bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors associated with recurrence and metastasis in sacrococcygeal teratoma
Authors: Derikx J P M , De Backer A , van de Schoot L , Aronson D C , de Langen Z J , van den Hoonaard T L , Bax N M A , van der Staak F , van Heurn L W E
Published: October 2006

Background

Sacrococcygeal teratoma (SCT) is a relatively uncommon tumour, with a high risk of recurrence and metastasis. The factors associated with recurrence and metastatic disease were studied.

Methods

A retrospective review was conducted of 173 children with SCT treated between January 1970 and February 2003 at the paediatric surgical centres in the Netherlands. Risk factors were identified by univariate and multivariate analysis.

Results

Eight children died shortly after birth or around the time of operation. Nine children, all over 18 months old, had metastases at presentation. Four teratomas with metastasis showed mature histology of the primary tumour. Nineteen children had recurrence of SCT a median interval of 10 months (range 32 days to 35 months) after primary surgery. Risk factors for recurrence were pathologically confirmed incomplete resection (odds ratio (OR) 6·54 (95 per cent confidence interval (c.i.) 2·11 to 20·31)), immature histology (OR 5·74 (95 per cent c.i. 1·49 to 22·05)) and malignant histology (OR 12·83 (95 per cent c.i. 3·27 to 50·43)). Size, Altman classification, age and decade of diagnosis were not risk factors for recurrence. One-third of the recurrences showed a shift towards histological immaturity or malignancy, compared with the primary tumour. Seven patients died after recurrence, five with malignant disease.

Conclusion

This national study showed that SCT recurred in 11 per cent of the children within 3 years of operation. Risk factors were immature and malignant histology, or incomplete resection. Mature teratoma has the biological capability to become malignant.
Polymere Hydrogele in der Abdichtungstechnik – Untersuchungen zum Quellungsdruck
Authors: Wack H. , Ulbricht M.
Published: October 2006

Polymere Hydrogele werden in der letzten Zeit vermehrt auch im Bereich der Abdichtungstechnik eingesetzt. Die Anwendung der Materialien erfolgt dabei zumeist empirisch und basiert auf dem Quellungsdruck, den die Polymere bei der Aufquellung in einem fest vorgegebenen Volumen entwickeln. Die hier entwickelte Methode der Bestimmung des Quellungsdrucks bei vorgegebenem Endvolumen der Quellung ist für detaillierte Untersuchungen, wie sie im Hinblick auf die Optimierung von Materialien für die Abdichtungstechnik notwendig sind, sehr gut anwendbar. Darüber hinaus ermöglicht sie auch mechanistische Aussagen zum Stofftransport während des Quellungsprozesses.
Anregungen für eine präzisere Formelsprache in der Organischen Chemie
Authors: Fernberg Nicole , Martens Jürgen
Published: October 2006

Formeln, Symbole und Zeichen sind essentiell für die Verständigung innerhalb der Chemie. Die Formelsprache ist ein wichtiger Bestandteil der Fachsprache der Chemie und damit bedeutend für das Verständnis fachwissenschaftlicher Zusammenhänge. Sie stellt daher auch ein allgemeines Lernziel des Chemieunterrichtes dar.
Julius Wagner ‐ Deutschlands erster Professor für Didaktik der Chemie
Authors: Boeck Gisela
Published: October 2006

Mit Julius Wagner hat es auf Initiative von Wilhelm Ostwald den ersten Versuch gegeben, Chemiedidaktik an einer Universität zu institutionalisieren. Es ist Ostwalds Verdienst gewesen, die Notwendigkeit einer guten Chemielehre in der Schule erkannt zu haben. Eine Voraussetzung dafür ist eine gute Lehrerausbildung. Ostwald hat das laut genug betont und dadurch eine etatmäßige außerordentliche Professur durchgesetzt. Wagner führte die damit verbundenen Lehraufgaben durch. Mit dem Ausscheiden Ostwalds aus der Leipziger Universität hat Wagners wissenschaftliches Engagement nachgelassen, obwohl er seinen Lehrauftrag erfüllte. Damit hatte er der Didaktik aber nicht die Position geschaffen, die es ermöglichte, die außer‐ordentliche Professur in Leipzig weiterzuführen. Erst über 40 Jahre später kam es dort zur Schaffung einer Dozentur für „Methodik des Chemieunterrichts”︁.
Optimization strategies for sediment reduction practices on roads in steep, forested terrain
Authors: Madej Mary Ann , Eschenbach Elizabeth A. , Diaz Carlos , Teasley Rebecca , Baker Kristine
Published: October 2006

Many forested steeplands in the western United States display a legacy of disturbances due to timber harvest, mining or wildfires, for example. Such disturbances have caused accelerated hillslope erosion, leading to increased sedimentation in fish‐bearing streams. Several restoration techniques have been implemented to address these problems in mountain catchments, many of which involve the removal of abandoned roads and re‐establishing drainage networks across road prisms. With limited restoration funds to be applied across large catchments, land managers are faced with deciding which areas and problems should be treated first, and by which technique, in order to design the most effective and cost‐effective sediment reduction strategy. Currently most restoration is conducted on a site‐specific scale according to uniform treatment policies. To create catchment‐scale policies for restoration, we developed two optimization models – dynamic programming and genetic algorithms – to determine the most cost‐effective treatment level for roads and stream crossings in a pilot study basin with approximately 700 road segments and crossings. These models considered the trade‐offs between the cost and effectiveness of different restoration strategies to minimize the predicted erosion from all forest roads within a catchment, while meeting a specified budget constraint. The optimal sediment reduction strategies developed by these models performed much better than two strategies of uniform erosion control which are commonly applied to road erosion problems by land managers, with sediment savings increased by an additional 48 to 80 per cent. These optimization models can be used to formulate the most cost‐effective restoration policy for sediment reduction on a catchment scale. Thus, cost savings can be applied to further restoration work within the catchment. Nevertheless, the models are based on erosion rates measured on past restoration sites, and need to be updated as additional monitoring studies evaluate long‐term basin response to erosion control treatments. Copyright © 2006 John Wiley & Sons, Ltd.
Determining hydraulic resistance in gravel‐bed rivers from the dynamics of their water surfaces
Authors: Cooper James R. , Tait Simon J. , Horoshenkov Kirill V.
Published: October 2006

Traditionally, approaches to account for the effect of the boundary roughness of a gravel‐bed river have used a grain‐size index of the bed surface as a surrogate for hydraulic resistance. The use of a single grain‐size does not take into account the spatial heterogeneity in the bed surface and how this heterogeneity imparts resistance on the flow, nor the way in which this relationship changes with variables such as flow stage. A new technique to remotely quantify hydraulic resistance is proposed. It is based on measuring the dynamics of a river's water surface and relating this to the actual hydraulic resistance created by a rough sediment boundary. The water surface dynamics are measured using a new acoustic technique, grazing angle sound propagation (GRASP). This proposed method to measure hydraulic resistance is based on a greater degree of physical reasoning, and this is discussed in the letter. By measuring acoustically the temporal dynamics of turbulent water surfaces over a water‐worked gravel bed in a laboratory flume, a dependency is demonstrated between the temporal variation in the reflected acoustic pressure and measured hydraulic resistance. It is shown that the standard deviation in acoustic pressure decreases with increasing hydraulic resistance. This is shown to apply for a range of relative submergences and bed slopes that are typical of gravel‐bed rivers. This remote sensing technique is both rapid and inexpensive, and has the potential to be applied to natural river channels and to other environmental turbulent flows, such as overland flows. A whole new class of low‐cost, remote and non‐intrusive instruments could be developed as a result and used in a wide range of hydraulic and hydrological applications. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis and Characterization of Highly Soluble Poly(aryl ether ketone‐benzoxazole) Copolymers with Hexafluoroisopropylidene Moieties by Direct Copolymerization
Authors: Li Jinhuan , Lee Young Moo
Published: October 2006

Summary: A series of new poly(aryl ether ketone‐benzoxazole)s (PAEKBOs) with hexafluoroisopropylidene moieties were synthesized directly by the aromatic nucleophilic polycondensation of 2,2′‐bi[2‐(4‐fluorophenyl)benzoxazol‐6‐yl]hexafluoropropane(6F‐BO), 4,4′‐difluorobenzophenone (DFBP) and 4,4′‐(hexafluoroisopropylidene)diphenol (6F‐OH) at various molar ratios. High molecular weight polymers with both benzoxazole and ether‐ketone units were readily obtained. The copolymers with >20 mol‐% content of ether‐ketone units were highly soluble in organic solvents such as N‐methyl‐2‐pyrrolidone (NMP), N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide (DMF), m‐cresol, tetrahydrofuran (THF) and CHCl3. The thermal stability of PAEKBOs was not significantly compromised compared with the relevant homopolymer compositions, hexafluoroisopropylidene containing poly(aryl ether ketone) (6F‐PAEK) without benzoxazole units and hexafluoroisopropylidene containing poly(ether benzoxazole) (6F‐PEBO) without ether‐ketone units. A 5% weight loss of the copolymers occurred at above 440 °C in air and above 480 °C in N2. Single glass transition temperatures (Tgs) were observed and ranged from 182 to 228 °C depending on the composition of the copolymers. The PAEKBO copolymers were essentially in the amorphous state, as determined using DSC, WAXD and DMA. For polymer films with a thickness of 30–80 µm, moduli between 1 700 and 2 100 MPa and strengths between 40 and 90 MPa were achieved. The PAEKBO copolymers behaved in many respects as engineering thermoplastics and could be processed from solution and the melt.

Structure of PAEKBO.

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Structure of PAEKBO.
Synthesis and Characterization of Functionalized Crosslinkable Poly(ε‐caprolactone)
Authors: Laurienzo Paola , Malinconico Mario , Mattia Giuditta , Romano Gennaro
Published: October 2006

Summary: A new and rather simple method to obtain randomly crosslinked PCL is reported. PCL was previously functionalized through radical grafting of MA and GMA in the melt, using a Brabender‐like apparatus. GMA was added in order to obtain higher grafting efficiency. The structure of PCL‐g‐MAGMA was elucidated by 1H NMR spectroscopy, and the content of grafted MA was determined by FT‐IR spectroscopy. PCL‐g‐MAGMA was successively crosslinked through reaction with HMDI. The degree of crosslinking was determined by solvent extractions with chloroform. Thermal and dynamic mechanical analysis and tensile tests were performed on plain PCL, on PCL‐g‐MAGMA and on crosslinked PCL samples.

Schematic representation of PCL‐g‐MAGMA structure.

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Schematic representation of PCL‐g‐MAGMA structure.
Self‐Assembled Structures in Blends of Block Copolymer A‐block‐B with Homopolymer A: SAXS and SANS Study
Authors: Holoubek Jaroslav , Baldrian Josef , Lednický František , Málková Šárka , Lal Jyotsana
Published: October 2006

Summary: The study describes the investigation of the microphase‐separated morphology of a block copolymer A‐block‐B with the parent homopolymer A, where A is polystyrene and A‐block‐B is poly(perdeuterated styrene)‐block‐poly(methyl methacrylate) (dPS‐block‐PMMA). The microdomain morphology and phase behavior in blends of dPS‐block‐PMMA with polystyrene of $\overline M _{\rm w}$ = 8 000 and 35 000 were investigated. Binary blends of the diblock copolymer and homopolymers were prepared with various amounts of homopolymers. The criterion for “wet and dry brush” taking into account different solubilization of homopolymer has been applied to explain the changes in microdomain morphology during the self‐assembling process.

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NMR Study of Hyperbranched Polyphenylenes from the AB2, (AB2 + AB) and (A2 + B3) Methods
Authors: Komber Hartmut , Stumpe Katrin , Voit Brigitte
Published: October 2006

Summary: The 1H NMR and 13C NMR spectra of hyperbranched polyphenylenes synthesised from AB2, (AB2 + AB) and (A2 + B3) monomers (A: ethynyl group; B: cyclopentadienonyl group) were analysed with respect to the characteristic substructures of these polymers. The broad and overlapping NMR spectra were studied by a combination of 1D and 2D NMR techniques. Furthermore, appropriate model compounds were synthesised, and their 1H and 13C NMR spectra were fully assigned. The signal assignments achieved allow to substantiate the different hyperbranched polyphenylene structures. Steric hindrance in densely packed di‐ and trihexaarylphenyl substituted units of the (A2 + B3) polyphenylenes results in the decrease of the rotation frequency of phenyl rings in these structures to such an extent that the motion is slow on the 1H NMR time scale. This can be proved both by EXSY and variable‐temperature experiments. Steric constraints were also deduced for the AB2 polyphenylenes from signal line shape.

Selected spectra from a VT 1H NMR experiment on polymer 7b (solvent: C2D2Cl4; *–13C satellites of the solvent; signal at 7.3 ppm due to traces of CHCl3).

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Selected spectra from a VT 1H NMR experiment on polymer 7b (solvent: C2D2Cl4; *–13C satellites of the solvent; signal at 7.3 ppm due to traces of CHCl3).
Uniform Sub‐Micron Polymer Spheres Coated with Ag Nanoparticles
Authors: Mohammed Halimatu S. , Shipp Devon A.
Published: October 2006

Summary: The synthesis of well‐defined uniform and spherical sub‐micron polymeric spheres, specifically poly[styrene‐co‐(glycidyl methacrylate)] (PSGMA) with a uniform size distribution and surface chemical functionality, is described. It is shown that the surface can be modified with a multi‐amine functional polymer, polyethyleneimine (PEI), most likely through covalent bonding in addition to electrostatic attraction. The PEI acts both as a stabilizing agent and a complexation agent for the deposition of noble metal Ag nanoparticles.

Reaction of PSGMA samples with excess PEI, and its TEM image.

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Reaction of PSGMA samples with excess PEI, and its TEM image.
Effect of Temperature on Shear‐Induced Anisotropic Structure in Polymer Clay Hydrogels
Authors: Li Jun , Jiang Jun , Li Chunhua , Lin Min Y. , Schwarz Steven A. , Rafailovich Miriam H. , Sokolov Jonathan
Published: October 2006

Summary: Shear‐induced orientation of nanoparticles in poly(ethylene oxide)/Laponite RD hydrogels has been investigated by small angle neutron scattering (SANS). As temperature is reduced, anisotropy develops at lower shear rates. The two‐correlation length Debye–Anderson–Brumberger (DAB) model provides a good fit to the experimental data. The deduced short‐range correlation length (≈5 nm) is observed to increase with shear. The long‐range correlation length (≈50 nm) shows a strong directional dependence, and decreases when shear is applied. The relative contribution of long‐range order to the SANS intensity is observed to increase with shear and decrease with temperature.

SANS anisotropy |(Iy − Ix)/(Iy + Ix)| as a function of shear rate and q at 2 °C.

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SANS anisotropy |(Iy − Ix)/(Iy + Ix)| as a function of shear rate and q at 2 °C.
Cover Picture: Macromol. Rapid Commun. 20/2006
Authors: Lange Birger , Wagner Jürgen , Zentel Rudolf
Published: October 2006

Cover: On the cover you can see the iridescent green colour of an inverse ORMOCER opal. These photonic crystals have several advantages, they can be made in high quality what is shown with optical measurements and they have enhanced mechanical properties. Further details can be found in the article by B. Lange, J. Wagner, and R. Zentel* on page 1746.
Heat transfer at high energy devices with prescribed cooling flow
Authors: Breuer Jens
Published: October 2006

We study the heat transfer from a high‐energy electric device into a surrounding cooling flow. We analyse several simplifications of the model to allow an easier numerical treatment. First, the flow variables velocity and pressure are assumed to be independent from the temperature which allows a reduction to Prandtl's boundary layer model and leads to a coupled nonlinear transmission problem for the temperature distribution. Second, a further simplification using a Kirchhoff transform leads to a coupled Laplace equation with nonlinear boundary conditions. We analyse existence and uniqueness of both the continuous and discrete systems. Finally, we provide some numerical results for a simple two‐dimensional model problem. Copyright © 2006 John Wiley & Sons, Ltd.
Numerical analysis of a model of cure process for composites
Authors: Meliani Salha , Paoli Laetitia
Published: October 2006

We consider a composite material composed of fibres included in a resin which becomes solid when it is heated up (reaction of reticulation). The mathematical modelling of the cure process is given by a kinetic equation describing the evolution of the reaction of reticulation coupled with the heat equation.

In this paper, we are interested in the computation of approximate solutions. We propose a family of discretized problems depending on two parameters (β1, β2) ε [0, 1]2 which split the linear and non‐ linear terms in implicit and explicit parts. We prove the stability and convergence of the discretization for any (β1, β2) ε [½, 1 ] × [0, 1]. We present also some numerical results. Copyright © 2006 John Wiley & Sons, Ltd.
Mortality in schizophrenia
Authors: Auquier Pascal , Lançon Christophe , Rouillon Frédéric , Lader Malcolm , Holmes Catriona
Published: October 2006

Purpose

The purpose of this article is to describe the current status of knowledge on excess mortality in schizophrenia and its causative factors, and to expand upon previous work evaluating approaches that may reduce mortality rates.

Methods

Literature available since 1995 was identified in a computerized search of the bibliographical databases Medline and Embase, using the topics ‘mortality’ and ‘schizophrenia’, and in a cross‐reference search for articles that were particularly relevant.

Results

Schizophrenia is associated with mortality rates that are two to three times higher than those expected or observed in the general population. This excess of mortality is accounted for by a combination of an increased risk of suicide, in particular in young male patients soon after diagnosis, and more importantly, a higher number of natural deaths. In order to diminish the level of suicide among people with schizophrenia, the majority of research has focused on the identification of risk factors that predispose patients to attempt or commit suicide, while unhealthy styles, polypharmacy and inadequate healthcare have been shown to contribute to the high natural mortality. The link between the use of antipychotics and mortality has not been yet clarified.

Conclusion

Dramatically increased mortality of schizophrenia patients is well established. It is time to move beyond this topic, and work towards interventions that aim at reducing the mortality risk in such patients. Copyright © 2006 John Wiley & Sons, Ltd.
Application of X‐ray Microtomography and Image Processing to the Investigation of a Compacted Granular System
Authors: Fu Xiaowei , Elliott James A. , Bentham A. Craig , Hancock Bruno C. , Cameron Ruth E.
Published: October 2006

This paper outlines a novel technique, based on modern desktop X‐ray microtomography (XMT) and image processing, to visualize and quantitatively investigate powder packing and particle movement during compaction, which relate to materials properties and processing conditions of pharmaceutical tablet manufacture by compaction. This technique has been validated by direct comparison with measurements of particle shape and size by Scanning Electron Microscopy (SEM), and the results are also consistent with predictions made by Discrete Element Method (DEM) computer simulations. The technique has the potential for further quantitative investigation of powder compaction in pharmaceutical powder blends containing multiple components with ranges of particle sizes and shapes.
Watershed Functions Applied to a 3D Image Segmentation Problem for the Analysis of Packed Particle Beds
Authors: Videla Alvaro , Lin Chen‐Luh , Miller Jan D.
Published: October 2006

In an effort to advance the area of particle science and technology the University of Utah has been using cone beam X‐ray microtomography as a major tool for the quantitative three dimensional (3D) analysis of packed beds of multiphase particles. In this regard, efficient imaging algorithms have been developed and applied in order to extend two dimensional (2D) image analysis techniques for the solution of three 3D problems. Based on this research, image analyses of different particle samples were carried out for identification, segmentation, and quantitative volume characterization of irregularly shaped particles. The whole analysis involves acquisition of a 3D image by X‐ray microtomography and a sequence of image processing tools for thresholding, distance transformation, maxima detection using reconstruction by dilation, and a watershed 3D algorithm for segmentation and identification of irregularly shaped particles in three dimensions. Several examples of the 3D analysis for irregularly shaped particles are presented and the results discussed. Application of these algorithms is demonstrated by the determination of coal washability curves.
A Dual Modality Tomography System for Imaging Gas/Solids Flows
Authors: Dyakowski Tom , Johansen Geir A. , Hjertaker Bjorn T. , Sankowski Dominik , Mosorov Volodymyr , Wlodarczyk Jaroslaw
Published: October 2006

The paper presents a novel dual modality reconstruction algorithm (DMR) based on processing data collected from γ‐ray and electrical capacitance tomography systems. The tomograms are shown for noise‐free data as well as for data captured for a gas/solids flow in a vertical channel.
Electrical Resistance Tomography for Suspended Sediment Measurements in Open Channel Flows Using a Novel Sensor Design
Authors: Schlaberg H. Inaki , Baas Jaco H. , Wang Mi , Best Jim L. , Williams Richard A. , Peakall Jeff
Published: October 2006

Understanding the transport and deposition of sediment (such as sand and clay) is essential to allow the modelling and prediction of sediment dispersal, and the development of depositional morphology, within modern environments and ancient sedimentary basins. Electrical Resistance Tomography (ERT) has previously been used to provide a measure of particle concentration within moving suspensions. ERT measurements normally employ electrodes around a circular boundary of a container that allows measurement of multiple projections. However, measuring the concentration of a flow in a rectangular channel without disturbing the flow cannot use these well‐established sensor rings. This paper investigates the use of a linear sensor array in the channel bed, and a U‐shaped sensor array in the channel bed and walls, to measure spatial and temporal gradients in sediment concentration/conductivity of a channellised flow. To overcome the problems with the effect of sediment‐covered electrodes and the limited number of projection angles of a linear sensor configuration, the properties of a U‐shaped sensor are explored. Due to the additional projection angles in a U‐shaped sensor, improved reconstructions are obtained. This paper presents the first measurements of suspended sediment concentration and sediment deposition and test objects using linear and U‐shaped tomographic sensors.
Visualisation of Bubbly Velocity Distribution in a Swirling Flow Using Electrical Resistance Tomography
Authors: Wang Mi , Lucas Gary , Dai Yunfeng , Panayotopoulos Nikolaos , Williams Richard A.
Published: October 2006

This paper describes a dual‐plane Electrical Resistance Tomography (ERT) system for measuring local air volume fraction and 3‐D velocity distribution in gas‐liquid flows. An implementation based on a so‐called ‘best‐correlated pixels' method has been developed. Applying the 3‐D velocity implementation to tomographic data sets obtained from an air‐water swirling flow, axial, angular and radial velocity profiles have been successfully extracted. With the volume fraction distribution reconstructed using the “sensitivity theory based inverse solution using conjugate gradient” (SCG) method, the dispersed phase flow volumetric rate can be obtained. The experimental results obtained using the ERT system are in good agreement with the measurements obtained using a local probing technique.
Mechanism of the decrease of barriers for oxygen ionic conductivity in nanocrystalline ceramics
Authors: Glinchuk M. D. , Bykov P. I. , Hilczer B.
Published: October 2006

We calculate the influence of surface tension on the barriers for oxygen ionic conductivity in nanograin ceramics. Namely, we evaluate the activation energy for diffusion of oxygen ions via its vacancies. In our model, latter vacancies have been considered as dilatational centers. We have shown, that the activation energy decreases with nanoparticle size decreasing. We derive the distribution function of activation energy on the base of distribution of nanoparticle sizes. We obtain analytical expressions for dependence of ionic conductivity on the temperature and nanograin sizes. The obtained expressions describe the observed behaviour of oxygen conductivity in nanograin ceramics of ZrO2:16% Y pretty good. Our theoretical studies show that the surface tension in nanoparticles is indeed a physical mechanism responsible for the essential enhancement of the oxygen ionic conductivity observed in nanograin samples, where the main contribution to the conductivity goes from the region near the particle surface. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Geometry dependence of the conductance oscillations of monovalent atomic chains
Authors: Major Péter , Tichy Géza , Cserti József , García‐Suárez Víctor Manuel , Sirichantaropass Skon
Published: October 2006

Using a tight binding model we calculate the conductance of monovalent atomic chains for different contact geometries. The leads connected to the chains are modelled as semi‐infinite fcc lattices with different orientations and couplings. Our aim is twofold: To check the validity of a three‐parametric conductance formula for differently oriented leads, and to investigate the geometry dependence of the conductance oscillations. We show that the character of these oscillations depends strongly on the geometry of the chain–lead coupling. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Functionalization of multi‐walled carbon nanotubes: Direct proof of sidewall thiolation
Authors: Čech Jiří , Curran Seamus A. , Zhang Donghui , Dewald James L. , Avadhanula Aditya , Kandadai Madhu , Roth Siegmar
Published: October 2006

We analyzed structural changes and clearly revealed position and character of newly attached, sulfur containing, functional groups. Multi‐walled carbon nanotubes (MWCNTs) have been first exposed to harsh acid treatment to induce defects and oxygen containing hydroxyl and carboxyl groups. Such tubes were imaged by High Resolution Transmission Electron Microscopy (HRTEM) to visualize the structural changes that have occurred to due to extensive acid‐treatment. Consequently the MWCNT were thiolated using P4S10 and we used Electron Energy Loss Spectroscopy (EELS) to characterize the changes and to visualize sulfur containing sites on the nanotubes due to sidewall functionalization. The determined sulfur content is 0.6%. We also present vibrational modes around 500 cm–1. Such modes appears only on thiolated MWCNT and may be explained by creation of characteristic carbon–sulfur bonds. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparative structural–vibrational study of nano‐urchin and nanorods of vanadium oxide
Authors: Lavayen V. , O'Dwyer C. , Santa Ana M. A. , Newcomb S. B. , Benavente E. , González G. , Sotomayor Torres C. M.
Published: October 2006

We present a comparative structural–vibrational study of nanostructured systems of V2O5: nano‐urchin (VONURs) which are spherical structures composed of a radially oriented array of VOx nanotubes (VOx‐NTs) with a volumetric density of ∼40 sr–1, and vanadium oxide nanorods (VOx‐NRDs) with an average length of ∼100 nm. The Raman scattering spectrum of the nano‐urchin exhibits a band at 1014 cm–1 related to the distorted gamma conformation of the vanadium pentoxide (γ‐V5+). The infrared vibrational spectra of the nanorods sample also exhibit a distorted laminar V2O5 structure with evidence observed for quadravalent V4+ species at 921 cm–1. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Origin of superconductivity of CaC6 and of other intercalated graphites
Authors: Calandra Matteo , Mauri Francesco
Published: October 2006

By intercalation of donor the low conductivity of graphite can be enhanced and a superconducting state can occur at low temperature. The first discovered superconductors were alkali‐intercalated compounds, with a critical temperatures (T c) of the order of 1 K. In 2005 we learned with surprise that Ca intercalated graphite (CaC6) is a superconductor with the sizable T c of 11.5 K. Using density functional theory we demonstrate that superconductivity in CaC6 is phonon‐mediated with an electron–phonon coupling λ equal to 0.83 and a phonon‐frequency logarithmic‐average equal to 25 meV. Superconductivity is mostly due C vibrations perpendicular and Ca vibrations parallel to the graphite layers. A non zero electron–phonon coupling for these modes can not be associated to the Fermi surface of the graphite pi bands but requires the presence of a second Fermi surface associated to the intercalant atoms. This result suggests a general mechanism for the occurrence of superconductivity in intercalated graphite. In order to stabilize a superconducting state it is necessary to have an intercalant Fermi surface since the simple doping of the π bands in graphite does not lead to a sizeable electron–phonon coupling. This condition occurs if the intercalant band is partially occupied, i.e. when the intercalant is not fully ionized. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electron spin resonance of single‐walled carbon nanotubes and related structures
Authors: Náfrádi B. , Nemes N. M. , Fehér T. , Forró L. , Kim Y. , Fischer J. E. , Luzzi D. E. , Simon F. , Kuzmany H.
Published: October 2006

We report new results on the electron spin resonance of single walled carbon nanotubes, peapods and double walled carbon nanotubes. A small ESR line is present in well purified samples and its temperature dependence reveals a striking ‘super‐Curie’ paramagnetic rise. In addition, we identify a narrower line in peapod and DWNT samples, which displays similar behavior. The linewidth of both inner and outer species are metallic and the outer tube's resonance broadens upon growth of the inner tubes. We observe a sudden decrease of relaxation rate below 20 K, in accordance with the opening of a spin‐gap. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Aharonov–Bohm effects on conductivity in carbon nanotubes: A tool for determination of a gap due to strain and curvature
Authors: Nakanishi Takeshi , Ando Tsuneya
Published: October 2006

The Boltzmann conductivity is calculated for carbon nanotubes in the presence of an Aharonov–Bohm magnetic flux. Effects of strain or curvature manifest themselves as a prominent conductivity peak as a function of the flux. The appearance of the peak corresponds to the absence of backscattering in metallic linear bands and makes it possible to determine a gap due to curvature and strain. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Formation of symmetric and asymmetric metal–semiconductor hybrid nanoparticles
Authors: Mokari T. , Costi R. , Sztrum C. G. , Rabani E. , Banin U.
Published: October 2006

Multi‐component nano‐systems are created by combining two or more different materials yielding new chemical and physical properties. Here we report the selective anisotropic growth creating hybrid nanparticles of two different material systems, a metal onto a semiconductor. We developed a simple method for the selective growth of gold tips onto the apexes of colloidal semiconductor nanorods and tetrapods. This combination provides new functionalities to the nanostructures, the most important of which is the formation of natural anchor points that can serve as a recognition element for directed self assembly and for wiring them onto electrical circuitry. At higher gold concentrations we observe a transition from two to one‐sided gold growth. This behavior is attributed to a ripening process as was also studied using a theoretical model. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High fidelity measurement of singlet–triplet state in a quantum dot
Authors: Meunier T. , Tielrooij K.‐J. , Vink I. T. , Koppens F. H. L. , Tranitz H. P. , Wegscheider W. , Kouwenhoven L. P. , Vandersypen L. M. K.
Published: October 2006

We demonstrate experimentally a read‐out method that distinguishes between two‐electron spin states in a quantum dot. This scheme combines the advantages of the two existing mechanisms for spin‐to‐charge conversion with single‐shot charge detection: a large difference in energy between the two states and a large difference in tunnel rate between the states and a reservoir. As a result, a spin measurement fidelity of 97% was achieved, which is much higher than previously reported fidelities. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin properties of charged single Mn‐doped quantum dots
Authors: Léger Y. , Besombes L. , Maingault L. , Fernández‐Rossier J. , Ferrand D. , Mariette H.
Published: October 2006

The optical properties of individual quantum dots doped with a single Mn atom and charged with a single carrier (electron or hole) are analyzed. The emission of the neutral, positively charged and negatively charged excitons coupled with a single magnetic atom are observed in the same quantum dot. The spectrum of the charged excitons in interaction with the Mn atom shows a rich pattern attributed to a strong anisotropy of the hole–Mn exchange interaction slightly perturbed by a small valence band mixing. For the positively charged exciton, the emission pattern shows that the different spin states of the hole–Mn complex remain split in the final state after the exciton recombination. This opens the possibility of storing information on a single carrier spin on a long time scale in the absence of external magnetic field. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin blockade in lateral quantum dots – Negative differential conductance and spin spectroscopy
Authors: Rogge M. C. , Kupidura D. , Reinwald M. , Wegscheider W. , Haug R. J.
Published: October 2006

We report on spin blockade observed in several different lateral quantum dot systems. We observe the typical features of alternating position and amplitude of Coulomb peaks as a function of a magnetic field perpendicular to the sample surface. In a nonlinear regime strong negative differential conductance is observed with a striking regularity. This is not a universal behaviour. Instead we propose a complex interplay of spin blockade, electron interaction and relaxation. At strong tunnel coupling to the leads we use spin blockade as a spectroscopy tool to reveal the spin configuration in a Kondo regime with a pronounced chessboard pattern. By comparing measurements of different samples we find that Kondo effect and spin blockade can be combined in two different ways depending on the spin configuration of the dot. Thus the combination of both effects can be used to detect spin polarized filling of dot orbitals instead of regular filling. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hole and electron wave functions in self‐assembled InAs quantum dots: a comparison
Authors: Reuter D. , Kailuweit P. , Roescu R. , Wieck A. D. , Wibbelhoff O. S. , Lorke A. , Zeitler U. , Maan J. C.
Published: October 2006

We have investigated the conduction and the valence band states of self‐assembled InAs quantum dots embedded in n‐ and p‐type Schottky diodes, respectively, by magneto‐capacitance voltage spectroscopy. The dispersion behaviour of the individual charging peaks in a perpendicular magnetic field shows qualitative differences between the two carrier types. By applying an in‐plane magnetic field, the momentum space wave function corresponding to the individual charging peaks could be mapped. For electrons, the s‐like wave function for the ground state is slightly asymmetric with the low energy direction along [0$ \bar 1 $1] in real space. Also the s‐like wave function for the hole ground state is asymmetric but here the low energy direction is along [011], i.e. orthogonal to that for electrons. This hints to an asymmetry in the confinement potential that is caused by piezoelectric effects. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin relaxation of positive trions in InAs/GaAs quantum dots: the role of hyperfine interaction
Authors: Braun Pierre‐François , Eble Benoît , Lombez Laurent , Urbaszek Bernhard , Marie Xavier , Amand Thierry , Renucci Pierre , Krebs Olivier , Lemaître Aristide , Voisin Paul , Kalevich Vladimir K. , Kavokin Kyrill V.
Published: October 2006

We report on positive trion (X+) spin relaxation in self‐assembled InAs/GaAs quantum dots. The hyperfine interaction between the electron and nuclear spins acts as a randomly oriented magnetic field for the electron spin, giving rise to ensemble dephasing and thus to partial relaxation in less than 1 ns. Time‐resolved photoluminescence polarization measurements carried out on an ensemble of InAs/GaAs quantum dots, charged with excess holes by proximity p‐doping, reveal this peculiar dynamics. The fast polarization decrease can be efficiently suppressed by screening the hyperfine interaction with a longitudinal magnetic field of 100 mT. The quenching of this hyperfine‐induced relaxation is also evidenced for a single charge‐tunable quantum dot in the regime of X+ photoluminescence and excited with modulated polarization to prevent dynamic nuclear polarization. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Controlled Ge quantum dots positioning with nano‐patterned Si(001) substrates
Authors: Bavard A. , Eymery J. , Pascale A. , Fournel F.
Published: October 2006

A square nanometric patterned substrate (period 20 nm) is obtained by direct twist bonding of two twin Si(001) surfaces, thinning and preferential chemical etching. Molecular beam epitaxy of Ge is carried out on a sample having heterogeneous trench depths to analyse islands positioning as a function of the surface morphology. Scanning electron microscopy observations show that small single dots per mesa or large dots covering several mesas can be observed. It highlights the influence of the mesa aspect ratio on the control of Ge islands self‐organization, and suggests the occurrence of an effective activation barrier depending on the surface profile. The position‐dependent energy stored in a dot for a given surface profile is estimated from a very simple model based on the balance between capillarity and elastic relaxation terms. By choosing a cycloid‐like profile, experimental observations can be explained without fitting parameters. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Soil organic carbon budget and fertility variation of black soils in Northeast China
Authors: Yu Guirui , Fang Huajun , Gao Lupeng , Zhang Wenjuan
Published: October 2006

Black soils in Northeast China are characteristic of high soil organic carbon (SOC) density and were strongly influenced by human activities. Therefore, any change in SOC pool of these soils would not only impact the regional and global carbon cycle, but also affect the release and immobilization of nutrients. In this study, we reviewed the research progress on SOC storage, budget, variation, and fertility under different scenarios. The results showed that the organic carbon storage of black soils was 646.2 TgC and the most potential sequestration was 2887.8 g m−2. According to the SOC budget, the net carbon emission of black soils was 1.3 TgC year−1 under present soil management system. The simulation of CENTURY model showed that future climate change and elevated CO2 concentration, especially the increase of precipitation, would increase SOC content. Furthermore, fertilization and cropping sequence obviously influenced SOC content, composition, and allocation among different soil particles. Long‐term input of organic materials such as manure and straw renewed original SOC, improved soil structure and increased SOC accumulation. Besides, soil erosion preferred to transport soil particles with low density and fine size, decreased recalcitrant SOC fractions at erosion sites and increased activities of soil microorganism at deposition sites. After natural grasslands were converted into croplands, obvious variation of soil chemical nutrients, physical structure, and microbial activities had taken place in surface and subsurface soils, and represented a degrading trend to a certain degree. Our studies suggested that adopting optimal management such as conservation tillage in black soil region is an important approach to sequester atmospheric CO2 and to slow greenhouse effects.
International Biodiversity Observation Year in Western‐Pacific and Asian regions (DIWPA‐IBOY): a case report on species rarity and spatio‐temporal variability of species composition in Lepidoptera and Coleoptera communities from a temperate forest of northern Japan
Authors: Hirao Toshihide , Murakami Masashi , Kogi Hiroyuki , Kashizaki Akira , Hirai Yoshiyuki , Tanabe Shin‐ich , Inari Naoki , Yorozuya Hiroshi , Toda Masanori J.
Published: October 2006

An international project, DIWPA‐IBOY, took place for simultaneously observing biodiversity throughout the Western‐Pacific and Asian regions in 2001–2003, as one of the core projects for International Biodiversity Observation Year, a crosscutting network activity of DIVERSITAS (an international programme of biodiversity science). DIWPA‐IBOY provides extensive data on species diversity obtained by the standardized method. Under this project, 51,742 individuals of Lepidoptera and 11,633 of Coleoptera were collected by light traps from the Tomakomai Experimental Forest of Hokkaido University, one of the core DIWPA‐IBOY sites, in the cool‐temperate region of northern Japan. Based on these data, this study examined the relative abundance distribution (RAD) to evaluate the amount of rare species in the Lepidoptera and Coleoptera communities. The beta diversities between sampling seasons, forest strata, and trap sites were also assessed to evaluate the spatio‐temporal variability of species composition in these communities. In the analysis of the RAD, the best‐fit model was selected from the log‐Normal, Zipf–Mandelbrot, and Zipf models differing in the tail length of the RAD, i.e., the proportion of rare species. To explore the beta diversity between samples, the abundance‐based Jaccard index with an unseen species estimator was calculated, and then a hierarchical clustering analysis was conducted. As a result of RAD analysis, the Coleoptera community was regarded as containing a larger proportion of rare species than the Lepidoptera community. The seasonal compartmentalization of the community, deduced from the beta‐diversity analysis, was finer in Lepidoptera (seven assemblages recognized) than in Coleoptera (three assemblages). The spatial (vertical and horizontal) compartmentalization was negligible in both communities. The coincidence of the larger proportion of rare species and the lower beta diversity between seasons in the Coleoptera community was explained by the longer life spans of beetles compared to moths, based on the assumption that the length of life span acts as a temporal agent for mass effect on the analogy of the migration rate as a spatial agent for mass effect.
Assessment of higher insect taxa as bioindicators for different logging‐disturbance regimes in lowland tropical rain forest in Sabah, Malaysia
Authors: Akutsu Kosuke , Khen Chey Vun , Toda Masanori J.
Published: October 2006

One of the serious environmental problems since the 1980s has been the conflict between the high rate of deforestation and maintenance of healthy ecosystem services and biological values in tropical forests. There is an urgent demand for setting up an appropriate environmental assessment to keep healthy ecosystem functions and biodiversity along with sustainable forest use based on ecology. In this study, we tried to assess logging‐disturbance effects on the abundances of several flying insect groups (higher‐taxon approach) in lowland tropical rain forest (Deramakot Forest Reserve, Sabah, Malaysia), while considering seasonal changes and vertical forest stratification. The season was the most important factor affecting the abundances of all the insect groups. Effects of logging disturbance were prominent in the understorey but obscure in the canopy. Changes in physical conditions caused by logging—possibly an increased evaporation due to solar radiation—may have decreased the abundance of desiccation‐sensitive insects, especially in the understorey. There are also two probable reasons for the difference between events in the understorey and those in the canopy: (1) noise effects of various physical, environmental factors may have obscured insect responses to logging disturbance in the canopy; (2) higher spatio‐temporal variation in quality and quantity of living food resources—such as leaves, flowers and fruits—provided in the canopy may have affected the abundance of their consumer insects independently of logging disturbance. Thus, this study suggests that the abundance of some insect groups at higher‐taxon level, especially in the understorey, can be used as bioindicators for assessing effects of logging disturbance on the forest ecosystem.
Arctic charr (Salvelinus alpinus) is a suitable host for Gyrodactylus salaris (Monogenea, Gyrodactylidae) in Norway
Authors: ROBERTSEN G. , HANSEN H. , BACHMANN L. , BAKKE T. A.
Published: October 2006

Gyrodactylus specimens infecting both anadromous Arctic charr (Salvelinus alpinus) from River Signaldalselva (northern Norway) and resident Arctic charr from Lake Pålsbufjorden (southern Norway) were identified as G. salaris using molecular markers and morphometrics. The infection in Pålsbufjorden represents the first record of a viable G. salaris population infecting a host in the wild in the absence of salmon (Salmo salar). G. salaris on charr from Signaldalselva and Pålsbufjorden bear different mitochondrial haplotypes. While parasites infecting charr in Signaldalselva carry the same mitochondrial haplotype as parasites from sympatric Atlantic salmon, G. salaris from charr in Pålsbufjorden bear a haplotype that has previously been found in parasites infecting rainbow trout (Oncorhynchus mykiss) and Atlantic salmon, and an IGS repeat arrangement that is very similar to those observed earlier in parasites infecting rainbow trout. Accordingly, the infection may result from 2 subsequent host-switches (from salmon via rainbow trout to charr). Morphometric analyses revealed significant differences between G. salaris infecting charr in the 2 localities, and between those on sympatric charr and salmon within Signaldalselva. These differences may reflect adaptations to a new host species, different environmental conditions, and/or inherited differences between the G. salaris strains. The discovery of G. salaris on populations of both anadromous and resident charr may have severe implications for Atlantic salmon stock-management as charr may represent a reservoir for infection of salmon.