bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seafloor evidence for ice shelf flow across the Alaska–Beaufort margin of the Arctic Ocean
Authors: Engels Jennifer L. , Edwards Margo H. , Polyak Leonid , Johnson Paul D. 
Published: September 2007

AbstractNew imagery of ∼14 100 km2of seafloor along a 640 km stretch of the Alaska and Beaufort margins (ABM) in water depths from 250 to 2800 m depicts a repetitive association of glaciogenic bedforms (lineations and iceberg scours), broad erosional bathymetric features and adjacent downslope turbidite gullies. These bedforms have styles, depths and orientations similar to features discovered earlier on the Chukchi Borderland, up to 800 km northwest of the ABM. Lineations occur across the surface of a flattened bathymetric bench interpreted to have formed by an ice shelf sliding along the continental slope and scraping the seafloor at temporary grounding locations. The glacial geology of surrounding areas suggests that an ice shelf probably flowed from the mouths of overdeepened glacial troughs in the Canadian Arctic Archipelago westward along the ABM and across the Chukchi Borderland. This curved pathway indicates an obstruction to ice flow in the central Canada Basin, possibly caused by either a basin‐wide ice shelf or by a pile‐up of mega‐bergs originating from the Eurasian side of the Arctic Ocean. The ice shelf that affected the ABM may have formed between Oxygen Isotopic Stage 4 to 5b, possibly correlating to an inferred intra‐Stage 5 widespread Beringian glaciation. Evidence for glaciogenic features on the ABM corroborates suggestions that large ice volumes and extents existed in the Arctic during Pleistocene glacial periods. These findings have far‐reaching implications for Arctic climate studies, ocean circulation, sediment stratigraphy and the stability of circum‐Arctic continental ice masses. Copyright © 2007 John Wiley & Sons, Ltd.
Comparative proteomic analysis of primary mouse liver c‐Kit−(CD45/TER119)− stem/progenitor cells
Authors: He Yu‐Fei , Liu Yin‐Kun , Lu Hao‐Jie , Chen Jun , Yang Peng‐Yuan 
Published: September 2007

AbstractLiver stem/progenitor cells play a key role in liver development and maybe also in liver cancer development. In our previous study a population of c‐Kit−(CD45/TER119)− liver stem/progenitor cells in mouse fetal liver, was successfully sorted with large amount (106–107) by using immuno‐magnetic microbeads. In this study, the sorted liver stem/progenitor cells were used for proteomic study. Proteins of the sorted liver stem/progenitor cells and unsorted fetal liver cells were investigated using two‐dimensional electrophoresis. A two‐dimensional proteome map of liver stem/progenitor cells was obtained for the first time. Proteins that exhibited significantly upregulation in liver stem/progenitor cells were identified by peptide mass fingerprinting and peptide sequencing. Nineteen protein spots corresponding to 12 different proteins were identified as showing significant upregulation in liver stem/progenitor cells and seem to play important roles in such cells in cell metabolism, cell cycle regulation, and stress. An interesting finding is that most of the upregulated proteins were overexpressed in various cancers (11 of 12, including 6 in human hepatocellular carcinoma (HCC)) and involved in cancer development as reported in previous studies. Some of the identified proteins were validated by real‐time PCR, Western blotting, and immunostaining. Taken together, the data presented provide a significant new protein‐level insight into the biology of liver stem/progenitor cells, a key population of cells that might be also involved in liver cancer development. J. Cell. Biochem. 102: 936–946, 2007. © 2007 Wiley‐Liss, Inc.
Analysis of native amino acids by liquid chromatography/electrospray ionization mass spectrometry: comparative study between two sources and interfaces
Authors: de Person Marine , Chaimbault Patrick , Elfakir Claire 
Published: September 2007

AbstractThe analytical performances of two triple‐quadrupole instruments, which differ in their atmospheric‐pressure sources, were evaluated for native amino acid analysis. The Applied Biosystems/Sciex API 300 instrument was equipped with a turboIon Spray source and a curtain gas interface while the Waters/Micromass Quattro Ultima instrument was characterized by its Z‐spray source.Liquid chromatography/mass spectrometry analysis of native amino acids requires volatile ion‐pairing mobile phase additives (mainly perfluorinated carboxylic acids). The effects of the structure and concentration of the ion‐pairing reagents as well as the organic modifier percentage on the electrospray response of amino acids were studied in detail. The most favourable chromatographic conditions depend strongly on the mass spectrometer used. Several instrumental parameters were also studied, including spray voltage, transmission lens voltages, temperature of desolvation and auxiliary gas flow rates. The results show substantial qualitative differences depending on the instrument geometry. The quantitative performances of the two triple‐quadrupole mass spectrometers were evaluated in terms of limits of detection and quantification. The effects of the matrix on the analyte ionization were also examined, and the long‐term stability of the electrospray performance was studied over 12 h using a mobile phase containing the perfluorinated ion‐pairing reagents. The study provides information on the robustness of the MS instrument and its detection sensitivity towards native amino acid analysis. It appears that each instrument has its good and bad points since one provides higher sensitivity while another is more robust. Copyright © 2007 John Wiley & Sons, Ltd.
Gene amplification is a relatively frequent event leading to ZBTB7A (Pokemon) overexpression in non‐small cell lung cancer
Authors: Apostolopoulou K , Pateras IS , Evangelou K , Tsantoulis PK , Liontos M , Kittas C , Tiniakos DG , Kotsinas A , Cordon‐Cardo C , Gorgoulis VG 
Published: September 2007

AbstractZBTB7A (Pokemon) is a member of the POK family of transcriptional repressors. Its main function is the suppression of the p14ARF tumour suppressor gene. Although ZBTB7A expression has been found to be increased in various types of lymphoma, there are no reports dealing with its expression in solid tumours. Given that p14ARF inhibits MDM2, the main negative regulator of p53, we hypothesized that overexpression of ZBTB7A could lead indirectly to p53 inactivation. To this end, we examined the status of ZBTB7A and its relationship with tumour kinetics (proliferation and apoptosis) and nodal members of the p53 network in a panel of 83 non‐small cell lung carcinomas (NSCLCs). We observed, in the majority of the samples, prominent expression of ZBTB7A in the cancerous areas compared to negligible presence in the adjacent normal tissue elements. Gene amplification (two‐ to five‐fold) was found in 27.7% of the cases, denoting its significance as a mechanism driving ZBTB7A overproduction in NSCLCs. In the remaining non‐amplified group of carcinomas, analysis of the mRNA and protein expression patterns suggested that deregulation at the transcriptional and post‐translational level accounts for ZBTB7A overexpression. Proliferation was associated with ZBTB7A expression (p = 0.033) but not apoptosis. The association with proliferation was reflected in the positive correlation between ZBTB7A expression and tumour size (p = 0.018). The overexpression of ZBTB7A in both p53 mutant and p53 wild‐type cases, implies either a synergistic effect or that ZBTB7A exerts its oncogenic properties independently of the p14ARF–MDM2–p53 axis. The concomitant expression of ZBTB7A with p14ARF (p = 0.039), instead of the anticipated inverse relation, supports the latter notion. In conclusion, regardless of the pathway followed, the distinct expression of ZBTB7A in cancerous areas and the association with proliferation and tumour size pinpoints a role for this novel cell cycle regulator in the pathogenesis of lung cancer. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Evaluation of the interfacial state in high impact polystyrene through dynamic mechanical analysis as a function of the synthesis conditions
Authors: de León R. Díaz , Morales G. 
Published: September 2007

AbstractHigh impact polystyrene was synthesized using two series of styrene/butadiene (SB) tapered block copolymers with a polystyrene (PS)/polybutadiene (PB) composition of 30/70 and 10/90 wt%. During the synthesis, concentration of initiator, SB and transfer agent were varied. From dynamic mechanical analysis, the corresponding α relaxation of the rubber phase was detected at low temperature (near −100°C) and that of the glassy PS phase at high temperature (near 100°C). Also, another relaxation at temperature near 40°C was identified, which was associated to the β relaxation of the glassy PS phase. The variations found in the α relaxation of the rubber phase, were attributed to changes in the morphological structure as a consequence of variation in initiator, SB or transfer agent concentrations and in SB composition. β relaxation showed a strong dependency with the interfacial state between the rubber and the glassy phase, where an increase in the amount of graft PS at the interface, which promotes the interfacial adhesion between phases, causes an increase in the magnitude of β relaxation of the PS phase. The results were attributed to variations in the interfacial area as a result of the change in the particle size and to the contribution of molecular chains of each phase in participating in the relaxation process. POLYM. ENG. SCI., 47:1827–1838, 2007. © 2007 Society of Plastics Engineers
A stochastic flow model for a tubular solution polymerization reactor
Authors: Vianna Ardson dos S. , Biscaia Evaristo C. , Pinto José Carlos 
Published: September 2007

AbstractResidence time distributions were evaluated experimentally for three tubular solution polymerization reactors to analyze aspects of the fluid‐dynamic behavior of these reactors. The analysis of the available experimental data indicates that the flow characteristics of these reactors may be subject to stochastic perturbations. A stochastic flow model is then proposed by assuming that a viscous polymer layer is formed in the proximities of the reactor walls and that plugs of polymer material are released at random during the operations. This model is able to represent the available experimental data fairly well for three tubular reactors with different configurations. POLYM. ENG. SCI., 47:1839–1846, 2007. © 2007 Society of Plastics Engineers
Mechanical properties of wollastonite‐reinforced polypropylene composites modified with SEBS and SEBS‐g‐MA elastomers
Authors: Švab Iztok , Musil Vojko , Šmit Ivan , Makarovič Matjaž 
Published: September 2007

AbstractMechanical properties of isotactic polypropylene/wollastonite/styrene rubber block copolymers (iPP/wollastonite/SRBC) composites were studied as a function of elastomeric poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) triblock copolymer (SEBS) and SEBS grafted with maleic anhydride (SEBS‐g‐MA) content from 0 to 20 vol%. Microphase morphology was stronger influenced by SRBC elastomers than by different wollastonite types. Higher encapsulation ability of SEBS‐g‐MA than SEBS caused more expressive core‐shell morphology and consequently higher notched impact strength as well as yield parameters, but lower Young's modulus. Higher ductility of the composites with SEBS than with SEBS‐g‐MA has been primarily caused by better miscibility of the polypropylene chains with SEBS molecules. Surface properties of components and adhesion parameters also indicated that adhesion at SEBS‐g‐MA/wollastonite interface, which was stronger than the one at the SEBS/wollastonite interface, influenced higher encapsulation of wollastonite particles by SEBS‐g‐MA. POLYM. ENG. SCI., 47:1873–1880, 2007. © 2007 Society of Plastics Engineers
Modification of epoxy resin by addition of bismaleimide and diallyl phthalate
Authors: Shenoy M.A. , Patil Mrinalini , Shetty Aditya 
Published: September 2007

AbstractEpoxy resins are a very versatile class of compounds. They have excellent mechanical properties and are easily processable; however, their major drawback is their brittleness. An attempt was made to improve the impact strength of the epoxy without decreasing its other properties. In the present study a commonly used epoxy resin, diglycidyl ether of Bisphenol‐A, was modified by the addition of bismaleimide (BMI) and diallyl phthalate (DAP) and was cured with diaminodiphenylmethane and benzoyl peroxide. The composition incorporating 5 phr BMI showed maximum heat deflection temperature (HDT) and flexural strength with impact properties remaining almost unaffected. Further addition of BMI reduced the HDT and flexural properties but increased the impact strength. For epoxy‐DAP systems the maximum HDT and flexural strength were observed on addition of 5 phr DAP. Further addition of DAP lead to a decrease in all properties except impact strength, which was observed to increase. Incorporation of both BMI and DAP, simultaneously, into the epoxy resin resulted in improvement in mechanical properties for most of the compositions. However, the HDT was found to be less than that for unmodified epoxy. POLYM. ENG. SCI., 47:1881–1888, 2007. © 2007 Society of Plastics Engineers
Extruded starch–nanoclay nanocomposites: Effects of glycerol and nanoclay concentration
Authors: Chiou Bor‐Sen , Wood Delilah , Yee Emma , Imam Syed H. , Glenn Greg M. , Orts William J. 
Published: September 2007

AbstractWheat starch‐Cloisite Na+ nanoclay composites containing different glycerol and nanoclay concentrations were extruded using a twin‐screw extruder. X‐ray diffraction and transmission electron microscopy were used to determine the extent of nanoclay dispersion and thermogravimetric analysis was used to characterize thermal stability of composites. Also, water absorbance was measured for each sample. The extent of nanoclay dispersion in samples containing 47 wt% total plasticizer concentration depended on glycerol concentration. For these samples, adding 5 wt% glycerol produced mostly exfoliated nanoclay, whereas adding 10 or 15 wt% glycerol produced intercalated nanoclay. Also, nanoclay composites exhibited improved thermal stability and reduced water uptake compared to samples with no nanoclay. However, thermal stability and water absorbance were not affected by the extent of nanoclay dispersion. POLYM. ENG. SCI., 47:1898–1904, 2007. © 2007 Society of Plastics Engineers
Effect of thermal aging on the crystal structural characteristics of poly(tetra fluoro ethylene)
Authors: Jain Anjana , Vijayan Kalyani 
Published: September 2007

AbstractThe residual effects of cumulative thermal aging on the crystal structural characteristics of the fluoro carbon poly(tetra fluoro ethylene) (PTFE) have been studied by X‐ray diffraction methods. The initial hexagonal arrangement of the PTFE chains in a 157 helical conformation is left unaffected by the exposures to temperatures (T), up to and beyond its melting point, Tm. The unit cell registers a residual anisotropic volume expansion. The anisotropy arises from the enhanced enlargement of the basal plane dimension a compared with the axial dimension c. Conformational changes contributing to the observed increase in the chain length have been examined. Enhancement of residual crystallinity of samples aged at T's < Tm suggests that the selective thermal aging could be used as an effective tool to improve the initial crystallinity of commercially available PTFE. The activation energy for 50% enhancement in initial crystallinity has been estimated as 53.9 kJ mol−1. Aging at 400°C, a temperature above Tm, is accompanied by markedly different features viz., deterioration in crystallinity and other structural characteristics. The overall behavior of thermally aged PTFE bears a marked similarity to many polyamides. POLYM. ENG. SCI., 47:1724–1729, 2007. © 2007 Society of Plastics Engineers
Slow crack growth‐notches‐pressurized polyethylene pipes
Authors: Brown Norman 
Published: September 2007

AbstractA general method for predicting the lifetime of a polyethylene structure that fails by slow crack growth was applied to the case of externally notched pressurized pipes. An analysis of experimental data indicated that the residual stress must be taken into account. The critical notch depths associated with a given lifetime were calculated as a function of pipe size, PENT value of the resin, and temperature. The results were tabulated to serve as practical guide lines for deciding whether a pipe should be discarded if the notch is too deep. The current 10% of the thickness rule now used by industry was found to be invalid. POLYM. ENG. SCI., 47:1951–1955, 2007. © 2007 Society of Plastics Engineers
Transverse Stark effect in a rectangular semiconducting quantum wire
Authors: Yi Guangyu , Wei Guozhu , Wu Haina 
Published: September 2007

AbstractThe transverse Stark effect in a rectangular quantum wire is investigated in the presence of an electric field by means of the variational calculation method and effective‐mass approximation. We obtain the asymptotic expansions of the Stark shift for low electric fields and for strong electric fields respectively, and find that the Stark shift is a quadratic function of the electric field for low electric fields and is an approximate linear function of the electric field for strong electric fields. The Stark shift and the polarization effect of electron and hole are influenced intensively by the cross‐sectional shape of quantum wires and direction of the electric field. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth mechanisms of inner‐shell tubes in double‐wall carbon nanotubes
Authors: Pfeiffer R. , Peterlik H. , Kuzmany H. , Shiozawa H. , Grüneis A. , Pichler T. , Kataura H. 
Published: September 2007

AbstractThe growth process of inner‐shell tubes from C60 peapods and ferrocene (FeCp2) filled single‐wall carbon nanotubes was studied with Raman spectroscopy and X‐ray diffraction (XRD). In the peapod case, it is shown that the Raman signal of the fullerenes decays about a factor five faster than the XRD peak of the 1D fullerene chain. The growth of the inner‐shell tubes coincides well with the 1D chain decay. In the FeCp2 case, the inner tubes grow already at 600 °C in about one hour. Additionally, even for the same starting material, the inner‐outer tube pair distribution is different than for C60 based inner tubes. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The effects of inhomogeneous isotope distribution on the vibrational properties of isotope enriched double walled carbon nanotubes
Authors: Zólyomi V. , Simon F. , Rusznyák Á. , Pfeiffer R. , Peterlik H. , Kuzmany H. , Kürti J. 
Published: September 2007

AbstractThe radial breathing mode in the Raman spectrum of 13C isotope enriched single walled carbon nanotubes is inhomogeneously broadened due to the random distribution of isotopes. We study this effect theoretically using density functional theory within the local density approximation and compare the result with experiments on isotope engineered double walled carbon nanotubes in which the inner tubes were grown from a mixture of 13C enriched fullerenes and natural fullerenes. As explained by the calculations, this synthesis procedure leads to an increased inhomogeneity compared to a case when only enriched fullerenes are used. The good agreement between the measurements and calculations shows the absence of carbon diffusion along the tube axis during inner tube growth, and presents a strong support of the theory that inner tube growth is governed by Stone–Wales transformations following the interconnection of fullerenes. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman spectroscopy and spectroelectrochemistry of the chemically n‐doped DWCNT
Authors: Kalbac M. , Kavan L. , Zukalova M. , Dunsch L. 
Published: September 2007

AbstractThe Raman spectroscopy and in situ Raman spectroelectrochemistry have been employed to evaluate the state of chemical dopants in the inner space of potassium vapor treated double walled carbon nanotubes (DWCNT) for samples heavily doped. The high doping level was confirmed by the disappearance of the radial breathing mode (RBM) signal of the outer tubes. The RBMs of inner tubes are still detected even after heavy doping. Furthermore the Raman spectra of doped samples show the RBM of inner tubes, which were not in resonance for undoped sample. The removal of potassium from doped DWCNT led to an almost complete recovery of the DWCNT spectra. The possible presence of potassium inside DWCNT has been investigated by electrochemical charging after a treatment of the sample with water. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Curvature effects in the D* band of small diameter carbon nanotubes
Authors: Kürti J. , Zólyomi V. , Koltai J. , Simon F. , Pfeiffer R. , Kuzmany H. 
Published: September 2007

AbstractThe energy dispersion of the D* (G′) band shows a strong diameter dependence according to Raman measurements on double walled carbon nanotubes. The Raman shift of the small diameter inner tubes shows an average softening. There is an oscillation around an average linear behavior with slopes of 108 cm–1/eV and 61 cm–1/eV for the outer and inner tubes, respectively. We show that the experimental observation can be reproduced by simple model calculations if the curvature effects are taken into account. The phonon softening with increasing curvature was proven by first principles calculations. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Frequency, transition‐energy, and bundling behavior of a new class of carbon nanotube intermediate frequency modes
Authors: Doorn Stephen K. , Luo Zhengtang , Papadimitrakopoulos Fotios 
Published: September 2007

AbstractA new class of intermediate frequency modes (IFMs) observed with Raman excitation from 700 nm to 985 nm in the 380–500 cm–1 region are described. These IFMs parallel behaviour previously observed at higher frequencies and resonance energies [Phys. Rev. Lett. 93, 087401 (2004); Phys. Rev. B 72, 085446 (2005)], but in the present case occur through coupling to transitions intermediate in energy between E11 and E22. The IFM intensity behaviour on bundling is found to be the opposite of that for the radial breathing modes (RBMs). We demonstrate that exciton–phonon coupling for the IFMs is enhanced by the bundling process, while the opposite is found for the RBMs. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the selectivity of nanostructured semiconductor gas sensors
Authors: Heszler P. , Ionescu R. , Llobet E. , Reyes L. F. , Smulko J. M. , Kish L. B. , Granqvist C. G. 
Published: September 2007

AbstractDifferent methods are presented for improving chemical selectivity and sensitivity of semiconductor gas sensors consisting of nanostructured thin films. Pure and doped WO3nanoparticles, forming nanoporous layers, are used as test material. The chemical selectivity is increased by applying different operating temperatures, using temperature modulation and pattern recognition methods, and by a fluctuation enhanced spectroscopy technique. The selectivity improvement of a fluctuation enhanced sensor is compared to that of a classical resistive sensor. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Graphite under the magnetic force microscope
Authors: Makarova T. L. , Han K.‐H. 
Published: September 2007

AbstractIn search for magnetically active carbon structures, we have undertaken the magnetic force microscopy study of intrinsic defects at the surface of highly oriented pyrolytic graphite. Most of the observed defects, such as ridges and cleavage edges, are found magnetically inert. However, some of the observed sharp cleavage edges do show magnetic activity – a built‐in surface magnetization, which reveals itself as the magnetic force gradient signal sensitive to the polarity of the tip magnetization. These results indicate the existence of a defect related magnetism at room temperature on graphite surface. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)