bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thymic carcinoma in children: A report from the Polish pediatric rare tumors study
Authors: Stachowicz‐Stencel Teresa , Bien Ewa , Balcerska Anna , Godzinski Jan , Synakiewicz Anna , Madziara Wojciech , Perek‐Polnik Marta , Peregud‐Pogorzelski Jarosław , Pietras Wojciech , Pobudejska Aneta , Kurylak Andrzej , Mankowski Przemyslaw 
Published: April 2010

AbstractBackgroundInvasive thymomas and thymic carcinomas are rare tumors jointly accounting between 0.2% and 1.5% of malignancies in adults. They are usually at an advanced stage when diagnosed and have both high recurrence and poor survival rates. In this report, the aim is to explore our experience in the treatment of thymic carcinomas in Polish children.ProcedureThe clinical data of nine children with thymic carcinomas, treated between 1992 and 2008 in the Polish oncological and surgical centers was retrospectively analyzed.ResultsIn five cases, presenting symptoms resulted from the compression of the respiratory ways by the mediastinal tumor. In two children paraneoplastic autoimmune syndromes were associated with thymic carcinoma. In accordance with the Masaoka classification, two patients had stage II, five had stage III, and two had stage IV of the disease. Diagnostic biopsy of mediastinal tumor was performed on eight patients and one underwent complete primary resection and subsequently received radiotherapy; he has passed 11 years since the conclusion of therapy. Six patients received multi‐drug chemotherapy with or without steroids. Delayed surgery was performed in four children (R0‐2, R1‐1, and R2‐1). After complete resection, one child received chemotherapy. In three patients, chemotherapy and radiotherapy was administered. Seven patients died, including six due to progression of the disease with the other as a result of complications following chemotherapy; only two patients classed at stage II remain alive.ConclusionsMost thymic tumors in pediatric patients are inoperable at diagnosis, which results in poor prognosis. Improved chemotherapy approaches are needed. Pediatr Blood Cancer 2010;54:916–920 © 2010 Wiley‐Liss, Inc.
Theoretical and experimental studies on stability of the C‐ON bond in new ketone functionalized N‐alkoxyamines
Authors: Megiel Elżbieta , Kaim Andrzej , Cyrański Michał Ksawery 
Published: April 2010

AbstractThree new ketone functionalized N‐alkoxyamines derived from 2,2,6,6‐tetramethylpiperidin‐1‐oxyl (TEMPO) were prepared: N‐(1‐phenylpropyloxy)‐2,2,6,6‐tetramethylpiperidin‐4‐one, 1‐phenyl‐1‐(2,2,6,6‐tetramethylpiperidinoxy)propanone, 1‐phenyl‐1‐(4‐oxo‐2,2,6,6‐tetramethylpiperidinoxy)propanone. The rate constants of C‐ON bonds homolysis in the synthesized alkoxyamines were determined over a range of temperatures via nitroxide‐exchange experiments using HPLC to monitor the concentration. The Arrhenius parameters of homolysis for the investigated alkoxyamines were determined (lnA, Ea). Homolytic bond dissociation energies (BDE) of the C‐ON bond in the synthesized compounds were determined from quantum‐mechanical calculations at the B3‐LYP/6‐31G(d) and BMK/6‐311+G(3df,2p) levels. Ketone functionalization of the alkyl fragment of alkoxyamine in β position dramatically increases the rate constant of homolysis (by a factor of ca. 500 at the temperature of 363 K) suggesting that the new ketone functionalized N‐alkoxyamines should be effective as C‐radical precursor and unimolecular initiators in NMRP at lower temperatures than the alkoxyamines applied earlier. The analyses of natural bond, frontal orbitals and spin distribution indicated that the decrease in the strength of C‐ON bonds in ketone fuctionalized alkoxyamines in the alkyl fragment predominantly originates from a substantially smaller HOMO–LUMO gap and more delocalized spin density in leaving alkyl radicals as compared with unfunctionalized alkoxyamines. Copyright © 2010 John Wiley & Sons, Ltd.
Can tetra‐tert‐butylethylene be formed by ion–ion recombination or ion–molecule reaction of two di‐tert‐butylcarbene units?—a DFT study
Authors: Kanawati Basem , Lenoir Dieter , Schmitt‐Kopplin Philippe 
Published: April 2010

AbstractThe reaction channels of di‐tert‐butylcarbene (2), its radical anion, (3) and its radical cation (4) were investigated theoretically by using DFT/B3LYP with 6‐31+G(d) basis set and 6‐311+G(2d,p) for single point energy calculations. Conversion of the neutral carbene 2 to the charged species 3 and 4 results in significant geometric changes. In cation 4 two different types of C(CH3)3 bonds are observed: one elongated sigma bond called “axial” with 1.61 Å and two normal sigma bonds with a bond length of 1.55 Å. Species 2 and 4 have an electron deficient carbon center; therefore, migration of CH3 and H is observed from adjacent tert‐butyl groups with low activation energies in the range of 6–9 kcal/mol like similar Wagner–Meerwein rearrangements in the neopentyl‐cation system. Neutral carbene 2 shows CH insertion to give a cyclopropane derivative with an activation energy of 6.1 kcal/mol in agreement with former calculations. Contrary to species 2 and 4, the radical anion 3 has an electron rich carbon center which results in much higher calculated activation energies of 26.3 and 42.1 kcal/mol for H and CH3 migrations, respectively. NBO charge distribution indicates that the hydrogen migrates as a proton. The central issue of this work is the question: how can tetra‐tert‐butylethylene (1) be prepared from reaction of either species 2, 3, or 4 as precursors? The ion–ion reaction between 3 and 4 to give alkene 1 with a calculated reaction enthalpy of 203.5 kcal/mol is extremely exothermic. This high energy decomposes alkene 1 after its formation into two molecules of carbene 2 spontaneously. Ion–molecule reaction of radical anion 3 with the neutral carbene 2 is a much better choice: via a proper oriented charge–transfer complex the radical anion of tetra‐tert‐butylethylene (11) is formed. The electron affinity of 1 was calculated to be negligible. Copyright © 2010 John Wiley & Sons, Ltd.
Structural instability of N‐acceptors in homo‐ and heteroepitaxially grown ZnO by MBE
Authors: Ando K. , Abe T. , Taya T. , Ishihara Y. , Enomoto K. , Yamazaki Y. , Yoshikawa J. , Fujino K. , Nakamura H. , Ohno T. , Kasada H. 
Published: April 2010

AbstractUnique properties of the N‐acceptor in homo‐ and heteroepitaxially grown ZnO by molecular beam epitaxy (MBE) are studied by means of microproving of surface sheet‐resistance, Hall‐effect measurement, persistent photoconduction (PPC) and thermally stimulated current (TSC). Rapid postanneal of N‐doped ZnO is found to induce the change in the conduction type from n‐type (as‐grown) to p/n‐type mixed conduction, forming island structure, and these properties are related to a structural instability of the N‐acceptor.
Seeded growth of bulk ZnO by chemical vapor transport
Authors: Skupiński Paweł , Grasza Krzysztof , Mycielski Andrzej , Paszkowicz Wojciech , Łusakowska Elżbieta , Tymicki Emil , Jakieła Rafał , Witkowski Bartłomiej 
Published: April 2010

AbstractThe results of the seeded growth of bulk zinc oxide by chemical vapor transport (CVT) are presented. Hydrogen is used as the transport agent. Crystals with three different crystallographic directions were obtained, Zn‐terminated (0001), O‐terminated (000‐1), and non‐polar (1‐100). The tendency to maintain the crystallographic orientation of seed was observed. The investigation shows that the quality of the growing crystal depends on the crystallographic orientation and the polarity of the seed. Three kinds of macroscopic defects, not yet reported for ZnO crystals, were observed, (i) flat voids with transverse size of about 200 µm, (ii) spherical voids or “bubbles” about 10 µm in diameter, and (iii) the micropipes. The nature of these defects is discussed.
Random lasing in nanocrystalline ZnO powders
Authors: Kalt Heinz , Fallert Johannes , Dietz Roman J. B. , Sartor Janos , Schneider Daniel , Klingshirn Claus 
Published: April 2010

AbstractWe investigate the properties of random lasing in nanocrystalline ZnO powders. The lowest threshold for lasing occurs for average particle diameters of about 260 nm. Reproducible lasing features are achieved for reduced ensemble sizes. Spatially resolved luminescence spectroscopy is used to probe directly the degree of localization of random laser mode. We find that strongly confined and extended modes can co‐exist in the same spatial area. However, localized modes appear for small optical gain while extended modes are only supported in the presence of large optical gain, as is expected from theory. Localized and extended random‐laser modes co‐exist in space but appear in spectral regions of low and high optical gain, respectively. magnified image
The role of stacking faults and their associated 0.13 eV acceptor state in doped and undoped ZnO layers and nanostructures
Authors: Thonke K. , Schirra M. , Schneider R. , Reiser A. , Prinz G. M. , Feneberg M. , Sauer R. , Biskupek J. , Kaiser U. 
Published: April 2010

AbstractCathodoluminescence spectra recorded with high spatial and wavelength resolution on tilted ZnO epitaxial layers allow to identify a very prominent emission peak at 3.314 eV as a free electron to shallow acceptor (EA ≈ 130 meV) transition. By correlation with TEM cross‐section images recorded on the same samples we can find these acceptor states to be located on basal plane stacking faults (BSFs). Locally, high concentrations of acceptor states are found. Since this spectral feature is often reported in literature especially after attempts to obtain p‐type or transition metal doping, we conclude that stacking faults are a common by‐product when group V or other extrinsic atoms are incorporated in ZnO layers or nanostructures.
Magnetic field induced changes of the magnetic phase transition in metastable zinc blende MnS layers grown by MBE
Authors: Demper M. , Chen L. , Krug von Nidda H.‐A. , Bradford C. , Loidl A. , Prior K. A. , Heimbrodt W. 
Published: April 2010

AbstractWe studied the magnetic and optical properties of antiferromagnetic zinc blende MnS layers with thicknesses of 1.8 nm and 8.3 nm, which were grown between ZnSe cladding layers by molecular beam epitaxy on a (100)‐GaAs substrate. The paramagnetic to antiferromagnetic phase transition has been studied by optical and SQUID‐measurements. The yellow emission band of the internal manganese 3d‐states undergoes a significant blue shift below the magnetic phase transition, which is caused by the total spin orientation in this magnetic phase. It was found that the phase transition itself can be influenced by an external magnetic field in case of the 1.8 nm sample but remains unchanged for the 8.3 nm sample. SQUID‐measurements confirm the results of the optical techniques and reveal moreover the occurrence of a field induced ferromagnetic phase transition in case of the thinner sample. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surprising stability of the trion against the free carrier screening
Authors: Klochikhin Albert A. , Kochereshko Vladimir P. , Besombes Luciene , Karczewski Greg , Wojtowicz Tomek , Kossut Jacek 
Published: April 2010

AbstractThe effects of charge‐density fluctuations on trion states and spin‐density fluctuation on the exciton states in quantum well are considered in the limit of low doping by electrons. In both cases the quasi‐two dimensionality of the systems is taken into account. The trion‐chargedensity interaction is considered in the random phase approximation.The influence of the exchange electron‐electron interaction on the excitons is considered using a simplified approach. It is shown that the broadening of the trion absorption band profile with free carrier concentration increase is essentially weaker than the broadening of the exciton absorption band. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Isothermal close space sublimation of CdTe/ZnTe heterostructures in vacuum conditions
Authors: de Melo O. , Sánchez M. , García B. J. , Hernández‐Vélez M. 
Published: April 2010

AbstractThin films and structures of ZnTe and CdTe have been grown by isothermal close space sublimation using alternated exposure of single crystalline substrates to elemental Zn, Te and Cd sources. The results show that the use of vacuum conditions promotes the transport of vapors towards the surface and then efficient growth at lower temperatures. Films thickness ranged between 200 and 600 nm for 50 cycles samples. ZnTe and CdTe films were obtained even at temperatures as low as 310 °C. This is important because low temperatures worsen the inter‐ diffusion processes; as a consequence we have obtained relatively abrupt interfaces in the ZnTe/CdTe system. Its compositional, structural and optical properties are presented. These results offer new possibilities of this low cost technique for growing heterostructures. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Self‐activated luminescence spectra of CdS(O) in the context of the band anticrossing theory
Authors: Morozova Nataliya , Danilevich Nadezhda , Kanakhin Alexey 
Published: April 2010

AbstractThis work proposes an interpretation of self‐activated luminescence in CdS(O), based on the band anticrossing theory, which takes into account the influence of an oxygen isoelectronic impurity on the band structure. Analogous to ZnS‐ZnSe(O), two luminescence bands were discovered in CdS(O), which we named SA and SAL. It was found, that in the presence of dissolved oxygen the SA luminescence consists of two supplementary H and L components. They owe existence to the transitions from E+and E– subbands of the bifid conduction band in CdS(O) to the recombination level of SA luminescence. Their spectral dependence on the concentration of the dissolved oxygen was estimated.SAL self‐activated luminescence in CdS(O) doesn't contain H component, which lies into the fundamental absorption area of the crystal. The structure of SA and SAL centres of luminescence has shown their equivalence to the respective centres in ZnS(ZnSe). In the work we present the position of the localized level of oxygen E0, the band gap Eg versus the dissolved oxygen concentration as well as the general band model of CdS(O). This study supplements the analogous research, performed earlier for ZnS‐ZnSe(O). (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Recrystallization and grain growth in nano‐structured austenitic stainless steel under electric current heating
Authors: Krawczynska Agnieszka T. , Lewandowska Małgorzata , Kuziak Roman , Kurzydłowski Krzysztof J. 
Published: April 2010

AbstractSamples of 316LVM austenitic stainless steel were hydrostatically extruded (HE), in a multi‐step process with the total true strain of 1.84 to produce a microstructure consisting of nanotwins separated by shear bands. The twins average width is 19 nm and length 168 nm. Earlier results proved that a post‐deformation annealing at 700°C for 1 hour results in the formation of a recrystallized structure with nanograins of 93 nm in diameter. In the present study samples were heated to 700°C by an alternating current, AC, using Gleeble 3800 thermo‐mechanical simulator. Changes in the nanostructure were investigated using transmission and scanning electron microscopes. Microhardness was also measured under the load of 200g. The results are discussed in terms of the possibility to use AC heating for post deformation treatment of nano‐sized metals obtained by methods of severe plastic deformation, SPD. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure and properties of copper after large strain deformation
Authors: Rodak Kinga , Molak Rafal M. , Pakiela Zbigniew 
Published: April 2010

AbstractStructure and properties of Cu in dependence on strain (from ε ∼ 0.9 to ε ∼ 15) during multi‐axial compression processing at room temperature was investigated. The evolution of dislocation structure, misorientation distribution and crystallite size were observed by using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) equipment with electron back scattered diffraction (EBSD) facility. The mechanical properties of yield strength (YS), ultimate tensile strength (UTS) and uniform elongation was performed on MTS QTest/10 machine equipped with digital image correlation method (DIC).The structure–flow stress relationship of multi‐axial compression processing material at strains ε ∼ 3.5 and ε ∼ 5.5 is discussed. It is found that processing does not produce any drastic changes in deformation structure and the microstructural refinement is slow. These results indicate that dynamic recrystallization plays an important role during multi‐axial compression process in this range of deformation (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
ZnFe2O4/ZnO nanoparticles obtained by coprecipitation route, XPS and TEM study
Authors: Sibera Daniel , Kaszewski Jarosław , Moszyński Dariusz , Borowiak‐Paleń Ewa , Łojkowski Witold , Narkiewicz Urszula 
Published: April 2010

AbstractThe paper deals with preparation of nanocrystalline zinc oxide doped with iron oxide obtained via calcination process. A mixture of iron and zinc hydroxides of various compositions was used as precursors of nanopowders. The samples were prepared by wet chemistry method – precipitation from the corresponding metals' nitrates' solutions using ammonia. The obtained hydroxides were filtered, dried and calcined at 573 K for 1 hour. A series of samples containing 5 to 95 wt.% of Fe2O3 was obtained. The phase composition of the samples was determined using XRD. Depending on the chemical composition the phases of hexagonal ZnO, and/or romboedric Fe2O3 and/or cubic ZnFe2O4 were identified. The mean crystallite size of ZnFe2O4 phase present in all the samples, determined using Scherrer's formula, varied from 8 to 12 nm. The morphology of the samples was investigated using SEM and HRTEM. X‐ray photoelectron spectra of all the samples were analysed. A detailed spectroscopic and morphological analysis of the samples suggests a core‐shell structure of the produced grains. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of grain size on reactive diffusion between titanium and aluminium
Authors: Wiecinski Piotr , Garbacz Halina , Murakami Hideyuki , Kurzydłowski Krzysztof J. 
Published: April 2010

AbstractThe aim of this paper was to examine the effect of titanium substrate structure refinement (to the nanometric scale) on the chemical and phase composition of Ti‐Al intermetallic layers. The material examined in the study was commercially available pure titanium with average grain size of 65 μm and 60 nm. The aluminium layer with thickness of 5 μm were obtained on both substrates using magnetron sputtering technique. After annealing more phase from Ti – Al system on nano‐crystalline titanium were observed compared to micro‐crystalline one. The obtained intermetallic layer was thicker and more homogeneous on nano‐crystalline substrate. The grain size of the substrate was effected on the topography, thickness and microstructure of the diffusive Ti‐Al layers. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Documentation of the temporal and spatial patterns of pimelodidae catfish spawning and larvae dispersion in the madre de Dios River (Peru): Insights for conservation in the Andean‐Amazon headwaters
Authors: Cañas C. M. , Pine W. E. 
Published: April 2010

AbstractCatfishes (Siluriformes: Pimelodidae) in the Amazon River Basin serve important ecological and economic roles in structuring foodwebs, transferring nutrients and providing food resources for human populations. Large‐scale developments such as construction of the Interoceanic Highway and associated proposed hydroelectric facilities could lead to alterations in river hydrology and aquatic ecosystems within Amazon headwater regions. We assessed temporal and spatial distribution patterns of catfish larvae to determine spawning location (highlands or lowlands) and larval drift patterns associated with rainfall events in the Andean‐Amazon headwaters. We found significant differences in larval fish catch between transects with highest catches occurring in the Madre de Dios River, suggesting that the primary spawning habitats for these catfishes were in regions upstream of our sampling region within the Peruvian Andes. Highest larval catfish catches generally occurred near shore and in association with seasonal pulses in river flow. Based on our observations, we propose that this section of the Madre de Dios River is near the first identified spawning area for Pimelodidae species in the Peruvian Andes, and from this river reach larvae are transported downstream with each seasonal flood event with peak transport generally occurring in October, November and December. This research documents the important role the Madre de Dios Basin plays as spawning habitat for a key fish family in the Amazon River by serving as a corridor both for adult catfish spawning migrations and downstream larval fish transport. Given the critical role these catfishes play in structuring aquatic ecosystems in the Andean‐Amazon region, their importance as a food resource for local people, and increasing threats to this riverine ecosystem associated with dam construction and channel modification, it is important to maintain and protect natural hydrologic conditions in the Madre de Dios to minimize losses of these ecosystem goods and services. Copyright © 2010 John Wiley & Sons, Ltd.
Longitudinal spatial variation in ecological conditions in an in‐channel floodplain river system during flow pulses
Authors: Kobayashi Tsuyoshi , Ryder Darren S. , Ralph Timothy J. , Mazumder Debashish , Saintilan Neil , Iles Jordan , Knowles Lisa , Thomas Rachael , Hunter Simon 
Published: April 2010

AbstractA field survey was conducted during flow pulses to investigate the longitudinal spatial patterns in water quality, dissolved inorganic and organic matter, phytoplankton, planktonic bacteria, zooplankton, gross primary productivity (GPP) of phytoplankton and planktonic respiration (PR) in channels of the large floodplain system (∼124 km in length) of the Macquarie Marshes, south‐eastern Australia. Four river reaches (areas) with distinct hydrogeomorphological characteristics within the distributary zone of the lower Macquarie River were chosen for analysis of abiotic and biotic variables in their in‐stream environments. The results showed marked longitudinal spatial variation in the values within and among the measured environmental variables including such functional aspects as primary productivity and PR. The variables that tended to have increasing values in a downstream direction were conductivity, total nitrogen (TN), total phosphorus (TP), dissolved reactive phosphorus (DRP), dissolved silica, dissolved organic carbon (DOC), dissolved organic nitrogen (DON), dissolved organic phosphorus (DOP), ratio of DOC/DON and counts of planktonic bacteria. Conversely, the values that tended to decrease downstream were the ratios of TN/TP, DIN/DRP, DOC/DOP, DON/DOP and GPP/PR. Variables that had a localized peak(s) were dissolved oxygen, turbidity, dissolved inorganic nitrogen, GPP, PR and counts of cyanobacteria, diatoms, green algae, cryptomonads, protozoans, rotifers, copepods and cladocerans. Overall, two distinct ecological zones were identified within the broader distributary functional process zone (FPZ): these being the upstream zone with relatively high levels of DO, turbidity, diatoms and GPP/PR ratio, and the downstream zone with relatively high levels of nutrients, dissolved organic matter, cyanobacteria, planktonic bacteria, protozoans and cladocerans. The results of this study describe the spatial connectivity of ecological processes related to hydrogeomorphological factors within a FPZ of a riverine ecosystem, and support the predictions of the riverine ecosystem synthesis framework that ecological patterns and processes can be discontinuous on a longitudinal spatial scale. Copyright © 2010 John Wiley & Sons, Ltd.