bluuebunny/crossref_metadata_2025 huggingface dataset:
Mapping of road‐salt‐contaminated groundwater discharge and estimation of chloride load to a small stream in southern New Hampshire, USA
Authors: Harte Philip T. , Trowbridge Philip R.
Published: April 2010

Concentrations of chloride in excess of State of New Hampshire water‐quality standards (230 mg/l) have been measured in watersheds adjacent to an interstate highway (I‐93) in southern New Hampshire. A proposed widening plan for I‐93 has raised concerns over further increases in chloride. As part of this effort, road‐salt‐contaminated groundwater discharge was mapped with terrain electrical conductivity (EC) electromagnetic (EM) methods in the fall of 2006 to identify potential sources of chloride during base‐flow conditions to a small stream, Policy Brook. Three different EM meters were used to measure different depths below the streambed (ranging from 0 to 3 m). Results from the three meters showed similar patterns and identified several reaches where high EC groundwater may have been discharging. Based on the delineation of high (up to 350 mmhos/m) apparent terrain EC, seven‐streambed piezometers were installed to sample shallow groundwater. Locations with high specific conductance in shallow groundwater (up to 2630 mmhos/m) generally matched locations with high streambed (shallow subsurface) terrain EC. A regression equation was used to convert the terrain EC of the streambed to an equivalent chloride concentration in shallow groundwater unique for this site. Utilizing the regression equation and estimates of one‐dimensional Darcian flow through the streambed, a maximum potential groundwater chloride load was estimated at 188 Mg of chloride per year. Changes in chloride concentration in stream water during streamflow recessions showed a linear response that indicates the dominant process affecting chloride is advective flow of chloride‐enriched groundwater discharge. Published in 2010 by John Wiley & Sons, Ltd.
Regional classification, variability, and trends of northern North Atlantic river flow
Authors: Kingston Daniel G. , Hannah, David M. , Lawler Damian M. , McGregor Glenn R.
Published: April 2010

Regional classification techniques can help in identifying spatial structure in river flow variation. As such, a framework can be provided around which to test hypotheses, making regional classification an important tool for hydrological research, particularly over large and complex geographical domains. Here, the results of a regional classification of monthly river flow for the northern North Atlantic region over the period 1968–1997 are presented. Importantly, regional classes are identified on the basis of inter‐annual variation in river flow time series, rather than the more commonly used intra‐annual flow regime. This is beneficial because it provides an improved basis for the investigation of regional‐scale inter‐annual trends in river flow: an important aim given the potential for future changes in river discharge linked to climate change and land‐use change. Seven regions (four in northern Europe and three in eastern North America) are identified using hierarchical cluster analysis (Wards algorithm). Analysis of the hydrological homogeneity of the emergent river flow regions reveals them to be useful groupings to frame further analyses. Investigation of the statistical characteristics of each mean regional time series follows, including the annual flow regime, time series variability, and the presence of trends (as indicated by the Mann‐Kendall test). Key findings identified by the latter analysis include an increasing trend in late winter discharge for some northern European regions for 1968–1997, but overall few statistically significant trends. Copyright © 2010 John Wiley & Sons, Ltd.
Controls of surface soil moisture spatial patterns and their temporal stability in a semi‐arid steppe
Authors: Zhao Y. , Peth S. , Wang X. Y. , Lin H. , Horn R.
Published: April 2010

Temporal stability of soil moisture spatial patterns has important implications for optimal soil and water management and effective field monitoring. The aim of this study was to investigate the temporal stability of soil moisture spatial patterns over four plots of 105 m × 135 m in grid size with different grazing intensities in a semi‐arid steppe in China. We also examined whether a time‐stable location can be identified from causative factors (i.e. soil, vegetation, and topography). At each plot, surface soil moisture (0–6 cm) was measured about biweekly from 2004 to 2006 using 100 points in each grid. Possible controls of soil moisture, including soil texture, organic carbon, bulk density, vegetation coverage, and topographic indices, were determined at the same grid points. The results showed that the spatial patterns of soil moisture were considerably stable over the 3‐y monitoring period. Soil moisture under wet conditions (averaged volumetric moisture contents > 20%) was more stable than that under dry ($\bar{\theta}_{j, t} < 10\%$) or moist ($\def\endash{\hbox{--}} \bar{\theta}_{j, t} = 10\endash 20\%$) conditions. The best representative point for the whole field identified in each plot was accurate in representing the field mean moisture over time (R2 ≥ 0·97; p < 0·0001). The degree of temporal persistence varied with grazing intensity, which was partly related to grazing‐induced differences in soil and vegetation properties. The correlation analysis showed that soil properties, and to a lesser extent vegetation and topographic properties, were important in controlling the temporal stability of soil moisture spatial patterns in this relatively flat grassland. Response surface regression analysis was used to quantitatively identify representative monitoring locations a priori from available soil‐plant parameters. This allows appropriate selection of monitoring locations and enhances efficiency in managing soil and water resources in semi‐arid environments. Copyright © 2010 John Wiley & Sons, Ltd.
Soil saturation index of salt marshes subjected to spring‐neap tides: a new variable for describing marsh soil aeration condition
Authors: Xin Pei , Gibbes Badin , Li Ling , Song Zhiyao , Lockington David
Published: April 2010

Organized spatial distribution of plants (plant zonation) in salt marshes has been linked to the soil aeration condition in the rhizosphere through simplistic tidal inundation parameters. Here, a soil saturation index (ratio of saturation period to tidal period at a soil depth) is introduced to describe the soil aeration condition. This new index captures the effects of not only the tidal inundation period and frequency but also the flow dynamics of groundwater in the marsh soil. One‐dimensional numerical models based on saturated flow with the Boussinesq approximations and a two‐dimensional variably saturated flow model were developed to explore the behaviour of this new soil aeration variable under the influence of spring‐neap tides. Simulations revealed two characteristic zones of soil aeration across the salt marsh: a relatively well aerated near‐creek zone and a poorly aerated interior zone. In the near‐creek zone, soils undergo periodic wetting and drying as the groundwater table fluctuates throughout the spring‐neap cycle. In the interior, the soil remains largely water saturated except for neap tide periods when limited drainage occurs. Although such a change of soil aeration condition has been observed in previous numerical simulations, the soil saturation index provides a clear delineation of the zones that are separated by an ‘inflexion point’ on the averaged index curve. The results show how the saturation index represents the effects of soil properties, tidal parameters and marsh platform elevation on marsh soil aeration. Simulations of these combined effects have not been possible with traditional tidal inundation parameters. The saturation index can be easily derived using relatively simple models based on five non‐dimensional variables. Copyright © 2010 John Wiley & Sons, Ltd.
Hydraulic parameter estimations of a 2D model validated with sedimentological findings in the point bar environment
Authors: Alho Petteri , Mäkinen Joni
Published: April 2010

There have been a number of flume tests of flow round bends with idealized geometry and recently hydraulic simulations of such experiment. However, studies of hydraulic models in natural river bend are rather limited because of greater complexity of the flow characteristics and lack of detailed data. In this article, we study how 2D hydraulic model and raster‐based hydraulic parameter calculations predict flow characteristics on the natural point bar environment. We will compare calculations of various hydraulic parameters (velocity, bed shear stress and stream power) by the 2D model and the associated sedimentology of the point bars. As a result of comparison, the usability of the 2D model for flow‐form‐product relationship predictions will be evaluated in natural river bend environment. The study shows that the 2D model can be generally utilized to predict the flood‐generated flow‐form‐product relationship in coarse‐grained and structurally complex point bar environments with sand‐dominated bedload. For example, point bar sections submerged in water depths greater than 50 cm showed a relatively good match laterally between the model and sedimentological estimations. Furthermore, this approach allows us to estimate flood processes on a local scale in similar point bar environments with ${\sim}1:50$ width–length ratio. The flow direction estimates of the 2D model coincided relatively well with the sedimentological estimations on the bar head. However, flow directions on the downstream section could not be modelled because the 2D model cannot handle the helicoidal flow of the river bend. Copyright © 2010 John Wiley & Sons, Ltd.
Autocrine fibroblast growth factor 18 mediates dexamethasone‐induced osteogenic differentiation of murine mesenchymal stem cells
Authors: Hamidouche Zahia , Fromigué Olivia , Nuber Ulrike , Vaudin Pascal , Pages Jean‐Christophe , Ebert Regina , Jakob Franz , Miraoui Hichem , Marie Pierre J.
Published: April 2010

The potential of mesenchymal stem cells (MSC) to differentiate into functional bone forming cells provides an important tool for bone regeneration. The identification of factors capable of promoting osteoblast differentiation in MSCs is therefore critical to enhance the osteogenic potential of MSCs. Using microarray analysis combined with biochemical and molecular approach, we found that FGF18, a member of the FGF family, is upregulated during osteoblast differentiation induced by dexamethasone in murine MSCs. We showed that overexpression of FGF18 by lentiviral (LV) infection, or treatment of MSCs with recombinant human (rh)FGF18 increased the expression of the osteoblast specific transcription factor Runx2, and enhanced osteoblast phenotypic marker gene expression and in vitro osteogenesis. Molecular silencing using lentiviral shRNA demonstrated that downregulation of FGFR1 or FGFR2 abrogated osteoblast gene expression induced by either LV‐FGF18 or rhFGF18, indicating that FGF18 enhances osteoblast differentiation in MSCs via activation of FGFR1 or FGFR2 signaling. Biochemical and pharmacological analyses showed that the induction of phenotypic osteoblast markers by LV‐FGF18 is mediated by activation of ERK1/2‐MAPKs and PI3K signaling in MSCs. These results reveal that FGF18 is an essential autocrine positive regulator of the osteogenic differentiation program in murine MSCs and indicate that osteogenic differentiation induced by FGF18 in MSCs is triggered by FGFR1/FGFR2‐mediated ERK1/2‐MAPKs and PI3K signaling. J. Cell. Physiol. 224: 509–515, 2010. © 2010 Wiley‐Liss, Inc.
Analysis of 5S rDNA organization and variation in polyploid hybrids from crosses of different fish subfamilies
Authors: Qin Qinbo , He Weiguo , Liu Shaojun , Wang Jing , Xiao Jun , Liu Yun
Published: April 2010

In this article, sequence analysis of the coding region (5S) and adjacent nontranscribed spacer (NTS) were conducted in red crucian carp (RCC), blunt snout bream (BSB), and their polyploid offspring. Three monomeric 5S rDNA classes (designated class I: 203 bp; class II: 340 bp; and class III: 477 bp) of RCC were characterized by distinct NTS types (designated NTS‐I, II, and III for the 83, 220, and 357 bp monomers, respectively). In BSB, only one monomeric 5S rDNA was observed (designated class IV: 188 bp), which was characterized by one NTS type (designated NTS‐IV: 68 bp). In the polyploid offspring, the tetraploid (4nRB) hybrids partially inherited 5S rDNA classes from their female parent (RCC); however, they also possessed a unique 5S rDNA sequence (designated class I‐L: 203 bp) with a novel NTS sequence (designated NTS‐I‐L: 83 bp). The characteristic paternal 5S rDNA sequences (class IV) were not observed. The 5S rDNA of triploid (3nRB) hybrids was completely inherited from the parental species, and generally preserved the parental 5S rDNA structural organization. These results first revealed the influence of polyploidy on the organization and evolution of the multigene family of 5S rDNA of fish, and are also useful in clarifying aspects of vertebrate genome evolution. J. Exp. Zool. (Mol. Dev. Evol.) 314B:403–411 2010. © 2010 Wiley‐Liss, Inc.
Photodegradation kinetics and byproducts identification of the Aflatoxin B1 in aqueous medium by ultra‐performance liquid chromatography–quadrupole time‐of‐flight mass spectrometry
Authors: Liu Ruijie , Jin Qingzhe , Tao Guanjun , Shan Liang , Huang Jianhua , Liu Yuanfa , Wang Xingguo , Mao Wenyue , Wang Shanshan
Published: April 2010

A photodegradation study of Aflatoxin B1 (AFB1) in water solution was performed under UV irradiation at different AFB1 initial concentrations and UV irradiation intensities. The effect of UV intensity on the AFB1 photodegradation ratio is dominative, when compared with AFB1 initial concentration. The photodegradation of AFB1 was proved to follow first‐order reaction kinetics (R2 ≥ 0.99). Three photodegradation products, i.e. P1 (C17H14O7), P2 (C16H14O6) and P3 (C16H12O7), were identified on the basis of low mass error and high matching property by ultra‐performance liquid chromatography–quadrupole time‐of‐flight mass spectrometry (UPLC–Q‐TOF MS), and the degradation pathway was proposed. This study first reports the appearance of these photodegradation products and the proposed degradation pathway in aqueous media. Copyright © 2010 John Wiley & Sons, Ltd.
Long‐lasting post‐mortem activity of spinal microglia in situ in mice
Authors: Dibaj Payam , Steffens Heinz , Nadrigny Fabien , Neusch Clemens , Kirchhoff Frank , Schomburg Eike D.
Published: April 2010

As CNS macrophages, microglia show a high spontaneous motility of their processes, continuously surveying their microenvironment. Upon CNS injury, microglia react by immediate cellular polarization and process extension toward the lesion site as well as by subsequent amoeboid lesion‐directed migration and phagocytosis. To determine the ability of microglia to fulfill their role within distinctively lesioned tissue in the absence of life support, we investigated microglial activity and responsiveness to laser‐induced axonal injuries in the spinal dorsal columns in situ after cardiac and respiratory arrest, i.e., post‐mortem, in the progressively degrading nervous tissue. For this purpose, we used time‐lapse two‐photon laser scanning microscopy in double transgenic mice expressing enhanced green fluorescent protein in microglia and enhanced yellow fluorescent protein in projection neurons. Depending on the premortal condition of the animal, microglial activity and responsiveness remain for up to5–10 hr post‐mortem. Thereby, the continuously decreasing glial reaction is independent of oxygen and glucose supply but requires residual ATP, suggesting a parasitic form of energy, such as a transmembrane uptake of ATP released from injured nervous tissue. Even though initially microglia are able to detect axonal injury after disruption of the blood supply, the later aspects of glial reaction, for example amoeboid conversion and migration, are absent post‐ mortem, corresponding to the failure of microglia to prevent secondary damage after injury of nervous tissue. © 2010 Wiley‐Liss, Inc.
Chronic social isolation suppresses proplastic response and promotes proapoptotic signalling in prefrontal cortex of Wistar rats
Authors: Djordjevic Ana , Adzic Miroslav , Djordjevic Jelena , Radojcic Marija B.
Published: April 2010

Successful adaptation to stress involves synergized actions of glucocorticoids and catecholamines at several levels of the CNS, including the prefrontal cortex (PFC). Inside the PFC, hormonal signals trigger concerted actions of transcriptional factors, such as glucocorticoid receptor (GR) and nuclear factor kappa B (NFκB), culminating in a balanced, proadaptive expression of their common genes, such as proplastic NCAM and/or apoptotic Bax and Bcl‐2. In the present study, we hypothesized that chronic stress may compromise the balance between GR and NFκB signals and lead to an altered/maladaptive expression of their cognate genes in the PFC. Our results obtained with Wistar rats exposed to chronic social isolation indicated alterations of the GR relative to the NFκB, in favor of the GR, in both the cytoplasmic and the nuclear compartments of the PFC. Although these alterations did not affect the induction of proplastic NCAM gene, they decreased the NCAM sialylation necessary for plastic response and caused marked relocation of the mitochondrial membrane antiapoptotic Bcl‐2 protein to its cytoplasmic form. Moreover, the compromised PSA‐NCAM plastic response found under chronic stress was sustained after exposure of animals to the subsequent acute stress, whereas the proapoptotic signals were further emphasized. It is concluded that chronic social isolation of Wistar animals leads to a maladaptive response of the PFC, considering the diminishment of its plastic potential and potentiating of apoptosis. Such conditions in the PFC are likely to compromise its ability to interact with other CNS structures, such as the hippocampus, which is necessary for successful adaptation to stress. © 2010 Wiley‐Liss, Inc.
Peptidylgycine α‐amidating monooxygenase and copper: A gene–nutrient interaction critical to nervous system function
Authors: Bousquet‐Moore Danielle , Mains Richard E. , Eipper Betty A.
Published: April 2010

Peptidylgycine α‐amidating monooxygenase (PAM), a highly conserved copper‐dependent enzyme, is essential for the synthesis of all amidated neuropeptides. Biophysical studies revealed that the binding of copper to PAM affects its structure, and cell biological studies demonstrated that the endocytic trafficking of PAM was sensitive to copper. We review data indicating that genetic reduction of PAM expression and mild copper deficiency in mice cause similar alterations in several physiological functions known to be regulated by neuropeptides: thermal regulation, seizure sensitivity, and anxiety‐like behavior. © 2010 Wiley‐Liss, Inc.
An integer decomposition algorithm for solving a two‐stage facility location problem with second‐stage activation costs
Authors: Penuel John , Smith J. Cole , Yuan Yang
Published: April 2010

We study a stochastic scenario‐based facility location problem arising in situations when facilities must first be located, then activated in a particular scenario before they can be used to satisfy scenario demands. Unlike typical facility location problems, fixed charges arise in the initial location of the facilities, and then in the activation of located facilities. The first‐stage variables in our problem are the traditional binary facility‐location variables, whereas the second‐stage variables involve a mix of binary facility‐activation variables and continuous flow variables. Benders decomposition is not applicable for these problems due to the presence of the second‐stage integer activation variables. Instead, we derive cutting planes tailored to the problem under investigation from recourse solution data. These cutting planes are derived by solving a series of specialized shortest path problems based on a modified residual graph from the recourse solution, and are tighter than the general cuts established by Laporte and Louveaux for two‐stage binary programming problems. We demonstrate the computational efficacy of our approach on a variety of randomly generated test problems. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010
Path optimization for the resource‐constrained searcher
Authors: Sato Hiroyuki , Royset Johannes O.
Published: April 2010

We formulate and solve a discrete‐time path‐optimization problem where a single searcher, operating in a discretized three‐dimensional airspace, looks for a moving target in a finite set of cells. The searcher is constrained by maximum limits on the consumption of one or more resources such as time, fuel, and risk along any path. We develop a specialized branch‐and‐bound algorithm for this problem that uses several network reduction procedures as well as a new bounding technique based on Lagrangian relaxation and network expansion. The resulting algorithm outperforms a state‐of‐the‐art algorithm for solving time‐constrained problems and also is the first algorithm to solve multi‐constrained problems. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010
Improvement of PUFEM for the numerical solution of high‐frequency elastic wave scattering on unstructured triangular mesh grids
Authors: El Kacimi A. , Laghrouche O.
Published: April 2010

The purpose of this paper, which builds on previous work (Int. J. Numer. Meth. Engng 2009; 77:1646–1669), is to improve a numerical scheme based on the partition of unity finite element method (PUFEM) for the solution of the time harmonic elastic wave equations. The approach consists to approximate the displacement field by the standard finite element shape functions, enriched locally by superimposing pressure (P) and shear (S) plane waves. The aim is to accurately model two‐dimensional elastic wave problems on relatively coarse mesh grids, capable of containing many wavelengths per nodal spacing, for wide ranges of frequencies. This allows us to relax the traditional requirement of about 10 nodal points per S wavelength. In this work, an exact integration scheme for the linear triangular finite element is developed to evaluate the oscillatory integrals arising from the use of the PUFEM. The main contribution here consists in developing an explicit closed‐form solution for two‐dimensional wave‐based integrals, when the phase variation is linear in the local coordinate element system. The evaluation of the element mass matrix is performed from appropriate edge integrals. All other element matrices, obtained by adequate splitting of the element stress tensor matrix, are simply deduced from the element mass matrix entries.

The results show clearly that the proposed integration scheme evaluates accurately the entries of the global matrix with drastic reduction of the computational time. Numerical tests dealing with the scattering of S elastic plane waves by a circular rigid body show that, for the same discretization level, it is possible to improve the accuracy by using large elements associated with high numbers of approximating plane waves rather than using small elements with less plane waves. However, this increases the conditioning and the fill‐in of the global matrix. At high frequency, it is even possible to push the number of degrees of freedom per S wavelength under 2 and still achieve good accuracy. Finally, some remarks on the choice of the numbers of P and S plane waves leading to better accuracy and conditioning are discussed. Copyright © 2010 John Wiley & Sons, Ltd.
A modified version of a T‐Cell Algorithm for constrained optimization problems
Authors: Aragón Victoria S. , Esquivel Susana C. , Coello Carlos A. Coello
Published: April 2010

In this paper, we present a heuristic inspired on the T‐Cell model of the immune system (i.e. an artificial immune system). The proposed approach (called T‐Cell) is used for solving constrained (numerical) optimization problems, and is validated using several test functions taken from the specialized literature on evolutionary optimization. Additionally, several engineering optimization problems are also used for assessing the performance of the proposed approach. The results are compared with respect to approaches representative of the state‐of‐the‐art in constrained evolutionary optimization. Copyright © 2010 John Wiley & Sons, Ltd.
Nuclear β‐catenin expression and Wnt signalling: in defence of the dogma
Authors: Fodde Riccardo , Tomlinson Ian
Published: April 2010

Inactivation of the APC tumour suppressor gene represents the rate‐limiting event in colorectal cancer. Loss of APC function leads to constitutive activation of the canonical Wnt–β‐catenin signalling pathway, thus resulting into a broad spectrum of cellular defects, ranging from stem cell self‐renewal and differentiation, apoptosis, migration and proliferation. Recently, Phelps et al 1 presented an alternative model where loss of APC does not primarily result in Wnt signalling activation but rather involves the transcriptional co‐repressor CtBP1. According to this alternative scenario, oncogenic KRAS activation represents a conditio sine qua non for nuclear β‐catenin translocation and Wnt activation. In a recent issue of the Journal of Pathology, Obrador‐Hevia and collaborators 2 reaffirmed the broadly accepted textbook model by showing the presence of nuclear β‐catenin in both the presence and, more often, the absence of KRAS mutations. Copyright © 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Influence of racemization on stereocomplex‐induced gelation of water‐soluble polylactide–poly(ethylene glycol) block copolymers
Authors: Nouailhas Helene , Li Feng , El Ghzaoui Abdelsalm , Li Suming , Coudane Jean
Published: April 2010

Ring‐opening polymerization of L‐ or D‐lactide was realized at 140 °C for a period of 7 days in the presence of dihydroxyl poly(ethylene glycol) (PEG), with M̄n = 4000 g mol−1, using zinc lactate as initiator. The resulting poly(L‐lactide)–PEG–poly(L‐lactide) and poly(D‐lactide)–PEG–poly(D‐lactide) triblock copolymers are water soluble with polylactide (PLA) block length ranging from 11 to 17 units. Both the tube inverting method and rheological measurements were used to evaluate the gelation properties of aqueous solutions containing single copolymers or L/D copolymer pairs. Stereocomplexation between poly(L‐lactide) and poly(D‐lactide) blocks is observed for mixed solutions. Hydrogel formation is detected in the case of relatively long PLA blocks (DPPLA = 17), but not for copolymers with shorter PLA blocks (DPPLA = 11–13) due to partial racemization of L‐lactyl units. Racemization is largely reduced when the reaction time is shortened to 1 day. Under these conditions, DPPLA of 8 is sufficient for the stereocomplexation of PLA–PEG block copolymers, and DPPLA above 10 leads to the formation of hydrogels of PLA–PEG block copolymers. On the other hand, racemization appears as a general phenomenon in the (co)polymerization of L‐lactide with Zn(Lac)2 as initiator, although it is negligible or undetectable in the case of high molar mass polymers. Therefore, racemization is the limiting factor for the stereocomplexation‐induced gelation of water‐soluble PLA–PEG block copolymers where the PLA block length generally ranges from 10 to 30. Reaction conditions including initiator, time and temperature should be strictly controlled to minimize racemization. Copyright © 2010 Society of Chemical Industry
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

The 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

The 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

Reduced 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

Alanine 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

BACKGROUND: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

After 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

Im 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

Neuartige 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

The 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

Statistical 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

Rare 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

The 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.