bluuebunny/crossref_metadata_2025 huggingface dataset:
Fügen von Bauteilen aus UHPC durch Kleben. Voruntersuchungen und Anwendung bei der Gärtnerplatzbrücke in Kasse
Authors: Schmidt Michael , Krelaus Ralf , Teichmann Thomas , Leutbecher Torsten , Fehling Ekkehard
Published: September 2007

Die 136 m lange Gärtnerplatzbrücke über die Fulda in Kassel ist die erste größere Fußgänger‐ und Radbrücke in Deutschland, bei der im größeren Umfang Ultrahochfester Beton (UHPC) verwendet wurde. Weltweit erstmals wurden die vorgefertigten konstruktiven Bauteile aus diesem stahlähnlich festen, sehr gefügedichten Werkstoff auf der Baustelle mit einem Epoxidharzklebstoff tragend miteinander verklebt. Für die Zustimmung im Einzelfall wurden an der Universität Kassel umfangreiche Untersuchungen durchgeführt, um die für die Bemessung der Klebverbindungen notwendigen mechanischen Kennwerte zu ermitteln und um die Dauerhaftigkeit der Klebverbindung abschätzen zu können. Über die Ergebnisse dieser Untersuchungen und über die Ausführung der Baumaßnahme wird nachstehend berichtet. Das praktische Verhalten der hybriden Brückenkonstruktion mit den schubbeanspruchten Klebfugen wird durch ein umfangreiches Monitoringsystem über mehrere Jahre hin online erfasst.
Ingenieurbaukunst: 100 Jahre “Handbuch für Eisenbetonbau”. Vom publizistischen Kraftakt zum literarischen Monument einer neuen Bauweise
Authors: Kierdorf Alexander
Published: September 2007

Nach der Zeitschrift “Beton & Eisen” (1901/02) und dem Beton‐Kalender (1905/06) gilt das 1907–1909 erstmals erschienene “Handbuch für Eisenbetonbau” als die “Krönung des fachpublizistischen Lebenswerks von Emperger”. Die auf vier Bände konzipierte, schon während des Erscheinens auf acht Bände angewachsene Erstauflage erweiterte man in den folgenden Auflagen auf zwölf (1909–1921) bzw. vierzehn Bände (1921–1931) mit zuletzt fast 8000 Seiten, 12.000 Abbildungen, verfasst von etwa 40 Autoren. In seiner systematischen Gliederung, detailfreudigen Darstellung und fachlichen Reife erreichte es das Ziel seiner Väter und Mitarbeiter, die Möglichkeiten des Eisenbetonbaus im Bauwesen aufzuzeigen und ihm solide und dauerhafte Anerkennung zu verschaffen. Zusammen mit der Einrichtung des Deutschen Ausschusses für Eisenbetonbau (Januar) und den von diesem erarbeiteten verbindlichen Bauvorschriften (April) markiert der Erscheinungsbeginn des Eisenbeton‐Handbuchs im Sommer 1907 das Jahr der endgültigen Etablierung dieser Bauweise in Deutschland.
Tunable Photoactivation of a Post‐translationally Modified Signaling Protein and its Unmodified Counterpart in Live Cells
Authors: Hahn Michael E. , Pellois Jean‐Philippe , Vila‐Perelló Miquel , Muir Tom W.
Published: September 2007

An ideal technology for direct imaging of post‐translationally modified proteins would be one in which the appearance of a fluorescent signal is linked to a modification dependent protein‐activation event. Herein, we utilize the protein semisynthesis technique, expressed protein ligation (EPL), to prepare caged analogues of the signaling protein Smad2; the function and fluorescence of the analogues were then photocontrolled in a correlated fashion. We show that this strategy permits titration of the cellular levels of active phosphorylated Smad2 in its biologically relevant, full‐length form. We also prepared a nonphosphorylated, caged full‐length Smad2 analogue labeled with an orthogonal fluorophore, and simultaneously imaged the phosphorylated and nonphosphorylated forms of the protein in the same cell. This strategy should enable the dissection of the cellular consequences of post‐translational modifications (PTMs) by direct comparison of the behavior of the modified and unmodified forms of the protein following uncaging.
Characteristics of a Float Nozzle Designed for CFB Boilers
Authors: Yang H.‐R. , Huang Z.‐M. , Yue G.‐X. , Lu J.‐F.
Published: September 2007

A float nozzle was designed and developed for use with large‐scale industrial circulating fluidized bed (CFB) boilers. The gas distributor equipped with the float nozzle has a unique pressure drop characteristic. It has a higher resistance than other nozzles which results in the formation of an effective barrier against backflow at low boiler loads, which results from the pressure fluctuation caused by bubble burst and solids coming from the recycle system. In addition, it has a relatively low pressure drop at high or full boiler loads, which can greatly reduce the energy cost of the primary air fan.
Performance of a Pinch Analysis for the Process of Recovery of Ethanol from Fermentation
Authors: Khan S. , Riverol C.
Published: September 2007

The objectives of the project reported here were to perform an energy analysis for the process of the recovery of ethanol from fermentation broths by catalytic conversion to gasoline and to conduct a pinch analysis to obtain a new heat exchanger network, and thus, reduce the utility costs. A minimum temperature difference of 10 °C was used. A temperature interval diagram and cascade diagram were drawn to identify the pinch points and four such points were observed. New heat exchanger networks were formulated from this information. The least number of heat exchangers for the different networks created was 19, whereas the original process had 9. The cost of utilities was the same for both systems. Therefore, it was concluded that the implementation of this system in the Caribbean could be expensive since in the first instance, ethanol is not particularly plentiful. Secondly, electricity and water costs are expensive in the Caribbean compared to other countries in America, such that any effort in reducing CO2 emissions by using ethanol would not be feasible.
The First Open‐Paddlewheel Structures in Diruthenium Chemistry: Examples of Intermediate Magnetic Behaviour between Low and High Spin in Ru25+ Species
Authors: Barral M. Carmen , Gallo Teresa , Herrero Santiago , Jiménez‐Aparicio Reyes , Torres M. Rosario , Urbanos Francisco A.
Published: September 2007

The reaction of [Ru2Cl(O2CMe)(DPhF)3] (DPhF=N,N′‐diphenylformamidinate) with aqueous HCl leads to the substitution of the acetate ligand to give the complex [Ru2Cl2(DPhF)3] (1). Similar reaction of [Ru2(O2CMe)(DPhF)3(H2O)]BF4 with aqueous HBr or HI produces [Ru2Br2(DPhF)3] (2), and [Ru2I2(DPhF)3] (3), respectively. The reaction of 1 with AgBF4 to form the highly unsaturated unit [Ru2(DPhF)3]2+, which is isolated as [Ru2(BF4)(DPhF)3(H2O)]BF4 (4), and [Ru2(MeCN)2(DPhF)3](BF4)2 (5), is also reported. The use of AgNO3 instead of AgBF4 leads to [Ru2(NO3)2(DPhF)3] (6). The magnetic behaviour of complexes 1–4 and 6 is intermediate between high‐ and low‐spin configurations. A relationship between the magnetic behaviour and the visible‐near‐infrared (Vis‐NIR) spectra is apparent. In addition, the crystal structure determinations of 2, 4⋅THF, and 6, have been carried out. Complexes 1–3, 5 and 6 are the first examples of open‐paddlewheel structures in diruthenium chemistry. The BF4− bridging the metal centres in 4⋅THF is activated and forms very short RuF bonds.
Solvent‐Dependent Interconversions between RhI, RhII, and RhIII Complexes of an Aryl–Monophosphine Ligand
Authors: Montag Michael , Leitus Gregory , Shimon Linda J. W. , Ben‐David Yehoshoa , Milstein David
Published: September 2007

Reaction of the aryl‐monophosphine ligand α2‐(diisopropylphosphino)isodurene (1) with the RhI precursor [Rh(coe)2(acetone)2]BF4 (coe=cyclooctene) in different solvents yielded complexes of all three common oxidation states of rhodium, depending on the solvent used. When the reaction was carried out in methanol a cyclometalated, solvent‐stabilized RhIII alkyl‐hydride complex (2) was obtained. However, when the reaction was carried out in acetone or dichloromethane a dinuclear η6‐arene RhII complex (5) was obtained in the absence of added redox reagents. Moreover, when acetonitrile was added to a solution of either the RhII or RhIII complexes, a new solvent‐stabilized, noncyclometalated RhI complex (6) was obtained. In this report we describe the different complexes, which were fully characterized, and probe the processes behind the remarkable solvent effect observed.
The Electronic Structure of the Tris(ethylene) Complexes [M(C2H4)3] (M=Ni, Pd, and Pt): A Combined Experimental and Theoretical Study
Authors: Hebben Nicole , Himmel Hans‐Jörg , Eickerling Georg , Herrmann Carmen , Reiher Markus , Herz Verena , Presnitz Manuel , Scherer Wolfgang
Published: September 2007

In this article we analyze in detail the electronic properties of theD3h‐symmetric tris(ethylene) complexes of nickel, palladium, and platinum ([M(C2H4)3] M=Ni, Pd, Pt). In the case of [Pd(C2H4)3] the analysis is based on new experimental IR and Raman spectra for the matrix‐isolated molecules and in all cases on the results of quantum‐chemical (DFT) calculations. The experimental spectra collected for [Pd(C2H4)3] provide evidence for several previously unobserved vibrational modes, including the in‐phase and out‐of‐phase ν(CC) andδ(CH2) modes, and the in‐phase ν(MC) mode. Special consideration is given to possible inter‐ligand interactions. The interaction force constantfCC,CCbetween two C2H4ligands can be directly estimated from the spectra, and its very small value (0.002 N m−1) indicates the absence of any significant inter‐ligand interaction. An analysis of the topology of the theoretical electron density distribution,ρ(r), and the corresponding Laplacian, ∇2ρ(r), for [Pd(C2H4)3] and its lighter and heavier homologues [Ni(C2H4)3] and [Pt(C2H4)3], respectively, is in full agreement with the conclusions drawn from the experimental results. The combined experimental and quantum‐chemical results provide detailed insights in the electronic properties of these prototypical ethylene complexes.
Unser tägliches Brot. Zum Erntedank
Authors: Roth Klaus
Published: September 2007

Man könnte glauben, Brot ist das ultimative “Bioprodukt ganz ohne Chemie”. Das stimmt einfach nicht, denn die Chemie spielt bei der gesamten Brotherstellung vom Korn bis zum gebackenen Brot eine zentrale Rolle. Die vielen ablaufenden chemischen Reaktionen sind komplex und nur in ihren Grundzügen bekannt. Versuche laborerfahrener aber küchenunerfahrener Chemiker, ein Brot nach wissenschaftlichen Prinzipien herzustellen, führen zwar zu mehr oder weniger ess‐ und verdaubaren Endprodukten, dem Vergleich mit den Prachtstücken eines Bäckermeister halten sie aber nicht stand. Aber so ist es eben, kulinarische Wunder sind nur mit Hilfe der Chemie möglich, aber manchmal sollten wir chemische Meisterstücke besser Handwerkern mit ihrem Können überlassen, uns gelassen zurücklehnen und einfach nur genießen!
Wir lernen im Schlaf
Authors: Feil Sylvia
Published: September 2007

Im Schlaf ist der Mensch wehrlos. Allerdings regeneriert sich der Körper und gerade Erlerntes wird langfristig gespeichert. Diese Prozesse werden durch verschiedene Neurotransmitter und Hormone gesteuert. Erst mit dem Absinken etwa der Konzentration von Acetylcholin und Cortisol während des Tiefschlafs kann die Gedächtniskonsolidierung in Gang gesetzt werden.
Ein chemischer Spiegel für den Mond?
Authors: Groß Michael
Published: September 2007

Die Oberfläche einer gleichmäßig rotierenden Flüssigkeit nimmt die Form eines Paraboloids an. Mit einer schön spiegelnden Flüssigkeit wie Quecksilber kann man deshalb sehr große Spiegel für astronomische Teleskope bauen. Nun würden die Kosmologen aber am liebsten ein solches Teleskop auf dem Mond stationieren. Mit Hilfe der Chemie wird selbst das bald möglich.
Vulkanasche als Dünger für den Pazifik
Authors: Feil Sylvia
Published: September 2007

Vulkanausbrüche können große Mengen schwefelhaltiger Asche und Gase wie Kohlendioxid und Wasserdampf in hohe Luftschichten befördern. Diese Effekte sind bekannt, aber inwiefern die ausgespiene Asche einen düngenden Einfluss auf das Meerwasser und dadurch auf das Klima hat, wurde nun untersucht.
Jena
Authors: Schwedt Georg
Published: September 2007

An Johann Wolfgang Döbereiner – den Entdecker der katalytischen Wirkung von Platin, in der Praxis als Feuerzeug genutzt, und den Vater der Triadenregel als Vorläuferin des Periodensystems der chemischen Elemente – wird in der Universitätsstadt Jena an mehreren Orten erinnert. Bereits 1641 gab es für den Mediziner Rolfinck die erste Professur für Iatrochemie.
A numerical approach for efficient and accurate modeling of spot‐welding connection in automotive crash analysis
Authors: Wen He , Weigang Zhang , Zhihua Zhong
Published: September 2007

Modeling of spot‐welding connection is very important in automotive crash analysis, as spot welding is the main approach to assemble the automobile body from hundreds of press‐formed components. Although alternative methods are available for modeling the spot welding, new methods are desirable for better efficiency and accuracy. In this paper, a new approach is proposed for the modeling in an explicit analysis environment. Virtual welding nodes are introduced and constructed from actual nodes of the associated finite element. Given constraints are then imposed on the welding nodes using the Lagrange approach. Good accuracy may be obtained while compatibility with the explicit approach is achieved and numerical stability is unaffected for general mesh layout. The approach is implemented in an explicit code and validated with numerical examples. Copyright © 2007 John Wiley & Sons, Ltd.
Embryonic cells depleted of β‐catenin remain competent to differentiate into dorsal mesodermal derivatives
Authors: Chu Francie H. , Afonin Bonnie , Gustin Jean K. , Bost Alyssa , Sanchez Michael , Domingo Carmen R.
Published: September 2007

Disruption of axis specification leads to defects in dorsal tissue patterning and cell movements. Here, we examine how β‐catenin coordinately affects gastrulation movements and dorsal mesoderm differentiation. The reduction of β‐catenin protein levels by morpholino oligonucleotides complementary to β‐catenin mRNA causes a disruption in gastrulation movements. Time‐lapse imaging of β‐catenin morphants during gastrulation reveals that involution occurs simultaneously around the blastopore in the absence of convergent extension cell movements. Transplantation experiments show that morphant cells grafted from the marginal zone into wild‐type hosts differentiate into notochord and muscle. However, wild‐type mesoderm cells grafted to the marginal zone of β‐catenin morphants do not form dorsal tissues. These data argue that β‐catenin is not required for the initial establishment of dorsal mesoderm cell competency, but it is required for the maintenance of that competency. We propose that tissue interactions that occur during convergent extension movements are necessary for maintaining dorsal tissue competency. Developmental Dynamics 236:3007–3019, 2007. © 2007 Wiley‐Liss, Inc.
The teleost intervertebral region acts as a growth center of the centrum: In vivo visualization of osteoblasts and their progenitors in transgenic fish
Authors: Inohaya Keiji , Takano Yoshiro , Kudo Akira
Published: September 2007

The vertebral column is a defined feature of vertebrates. In birds and mammals, the sclerotome yields cartilaginous material for the vertebral column. In teleosts, however, it remains uncertain whether the sclerotome participates in vertebral column formation. To investigate osteoblast development in the teleost, we established transgenic systems that allow in vivo observation of osteoblasts and their progenitors marked by fluorescence of DsRed and enhanced green fluorescent protein (EGFP), respectively. In twist‐EGFP transgenic medaka, EGFP‐positive cells first appeared in the ventromedial portion of respective somites corresponding to the sclerotome, migrated dorsally around the notochord, and concentrated in the intervertebral regions. Ultrastructural analysis of the intervertebral regions revealed that some of these cells were directly located on the osteoidal surface of the perichordal centrum, and enriched with rough endoplasmic reticulum in their cytoplasm. By using the double transgenic medaka of twist‐EGFP and osteocalcin‐DsRed, we clarified that the EGFP‐positive cells in the intervertebral region differentiated into mature osteoblasts expressing the DsRed. In vivo bone labeling in fact confirmed active matrix formation and mineralization of the perichordal centrum exclusively in the intervertebral region of zebrafish larvae as well as medaka larvae. These findings strongly suggest that the teleost intervertebral region acts as a growth center of the perichordal centrum, where the sclerotome‐derived cells differentiate into osteoblasts. Developmental Dynamics 236:3031–3046, 2007. © 2007 Wiley‐Liss, Inc.
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

New 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

Liver 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

The 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

ZBTB7A (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

High 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

Residence 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

Mechanical 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

Epoxy 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

Wheat 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

The 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

A 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

The 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

The 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

The 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

The 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

The 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

A 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

Different 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

In 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)
Simultaneous determination of amiloride and hydrochlorothiazide in human plasma by liquid chromatography/tandem mass spectrometry with positive/negative ion‐switching electrospray ionisation
Authors: Song Min , Hang Taijun , Zhao Hua , Wang Li , Ge Ping , Ma Pengcheng
Published: September 2007

A new method for simultaneous determination of amiloride and hydrochlorothiazide by liquid chromatography/electrospray tandem mass spectrometry (LC/MS/MS) operated in positive and negative ionization switching mode was developed and validated. Protein precipitation with acetonitrile was selected for sample preparation. The analytes were separated on a Phenomenex Curosil‐PFP (250 × 4.6 mm, 5 µm) column by a gradient elution with a mobile phase consisting of 0.15% formic acid solution containing 0.23% ammonium acetate and methanol pumped at a flow rate of 1.0 mL·min−1. Rizatriptan was used as the internal standard (IS) for quantification. The determination was carried out on a Waters Quattro‐micro triple‐quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode using the following transitions monitored simultaneously: positive m/z 230 → 171 for amiloride, m/z 270 → 158 for rizatriptan, and negative m/z 296 → 205 for hydrochlorothiazide. The lower limits of quantification (LLOQs) were 0.1 and 1.0 ng·mL−1 for amiloride and hydrochlorothiazide, respectively, which were lower than other published methods by using ultraviolet (UV), fluorimetric or mass spectrometric detection. The intra‐ and inter‐day precision and accuracy were studied at three different concentration levels and were always better than 15% (n = 5). This simple and robust LC/MS/MS method was successfully applied to the pharmacokinetic study of compound amiloride and hydrochlorothiazide tablets in healthy male Chinese volunteers. Copyright © 2007 John Wiley & Sons, Ltd.
Overexpression of the Rho‐guanine nucleotide exchange factor ECT2 inhibits nuclear translocation of nuclear receptor CAR in the mouse liver
Authors: Hosseinpour Fardin , Timsit Yoav , Koike Chika , Matsui Kenji , Yamamoto Yukio , Moore Rick , Negishi Masahiko
Published: September 2007

Various drugs such as phenobarbital (PB) trigger translocation of constitutive active/adrostane receptor (CAR) from the cytoplasm into the nucleus of mouse liver cells without directly binding to the receptor. We have now characterized the guanine nucleotide exchange factor epithelial cell‐transforming gene 2 (ECT2) as a PB‐inducible factor as well as a cellular signal that represses PB‐triggered nuclear translocation of CAR. When CFP‐tagged ECT2 was co‐expressed with YFP‐tagged CAR in the liver of Car
−/− mice, ECT2 repressed CAR nuclear translocation. Coexpression of various deletion mutants delineated this repressive activity to the tandem Dbl homology/pleckstrin homology domains of ECT2 and to their cytosolic expression. CAR directly bound to the PH domain. Thus, ECT2 may comprise a part of the PB response signal regulating the intracellular trafficking of CAR.
The use of film subtitles to estimate word frequencies
Authors: NEW BORIS , BRYSBAERT MARC , VERONIS JEAN , PALLIER CHRISTOPHE
Published: September 2007

We examine the use of film subtitles as an approximation of word frequencies in human interactions. Because subtitle files are widely available on the Internet, they may present a fast and easy way to obtain word frequency measures in language registers other than text writing. We compiled a corpus of 52 million French words, coming from a variety of films. Frequency measures based on this corpus compared well to other spoken and written frequency measures, and explained variance in lexical decision times in addition to what is accounted for by the available French written frequency measures.
Commentary on “Legislating for a Market Economy in China”
Authors: Zhang Xianchu
Published: September 2007

Donald Clarke's article provides a pretty full and accurate review of legislative activities in the course of China's economic developments since 1992. His perceptive analysis not only reflects the important achievements of economic legislation and its undeniable contribution to market developments in China, but also critically conceptualizes the many-featured legislative practice within an established theoretic framework with an emphasis on institutional capacity building.
The Police and the Rule of Law: Commentary on “Principals and Secret Agents”
Authors: Weifang He
Published: September 2007

Among Chinese political scientists and legal scholars, indeed within the Chinese academic world as a whole, research into the police is to a great degree marginalized. As the media have become more active, and in particular as internet media have arisen, it has become easier for some incidents of police infringements of human rights to attract nationwide attention. But there has been very little discussion of the relationship between these incidents and the police management system, or the division of police management power between the central and local governments and its ultimate influence on the construction of society in China under the rule of law.
Commentary on “China and the International Legal System: Challenges of Participation”
Authors: Zhaojie James Li
Published: September 2007

China's participation in the international legal system has long been a topic of academic inquiry both inside and outside China, and has produced a rich literature reflecting mainly two concerns. First, is China a help or a hindrance to the development of the international legal system? If China is a help, what impact has China made upon the contemporary international legal system and what can China contribute to its further development? Secondly, what impact has the international legal system in which China has participated had on China? In recent years, the context in which these questions are framed has changed greatly. After the founding of the PRC in 1949, China was seen as a potential rebel against the prevailing international legal system. Today, China is depicted, at least in the mind of US decision-makers, as a stakeholder of the world order.
Commentary on “Trade, Investment and Beyond”
Authors: Dongli Huang
Published: September 2007

In her article, Julia Ya Qin draws conclusions from the accession of China to the WTO which reflects the effects of WTO obligations on China's constitutional law, the development of foreign trade law, the foreign investment regime, intellectual property rights protections and general rule-of-law conditions. With respect to foreign trade law, the foreign investment regime and intellectual property rights protections, it is not difficult to observe the legal consequences the accession has brought and will bring to China. However, Qin's article goes beyond these general observations and provides profound insights on significant effects of the WTO obligations on China's economic reforms as well as rule of law processes. This essay comments on arguments she has presented on these issues.