bluuebunny/crossref_metadata_2025 huggingface dataset:
Residual Stress Measurements in Alumina and Silicon Carbide
Authors: Ruud C. O. , Gazzara C. P.
Published: June 2006

Residual stresses were measured in three types of ceramic components. Stresses were measured using X‐ray diffraction and an advanced X‐ray instrument. Measured stresses in alumina rods were shown to correlate well with breaking strength, and stress variations in an alumina tile were hypothesized to result from inhomogeneous cooling. The compressive stresses induced in a silicon carbide tube, by an outer steel sleeve, were seen to be balanced by tensile stresses in the sleeve.
Microstructures of SrTiO3 Internal Boundary Layer Capacitors During and After Processing and Resultant Electrical Properties
Authors: FUJIMOTO MASAYUKI , KINGERY W. DAVID
Published: June 2006

The microstructure of strontium titanate internal boundary layer capacitors at various stages in their processing was studied by transmission electron microscopy of rapidly quenched and normally cooled samples. Compositions containing excess TiO2, Al2O3, and SiO2 have a completely wetting liquid phase at the sintering temperature; during cooling TinO2n−1, Magneli phases precipitate at multiple grain junctions. Diffused metal oxides and flux (Bi2O3, PbO, CuO, and B2O3) rapidly penetrate as a liquid phase along boundaries in postsintering heat treatment. This liquid phase disappears during slow cooling.
Phase Equilibria and Ionic Conductivity in the System ZrO2−Yb2O3−Y2O3
Authors: CORMAN G. S. , STUBICAN V. S.
Published: June 2006

The phase equilibria in the zirconia‐rich part of the system ZrO2−Yb2O3−Y2O3 were determined at 1200°, 1400°, and 1650°C. The stabilizing effects of Yb2O3 and Y2O3 were found to be quite similar with <10 mol% of either being necessary to fully stabilize the cubic fluorite‐structure phase at 1200°C. The two binary ordered phases, Zr3Yb4O12 and Zr3Y4O12, are completely miscible at 1200°C. These were the only binary or ternary phases detected. The ionic conductivities of ternary specimens in this system were measured using the complex impedance analysis technique. For a given level of total dopant, the substitution of Yb2O3 for Y2O3 gives only minor increases in specimen conductivity.
Thermodynamic Analysis and Kinetic Implications of Chemical Vapor Deposition of Sic from Si‐C‐C1‐H Gas Systems
Authors: FISCHMAN GARY S. , PETUSKEY WILLIAM T.
Published: June 2006

Experimental results compiled from the literature were compared to thermodynamic calculations of the most stable proportion of condensed phases to deposit from gas mixtures of Si‐C‐Cl‐H. The calculations indicated that the predominant gas molecules participating in a deposition process are chlorides and chlorosilanes for silicon and methane and acetylene for carbon. The mismatch of the calculated and experimentally determined phase boundaries at 1473 and 1600 K led to the conclusion that silicon deposition occurs faster than carbon deposition in proportion to their partial pressures. The probable reason is that silicon‐bearing gas molecules have a greater sticking probability on polar Si and Sic surfaces because of their asymmetric geometries.
Crushing as a Mechanism of Material Removal During Abrasive Machining
Authors: LARCHUK T. J. , CONWAY J. C. , KIRCHNER H. P.
Published: June 2006

A crushing model, based on an elastic stress analysis and a strain energy density criterion for initiation of mixed‐mode fracture at uniformly distributed flaws, was used to estimate the extent of crushing under a diamond point subjected to an inclined load. The boundaries of the crushed region were compared with the estimated yield boundaries and the measured depths of grooves formed in several materials under similar conditions. Good agreement between the mixed‐mode fracture boundary and the groove depth was observed when the mixedmode fracture boundary was sufficiently far removed from the yield boundary. The results indicate that when the mixed‐mode fracture boundary and the yield boundary are close together, it will be necessary to use an elastic‐plastic solution for the stress distribution to estimate the depth of the mixed‐mode fracture boundary.
Effect of Moist Ammonia on the Strength of Polymer‐Coated Optical Fibers
Authors: CHANDAN HARISH C. , PERRY S. CAROLYN
Published: June 2006

The tensile strength of polymer‐coated fused silica optical fibers aged in a moist ammonia environment at 23°C was drastically reduced compared to that of fibers aged under ammonia‐free high‐humidity conditions. However, most of the strength lost on aging in ammonia was recoverable by ambient desorption of the ammonia, in analogy to the strength recovery which occurs when fibers aged in water are dried.
Polarized Raman Scattering in Rare‐Earth Fluoride Glasses
Authors: Bendow Bernard , Banerjee Pranab K. , Lucas Jacques , Fonteneau Gilles , Drexhage Martin G.
Published: June 2006

The polarized Raman spectra of rare‐earth fluoride glasses based on BaF2 and ThF4, in combination with ZnF2, YF3, YbF3, LuF3, andlor AlF3, are reported and compared with those of other heavy‐metal fluoride glasses. The spectra of rare‐earth fluoride glasses, especially those containing large amounts of AlF3, have relatively broad and mostly depolarized features, suggesting that these glasses are more highly disordered than fluorozirconate and transition‐metal fluoride glasses.
Limitation of Maximum Strength of Zirconia‐Toughened Ceramics by Transformation Toughening Increment
Authors: Swain Michael V.
Published: June 2006

Recent observations with both magnesia‐ and yttria‐partially‐stabilized zirconia (Mg‐ and Y‐PSZ) indicate an apparent anomaly between strength and toughness relations in these materials. The present communication attempts to rationalize these observations and suggests that the stress to initiate the tetragonal‐to‐monoclinic transformation in zirconia‐toughened ceramics may control their maximum strength.
Coalescence and Crystallization in Powdered High‐Cordierite (2MgO·2Al2O3·5SiO2) Glass
Authors: Watanabe Koichi , Giess Edward A.
Published: June 2006

Coalescence and crystallization in powdered high‐cordierite glass were investigated by DTA, SEM, and XRD methods, using also thermal expansion and viscosity data. The apparent activation energy for crystallization obtained from the DTA experiments was about half that for viscous flow estimated from the viscosity. Crystallization in such a system is believed to be controlled by a surface nucleation mechanism.
Metastable Modification of Y2CeO5
Authors: Yamaguchi Osamu , Sugiura Koji , Shimizu Kiyoshi
Published: June 2006

A metastable modification of Y2GeO5 is formed from an amorphous material prepared by the simultaneous hydrolysis of yttrium and germanium alkoxides. It has an orthorhombic unit cell with a =0.6068 nm, b =1.0695 nm, and c = 1.1994 nm. The chemical structure is described by the formula Y4(Ge2O6)O4.
Fractoemission from Lead Zirconate‐Titanate
Authors: DICKINSON J. T. , JENSEN L. C. , WILLIAMS W. DAVID
Published: June 2006

We present measurements of the electron, positive ion, and photon emission accompanying the fracture in vacuum of poly‐crystalline 95/5 lead zirconate‐titanate. The intensities of the charged‐particle components of this fractoemission are shown to depend strongly on the direction (relative to the direction of fracture) and magnitude of polarization. The most intense emission is observed when the fracture surfaces are perpendicular to the polarization direction. The emission intensity increases monotonically with polarization. These results are interpreted in terms of a model involving charge separation on the fracture surfaces leading to a microdischarge during fracture. Implications to the interpretation of triboluminesence effects are discussed.
Low‐Thermal‐Expansion Polycrystalline Zirconyl Phosphate Ceramic
Authors: YAMAI IWAO , OOTA TOSHITAKA
Published: June 2006

The synthesis of thermal‐shock‐resistant material from zirconyl phosphate, 2ZrO2P2O5, was investigated. Modifications of the compound were examined; only the a phase appears to be thermodynamically stable. Sintering of a‐phase powder to a dense ceramic was promoted by adding a metal oxide. Crystalline zirconyl phosphate has a low average thermal expansion coefficient. The relation of microcracking to grain size and strength was studied using specimens sintered under varied conditions. A strong low‐thermal‐expansion polycrystalline ceramic was obtained by controlling grain growth.
Segregation of Mg to the (0001) Surface of Doped Sapphire
Authors: BAIK S. , FOWLER D.E. , BLAKELY J.M. , RAJ R.
Published: June 2006

Auger electron spectroscopy (AES) and low‐energy electron diffraction (LEED) were used to study the segregation of Mg to the surface of a sapphire crystal doped with 40 ppm of Mg. In situ vacuum annealing and AES measurements at 900° to =1800°C failed to reveal Mg segregation on the (0001) plane above the detectability limit of the cylindrical mirror analyzer. However, when identical crystals were placed together to simulate a “closed system” and annealed in air, surface segregation of Me was detected above 1200°C. The variation of the equilibrium surface concentration of Mg with temperature in the range 1300° to =1500°C, gave an effective Langmuir heat Of segregation of Mg of =–146 kJ/mol. Evidence for the formation of a two‐dimensional ordered structure on the sapphire surface was also obtained through LEED studies. The implications of these segregation results for our understanding of the sintering behavior of magnesia‐doped alumina are discussed.
Decomposition of Ni2SiO4 in an Oxygen Potential Gradient
Authors: Wolfenstine Jeff , Dimos Duane , Kohlstedt D. L.
Published: June 2006

Polycrystalline Ni2SiO4 was exposed to a gradient in oxygen potential at 1336°C to cause kinetic decomposition into its component oxides, NiO and SO2. At the higher‐oxygen‐potential side NiO formed, and at the lower‐oxygen‐potential side SiO2 formed. This spatial distribution of SiO2 and NiO is consistent with diffusion data for silicate olivines which indicate that Ni diffuses much faster than either Si or O.
Vector Presentation of Liquid Immiscibility in Alkali‐Free CaO‐FeO‐MgO‐A12O3‐TiO2 Melts
Authors: Barron Lawrence M.
Published: June 2006

Problems with graphical display of immiscible liquids containing >3 components are overcome by recasting tie lines and reference compositional sections into vectors. The technique is demonstrated for experimental work and a theoretical model of liquid immiscibility in the system CaO‐FeO‐MgO‐A12O3‐SiO2‐TiO2. Both experimental and theoretical work indicate that tie lines simply project radially to SiO2, so that network‐forming components are partitioned like cation‐modifying components in these melts. The addition of alkali oxides destroys this simple radial partitioning.
A β‐Phase Based Superstructure in Bi2O3 Doped with PbF2
Authors: Horiuchi Shigeo , Uchida Kenji
Published: June 2006

A new phase was prepared from Bi2O3·15 mol% PbF2 by heating it at 700°C and then quenching to room temperature. The crystal structure (tetragonal, a =0.765 and c = 1.77 nm, P42/nmc) is related to that of the β‐phase of Bi2O3 by a supercell which is 3 times larger in the c direction.
Improvement of Crystallinity of KZr2P3O12 by Sol‐Gel Synthesis
Authors: Lenain Gerard E. , McKinstry Herbert A. , Agrawal Dinesh K.
Published: June 2006

The X‐ray diffraction pattern for potassium‐zirconium phosphate is significantly improved when the material is prepared by the sol‐gel route rather than the powder method. Peaks at high, low, and intermediate angles are presented and compared for the two methods. It is assumed that the more nearly homogeneous mixing of the elements in the sol‐gel process is responsible for the significant improvement in crystallinity.
Effect of Nitrogen on the α/β Phase Conversion in Silicon Nitride
Authors: Fukuhara Mikio
Published: June 2006

The effect of nitrogen on the α/β phase conversion of Si3N4‐based, pressure‐sintered bodies was investigated using nitrides and oxides as additives. When stable oxides are used, the α/β conversion is promoted, but when stable nitrides are present, the conversion is inhibited. α‐Sialon can also be made from Si3N4 and AIN without the use of oxide additives (e.g., Y2O3).
Transformation‐Range Behavior of Li2O‐(Al, Ga)2O3‐SiO2 Glasses
Authors: Piguet Joyce L. , Shelby James E.
Published: June 2006

The transformation‐range viscosity and the glass transformation temperatures were measured for three series of Li2O‐R2O3‐SiO2 glasses containing varying alumina‐to‐gallia ratios. The results indicate that these properties vary linearly with the alumina/gallia ratio. These results suggest that these glasses are isostructural and that no “mixed intermediate oxide” effect occurs.
Influence of Glass Additions on Particle‐Size‐Distribution Effects in Tape Casting of BaTiO3
Authors: Blum J. B. , Mackinnon R. J.
Published: June 2006

In earlier work it was shown that, by mixing a narrow‐particle‐size‐distribution BaTi03 powder and a wide‐distribution BaTiO3 powder, lower slurry viscosities and higher green densities were obtained. In the present work, the particle size distribution of a narrow‐distribution BaTiO3 powder was broadened by adding a bismuth borate glass phase. This broadened distribution resulted in lower slurry viscosities and higher tape green densities.
Abnormal Grain Growth and Microcracking in Boron Carbide
Authors: Prochazka S. , Dole S. L. , Hejna C. I.
Published: June 2006

Boron carbide compacts sintered between 2220° and 2250° C showed abnormal grain growth that was associated with twinning and microcracking. The twin direction was 〈011〉. The microcracking was linked to thermal expansion anisotropy determined by high‐temperature lattice constant measurement.
Lowering Crystallization Temperatures by Seeding in Structurally Diphasic Al2O3‐MgO Xerogels
Authors: Suwa Yoshiko , Roy Rustum , Komarneni Sridhar
Published: June 2006

Thermal reactions in 93% Al2O3‐7% MgO and 95.8% Al2O3‐4.2% MgO gels seeded with α‐Al2O3, MgAl2O4, α‐Fe2O3, and SiO2, sols were investigated by differential thermal analysis to determine the extent of nucleation catalysis of solid‐state reactions. Seeding with α‐Al2O3 lowered the α‐Al2O3 crystallization temperature in these xerogels by 100° to 150°C. Spinel seeds have much less effect on the γ‐α transition, and α‐Fe2O3 and SiO2 seeds do not affect it significantly. Isostructural seeding of gels may therefore permit lower ceramic processing temperatures.
Transformation Toughening in Composites Containing Dicalcium Silicate
Authors: Moya José S. , Pena Pilar , de Aza Salvador
Published: June 2006

By taking into account solid‐state Compatibility relations in the system CaO‐SiO2‐ZrO2, a series of dense, tough CaZrO3‐β‐Ca2SiO4 composites were obtained. The increase in KIC and σf values observed is interpreted in terms of the β‐Ca2SiO4→γ‐Ca2SiO4 polymorphic transformation.
Viscosity and Thermal Expansion of Mixed‐Alkali Sodium‐Potassium Borate Glasses
Authors: KUPPINGER CHRISTOPHER M. , SHELBY JAMES E.
Published: June 2006

The transformation‐range viscosity and thermal expansion be‐havior of sodium‐potassium borate glasses were studied. The results indicate that negative deviations from additivity in the viscosity of these glasses are a function of the Na2O to K2O ratio and that the magnitude of these deviations increases with alkali oxide content. The thermal expansion coefficient exhibits a maximum deviation from additivity as a function of the Na2o to K2O ratio. The magnitude of this deviation increases with increasing total alkali oxide content. The results indicate that there is little, if any, interaction between the factors which lead to the mixed‐alkali effect and the changes in the structure of the vitreous network which occur as the alkali oxide content of the glasses increases.
Mechanical Properties of Joined Silicon Nitride
Authors: JOHNSON SYLVIA M. , ROWCLIFFE DAVID J.
Published: June 2006

A technique is described to join Si3N4 ceramics using oxide glasses. The technique involves a glazing step, followed by a pressureless reaction treatment of 30 to 60 min at 1575° to 1650°C. Reactions between the glasses and Si3N4 are reported. Important events are dissolution of Si3N4 and the growth of Si2N2O crystals into the joint. The strength of joined bars depends on joint thickness. Two strength regimes are identified, and two corresponding fracture mechanisms are described. A maximum strength of ∼460 MPa is achieved for a joint thickness of ∼30 μm.
Fractoemission from Failure of Metal‐GIass Interfaces
Authors: K'SINGAM L. A. , DICKINSON J. THOMAS , JENSEN LESLIE C.
Published: June 2006

Electron and photon emissions accompanying the failure of a metal/glass interface were studied. Experimental evidence is given in support of a previously presented model involving microdischarges accompanying fracture which result from charge separation occurring between the metal and glass surfaces. The role of contact charging at the metal/glass interface in establishing this charge separation is discussed.
Evidence for Diffusion of Zerovalent Metal Atoms during Glass/Metal Sealing
Authors: Moddeman William E. , Craven Stephen M. , Kramer Daniel P.
Published: June 2006

Wavelength‐dispersive X‐ray analysis and X‐ray photoelectron spectroscopy were used to determine the presence of zerovalent nickel, chromium, and iron in the glass of a lithia‐alumina‐silica‐based glass/Inconel 718 seal. Evidence for the resultant diffusion of these atoms from the Inconel substrate into the glass network is presented.
Growth of Potassium Titanate Fibers in Flowing N2 Gas
Authors: Watanabe Akira , Takeuchi Yoshimitsu , Saeki Goji
Published: June 2006

The length of potassium titanate fibers produced by several conventional methods averages 50 μm, with a maximum of 100 μm. Extremely long fibers (most >1000 μm long) were obtained by calcination in N2 gas flowing at 5.2×10‐4 m/s.
Study by Extended X‐ray Absorption Fine‐Structure Technique and Microscopy of the Chemical State of Yttrium in α‐Polycrystalline Alumina
Authors: LOUDJANI M.K. , ROY J. , HUNTZ A.M. , CORTES R.
Published: June 2006

Yttrium‐doped a‐poly crystalline alumina was studied by microscopy observations and by extended X‐ray absorption fine‐structure experiments. The latter results were compared to those obtained for a standard Y2O3 powder and to theoretical spectra for Y2O3, and Y3Al5O12 calculated on the basis of crystallographic data. Most of the yttrium in the doped alumina is precipitated as a Y3Al5O12 phase. An observed threshold displacement involves a slight valence electron delocalization for the Y3+ ion.
Localization of Potassium in Al2O3
Authors: SUSNITZKY D. W. , CARTER C. B.
Published: June 2006

The accommodation of small amounts of intentionally added potassium in sintered and hot–pressed polycrystalline α‐alumina was studied. In sintered specimens, potassium was pushed out by, and accumulated along, the grain boundaries enclosing abnormally large α‐alumina grains. Potassium was also localized in hot‐pressed specimens and formed large (up to 1‐mm diameter), randomly dispersed precipitates of polycrystalline potassium β‐alumina. Each precipitate was enclosed within a thin shell (0.5– to 1.5‐mm radius) of potassium–rich material. The experimental observations of this precipitation are compared to the formation of Liesegang rings.
Swelling of Hot‐Pressed A12O3
Authors: BENNISON S. J. , HARMER M. P.
Published: June 2006

Fully dense aluminas, prepared by hot‐pressing, were found to swell during annealing at 1600°C in air, but not during annealing in a reducing atmosphere (po2= 10‐7 Pa). The reaction followed the relation p ‐ po = ‐K log t, where po and p are the initial and final densities, respectively, t is the time, and AT is a constant. The rate of swelling was enhanced by MgO solute. The reduction in density resulted from the nucleation and growth of grain‐boundary pores. Pore formation was attributed to the reaction of carbon and sulfur impurities at the boundaries with oxygen, which had diffused down the grain boundaries from the ambient, to form CO/CO2 and SO2 gas at high pressures. Preliminary results indicate that this reaction can be avoided by preannealing powders in flowing oxygen prior to hot‐pressing. The consequences of internal gas‐forming reactions to other processes such as high‐temperature creep and sintering are also discussed.
Evaluation of Grain‐Growth Parameters
Authors: IKEGAMI TAKAYASU , MORIYOSHI YUSUKE
Published: June 2006

The complicated texture of a thin sheet of MgO and MgO‐doped Al2O3 (∼15 pm) was statistically resolved into four typical grain geometries. Grain size distribution was related to the ratio of expressions describing the growth (or shrinkage) of individual grains and the growth of grains of average size R. Grain‐growth data for MgO indicate that the mobility of a grain boundary is independent of R (parabolic‐grain‐growth behavior) but depends strongly on the ratio of individual grain size to average grain size. When mobility is proportional to 1/R, the time dependence of grain growth is <1/2.
Microstructure‐Strength Properties in Ceramics: I, Effect of Crack Size on Toughness
Authors: COOK ROBERT F. , LAWN BRIAN R. , FAIRBANKS CAROLYN J.
Published: June 2006

A systematic study of the inert‐strength characteristics of ceramics as a function of crack size relative to grain size has been made using controlled indentation flaws. The focus of the test program is on aluminas, with barium titanates and glass‐ceramics providing support data in confirmation of general trends. On progressively diminishing the indentation load, the strengths first show a steady increase, but subsequently tend to a plateau, as the contact size begins to approach the characteristic grain size. A simple extension of conventional indentation fracture mechanics theory (incorporating residual contact stresses) is developed to describe this scale transition. The basis of the analysis is the postulated existence of a “microstructural driving force,” grain‐localized at the center of the pennylike radial crack, in direct analogy to the indentation driving force. This description provides closed‐form solutions to the fracture mechanics equations, such that the data are interpretable in terms of an apparent R‐curve function. Only two quantities are required to specify the function completely, one relating to the macroscopic toughness determined from large‐scale crack specimens and the other to a microstructure‐associated stress intensity factor. These quantities are advocated as useful reliability parameters. It is found that the second quantity can vary widely from material to material, even within a given class, to the extent that materials which show superior strength characteristics at large indentation loads may be dramatically weaker at low loads. The indications are that, at least for aluminas, the key to such weakening effects is to be found in the grain‐boundary structures. The study emphasizes the need for extreme caution in extrapolating macroscopic‐crack data unconditionally into the microscopic‐flaw region, and for more fundamental investigations into the underlying physical processes actually responsible for the microstructural driving forces.
Effect of Contact Residual Stress Relaxation on Fracture Strength of Indented Soda‐Lime Glass
Authors: ROACH D. H. , COOPER A. R.
Published: June 2006

The strength of Vickers‐indented soda‐lime glass measured in air at room temperature steadily increases with time after indentation, whereas optical retardation steadily decreases in the same interval. Annealing after indentation causes further strength increase and retardation decrease. The results are consistent with Marshall and Lawn's treatment of the slow crack growth of indentation flaws driven by the combined influence of residual contact stress and applied stress. Post‐indentation strengthening of indentation flaws can be explained without recourse to flaw blunting.
A first‐generation microsatellite‐based integrated genetic and cytogenetic map for the European rabbit (Oryctolagus cuniculus) and localization of angora and albino
Authors: Chantry‐Darmon C. , Urien C. , De Rochambeau H. , Allain D. , Pena B. , Hayes H. , Grohs C. , Cribiu E. P. , Deretz‐Picoulet S. , Larzul C. , Save J. C. , Neau A. , Chardon P. , Rogel‐Gaillard C.
Published: June 2006

Although the European rabbit (Oryctolagus cuniculus) is used both in agronomics and in research, genomic resources for this species are still limited and no microsatellite‐based genetic map has been reported. Our aim was to construct a rabbit genetic map with cytogenetically mapped microsatellites so as to build an integrated genetic and cytogenetic map. A reference population of 187 rabbits comprising eight three‐generation families with 10–25 offspring per family was produced. One hundred and ninety‐four of 305 previously identified microsatellites were included in this study. Of these, 158 were polymorphic with two to seven alleles. The map reported here comprises 111 markers, including 104 INRA microsatellites, five microsatellites from another source and two phenotypic markers (angora and albino). Ninety markers were integrated into 20 linkage groups. The remaining 21 microsatellites mapped to separate linkage groups, 19 with a precise cytogenetic position and two with only a chromosomal assignment. The genetic map spans 2766.6 cM and covers 20 rabbit chromosomes, excluding chromosomes 20, 21 and X. The density of this map is limited, but we used it to verify the location of angora and albino on chromosomes 15q and 1q, respectively, in agreement with previously published data. This first generation genetic/cytogenetic map will help gene identification and quantitative trait loci mapping projects in rabbit.
Haploidentical stem cell transplantation for children with acute leukaemia
Authors: Marks David I. , Khattry Navin , Cummins Michelle , Goulden Nicholas , Green Ann , Harvey John , Hunt Linda P. , Keen Leigh , Robinson Stephen P. , Steward Colin G. , Cornish Jacqueline M.
Published: June 2006

Some children with relapsed or high‐risk acute leukaemia have an improved outcome if they have an allogeneic stem cell transplant, preferably from a sibling or well‐matched unrelated donor. However, some children do not have these options or there is an urgent need to proceed to transplant because of disease status. We have investigated the role of haploidentical family members as donors in 34 patients with acute leukaemia (median age 11 years, range 1–16 years). Patients were conditioned with cyclophosphamide and total body irradiation (14·4 Gy in eight fractions) and received T‐cell depleted peripheral blood stem cell grafts with a median CD34 cell dose of 13·8 × 106/kg (range 4·2–35·1) and 0·7 × 104 CD3‐positive cells/kg. The actuarial survival at 2 years was 26% (13–41%, 95% CI). Eight patients have survived disease‐free with a median follow up of 62 months. They have good performance status and a median lymphocyte count of 1·8 × 109/l. Relapse (14 patients) and adenoviral (six patients) or fungal infections (four patients) were the major causes of death. Haploidentical stem cell transplantation can produce medium term disease‐free survival in a proportion of children with high‐risk or relapsed acute leukaemia. None of the nine patients with acute myeloid leukaemia not in remission have survived.
BCR–ABL activates STAT3 via JAK and MEK pathways in human cells
Authors: Coppo Paul , Flamant Stéphane , Mas Véronique De , Jarrier Peggy , Guillier Martine , Bonnet Marie‐Laure , Lacout Catherine , Guilhot François , Vainchenker William , Turhan Ali G.
Published: June 2006

Chronic myeloid leukaemia (CML) is characterised by a progression from a chronic towards an acute phase. We previously reported that signal transducer and activator of transcription 3 (STAT3), a major oncogenic signalling protein, is the target of p210–BCR–ABL in a murine embryonic stem (ES) cell model and in primary CD34+ CML cells. This activation was associated with inhibition of differentiation in ES cells. The present study found that BCR–ABL greatly phosphorylated STAT3 Ser727 residue and, to a lesser extent, Tyr705 residue in BCR–ABL‐expressing cell lines (UT7‐p210, MO7E‐p210, and K562) and in primary CD34+ CML cells. Using BCR–ABL mutants, it was shown that BCR–ABL tyrosine kinase activity and its Tyr177 residue were necessary for STAT3 Ser727 phosphorylation. Constitutive STAT3 Tyr705 phosphorylation was associated with constitutive phosphorylation of Janus kinase (JAK)1 and JAK2, and was inhibited by the JAK inhibitor AG490, suggesting the involvement of JAK proteins in this process. Specific MEK [mitogen‐activated protein (MAP) kinase/extracellular signal‐regulated kinase (ERK) kinase] inhibitors PD98056 and UO126, as well as the use of a dominant‐negative form of MEK1 abrogated STAT3 Ser727 phosphorylation, suggesting involvement of MAP‐Kinase/Erk pathway. Inhibition of BCR–ABL with imatinib mesylate led to a dose‐dependent downregulation of total STAT3 protein and mRNA, suggesting that BCR–ABL is involved in the transcriptional regulation of STAT3. Targeting JAK, MEK and STAT3 pathways could therefore be of therapeutic value, especially in advanced stage CML.
Autologous transplantation for relapsed or primary refractory peripheral T‐cell lymphoma
Authors: Kewalramani Tarun , Zelenetz Andrew D. , Teruya‐Feldstein Julie , Hamlin Paul , Yahalom Joachim , Horwitz Steven , Nimer Stephen D. , Moskowitz Craig H.
Published: June 2006

Autologous transplantation (ASCT) is the standard of care for chemosensitive relapsed or primary refractory aggressive lymphoma, but little is known about its efficacy in the subset of patients with peripheral T‐cell lymphoma (PTCL). We undertook a retrospective review of patients with PTCL who underwent ASCT for relapsed or refractory disease after responding to second‐line therapy, excluding patients with indolent histologies and those with anaplastic lymphoma kinase (ALK) expressing anaplastic large cell lymphoma. The results of 24 patients with PTCL were compared with those of 86 consecutive patients with chemosensitive relapsed or primary refractory diffuse large B‐cell lymphoma (DLBCL). With a median follow‐up time of 6 years for surviving patients with PTCL and DLBCL, the 5‐year progression‐free survival (PFS) rates for PTCL and DLBCL patients were 24% and 34% respectively (P = 0·14); the corresponding overall survival (OS) rates were 33% and 39% respectively. There were no significant differences between the two groups with respect to time to disease progression or survival after progression. The second‐line age‐adjusted international prognostic index was the only variable prognostic for PFS and OS in a multivariate analysis. The outcome of ASCT for patients with chemosensitive relapsed or primary refractory PTCL is similar to that for patients with DLBCL.
Methadone‐exposed newborn infants: outcome after alterations to a service for mothers and infants
Authors: Miles J. , Sugumar K. , Macrory F. , Sims D. G. , D’Souza S. W.
Published: June 2006

Objective  To evaluate the impact of a shared care approach in clinical management with a drug liaison midwife (DLM) service for mothers and infants established in 1995–1996 in an inner city area and to address the problem of congenital abnormality and microcephaly with fetal drug exposure.

Methods  Descriptive analysis of data in live births of women enrolled in a methadone maintenance programme in 1991–1994 (n = 78) and 1997–2001 (n = 98), including time spent in hospital, treatment for neonatal abstinence syndrome (NAS), admission to the neonatal medical unit (NMU) and follow‐up for child health checks.

Results  In 1997–2001 compared with 1991–1994, the mothers used more methadone in the last week of pregnancy (median 40.0 mg/day vs. 21.5 mg/day, P = 0.0006) and there were more preterm deliveries (36% vs. 21%, P = 0.03). The infants spent less time in hospital (median 5 days vs. 28 days, P < 0.0001), a smaller proportion had treatment for NAS (14% vs. 79%, P < 0.0001), and NMU admission was reduced (median 14 days vs. 26 days, P < 0.0003). Neonatal convulsions (P = 0.0001) and jaundice (P < 0.001) occurred less frequently, and more infants were breastfed (P = 0.001). One infant in each study group had a cleft palate and none had microcephaly. Child health checks for 18–24 months showed a favourable outcome in 1997–2001.

Conclusions  We altered antenatal care and modified neonatal management, subsequently infants spent less time in hospital and NMU admissions were reduced with less NAS treatment. Congenital abnormalities and microcephaly were not common and as regular child health checks were possible, the impact of the DLM service in shared management merits further investigation, for mother–infant bonding and developmental outcome.
Early life circumstances and atopic disorders in childhood
Authors: Bernsen R. M. D. , Van Der Wouden J. C. , Nagelkerke N. J. D. , De Jongste J. C.
Published: June 2006

The prevalence of childhood atopic disorders has risen dramatically in the last decades of the past century. Risk factors for the development of these disorders have been studied extensively. This review focuses on the role of early life risk factors such as pre‐natal development, perinatal circumstances, birth order and childhood vaccinations.
T‐helper type 2 polarization among asthmatics during and following pregnancy
Authors: Rastogi D. , Wang C. , Lendor C. , Rothman P. B. , Miller R. L.
Published: June 2006

Background
Asthma is the most common medical condition during pregnancy. While increased production of T helper cytokines has been reported to occur in both asthma and pregnancy, the effect of T‐helper type 2 (Th2) polarization on asthma symptoms during pregnancy has not been well‐characterized.

Objective
We hypothesized that systemic Th2 cytokine and chemokine polarization occurs among asthmatics to a greater extent during their pregnancy, and is associated with more severe asthma and increased Th2 polarization in the newborn.

Methods
Fifty‐six pregnant asthmatics were recruited from prenatal clinics affiliated with New York Presbyterian Hospital. Systemic production of interleukin‐4, interferon‐γ, eotaxin and IP10 were measured by intracytoplasmic staining or ELISA at recruitment, peripartum and post‐partum, and in the cord blood. The frequency of asthma symptoms was measured by questionnaires and compared with Th biomarkers.

Results
The chemokine ratio (IP10/eotaxin) declined over the course of pregnancy (from 3.3±1.3 to 1.4±0.2, P=0.016), but IP10 and eotaxin increased post‐partum. The decrease in the chemokine ratio was associated with more frequent asthma symptoms. A non‐significant trend towards decreased interferon‐γ and increased interleukin‐4 production was detected. Cord blood eotaxin levels correlated with maternal levels (r=0.35, P=0.03). Other peripartum biomarkers were not associated with Th2 polarization nor with subsequent respiratory symptoms in the newborn.

Conclusions
IP10/eotaxin declined over the course of pregnancy and was associated with worse asthma symptoms. Alterations of Th1/Th2 chemokine balance during pregnancy may identify women prone to more severe asthma during pregnancy.
Body composition in untreated adult patients with Laron syndrome (primary GH insensitivity)
Authors: Laron Zvi , Ginsberg Shira , Lilos Pearl , Arbiv Mira , Vaisman Nahum
Published: June 2006

Objective  To quantify body adiposity and its distribution in untreated adult patients with Laron syndrome (LS; primary GH insensitivity) caused by molecular defects of the GH receptor gene or postreceptor pathways and characterized by dwarfism, obesity, insulin resistance and hyperlipidaemia.

Patients  Eleven LS patients (seven females and four males) aged 28–53 years were studied. Seven healthy males and six healthy females served as controls.

Measurements  Body composition of the total body trunk, upper and lower extremities was determined using dual‐energy X‐ray absorptiometry (DEXA). Statistical analysis using an analysis of variance (anova) and Mann–Whitney nonparametric methods was performed separately in males and females.

Results  Percentage body fat in the LS patients was much higher (P < 0·01) than that in the control population and the female LS patients were significantly more obese (59% total body fat) than the male patients (39% total body fat) (P < 0·002). It was also evident that in these types of patients with markedly increased body fat and decreased muscle and bone mass, body mass index (BMI) does not accurately reflect the body composition.

Conclusions  Lifelong congenital IGF‐I deficiency leads to extreme adiposity.
Effects of Pacific salmon spawning and carcass availability on the caddisfly Ecclisomyia conspersa (Trichoptera: Limnephilidae)
Authors: WALTER JASON K. , BILBY ROBERT E. , FRANSEN BRIAN R.
Published: June 2006

1. The effects of spawning coho (Oncorhynchus kisutch) and chum salmon (Oncorhynchus keta) on the limnephilid caddisfly Ecclisomyia conspersa were evaluated by experimentally excluding salmon from the upper 14‐m stretch of a spawning channel by a wire‐meshed fence. Density, and development and growth rates, of larvae upstream of the fence (without salmon) were compared with those downstream (with salmon).

2. Larval density in the stretch with salmon declined during spawning, but increased again after spawning subsided and the carcasses of dead fish became available. In the stretch with salmon, larval density on salmon carcasses was seven to 37 times greater than on the adjacent channel substratum. The rate of larval development in the stretch with salmon was greater than that in the stretch without salmon. Two months after carcasses became available, 98% of larvae sampled from the stretch with salmon were in the fifth instar, compared to only 23% from the stretch without salmon. Body weight of E. conspersa in the stretches with and without salmon increased by an average of 3.04 and 2.38 mg, respectively, over a 6‐month period.

3. 15N values of larvae from the stretch with salmon increased following the arrival of the fish, suggesting that the larvae were feeding on salmon‐derived material, such as eggs and carcasses, which contain a high proportion of the heavier stable isotope. In contrast, 15N values of larvae from the stretch without salmon remained relatively constant throughout the experiment. The availability of salmon carcasses as a high‐quality food source late in larval development may increase survival and fecundity of E. conspersa.

4. These substantial differences were consistent with the view that they were due to the experimental exclusion of salmon and salmon carcasses from the upstream stretch, though the study was un‐replicated and thus precludes ascribing causation more definitely.
Encystment of Peridinium gatunense: occurrence, favourable environmental conditions and its role in the dinoflagellate life cycle in a subtropical lake
Authors: ALSTER ALLA , DUBINSKY ZVY , ZOHARY TAMAR
Published: June 2006

1. The abundance of cysts of the bloom‐forming dinoflagellate Peridinium gatunense in the sediments of Lake Kinneret and the effects of environmental conditions on encystment were studied in relation to bloom dynamics. Peak cyst formation coincided with the highest growth rate of the population, prior to bloom peak.

2. Peridinium cysts were counted in water and sediment corer samples from 2000 to 2003 and in archived sediment trap samples collected during 1993–94. The cyst data were examined in relation to ambient temperature and nutrient records, and revealed no direct correlation.

3. In laboratory encystment experiments with Peridinium cells collected from the lake, 0.2–3% of the vegetative cells encysted. Temperature, light and cell density had no significant effect on the percentage of encystment.

4. Cysts were always present in the lake sediments but their abundance in ‘non Peridinium’ years was much lower than after a massive bloom. Vegetative cells were always present in the water column after the collapse of the annual dinoflagellate bloom, potentially serving as the inoculum for the next bloom. We propose that the hardy cysts serve as an emergency ‘gene bank’ to initiate population build up following catastrophic die outs.
Population genetic structure of the endangered crayfishAustropotamobius pallipesin France based on microsatellite variation: biogeographical inferences and conservation implications
Authors: GOUIN N. , GRANDJEAN F. , SOUTY‐GROSSET C.
Published: June 2006

1. One important goal in conservation biology is to characterise evolutionary lineages within endangered species before management decisions are taken. Here, we assess population differentiation in the freshwater crayfishAustropotamobius pallipes, an endangered species endemic to western Europe and provide valuable information for the conservation of French populations.

2. Analysis of five microsatellite loci in 44 populations revealed very different within population levels of genetic diversity (0.000 < H0 < 0.564). Two groups, corresponding to northern and southern French populations, showed a high degree of genetic differentiation in both allele frequencies and allele sizes. Comparison of these results with previous studies ofA. pallipesstrongly suggests that the divergence between northern and southern populations could have occurred during the last glaciation period of the Pleistocene from one Atlantic and one Mediterranean refuge.

3. Evidence for genetic admixture between these two lineages was revealed by correspondence analyses in southern populations, probably as the result of artificial translocations.

4. French populations appeared significantly differentiated among the different river drainages and were highly structured within rivers. The impact of population size, population bottlenecks and founder events on the population genetic differentiation are discussed.

5. Based on these results, we propose the designation of two evolutionarily significant units forA. pallipesin France. Our data also support the maintenance of separate demographic management strategies for crayfish inhabiting different river systems. However, genetic analyses will have to be combined with demographic and ecological data for sustainable conservation programmes.
An experimental study of habitat choice by Daphnia: plants signal danger more than refuge in subtropical lakes
Authors: MEERHOFF MARIANA , FOSALBA CLAUDIA , BRUZZONE CARLA , MAZZEO NÉSTOR , NOORDOVEN WILLEMIJN , JEPPESEN ERIK
Published: June 2006

1. In shallow temperate lakes, submerged plants often provide refuge for pelagic zooplankton against fish predation, a mechanism with potential strong cascading effects on water transparency and on the entire ecosystem. In (sub)tropical lakes, however, the interaction between aquatic plants and predation may be more complex, particularly because fish density is high within the plant beds in such systems.

2. Using laboratory ‘habitat choice’ experiments, we determined the effects of three (sub)tropical free‐floating plants, Eichhornia crassipes, Pistia stratiotes and Salvinia auriculata and the cosmopolitan submerged Ceratophyllum demersum, on horizontal movement by the water flea Daphnia obtusa. We tested for avoidance of plants in the absence and presence of alarm signals from crushed conspecifics and chemical cues from the fish Cnesterodon decemmaculatus, the fish have been subjected to different feeding regimes.

3. In the absence of other stimuli, D. obtusa strongly avoided the plants and the crushed conspecifics, as expected. However, the response to fish was insignificant regardless of their previous feeding regime. The avoidance of free‐floating plants was more pronounced than that of the submerged plant. Contrary to predictions based on research in temperate lakes, Daphnia did not take refuge among the plants but rather swam away from them when exposed simultaneously to plants and alarm signals.

4. We hypothesise that the avoidance of plants by D. obtusa may ultimately be attributable to an expectedly higher predation risk within the plants than in the pelagic, because of a high density of associated zooplanktivorous fish in the former. In the (sub)tropics, therefore, aquatic plants and particularly the free‐floating ones, may not promote cascading effects via Daphnia grazing on phytoplankton as seen in temperate eutrophic lakes.
Movement, dispersal and refuge use of co‐occurring introduced and native crayfish
Authors: BUBB DAMIAN H. , THOM TIMOTHY J. , LUCAS MARTYN C.
Published: June 2006

1. Dispersal and habitat use are key elements in determining impacts of introduced species. We examined if an invasive crayfish species showed a different pattern of movement, dispersal and refuge use to that of a species that it displaces.

2. Fifteen adults of the introduced American signal crayfish, Pacifastacus leniusculus and 20 adult native white‐clawed crayfish Austropotamobius pallipes were radiotagged in an area of river where in 2003 they co‐occurred and the spatial behaviour and habitat use of the two species were examined. Subsequent surveys at the study site in 2005 recorded no A. pallipes and the density of P. leniusculus had increased.

3. Clear differences in the spatial behaviour of the two species were found. The median distance moved per day by signal crayfish was over twice that of white‐clawed crayfish, and dispersal from release locations was higher in signal crayfish. A similar range of refuges with a high degree of overlap was used by both species suggesting that the potential for competitive interaction between the two species exists.

4. The greater movement and dispersal by signal crayfish recorded here supports the hypothesis that invaders are better dispersers than the species that they displace. In addition, movements by signal crayfish may allow them to make better use of patchy resources than white‐clawed crayfish and this, coupled with similar microhabitat use, may contribute to the observed replacement.
Hatching and viability of rotifer diapausing eggs collected from pond sediments
Authors: GARCÍA‐ROGER EDUARDO M. , CARMONA MARÍA JOSÉ , SERRA MANUEL
Published: June 2006

1. Planktonic rotifers inhabiting variable environments produce diapausing eggs that accumulate in the sediment of lakes and ponds, forming egg banks that may withstand adverse periods. A common assumption in zooplankton diapausing egg bank studies is to count as viable all eggs in the sediment that look healthy. This assumption should be challenged by asking how effectively ‘healthy‐looking’ eggs represent viable eggs.

2. In this study, viability of more than 1100 ‘healthy‐looking’ diapausing eggs belonging to the Brachionus plicatilis species complex was assessed in a laboratory hatching experiment. Eggs were collected at different depths from sediment cores obtained from 15 ponds located in coastal and inland areas of Eastern Spain.

3. Only approximately one half of the ‘healthy‐looking’ diapausing eggs hatched after incubation in experimental conditions. Almost all the hatchlings (99.4%) survived to maturity. The proportion of ‘healthy‐looking’ diapausing eggs that hatched varied among areas and among ponds within area, and substantially declined with sediment depth. Most of the hatchlings (88%) were obtained from the uppermost 2 cm of sediment. ‘Healthy‐looking’ eggs from upper sediment layers hatched after significantly shorter incubation times than eggs recovered from deeper layers.

4. Both decreased hatching success and increased incubation time for hatching with sediment depth suggest that older ‘healthy‐looking’ eggs are less responsive to hatching stimuli and could become unviable. However, the strong correlation found between the number of ‘healthy‐looking’ eggs and the number of hatchlings indicates that the abundance of ‘healthy‐looking’ eggs is a good index of egg bank viability.