bluuebunny/crossref_metadata_2025 huggingface dataset:
Microprocesses of metal dusting on iron‐nickel alloys and their dependence on the alloy composition
Authors: Pippel E. , Woltersdorf J. , Grabke H. J.
Published: October 2003

Metal dusting of iron proceeds via the formation and disintegration of the metastable carbide Fe3C, and the resulting fine Fe particles in the coke further catalyse carbon deposition. By contrast, nickel disintegrates directly, and larger grains are released. As revealed by TEM and AEM techniques, in both cases the disintegration proceeds by inward growth of thin graphite filaments, the atomic basal planes of which being oriented perpendicular to the surface thus effecting a high reactivity at the growth front.

Consequently, successive alloying of iron with nickel should lead to a change over from one disintegration mechanism to the other, and, in fact, we could evidence that the carbide formation takes place only up to a nickel content of about 5 wt.%. Already at a Ni concentration of 10 wt.% a direct disintegration of the metal proceeds, as it is typical for pure nickel. Furthermore, in all investigated Ni‐Fe alloys a surface‐near enrichment of Ni was observed which indicates a selective corrosion of Fe, decreasing with increasing Ni content of the basic alloy.
Metal dusting behaviour of welded Ni‐base alloys with different surface finish
Authors: Grabke H. J. , Müller‐Lorenz E. M. , Zinke M.
Published: October 2003

Welded Ni‐base alloys and Alloy 800 were exposed under metal dusting conditions at 600°C and 650°C for up to 6000 hours. Alloy 800 was attacked very strongly already in the first days and Alloy 600 also rather soon and widespread, on both materials attack started mainly in the heat affected zone. Several surface states of Alloy 600: brushed, ground, sand‐blasted and pickled were tried only grinding caused a modest delay and decrease of metal dusting attack. Generally the attack was less widespread but deeper at 650°C than at 600°C, also for Alloy 601 and 602. The latter alloys show minor, mainly local attack, but especially the welds are affected. TIG welding led to better resistance than hand‐welding.
Effect of H2S on metal dusting of iron
Authors: Schneider A. , Grabke H. J.
Published: October 2003

A review is given on the effect of H2S on metal dusting of iron which has been studied by gas carburisation in CO‐H2‐H2O‐H2S and CH4‐H2‐H2S mixtures at 500 and 700°C.

The presence of H2S in carburising gas atmospheres leads to sulphur adsorption on the iron surface, which retards carbon transfer. Segregation experiments and surface analyses have shown that sulphur segregates (and thus adsorbs) on cementite surfaces as well as on iron surfaces. The adsorbed sulphur also suppresses graphite nucleation and thus can stop the reaction sequence of metal dusting.

Experiments by thermogravimetric analysis (TGA) have shown that the extent of retardation of metal dusting depends on temperature, carbon activity and H2S content. The higher the carbon activity, the higher is the H2S content required for suppression of metal dusting.

At carbon activities aC > aC(Fe/Fe3C) the metastable iron carbide, cementite (Fe3C), occurs as an intermediate phase during metal dusting. Carburisation experiments in CO‐H2‐H2O‐H2S mixtures at 500°C and X‐ray diffraction analysis (XRD) of carburised samples have revealed that at very high carbon activities a second iron carbide, Hägg carbide (Fe5C2), forms on the cementite surface. Microstructural investigations have shown that both metastable carbides decompose during metal dusting.

Metal dusting experiments on iron at 700°C have been performed in CH4‐H2‐H2S gas mixtures. By adding 15 ppm H2S to the CH4‐H2 atmosphere the onset of metal dusting can be retarded for more than 350 hours. By means of Auger electron spectroscopy (AES), scanning electron microscopy (SEM) and energy dispersive X‐ray analysis (EDX) it was shown that coke contains graphite, cementite and iron particles with adsorbed sulphur.
Mechanisms and driving forces of metal dusting
Authors: Szakálos P.
Published: October 2003

The mechanisms of metal dusting as it appears on different ferritic stainless steels and pure iron have been described in detail. A mechanism for metal dusting (MD) of chromia‐forming as well as alumina‐forming steels is proposed, based on results from laboratory exposures of 26Cr‐steel and FeCrAl‐alloy at 600–650°C for up to 5000 h in a synthesis gas low in water vapour, 25%CO + 3%H2O + H2. Metallographical examinations, FEG‐SEM, SEM‐EDX analysis and X‐ray diffraction, as well as thermodynamic calculations were made in order to identify and describe the different metal dusting processes. The work focuses on the role of carbides and oxides to explain the observations and give a description of the metal dusting phenomenon as it appears in engineering alloys. This mechanism was first observed and identified in a study of an austenitic stainless steel.

The driving force for steady state MD on pure iron and low alloyed steels is described and a secondary MD‐mechanism, carbon nanotube formation, is described in detail. With these additional results it is now possible to extend understanding of the MD‐processes to a wide range of engineering alloys.
Occurrence of metal dusting – referring to failure cases
Authors: Grabke H. J. , Spiegel M.
Published: October 2003

Twelve years of research on metal dusting at the Max‐Planck‐Institut for Iron Research have led to comprehensive knowledge on the mechanisms and kinetics of metal dusting and on ways and means for prevention of this corrosion phenomenon, – this knowledge is shortly summarized in this paper.

Inspite of this state of understanding, the present opinion in industry is that metal dusting is mysterious and not predictable and cannot be controlled. This paper is intended to show that the occurrence of metal dusting and its reasons can be well understood, by describing and explaining five failure cases.
Coke formation during metal dusting of iron in CO‐H2‐H2O gas with high CO content
Authors: Zhang J. , Schneider A. , Inden G.
Published: October 2003

Iron carburisation and coke formation during metal dusting of iron have been investigated in the gas mixture of 75%CO‐24.8%H2‐0.2%H2O at 600°C and 700°C. In all cases, cementite is formed at the surface, together with a coke layer on the top. In the coke layer, two morphologies of graphite are identified: compact bulk graphite with a uniform thickness and a columnar structure, and filamentous carbon with iron‐containing phases at the tip or along its length. The examination of coke formation in different stages of reaction at 700°C reveals that the coke contains two layers. The inner layer is composed of filaments, while the outer layer consists of the compact columnar graphite. After 2 h reaction the top compact graphite layer has suffered a serious deformation and has formed fractures because of the growth of catalytic filamentous carbon underneath. These filaments grow outside from these fractures and finally cover the whole surface after 4 h reaction. At 600°C, however, the coke contains a thick bulk graphite layer and non‐uniformly distributed filaments on the top. The bulk graphite layer is composed of many graphite columns which are loosely piled and are vertical to the surface. Each graphite column consists of many fine graphite fibres in parallel with the columnar axis. Filaments grow outside preferably from the gaps among these graphite columns and along the grinding scratches. TEM analysis of the coke detects very convoluted filaments with iron‐containing particles at the tip or along their length. XRD and TEM analyses show that these particles are Fe3C rather than metallic iron.
Synthesis and Characterization of α,ω‐Telechelic Polymers by Atom Transfer Radical Polymerization and Coupling Processes
Authors: Yurteri Seda , Cianga Ioan , Yagci Yusuf
Published: October 2003

Initiators for atom transfer radical polymerization (ATRP) bearing different functional groups (aldehyde, aromatic hydroxyl, dimethyl amino) were synthesized and characterized. Monotelechelics with low molecular weight were obtained by ATRP of styrene using these initiators in the presence of the CuBr/bpy catalytic complex. α,ω‐Telechelic polymers with double molecular weights with respect to the starting materials were prepared by coupling of monotelechelics under atom transfer radical generation conditions, in the absence of monomer, using CuBr as catalyst, tris[2‐(dimethylamino)ethyl]amine (Me6TREN) as a ligand, under Cu0 mediated reductive conditions and with toluene as solvent. Terminal Br atoms present in monotelechelic polystyrenes (PS) as a consequence of the ATRP mechanism also offer other routes for preparing telechelic polymers. Aldehyde functionalized polymer was etherified with hydroquinone furnishing telechelic PS with a molecular weight that was two times higher. All polymers were characterized by spectral methods (NMR, IR spectroscopy) as well as by GPC.

Synthesis of initiators for atom transfer radical polymerization bearing different functional groups, for example, aldehyde, aromatic hydroxyl, dimethyl amino.

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Synthesis of initiators for atom transfer radical polymerization bearing different functional groups, for example, aldehyde, aromatic hydroxyl, dimethyl amino.
Structure and Phase Transitions of Poly(heptamethylene p,p′‐bibenzoate): Time‐Resolved Synchrotron WAXS and DSC Studies
Authors: Pérez Ernesto , Todorova Ginka , Krasteva Mania , Pereña José M. , Bello Antonio , Marugán Mónica M. , Shlouf Miroslav
Published: October 2003

Time‐resolved wide‐angle X‐ray scattering (WAXS), as well as differential scanning calorimetry (DSC) and polarisation microscopy studies, were applied to investigate the structure and phase transitions of poly(heptamethylene p,p′‐bibenzoate). Temperature dependencies of several structural parameters were determined. Complete transformation from an isotropic melt to a smectic phase was suggested whereas the transition from a smectic to crystalline phase is only partial (around 30%), although it takes place from the ordered SCA phase. Crystals are formed within the SCA domains with nearly the same coherent length. On the basis of the analysis of the position and the profile of the diffuse wide‐angle X‐ray scattering and mesogenic layer spacing, it was assumed that either crystallisation modifies the smectic structure, or mesophase losses its positional order because of the lack of mobility of the spacers at low temperatures.

WAXS scattering profiles corresponding to P7MB: a) cooling from the isotropic melt at 2 °C · min−1; b) subsequent melting at 12 °C · min−1.

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WAXS scattering profiles corresponding to P7MB: a) cooling from the isotropic melt at 2 °C · min−1; b) subsequent melting at 12 °C · min−1.
13C NMR Study of Copolymers of Propene with Higher 1‐Olefins with New Microstructures by ansa‐Zirconocene Catalysts
Authors: Wahner Udo M. , Tincul Ioan , Joubert Dawid J. , Sadiku Emmanuel R. , Forlini Fabrizio , Losio Simona , Tritto Incoronata , Sacchi Maria Carmela
Published: October 2003

Copolymers of propene and higher 1‐olefins (1‐butene, 1‐pentene, 1‐hexene, 1‐heptene, 1‐octene, and 4‐methyl‐1‐pentene (4M1P)), prepared with rac‐Et(Ind)2ZrCl2 (EI) and rac‐Me2Si(2‐MeBenz‐[e]Ind)2ZrCl2 (MBI), were comprehensively analyzed by 13C NMR spectroscopy. These catalysts known to produce isotactic polypropene lead to two vastly different families of copolymers under the chosen experimental conditions. All copolymers produced with EI possessed comparable isotacticities as well as similar stereosequences. Furthermore, these copolymers did not significantly differ from those of the reference propene homopolymer. However, the copolymers produced with MBI significantly differed both from the reference propene homopolymer and among themselves. In fact, in contrast to the corresponding highly isotactic homopolymer, the whole series of copolymers was characterized by rather low isotacticities. The degree of tacticity was strongly influenced by the comonomer type. A detailed 13C NMR analysis revealed that these copolymers are constituted by highly isotactic sequences and by atactic sequences of various lengths. It is proposed that the formation of atactic sequences is triggered by the insertion of a comonomer. It seems likely that MBI can shift from a stereoselective to a non‐stereoselective state due to an interaction with higher linear or branched comonomer.

13C NMR spectra of propene/1‐pentene (a) and propene/4‐methyl‐1‐pentene (b) prepared with MBI.

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13C NMR spectra of propene/1‐pentene (a) and propene/4‐methyl‐1‐pentene (b) prepared with MBI.
Thermosensitive Hollow Capsules Based on Thermoresponsive Polyelectrolytes
Authors: Glinel Karine , Sukhorukov Gleb B. , Möhwald Helmuth , Khrenov Victor , Tauer Klaus
Published: October 2003

Thermosensitive hollow capsules were successfully fabricated by the layer‐by‐layer deposition onto colloid particles of oppositely charged diblock copolymers each containing a poly(N‐isoproprylacrylamide) (PNIPAM) block and by the subsequent decomposition of the core. The multilayer growth was characterized by electrophoresis and single particle light scattering. By combining confocal microscopy observation and FRAP measurements, we showed that the morphology and the permeability of the capsules change upon heating in aqueous solution. The decrease of size accompanied by a decrease of the permeability with increasing temperature was attributed to structural rearrangements in the shell. However, this process is only partially reversible upon cooling, limiting the thermoresponsive behavior of the capsules.

CLSM images of hollow capsules in presence of 6‐carboxyfluorescein (left) and fluorescein‐labeled dextran (right).

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CLSM images of hollow capsules in presence of 6‐carboxyfluorescein (left) and fluorescein‐labeled dextran (right).
Formation of Macrocycles in the Synthesis of Poly(N‐(2‐ethylhexyl)carbazol‐3,6‐diyl)
Authors: Ostrauskaite Jolita , Strohriegl Peter
Published: October 2003

A series of polymerizations of 3,6‐dibromo‐9‐(2‐ethylhexyl)carbazole was carried out in different monomer concentrations using standard Yamamoto reaction conditions. It was found that the molecular weight of the resulting poly(N‐(2‐ethylhexyl)carbazol‐3,6‐diyl) strongly depends on the monomer concentration in the reaction mixture. Matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) measurements confirmed the formation of low‐molar‐mass cyclic oligomers of the 3,6‐disubstituted carbazole. In this paper we describe, for the first time, the formation of large amounts of a cyclic tetramer and of higher macrocycles in the synthesis of poly(N‐alkyl‐3,6‐carbazoles) by the Yamamoto method. This seems to be a limiting factor in the synthesis of high molecular weight poly(N‐alkyl‐3,6‐carbazole)s. The optical, thermal, and electrochemical properties of poly(N‐(2‐ethylhexyl)carbazol‐3,6‐diyl) have been investigated. Poly(N‐(2‐ethylhexyl)carbazol‐3,6‐diyl) is thermally stable, with 5% weight loss at 460 °C in nitrogen. The polymer exhibits a weak blue fluorescence with a maximum at 425 nm. Poly(N‐(2‐ethylhexyl)carbazol‐3,6‐diyl) is electrochemically stable, its highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels are −5.0 and −1.6 eV, respectively.

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Use of Hydroxyl Functionalized (Meth)acrylic Cross‐Linked Polymer Microparticles as Chain Transfer Agent in Cationic Photopolymerization of Cycloaliphatic Epoxy Monomer, 2
Authors: Valette Ludovic , Pascault Jean‐Pierre , Magny Benoît
Published: October 2003

This study is related to the use of hydroxyl functional acrylic cross‐linked polymer microparticles (CPM, also named microgels) as a chain transfer agent in cationic photopolymerization of cycloaliphatic epoxy monomer. All CPM were based on butyl acrylate and were consequently rubbery at ambient temperature. The effect of the stabilizing acrylate monomer used during the CPM synthesis was evaluated with respect to the viscoelastic properties of the photopolymerized cationic‐type epoxy films. The viscoelastic properties were correlated to the photopolymerized film morphology observed by transmission electron microscopy. Two acrylate monomers used as stabilizing agents during CPM synthesis were compared: cardura acrylate (CA) and lauryl acrylate (LA). CA was a good stabilizer for CPM in epoxy monomer before photocure and the CPM were well dispersed into the network after reaction. In contrast, LA was a poor stabilizer resulting in large CPM aggregation. The blend of these two types of CPM led to intermediate morphology, probably because of the flocculation of the CPM stabilized with LA. Conversely, CPM synthesized with a blend of the two stabilizing acrylate monomers induced in epoxy matrix a specific bi‐continuous morphology and consequently unique viscoelastic properties.

TEM micrographs of a photopolymerized film with 15 wt.‐% CPM(BA + 20%HEA)‐20%CA + 15% CPM(BA + 18%HEA)‐27%LA used as chain transfer agents.

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TEM micrographs of a photopolymerized film with 15 wt.‐% CPM(BA + 20%HEA)‐20%CA + 15% CPM(BA + 18%HEA)‐27%LA used as chain transfer agents.
Laccases to Improve the Whiteness in a Conventional Bleaching of Cotton
Authors: Tzanov Tzanko , Basto Carlos , Gübitz Georg M. , Cavaco‐Paulo Artur
Published: October 2003

This study reports for the first time on the enhancement of the bleaching effect achieved on cotton using laccase enzyme. Laccases applied in short‐time batchwise or pad‐dry processes prior to conventional peroxide bleaching, improved the end fabric whiteness. The whiteness level reached in the combined enzymatic/peroxide process was comparable to the whiteness in two consecutive peroxide bleaches.

Effect of 10 min laccase pre‐treatment at 60 °C, pH 5 on fabrics whiteness before and after a conventional hydrogen peroxide bleaching.

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Effect of 10 min laccase pre‐treatment at 60 °C, pH 5 on fabrics whiteness before and after a conventional hydrogen peroxide bleaching.
Dry phosphorus silicate glass etching for multicrystalline silicon solar cells
Authors: Nositschka W. A. , Voigt O. , Kenanoglu A. , Borchert D. , Kurz H.
Published: October 2003

A dry plasma etching process for phosphorus silicate glass (PSG) in a SiN‐PECVD batch reactor is developed. In the same reactor PSG etching and anti‐reflective coating (ARC) can be performed successively. To demonstrate industrial feasibility, screen‐printed solar cells are manufactured and compared with cells prepared by a standard wet chemical process. Copyright © 2003 John Wiley & Sons, Ltd.
High‐efficiency copper indium gallium diselenide (CIGS) solar cells with indium sulfide buffer layers deposited by atomic layer chemical vapor deposition (ALCVD)
Authors: Naghavi N. , Spiering S. , Powalla M. , Cavana B. , Lincot D.
Published: October 2003

This paper presents optimization studies on the formation of indium sulfide buffer layers for high‐efficiency copper indium gallium diselenide (CIGS) thin‐film solar cells with atomic layer chemical vapour deposition (ALCVD) from separate pulses of indium acetylacetonate and hydrogen sulfide. A parametric study of the effect of deposition temperature between 160° and 260°C and thickness (15–30 nm) shows an optimal value at about 220°C for a layer thickness of 30 nm, leading to an efficiency of 16·4%. Analysis of the device shows that indium sulfide layers are characterised by an improvement of the blue response of the cells compared with a standard CdS‐processed cell, due to a high apparent band gap (2·7–2·8 eV), higher open‐circuit voltages (up to 665 mV) and fill factor (78%). This denotes high interface quality. Atomic diffusion processes of sodium and copper in the buffer layer are demonstrated. Copyright © 2003 John Wiley & Sons, Ltd.
Supramolecular polymers formed by cinnamoyl cyclodextrins
Authors: Harada Akira , Miyauchi Masahiko , Hoshino Taiki
Published: October 2003

6‐Cinnamoyl α‐cyclodextrin (6‐CiO‐α‐CD) and 6‐cinnamoyl β‐cyclodextrin (6‐CiO‐β‐CD) were prepared. 6‐CiO‐α‐CD formed intermolecular complexes to give supramolecular oligomers. 6‐CiO‐β‐CD formed insoluble supramolecular complexes in the solid state. The structures of these complexes are discussed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3519–3523, 2003
Nanostructured ion‐conductive films: Layered assembly of a side‐chain liquid‐crystalline polymer with an imidazolium ionic moiety
Authors: Hoshino Koji , Yoshio Masafumi , Mukai Tomohiro , Kishimoto Kenji , Ohno Hiroyuki , Kato Takashi
Published: October 2003

An ion‐conductive mesogenic monomer with an imidazolium ionic moiety has been designed to obtain self‐assembled materials forming ionic layers. Self‐standing polymer films are prepared by in situ photopolymerization of the monomer that forms homeotropic monodomain on a normal glass substrate in the smectic A phase. Macroscopically oriented, layered nanostructures are formed in the film. The ionic conductivity parallel to the smectic layer has been measured for the oriented film. In the smectic A phase at 150 °C, the magnitude of conductivity is about 10−2 S cm−1. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3486–3492, 2003
Electric properties of self‐assembled monolayers of helical peptides by scanning tunneling spectroscopy
Authors: Kitagawa Kazuya , Morita Tomoyuki , Kawasaki Megumi , Kimura Shunsaku
Published: October 2003

Helical peptides having a disulfide group at one terminal, Lipo‐(Leu‐Aib)12‐OBzl (Lipo and OBzl represent lipoic acid and benzyl ester, respectively, SSL24B), and Boc‐NHCH2CH2NHCO‐Fc‐CO‐Ala‐(Leu‐Aib)8‐lipoamide (Boc, Fc, and lipoamide represent t‐butyloxycarbonyl, ferrocene, and lipoamine, respectively, FcL16SS), were synthesized, and self‐assembled monolayers (SAMs) of the helical peptides were prepared on gold. When the SSL24B SAM was observed at high‐bias voltage by scanning tunneling microscopy (STM) under ultrahigh vacuum, bright spots with higher conductivity appeared in the STM image. The image was restored again to a homogeneous surface with lower bias voltage, suggesting that Au–S linkage should be reversibly changed to a conductive state. The current/voltage (I‐V) curve by scanning tunneling spectroscopy (STS) at the bright domains demonstrated a rectification behavior where current increases drastically at a positive bias voltage above 3.0 V. However, the I‐V curve of the FcL16SS SAM showed a current increase at negative bias voltage below −1.5 V. The redox group is, thus, a determining factor for the direction of this flow. However, STS at low‐bias voltage and with the tip being inserted in the peptide SAM revealed a zero‐conductance region in the I‐V curve. The peptide layer may act as a molecular capacitor because of a large dielectric constant of the helical peptide. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3493–3500, 2003
Synthesis and self‐organization of rod–dendron and dendron–rod–dendron molecules
Authors: Lecommandoux Sébastien , Klok Harm‐Anton , Sayar Mehmet , Stupp Samuel I.
Published: October 2003

We synthesized molecules containing one or two dendritic segments and a rigid‐rod‐like segment with their structures in the solid state. The molecules with rod–dendron or dendron–rod–dendron architecture had biphenyl ester rigid segments and 3,4,5 tris(n‐dodecyloxy)benzoate of first or second generation as their dendritic segments. The variables investigated included the rod segment length as well as dendron generation, and all materials obtained were characterized by optical microscopy, differential scanning calorimetry, and X‐ray scattering. Depending on the size of the rod segment and generation number of the dendritic segment, molecules organized into smectic, columnar, or cubic phases, and the symmetries observed were dominated by the anisotropic rod–rod interactions. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3501–3518, 2003
Aminosalicylate‐based biodegradable polymers: Syntheses and in vitro characterization of poly(anhydride‐ester)s and poly(anhydride‐amide)s
Authors: Anastasiou Theodore J. , Uhrich Kathryn E.
Published: October 2003

Poly(anhydride‐ester)s and poly(anhydride‐amide)s derived from both 4‐ and 5‐aminosalicylate acids (4‐ and 5‐ASA) were synthesized and characterized by physicochemical methods. Thermal and solubility characteristics directly correlated to the polymer backbone composition; polymers based on 5‐ASA had greater solubilities in organic solvents than polymers based on 4‐ASA, and the poly(anhydride‐ester)s thermally decomposed at temperatures nearly 100 °C higher than the corresponding poly(anhydride‐amide)s. The polymers were self‐contained, controlled‐release systems that combine the drug and controlled‐release mechanism into the polymer backbone. The erosion and degradation characteristics of the polymers were measured in physiologically relevant media. All polymer matrices fully degraded in media buffered to pH 7.4, whereas in acidic media (pH 1.2), all polymer matrices maintained greater than 50% mass over a 90‐day time period. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3667–3679, 2003
Sam Greenhouse's years at the Census Bureau and the UNRRA
Authors: Keller Jay , Clark Cynthia Z. F.
Published: October 2003

Sam Greenhouse joined the Census Bureau as a clerk at an interesting time period for the agency. The first use of sampling in the decennial census occurred in 1940. There was a major expansion of the amount of data collected. The organization of the Census Bureau underwent radical changes, including the growth of the Population Division of which Greenhouse was a part, and the Office of Statistical Assistant was established. After the 1940 census Greenhouse was also part of a new intercensal program which became the forerunner of today's Current Population Survey, and was on hand for the transition of the physical location of the agency from Washington D.C. to Suitland, Maryland. After America's entry into World War II, Sam Greenhouse left the Census Bureau and worked with the United Nations Relief and Rehabilitation Administration (UNRRA), designed to manage the support and eventual repatriation of refugees who would come under Allied control at the war's end. Published in 2003 by John Wiley & Sons, Ltd.
Sam Greenhouse: his contributions as a consultant to the Food and Drug Administration
Authors: O'Neill Robert T.
Published: October 2003

This paper recounts contributions made by Sam Greenhouse to the Food and Drug Administration during his tenure as an advisory committee member and as chair of the committee. The events and topics are taken from available recollections and minutes and selectively describe a range of topic areas and issues about which Sam Greenhouse played a substantial leadership role. Published in 2003 by John Wiley & Sons, Ltd.
Group sequential large sample T2‐like χ2 tests for multivariate observations
Authors: Lachin John M. , Greenhouse Samuel W. , Bautista Oliver M.
Published: October 2003

In many studies, a K degree of freedom large sample χ2 test is used to assess the effect of treatment on a multivariate response, such as an omnibus T2‐like test of a difference between two treatment groups in any of K repeated measures. Alternately, a K df χ2 test may be used to test the equality of K+1 groups in a single outcome measure. Jennison and Turnbull (Biometrika 1991; 78: 133–141) describe group sequential χ2 and F‐tests for normal errors linear models, and Proschan, Follmann and Geller (Statist. Med. 1994; 13: 1441–1452) describe group sequential tests for K+1 group comparisons. These methods apply to sequences of statistics that can be characterized as having an independent increments variance–covariance structure, thus simplifying the computation of the sequential variance–covariance matrix and the resulting sequential test boundaries. However, many commonly used statistics do not share this structure, including a Liang–Zeger (Biometrika 1986; 73: 13–22) GEE longitudinal analysis with an independence working correlation structure and a Wei‐Lachin (J. Amer. Statist. Assoc. 1984; 79: 653–661) multivariate Wilcoxon rank test, among others. For such analyses, this paper describes the computation of group sequential boundaries for the interim analysis of emerging results using K df tests that are expressed as quadratic forms in a statistics vector that is distributed as multivariate normal, at least asymptotically. We derive the elements of the covariance matrix of multiple successive K df χ2 statistics based on established theorems on the distribution of quadratic forms. This covariance matrix is estimated by augmenting the data from the successive interim analyses into a single analysis from which the component sequential tests and their variance–covariance matrix can then be extracted. Boundary values for the sequential statistics can then be computed using the method of Slud and Wei (J. Amer. Statist. Assoc. 1982; 77: 862–868) or using the α‐spending function of Lan and DeMets (Biometrika 1983; 70: 659–663) with a surrogate measure of information. An example is presented using the analysis of repeated cholesterol measurements in a clinical trial. Copyright © 2003 John Wiley & Sons, Ltd.
Bacidia adastra, a new sorediate lichen species from Western Europe
Authors: Sparrius Laurens B. , Aptroot André
Published: October 2003

Bacidia adastra Sparrius & Aptroot is newly described from the Netherlands, Belgium, England and Germany. It is related to Bacidia arnoldiana s. lat. and differs from Bacidia caligans, B. neosquamulosa and B. viridescens by thallus structure and pigmentation of the excipulum and epithecium. It usually grows on acid or neutral, eutrophicated bark. It is characterized by the remarkable, pale green, thick, leprose thallus, the pale apothecia with aeruginose or dark brown flecks in the epihymenium and excipulum, and the hyaline hymenium and hypothecium.
New species and new records of Xanthoparmelia (lichenized Ascomycota, Parmeliaceae) from Western Australia
Authors: Elix John A.
Published: October 2003

The following new species of Xanthoparmelia (Parmeliaceae) are described from Western Australia: X. cranfieldii Elix, X. elevata Elix, X. kimberleyensis Elix, X. monadnockensisX. nanoides Elix, X. nortegeta Elix, X. sleei Elix and X. toolbrunupensis Elix. In addition, X. luminosa (Elix) Hale and X. Victoriana Elix & J. Johnst. are reported from Western Australia for the first time.
Distribution patterns in the genus Peltigera Willd
Authors: Martínez Isabel , Burgaz Ana Rosa , Vitikainen Orvo , Escudero Adrián
Published: October 2003

The distribution of sixty-six Peltigera species in 230 biogeographic provinces or 40 regions are presented. A hierarchical clustering approach, used to identify clusters of species with similar distribution patterns (floristic elements), resolved four groups made up of Neotropical, Southern Hemisphere, Antarctic and mainly Holarctic species. The Holarctic Kingdom is species rich with the highest number of Peltigera species and also the highest number of endemic species; the Australian and Cape Kingdoms have the lowest number of species and endemics. The species rich provinces are briefly discussed.
A new Lichenostigma on vagrant Aspicilia species
Authors: Calatayud Vicent , Barreno Eva
Published: October 2003

Lichenostigma radicans Calat. & Barreno, a lichenicolous fungus growing on vagrant Aspicilia species, is described as new to science from Spain. It is superficially similar to L. maureri, with cushion-like ascomata, but differing mainly by its ascomata connected at their base to immersed, brown, vegetative hyphae. Comments on the variability of iodine reactions of asci and ascospore walls, and on an associated conidial fungus with small bacilliform conidia, are given for L. maureri.
Evaluation of the Shepherd and Cushing (1980) model of density-dependent survival: a case study using striped bass (Morone saxatilis) larvae in the Potomac River, Maryland, USA
Authors: Rutherford Edward S , Rose Kenneth A , Cowan James H
Published: October 2003

Quantifying the degree of density-dependence in stock–recruit relationships is critical to understanding fish population dynamics. The Shepherd and Cushing (1980) model couples a simple model of density-dependent larval growth with a constant rate of mortality to predict numbers surviving to recruitment. The model has not been evaluated using field data, nor have its predictions been compared with those from other models. Here, the S&C model, an individual-based model (IBM), and a regression model are applied to 8 years of field data for striped bass larvae in the Potomac River, Maryland, USA, to predict larval carrying capacity (K) and percentage of recruitment lost as a consequence of density-dependent growth. The IBM and the regression model were corroborated by comparing their predictions of average growth rates of larvae and relative recruitment strengths to observed values for the 8 years of field data. Although the IBM and the regression model differed in their predictions of several important intermediate variables, both models predicted higher values of K and lower values of density-dependent growth than did the S&C model. Over the 8 years, the IBM and the regression model predicted an average of 0.3 and 1.8% recruitment lost as a result of density-dependent growth, respectively. In contrast, the S&C model predicted much higher recruitment lost (average of 27%). Slight differences in the assumed rate of mortality used in the S&C model resulted in values of carrying capacity similar to those predicted by the IBM and the regression model. Difficulties in estimating parameters of the S&C model from field data are discussed.
Neogene changes in Southern Ocean sedimentation based on mass accumulation rates at four continental margins
Authors: Handwerger David A. , Jarrard Richard D.
Published: October 2003

High‐resolution mass accumulation rates (MAR) were determined from lithologic logs based on downhole log and continuous core data for six sites at four continental margins around the Southern Ocean. Total MAR was calculated at Ocean Drilling Program (ODP) Site 1095 on the margin of the Antarctic Peninsula and ODP Site 1165 on the margin of Prydz Bay, Antarctica. Carbonate and noncarbonate (terrigenous) MAR were calculated for ODP Sites 1123 and 1124 east of New Zealand and Sites 1168 and 1172 west and southeast of Tasmania. Shifts in carbonate MAR are seen around Tasmania and New Zealand at 23 and 14 Ma, suggesting changes in deep water circulation and surface carbonate productivity at these times. Carbonate MAR dropped at Sites 1124 and 1168 at 23 Ma and increased at 14 Ma at Sites 1123, 1168, and 1172. The overall character of total MAR at Antarctic Sites 1095 and 1165 is a continual and relatively constant decrease in total MAR during the Neogene, with periods of stepwise decrease. One such decrease is seen at 14 Ma at Site 1165, coincident with increased carbonate MAR in New Zealand and Tasmania (Sites 1123, 1124, 1168 and 1172) and likely related to mid‐Miocene expansion of the East Antarctic Ice Sheet. Another step drop in total MAR is seen at ∼9 Ma at Site 1165, possibly reflecting diversion of sediment to a newly formed Prydz Channel fan.
Theoretical description of a bistatic system for ocean altimetry using the GPS signal
Authors: Hajj George A. , Zuffada Cinzia
Published: October 2003

This paper presents the fundamental characteristics of bistatic altimetry performed using the Global Positioning System (GPS) signal scattered off the ocean surface and collected by a receiver in space. The advantage of the dense and rapid surface coverage afforded by the existing GPS constellation would enable new oceanographic applications such as eddy monitoring and the tracking of fast barotropic waves. To exploit the wealth of potentially available measurements, the paper provides a first cut at a system required to perform such measurements from space. In particular, the choice of pointing direction for the receiving antenna is discussed together with the implications in terms of instrument footprint and coherence time. The theoretical reflected signal is then derived by extension of the cross‐correlation process used for direct GPS signals, and the characteristics of the leading edge are emphasized, to identify analogies and differences with the traditional altimetry waveform. In particular, the derivative of the leading edge is examined to assess the sensitivity to mean sea height, wind speed, and significant wave height. An overall range accuracy rms value is predicted for several antenna gains, pointing directions, and different geometric scenarios. When averaging many measurements, the range error is progressively reduced yielding predicted accuracies in sea height with associated spatial and temporal resolutions. The effect of wind speed and significant wave height on the received signal is discussed by performing simulations with a realistic range of these variables. The range accuracy versus receiving antenna gain and scattering direction is discussed, and a specific guideline on the gain necessary for altimetry from space is provided.
Tracing hydrologic flow paths in a small forested watershed using variations in 87Sr/86Sr, [Ca]/[Sr], [Ba]/[Sr] and δ18O
Authors: Hogan James F. , Blum Joel D.
Published: October 2003

Natural variations in 87Sr/86Sr, [Ca]/[Sr], [Ba]/[Sr], and δ18O were used to investigate changing hydrologic flow paths during storm events in an 11.8 ha first‐order watershed of the Hubbard Brook Experimental Forest. Throughfall, soil water, and stream water were sampled during several storm events and a single snowmelt event. Throughfall had 87Sr/86Sr, [Ca]/[Sr], and δ18O values that were distinct from other water types. Soil water was highly variable in composition but could be separated into three distinct elevation zones in the watershed with 87Sr/86Sr and [Ba]/[Sr] both increasing with elevation in the watershed. Changes in 87Sr/86Sr, [Ba]/[Sr], and δ18O of stream water during storm events yielded complementary information about watershed hydrologic flow paths. Traditional hydrograph separation using δ18O values indicated that new water was only a small component of storm flow (9–18%), whereas 87Sr/86Sr and [Ba]/[Sr] ratios indicated that shallow subsurface flow (soil water) contributed significantly to storm flow in amounts up to 40%, depending on soil moisture conditions.
Space Weather Pioneer J. Virginia Lincoln Dies
Authors: Lifland Jonathan
Published: October 2003

J. Virginia Lincoln, a physicist who helped initiate the study of space weather and was responsible for some of the theories still in use today, died of natural causes on 1 August in Boulder, Colorado.
European Space Weather CD‐ROM Now Available
Authors: Lifland Jonathan
Published: October 2003

A new educational CD‐ROM dedicated solely to space weather has been produced by the University of Greifswald, Germany.
Is there a trade‐off between the plant's growth response to elevated CO2 and subsequent litter decomposability?
Authors: Hoorens Bart , Aerts Rien , Stroetenga Martin
Published: October 2003

Under elevated levels of atmospheric CO2, leaf N concentration usually decreases due to dilution of N by excess carbon. Thus, the larger the growth response to elevated CO2, the larger the decrease in leaf N concentration should be. This should, in turn, lead to a proportional decline in litter N concentration and litter decomposition rate. Thus, we hypothesize a trade‐off between a plant's growth response to elevated CO2 and subsequent litter decomposability. We tested this hypothesis by measuring the growth response, green leaf and leaf litter chemistry and litter respiration of six plant species grown under ambient and elevated atmospheric CO2 concentrations in the greenhouse.

Growth response increased in the order Calluna vulgaris<Sphagnum cf. recurvum<Carex rostrata<Calamagrostis epigejos<Molinia caerulea<Vicia lathyroides. We did not consistently find the hypothesized patterns (between growth response and green leaf N concentration, green leaf and litter N concentration and between litter N concentration and litter respiration) in our six‐species dataset. To be able to draw more robust conclusions, we supplemented our six‐species dataset with data from the literature. Regression analyses on this larger dataset did reveal the hypothesized positive correlations between green leaf and litter N concentration and between litter N concentration and litter decomposition response ratios. However, there was no significant negative correlation between growth response and green leaf N concentration response ratios. As a result, also in the large dataset there was no trade‐off between growth response to elevated CO2 and litter decomposability. This implies that the productivity response of plant species to elevated CO2 is, in general, uncoupled from the decomposition response.
Dispersal of the lycaenidPlebejus argusin response to patches of its mutualist antLasius niger
Authors: Seymour Adrian S. , Gutiérrez David , Jordano Diego
Published: October 2003

We examined the movement rates of individuals of an obligate myrmecophilous butterfly,Plebejus argus(Lycaenidae: Lepidoptera), in relation to a patch of its mutualist ant,Lasius niger. Marked male and femaleP. argusfrom local (resident), fragmented and continuous populations were released into and away from (>100m) a patch ofL. niger, and subsequently searched for in a 500×500 m area. Recaptures of males and females from all populations were strongly associated with the target patch of mutualist ants. First day recapture displacements were significantly higher for releases away from the target patch for males, but not for females. Mutualist ant presence was shown to be more important than nectar source density in determining persistence ofP. argusin release squares. There was no significant difference in displacement distances or recapture frequencies (standardised for search effort) in the target patch of individuals from local (resident of target patch), fragmented and continuous populations. The recapture frequency in the target patch of males from the local population released outside the target patch was greater than expected from a null model of random straight line movement, suggesting non‐random (systematic or orientated) search behaviour. The number of males remaining in the target patch following release into the target patch was greater than expected from a simple diffusion model, suggesting a behavioural response to patch boundaries or other cues related to the patch.
Dynamics of aquatic insect flux affects distribution of riparian web‐building spiders
Authors: Kato Chika , Iwata Tomoya , Nakano Shigeru , Kishi Daisuke
Published: October 2003

The flux of emerging aquatic insects from streams can provide a significant energy subsidy to riparian web‐building spiders. However, despite the high temporality of aquatic insect emergence, the effects of such aquatic insect dynamics on spider distribution are poorly understood. To examine the relationship, the aquatic insect flux from a headwater stream in a northern Japanese deciduous forest was experimentally manipulated by using a greenhouse‐type covering, during May to July. Under natural conditions, the aquatic and terrestrial insect abundances dramatically decreased and increased from May through July, respectively. The experimental reduction of aquatic insect flux depressed the density of horizontal orb weavers (Tetragnathidae) in both May and June, but not in July when aquatic insects were scarce, indicating a temporal limitation on spider distribution by aquatic insect flux. In contrast, the densities of both vertical orb weavers (Araneidae) and sheet weavers (Linyphiidae) were unaffected by the manipulation throughout the study period. These various responses, differing among months or spider guilds, may be attributed to the degree of specialization for aquatic prey in the spiders and their mobility in response to aquatic insect flux. The experimental results provided direct evidence that the temporal dynamics of aquatic insect flux, as well as spider characteristics, were primary factors determining the distributional patterns of riparian web‐building spiders.
Changing importance of habitat structure across multiple spatial scales for three species of insects
Authors: Krawchuk Meg A. , Taylor Philip D.
Published: October 2003

Considerable scientific effort has gone into examining how the spatial structure of habitat influences organism distribution and abundance in both theoretical and applied contexts. An emerging conclusion from these works is that the overall amount of habitat in the landscape matters most for species persistence and that more local attributes of habitat structure such as the size and arrangement of patches is of secondary importance. In this study, we quantify how and when the effects of habitat configuration (patch size and isolation) influence the density of three species of insects (Order: Diptera;Wyeomyia smithii,Metriocnemus knabi,Fletcherimyia fletcheri) whose larvae are found exclusively in identical habitats (the water‐filled leaves of pitcher plants –Sarracenia purpurea) in a system that is naturally patchy at multiple spatial scales. We illustrate that relationships with configuration exist regardless of the overall amount of habitat in the broader landscape, and that there are distinct changes in the relationship between insect density and habitat configuration across multiple spatial scales. In general, patch size is more important within the movement range of the individual and isolation is important at larger, aggregation scales. Thus we demonstrate that a) both the amount and configuration of habitat are important attributes of species distribution; b) responses to measures of configuration can be scaled to processes such as movement and c) that hierarchical frameworks extending across very broad scales are essential for understanding how species respond to habitat structure and their role in ecosystem function.
Plant species diversity, plant biomass and responses of the soil community on abandoned land across Europe: idiosyncracy or above‐belowground time lags
Authors: Hedlund K. , Santa Regina I. , Van der Putten W. H. , Lepš J. , Díaz T. , Korthals G. W. , Lavorel S. , Brown V. K. , Gormsen D. , Mortimer S. R. , Rodríguez Barrueco C. , Roy J. , Smilauer P. , Smilauerová M. , Van Dijk C.
Published: October 2003

We examined the relationship between plant species diversity, productivity and the development of the soil community during early secondary succession on former arable land across Europe. We tested the hypothesis that increasing the initial plant species diversity enhances the biomass production and consequently stimulates soil microbial biomass and abundance of soil invertebrates. We performed five identical field experiments on abandoned arable land in five European countries (CZ, NL, SE, SP and UK) which allowed us to test our hypothesis in a range of climate, soil and other environmental factors that varied between the experimental sites. The initial plant diversity was altered by sowing seed mixtures of mid‐successional grassland species with two or five grass species, one or five legumes and one or five forbs. The results of low and high sown diversity treatments were compared with plots that were naturally colonized by species present in the seed bank. In three out of the five field sites, there was no correlation between plant species number and plant biomass production, one site had a positive and the other a negative relation. Treatments with a high diversity seed mixture had a higher biomass than the naturally colonized plots. However, there was no significant difference between high and low sown diversity plots at four out of five sites. The three‐year study did not give any evidence of a general bottom‐up effect from increased plant biomass on biomass of bacteria, saprophytic fungi or abundance of microarthropods. The biomass of arbuscular mycorrhizal was negatively related to plant biomass. The abundance of nematodes increased after abandonment and was related to plant biomass at four sites. Our results support the hypothesis that plant species diversity may have idiosyncratic effects on soil communities, even though studies on a longer term could reveal time lags in the response to changes in composition and biomass production of plant communities.