one century of peptide chemistry, the main limitation to the accessibility of peptides and proteins via chemosynthesis is the arising of folding and aggregation phenomena. This is true not only for sequences above a critical length but also for several biologically relevant substrates that are relatively short yet form either highly folded structures (e.g. WW domains) or fibrils and aggregates after final deprotection (β‐amyloid peptide). Such so‐called difficult sequences may be more easily obtained via their corresponding depsipeptides (O‐acyl isopeptides), ester isomers that are often easier to assemble and purify, and are smoothly converted to the parent amides under mild conditions. The depsipeptide method is the most recent technique to improve the outcome of difficult syntheses, applicable to sequences containing residues of serine or threonine. A brief overview is presented about chemical aspects of the method, the steps that have been undertaken for its optimization, and the evaluation of its efficiency. Further applications of analogous principles to other critical topics in peptide synthesis such as condensation of peptide segments and solid‐phase synthesis of naturally occurring cyclodepsipeptides are addressed as well. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.
Entwicklung eines multifunktionalen Deckensystems mit erhöhter Ressourceneffizienz
Authors: Mensinger Martin , Fontana Mario , Frangi Andrea 
Published: April 2010

AbstractIm Zuge des nachhaltigen Bauens tritt die Multifunktionalität von Decken immer mehr in den Vordergrund und verdrängt rein statische Überlegungen beim Entwurf von Decken. Bereits vorhandene individuelle Lösungen und multifunktionale Deckensysteme werden vorgestellt. Ein Vorteil dieser Systeme stellt die Integration der Installationsebene in die Konstruktionshöhe dar.Eine Weiterentwicklung dieser Ansätze stellt das Deckensystem Topfloor integral dar, welches aus einem halben Wabenträger und einer Betonplatte besteht. Die Öffnungen in den Waben ermöglichen eine flexible Installationsführung und führen zu einer hohen Materialeffizienz. Versuchsergebnisse von statischen Trägerversuchen werden vorgestellt und mit üblichen Berechnungsmodellen des Verbundbaus verglichen. Anhand der Versuchsergebnisse werden die Schubübertragung und die aus ihr resultierenden lokalen Beanspruchungen im Bereich der Waben detailliert diskutiert. Ingenieurmäßige Nachweise zum Biegedrillknicken und zur Schubeinleitung in den Beton durch Bewehrungsstäbe werden ebenso vorgestellt wie Überlegungen zum Feuerwiderstand und zum dynamischen Verhalten der Decke. Am Ende des Beitrages werden erste Beispiele von mit dem neuen Deckensystem ausgeführten Bauten vorgestellt.Development of a composite slab system with integrated installation floor and increased material‐efficiency. The need of sustainable buildings demands the design of multifunctional slabs considering more than only structural aspects. The paper presents state‐of‐the‐art solutions for multifunctional slabs and a novel type of composite floor system using cellular beams. A major benefit of the multifunctional slabs is the integration of an installation floor. The new developed system “Topfloor integral” uses half cellular beams made of existing hot‐rolled sections with welded reinforcing bars. The openings in the cellular beams allow the placing of installations in all directions, thus providing excellent flexibility to the user when maintaining or changing installations. The results of tests on the structural behavior and the load‐carrying capacity are presented and compared to proposed design models for the “Topfloor integral” slabs. Local stresses caused by shear forces at the web openings are discussed. Additional information about lateral‐torsional‐buckling, the design of the shear connection using common reinforcing bars, the fire resistance and the dynamic behavior are given. Finally, the paper presents some examples of first buildings where the novel type of floor system is used.
Tragwirkung von Betondübeln für Sandwich‐Verbunddecken mit großen Stegöffnungen
Authors: Abramski Marcin , Friedrich Thomas , Kurz Wolfgang , Schnell Jürgen 
Published: April 2010

AbstractNeuartige Konzepte zur ökologisch und ökonomisch sinnvollen Ausrüstung von Büroimmobilien und vergleichbaren Gebäuden verlangen nach schlüssiger Integration gebäudetechnischer Anlagen in die Tragkonstruktion. In diesem Beitrag wird über experimentelle Untersuchungen an verformungsarmen Stahlverbund‐Sandwichelementdecken mit Spannweiten von bis zu 16 m und Breiten bis zu 3 m berichtet, bei denen bereits bei der Herstellung Haustechnikkomponenten (Elektro, Lüftung, Heizung, Klima usw.) integriert werden.Die Deckenelemente bestehen aus zwei Platten von je 10 cm Dicke mit einem dazwischenliegenden Hohlraum von 20 cm Höhe. Die Verbindung von oberer und unterer Platte erfolgt mit Stahlblechen sowie bewehrten Betonstegen. Die Bauelemente weisen einen vorgespannten Verbundquerschnitt auf. Die Vorspannung erfolgt ohne Verbund. An den Stegöffnungen werden lokal große Kräfte zwischen den Stahl‐ und den Betonquerschnitten übertragen. Hier wurde eine alternative Lösung zu der recht aufwendigen Ausführung mit liegenden Kopfbolzendübeln untersucht: puzzleförmige Betondübel an den Rändern des Stahlstegs mit und ohne wendelförmiger Umschnürung. Ein besonderes Augenmerk lag dabei auf der Tragfähigkeit der Bauelemente in der Nähe von Stegöffnungen. In diesem Beitrag werden die Systementwicklung dargestellt und experimentelle Untersuchungen der Beton‐Sandwich‐Elementdecke beschrieben.Transferring of loads by concrete dowels in sandwich composite floors with large web openings. Modern conceptions of economically and ecologically sensible HVACR installations in residential and public buildings require their integration in the structure. The paper presents experimental investigation on precast sandwich composite steelconcrete floor with spans of up to 16 m and width up to 3 m, in which the HVACR installations (heating, ventilation, air conditioning, electricity etc.) are integrated already at a concrete plant.The floor consists of two 10 cm thick concrete slabs on both top and bottom sides with 20 cm high blank space between them. Both slabs are connected with vertical steel plates as well as reinforced concrete webs. The floors are post‐tensioned prestressed. There are high local forces being transferred between the concrete slabs and the steel web. A standard solution for joining the both structural elements is the application of horizontal headed studs. An alternative solution was investigated: puzzle‐formed concrete dowels at both edges of the steel web. The concrete dowels were optionally confined with spiral reinforcement. A special attention was focused on the load‐carrying capacity of the floors in the area of large web openings. The floor system with its technical aspects is presented in the paper, as well as the experimental investigations carried out on the floor and separately on the puzzle‐formed concrete dowels.
Impact of fault ride‐through requirements on fixed‐speed wind turbine structural loads
Authors: Hansen Anca D. , Cutululis Nicolaos A. , Markou Helen , Sørensen Poul E. 
Published: April 2010

AbstractThe emphasis in this article is on the impact of fault ride‐through requirements on wind turbines structural loads. Nowadays, this aspect is a matter of high priority as wind turbines are required more and more to act as active components in the grid, i.e. to support the grid even during grid faults.This article proposes a computer approach for the quantification of the wind turbines structural loads caused by the fault ride‐through grid requirements. This approach, exemplified for the case of a 2MW active stall wind turbine, relies on the combination of knowledge from complimentary simulation tools, which have expertise in different specialized wind turbines design areas. Two complimentary simulation tools are considered i.e. the detailed power system simulation tool PowerFactory from DIgSILENT and the advanced aeroelastic computer code HAWC2, in order to assess of the dynamic response of wind turbines to grid faults. These two tools are coupled sequently in an offline approach, in order to achieve a thorough insight both into the structural as well as the electrical wind turbine response during grid faults.The impact of grid requirements on wind turbines structural loads is quantified by performing a rainflow and a statistical analysis for fatigue and ultimate structural loads, respectively. Two cases are compared i.e. one where the turbine is immediately disconnected from the grid when a grid fault occurs and one where the turbine is equipped with a fault ride‐through controller and therefore it is able to remain connected to the grid during the grid fault. Copyright copy; 2010 John Wiley & Sons, Ltd.
Comparison of bivariate distribution construction approaches for analysing wind speed and direction data
Authors: Erdem E. , Shi J. 
Published: April 2010

AbstractStatistical distribution models for estimating wind energy potential spurred a great interest among researchers and practitioners recently. Bivariate statistical models for representing both wind direction and speed are helpful for the design and implementation of more efficient systems for harnessing wind energy. In this study, we construct seven different bivariate joint distributions based on three construction approaches, namely, angular‐linear (AL), Farlie‐Gumbel‐Morgenstern (FGM) and anisotropic lognormal approaches, and then compare them using the adjusted R2 and root mean square error (RMSE) as measures of goodness of fit. For both AL and FGM approaches, the distributions of wind speed and direction need to be obtained separately before the construction of joint distribution. While using the mixture of von Mises distribution for representing the wind direction, we utilize two different mixtures of distributions for representing the wind speed, with one being the mixture of singly truncated below Normal and Weibull distribution, and the other being the mixture of three‐parameter inverse Gaussian and lognormal distributions. A case study is conducted for this purpose on multiple sites in North Dakota, USA. It indicates that the two mixtures of distributions for wind speed have comparable performances. Meanwhile, there is little difference in terms of adjusted R2 and RMSE values in modelling wind direction with AL and FGM approaches. Although the anisotropic approach significantly lags behind AL and FGM approaches, the adjusted R2 and RMSE values provided by the latter two approaches are comparable. Copyright © 2010 John Wiley & Sons, Ltd
Rare Earth Carbodiimide Silicates: RE2(CN2)(SiO4)
Authors: Kubus Mariusz , Glaser Jochen , Kłonkowski Andrzej , Meyer H.‐Jürgen 
Published: April 2010

AbstractRare earth carbodiimide silicates RE2(CN2)(SiO4) with RE = Y, La, and Pr were synthesised by solid state metathesis reactions of RECl3, Li2(CN2), and SiO2 or Li2SiO4, respectively, in silica tubes at 550 °C. All three compounds crystallise with different structures, although all of them represent distorted derivatives of the sodium chloride type structure. The structure of Y2(CN2)(SiO4) was refined monoclinically (C2/m, Z = 2, a = 1301.382(5) pm, b = 377.630(1) pm, c = 527.656(2) pm, β = 93.9816(2) °) from X‐ray powder data. The crystal structure of La2(CN2)(SiO4) was refined in a different monoclinic space group (P21/c, Z = 4, a = 660.3(1) pm, b = 1282.0(2) pm, c = 656.2(1) pm, β = 105.23(2) °), and the structure of Pr2(CN2)(SiO4) was refined triclinically (P\bar{1}, Z = 2, a = 646.7(2) pm, b = 669.2(2) pm, c = 671.8(2) pm, α = 86.18(3) °, β = 73.22(3) °, γ = 74.08(3) °) from X‐ray single crystal data.
Cu7Bi6S10Cl5 – Mobile Copper(I) Cations Inside Dendritic Channels of a Rigid Framework
Authors: Heerwig Andreas , Ruck Michael 
Published: April 2010

AbstractThe melting reaction of copper, CuCl, sulfur, and Bi2S3 yields black, shiny needles of the sulfide chloride Cu7Bi6S10Cl5. The compound decomposes peritectically above 639(5) K. Cu‐K‐XANES data confirm the oxidation state +I of Cu. Cu7Bi6S10Cl5 crystallizes in the monoclinic space group C2/m with a = 2878.3(9) pm, b = 396.59(9) pm, c = 1156.5(4) pm, and β = 111.55(3)° at T = 293(2) K. Three sulfur and four chlorine anions coordinate each of the three independent bismuth cations in the shape of mono‐capped trigonal prisms. The [BiS3Cl4] polyhedra share edges and faces resulting in furrowed layers parallel ($\bar2$01). Localized as well as disordered copper cations occupy trigonal or tetrahedral voids in the packing of anions. The Joint Probability Density Function (JPDF) reveals branched and unbranched continuous pathways along [010], which are available for cation conduction.
A Water Sensitive Hydrate: The Bis‐Catena Complex Salt [Mn(H2O)6][BiI4]2·2H2O
Authors: Erbe Manuela , Köhler Daniel , Ruck Michael 
Published: April 2010

AbstractBright red crystals of [Mn(H2O)6][BiI4]2·2H2O are obtained from a solution of MnI2, BiI3, and I2 in absolute ethanol, which is exposed to humid air. Reversible dehydratization sets in at about 50 °C. Added water decomposes the hydrate by irreversible precipitation of BiOI. The optical bandgap is about 1.9(1) eV. X‐ray diffraction on a single‐crystal revealed a monoclinic lattice (space group P21/c) with a = 760.39(4) pm, b = 1315.6(1) pm, c = 1398.37(7) pm, and β = 97.438(4)°. In the crystal structure zigzag chains of edge‐sharing [BiI2/1I4/2]– octahedra and linear strings of H2O‐bridged [Mn(H2O)6]2+ octahedra run parallel [100].
Synthesis, Structure, and Properties of Scandium Dysprosium Antimonide ScDySb
Authors: Nuss Jürgen , Wedig Ulrich , Jansen Martin 
Published: April 2010

AbstractScandium dysprosium antimonide ScDySb was synthesized from scandium metal and DySb in an all‐solid state reaction at 1770 K. According to X‐ray analysis of the crystal structure [P4/nmm,Z= 4,a= 430.78(1) pm,c= 816.43(4) pm,R1= 0.0238,wR(all) = 0.0688, 268 independent reflections], ScDySb adopts theanti‐PbFCl type of structure, but with pronounced deviations in structural details, which are related to specific bonding interactions between the atoms involved. ScDySb shows antiferromagnetic ordering below 35.4 K, which was verified by susceptibility, heat capacity, and resistivity measurements. X‐ray structure determination, performed at 30 K, showed no significant structural changes to occur during the magnetic phase transition. The band structure was calculated in the framework of Density Functional Theory. The bonding properties are comparable to those of Sc2Sb. Pronounced basins of the Electron Localization Function (ELF) appear in the tetragonal pyramidal Sc4Dy voids.