bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of New Triphenylene‐containing Discotic Liquid Crystals and the Influence of Fluorophilic Effect and Molecular Symmetry on Mesomorphism
Authors: Ke‐Qing Zhao , Bi‐Qin Wang , Ping Hu , Quan Li , Liang‐Fu Zhang
Published: July 2005

New symmetrical and asymmetrical triphenylene‐containing discotic liquid crystals with two different peripheral alkyl chains, known as sym‐TP(OC6H13)3(OR)3 and asym‐TP(OC6H13)3(OR)3, were synthesized. Their thermotropic liquid crystal properties were investigated through polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and X‐ray diffraction (XRD) analyses. The asymmetrical discogens are 2,6,11‐trialkoxy‐3,7,10‐trihexyloxytriphenylenes, with the alkyl chain carbon numbers varying from 3‐10, 12, and 14, while the symmetrical compounds are 2,6,10‐trialkyloxy‐3,7,11‐trihexyloxytriphenylene. Two fluoroalkoxy substituted triphenylene discogens, 2,6,10‐tri(4,4,4‐trifluorobutoxy)‐3,7,11‐trihexyloxytriphenylene and its asymmetrical isomer 2,6,11‐tri(4,4,4‐trifluorobutoxy)‐3,7,10‐trihexyloxytriphenylene were prepared. These two compounds show higher melting and clearing points than their alkoxy analogs, which implies that fluorophilic effect exists in the formation and stabilization of discotic columnar mesophase. The triphenylene derivatives TP(OC6H13)3(OR)3 with two different peripheral chains, symmetrically or asymmetrically attached on triphenylene cores, have lower melting points and clearing points than those of the higher symmetrical compounds TP(OR)6 with the same total chain carbon numbers. The mixed‐chain‐triphenylenes with longer alkoxy chains (n=9, 10, 12, 14) show columnar mesophase at room temperature.
Interactions with ATP, DNA Cleavage and Anti‐tumor Activities of Complexes with Anions [Mo(V)O2(O2C6H4)2]3‐, [Mo(V)0.5W(VI)0.5O2(O2C6H4)2]2.5‐and [W(VI)O2(O2C6H4)2]2‐
Authors: Xiao‐Ming Lu , Ling Jiang , Xi‐An Mao , Chao‐Hui Ye , Jing‐Fen Lu , Jing‐Rong Cui
Published: July 2005

(NH3CH2CH2NH2)3[Mo(V)O2(O2C6H4)2] (1), (NH3CH2CH2NH2)2.5[Mo(V)0.5W(VI)0.5O2(O2C6H4)2] (2) and (NH3CH2CH2NH2)2[W(VI)O2(O2C6H4)2] (3) were synthesized, structurally characterized by X‐ray diffraction analysis, and studied on their interactions with ATP, their DNA cleavage activities and antitumor properties. The redox state of molybdenum was not changed on going from crystal to aqueous solutions in complexes1and2, while tungsten underwent reduction from W(VI) to W(V) in complexes2and3. ATP promoted the oxidation of both molybdenum and tungsten from M(V) to M(VI) and the hydrolysis of catecholate ligands in solution consisting of ATP and the complexes. Complex1possesses fairly good activity to DNA cleavage and against tumor S180in mice, and is more effective than the control drug cyclophosphamide under the identical conditions. However, complexes2and3exhibited marginal effectiveness. The effectiveness of anti‐tumor of the complexes was related positively to their DNA cleavage activities and their hydrolysis of catecholate ligands.
Dinuclear Oxomolybdate(V) Species with Oxalato and Pyridine Ligands Revisited: cis/trans Isomerization of [Mo2O4(η2‐C2O4)2(R‐Py)2]2– (R‐Py = Pyridine, Alkyl‐Substituted Pyridine) in Water Evidenced by NMR Spectroscopy
Authors: Modec Barbara , Dolenc Darko , Brenčič Jurij V. , Koller Jože , Zubieta Jon
Published: July 2005

The simple oxohalomolybdate(V) ions [MoOCl4(H2O)]– and [MoOBr4]– were reacted with oxalic acid in mixtures containing an alcohol and a pyridine (R‐Py) to form the dinuclear anions [Mo2O4(η2‐C2O4)2(R‐Py)2]2– based on the {Mo2O4}2+ structural core. The dinuclear anion exists in two isomeric forms — as a trans and as a cis isomer. A trans arrangement of the pyridine ligands relative to the Mo2(μ2‐O)2 bridge was observed for (PyH)2[Mo2O4(η2‐C2O4)2Py2] (1), (PyH)2[Mo2O4(η2‐C2O4)2(3,5‐Lut)2] (2), [MeNC5H3(Me)2]2[Mo2O4(η2‐C2O4)2(3,5‐Lut)2]·H2O (3), (4‐MePyH)2[Mo2O4(η2‐C2O4)2(4‐MePy)2]·1/2(4‐MePy) (5), and [(C6H5)4P]2[Mo2O4(η2‐C2O4)2Py2]·H2O (7) [Py = pyridine; 3,5‐Lut = 3,5‐lutidine; MeNC5H3(Me)2+ = N‐methyl‐3,5‐lutidinium cation and 4‐MePy = 4‐methylpyridine], while a cis arrangement was found in only two compounds, namely (4‐EtPyH)2[Mo2O4(η2‐C2O4)2(4‐EtPy)2] (4) (4‐EtPy = 4‐ethylpyridine) and (4‐MePyH)3[Mo2O4(η2‐C2O4)2(4‐MePy)2]Br (6). The solution chemistry of the trans‐[Mo2O4(η2‐C2O4)2Py2]2– anion was monitored by 1H and 13C variable temperature NMR spectroscopy and showed evidence of two processes: the substitution of a pyridine ligand for water, coupled with cis/trans isomerization. Both reactions were exploited in the preparation of trans‐(PyH)2[Mo2O4(η2‐C2O4)2(H2O)2] (8) from a water/methanol solution of cis‐(4‐EtPyH)2[Mo2O4(η2‐C2O4)2(4‐EtPy)2] (4). trans‐(PyH)2[Mo2O4(η2‐C2O4)2(H2O)2] (8) was seen to react with methanol with the rupture of the molybdenum‐to‐oxalate bonds resulting in the cyclic octanuclear anion which crystallizes as a pyridinium salt, (PyH)2[Mo8O16(OCH3)8(μ8‐C2O4)]·2CH3OH (9). The compounds were fully characterized by X‐ray structural analysis and IR spectroscopy. MO calculations were performed on the isomeric pair of [Mo2O4(η2‐C2O4)2(4‐MePy)2]2– in order to establish their relative energies. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Towards Molecular Conductors with a Spin‐Crossover Phenomenon:Crystal Structures, Magnetic Properties and Mössbauer Spectra of[Fe(salten)Mepepy][M(dmit)2] Complexes
Authors: Faulmann Christophe , Dorbes Stéphane , Garreau de Bonneval Bénédicte , Molnár Gábor , Bousseksou Azzedine , Gomez‐Garcia Carlos J. , Coronado Eugenio , Valade Lydie
Published: July 2005

Three new iron(III) compounds of formula [Fe(salten)Mepepy][M(dmit)2]·CH3CN (M = Ni, Pd, Pt; H2salten = 4‐azaheptamethylene‐1,7‐bis(salicylideneiminate); Mepepy = 1‐(pyridin‐4‐yl)‐2‐(N‐methylpyrrol‐2‐yl) ethane; dmit2– = 1,3‐dithiole‐2‐thione‐4,5‐dithiolato) have been synthesised and the crystal structure of each compound has been solved at different temperatures. The structures consist of alternating layers of [M(dmit)2]– units and [Fe(salten)Mepepy] cations. In the Ni compound photo‐isomerisation of the Mepepy ligand can be observed in dichloromethane solution. The temperature dependence of the magnetic susceptibility of the compounds reveals a gradual S = 5/2 blabla S = 1/2 spin crossover of the FeIII ions. This phenomenon is confirmed by Mössbauer spectroscopy for the Ni compound, which also reveals a magnetic component at 4.5 K with a hyperfine magnetic field, Hi, of 442(3) Oe. Theoretical analysis of the thermal variation of the high‐spin proportion allows us to calculate the thermodynamical parameters of the spin‐crossover behaviour in this compound: energy‐gap (Δ) = 1536 cm–1, entropy change (ΔS) = 33 J K–1 mol–1 and a cooperative interaction, J, of 0 cm–1 (non‐cooperative spin crossover). The fractional oxidation state complex [Fe(salten)Mepepy][Ni(dmit)2]3 has been obtained after electrooxidation of [Fe(salten)Mepepy][Ni(dmit)2] in acetonitrile. It exhibits a gradual spin conversion coupled with antiferromagnetic interactions. Its room temperature electrical conductivity is 0.1 S cm–1. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Periodates of Tetravalent Titanium, Zirconium, Hafnium and Thorium: Synthesis, Characterisation and EXAFS Study
Authors: Hector Andrew L. , Levason William
Published: July 2005

Reaction of TiO(SO4)·xH2O with periodic acid in aqueous solution at pH = 2 yields a precipitate of Ti2O2HIO6·5H2O, while reaction of zirconyl, hafnyl or thorium nitrate with periodic acid in hot aqueous nitric acid solutions yields MHIO6·xH2O (M = Zr, Hf, Th; x = 4 or 5). The thorium periodate is soluble in aqueous KOH and KThIO6·4H2O can be precipitated from these solutions. The zirconium, hafnium and both thorium periodates are shown by EXAFS to consist of edge‐sharing chains of MO8 and IO6 units, IR and Raman studies indicate protonation of periodate in the MHIO6 modifications. The titanium periodate contains vertex‐sharing IO6 groups. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
The Electronic Interaction Between Au55(PPh3)12Cl6 Monolayers Through SiO2 Films
Authors: Neumeier Stefan , Reuter Torsten , Schmid Günter
Published: July 2005

Au55(PPh3)12Cl6 monolayers embedded between 5‐nm SiO2 barrier films have been successfully generated. The cluster monolayers were obtained by spin coating of very dilute solutions. The SiO2 films were prepared by means of a special anodic plasma arc technique. Systems of one up to eight cluster/SiO2 combinations on a gold surface have been generated and investigated. In the voltage region between –5 and +5 mV, all samples exhibited linear current‐voltage characteristics. Control samples with only SiO2 show very different I‐U behaviour. We interpret the behaviour observed as a result of electronic tunnelling from the cluster monolayers through the SiO2 barrier films. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Suzuki Reactions with Stable Organic Radicals – Synthesis of Biphenyls Substituted with Nitronyl‐Nitroxide Radicals
Authors: Stroh Christophe , Mayor Marcel , von Hänisch Carsten
Published: July 2005

The synthesis of biphenyls substituted with nitronyl‐nitroxide organic radicals is described. To investigate the Suzuki‐type cross‐coupling reaction conditions in the presence of the radical, a model compound 1 was prepared. The successful coupling was extended to cyano‐functionalized, biphenylic, paramagnetic molecules. Both the ortho‐ and meta‐iodophenyl‐nitronyl‐nitroxide radicals were used to synthesize radicals 2 and 3. The characterizations of the spin‐labelled molecules obtained by this synthetic strategy include two X‐ray crystal structures and magnetic measurements. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Perylene–Oligothiophene–Perylene Triads for Photovoltaic Applications
Authors: Cremer Jens , Bäuerle Peter
Published: July 2005

A series of novel acceptor–donor–acceptor triad systems, consisting of head‐to‐tail‐coupled oligo(3‐hexylthiophene)s integrated between two terminal perylenemonoimides are described. These hybrid molecules, which differ by the length of the oligothiophene units from a quaterthiophene up to a dodecithiophene were synthesized by an effective palladium‐catalyzed Ullmann‐type homo‐coupling reaction in good yields. The optical and electrochemical properties of these compounds were determined, and on the basis of this series structure‐property relationships have been established which provide vital information for the fabrication of the corresponding photovoltaic devices. Because the synthesized perylenyl‐oligothiophenes distinguish themselves by a high absorption between 300 and 550 nm and an almost complete fluorescence quenching of the perylene acceptor, they meet the requirements for organic solar cells. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Theoretical Study on the Reactivity and Regioselectivity of the Ene Reaction of 1Δg O2 with α,β‐Unsaturated Carbonyl Compounds
Authors: Maranzana Andrea , Canepa Carlo , Ghigo Giovanni , Tonachini Glauco
Published: July 2005

The ene reaction of singlet oxygen with α,β‐unsaturated carbonyl compounds gives unsaturated hydroperoxides and displays interesting features: Different reactivities of the s‐cis and s‐trans reactants and a marked regioselectivity, influenced to some extent by solvent polarity. All of these traits are accounted for by a polar diradical mechanism. A perepoxide intermediate is not a critical point on the reaction’s potential energy surface. Also, a trioxene intermediate is located too high in energy to be significantly populated. An alternative pathway leading to dioxetane is not as effective as the ene pathway giving the hydroperoxide. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Palladium‐Catalyzed C–S Bond Formation: Rate and Mechanism of the Coupling of Aryl or Vinyl Halides with a Thiol Derived from a Cysteine
Authors: Moreau Xavier , Campagne Jean Marc , Meyer Gilbert , Jutand Anny
Published: July 2005

The mechanism of the palladium‐catalyzed coupling reaction of aryl or vinyl halides with a thiol derived from a protected chiral cysteine 1 (RSH), leading to C–S bond formation, has been investigated in the context of catalytic reactions. All palladium complexes involved in the catalytic cycle have been characterized, successively, as PhPdI(dppf), PhPdI(SHR)(η1‐dppf) and PhPd(SR)(dppf). The oxidative addition reaction which generates PhPdI(dppf) is followed by the metallation of 1 whose mechanism has been investigated. In the case of the weakly acidic cysteine 1 (RSH) studied here, the anions RS– are not generated in detectable concentrations in the reaction with the NEt3 base. Even if the classical transmetallation reaction of PhPdI(dppf) by RS–, present at a very low concentration, cannot be entirely excluded, we propose that an alternative mechanism, complexation of the thiol, leads to the previously unreported PhPdI(SHR)(η1‐dppf) (observed by 31P NMR spectroscopy) after decomplexation of one of the phosphorus atoms of the dppf ligand, followed by the easier deprotonation of the coordinated RSH by the base, which generates PhPd(SR)(dppf). A classical reductive elimination reaction delivers the coupling product PhSR. The kinetics of all the steps have been investigated independently, one after the other, starting from Pd2(dba)3 and dppf, using the initial concentrations of the reagents used in the catalytic reaction. Under the experimental conditions used in the catalytic reaction involving phenyl iodide and NEt3 as the base, the reductive elimination reaction is the slowest step which mainly limits the rate of the catalytic cycle up to approximately 80 % conversion. The metallation reaction of RSH is very slow when propylene oxide was used as the probase. The reductive elimination is the slowest step in the cross‐coupling of a vinyl iodide. Diastereoisomers of the vinyl‐PdX(dppf) (X = I, SR) complexes were observed as a result of the atropisomerism induced by the bulkiness of the investigated vinyl group and the chiral center present on the vinyl or on the SR group. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Dithioacetals as Zwitterion Synthons
Authors: Luh Tien‐Yau , Lee Chin‐Fa
Published: July 2005

This microreview highlights recent advances in the synthetic applications of dithioacetal functionality. Propargylic dithioacetals and related compounds have been shown to be useful, with the aid of thiophilic organolithium or organocopper reagents, for the synthesis of polysubstituted allenes, trisubstituted furans, and pyrroles. An extension of this annulation reaction to the bidirectional iterative synthesis of furan‐containing oligoaryls and to cyclophane synthesis is described. Alternatively, the convergent synthesis of such oligoaryls from propargylic dithioacetals is briefly discussed. Not only can the carbon–sulfur bonds in dithioacetals be readily displaced by carbon–carbon and/or carbon–heteroatom bonds, but in addition a range of reactions involving polarity inversion in neighboring carbon atoms can also take place. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
New Polymer‐Supported Organosilicon Reagents
Authors: Fauvel Anne , Deleuze Hervé , Landais Yannick
Published: July 2005

New polymer‐supported organosilanes have been prepared using two different strategies. These involved the synthesis of soluble and insoluble supports through the copolymerization of styrene and monomers containing a thiophene ring. Selective metallation of the thiophene ring followed by silylation allowed the introduction of various functionalized organosilanes onto the polymer with a high degree of substitution. These supports can be used for solid‐phase organic synthesis, the product being released through a Tamao–Fleming oxidation, which generates an additional hydroxy group during the cleavage along with the recycled support. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Restricted Rotation in (Phenylpyrrolidino)fullerene Derivatives
Authors: Ajamaa Fettah , Figueira Duarte Teresa M. , Bourgogne Cyril , Holler Michel , Fowler Patrick W. , Nierengarten Jean‐François
Published: July 2005

A complete series of (phenylpyrrolidino)fullerene derivatives has been prepared. A detailed conformational analysis of these compounds has been carried out by variable‐temperature 1H NMR experiments and computational studies. In the case of (phenylpyrrolidino)fullerene derivatives without ortho substituents, dynamic phenomena arising from restricted rotation around the phenyl–pyrrolidine bond are observed. In contrast, as soon as one of the ortho positions of the phenyl ring is substituted, the rotational energy barrier is high enough to prevent observation under our experimental conditions (room temperature to 120 °C) of any dynamic exchange resulting from rotation of the phenyl substituent on the pyrrolidine ring. Whereas, in principle, two diastereoisomeric conformers can exist for the ortho‐substituted (phenylpyrrolidino)fullerenes, only the atropisomers in which the unsubstituted ortho position is located atop the fullerene sphere are obtained. We conclude that the reaction of the ortho‐substituted benzaldehyde derivatives with C60 is diastereoselective, affording only one of the two possible atropisomers. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Microwave‐Assisted Organic Synthesis in Near‐Critical Water at 300 °C –A Proof‐of‐Concept Study
Authors: Kremsner Jennifer M. , Kappe C. Oliver
Published: July 2005

Microwave‐assisted organic synthesis in near‐critical water (NCW) in the 270–300 °C temperature range has been investigated in a dedicated multimode microwave reactor utilizing heavy‐walled quartz reaction vessels. Several different known transformations such as the hydrolysis of esters or amides, the hydration of alkynes, Diels–Alder cycloadditions, pinacol rearrangements, and the Fischer indole synthesis were successfully performed in microwave‐generated NCW without the addition of an acid or base catalyst. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis of a Novel Series of 6,6'‐Disubstituted 4,4'‐Bipyrimidines by Radical Anion Coupling: New π‐Accepting Ligands for Coordination Chemistry
Authors: Ioachim Elena , Medlycott Elaine A. , Polson Matthew I. J. , Hanan Garry S.
Published: July 2005

A new family of 6,6'‐disubstituted 4,4'‐bipyrimidine ligands has been prepared and characterized. The reduction potentials of the new ligands, as determined by cyclic voltammetry, indicate that these new ligands are considerably better π‐acceptors than the ubiquitous 2,2'‐bipyridine ligand, and are even superior to the parent unsubstituted 4,4'‐bipyrimidine ligand. The substituents in 6,6' positions of the 4,4'‐bipyrimidine also cause a red‐shift in the π→π* and n→π* absorptions throughout the UV region. The X‐ray crystal structure of one member of the family of bipyrimidines demonstrates that the aryl substituents may lie coplanar with the pyrimidine rings in the solid state. The additional electron delocalization afforded by the aryl substituents on the pyrimidine rings contribute to the better π‐accepting ability of these compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
The case: Bunche–Da Vinci Learning Partnership Academy
Authors: Eisenberg Nicole , Winters Lynn , Alkin Marvin C.
Published: July 2005

The Bunche–Da Vinci case presents a situation at Bunche Elementary School that the four theorists were asked to address in their evaluation designs.
What theorists say they do: A brief description of theorists' approaches
Authors: Christie Christina A. , Azzam Tarek
Published: July 2005

The authors describe and compare the four theoretical perspectives represented by the theorists writing Chapters Three through Six, providing additional comparative analysis based on their published works.
A value‐engaged approach for evaluating the Bunche–Da Vinci Learning Academy
Authors: Greene Jennifer C.
Published: July 2005

As illustrated in the Bunche–Da Vinci context, a value‐engaged approach to evaluation emphasizes responsiveness to the particularities of the context, inclusion of and engagement with multiple stakeholder perspectives and experiences, and attention to the social and relational dimensions of evaluation practice.
The reality of unreal situations: Caveats and insights
Authors: Alkin Marvin C. , Christie Christina A. , Greene Jennifer C. , Henry Gary T. , Donaldson Stewart I. , King Jean A.
Published: July 2005

The editors give each of the theorists a chance to respond to questions posed about the context of the situation in relation to their own experience in the field, exploring how the exercise had an impact on their evaluation designs.
Unraveling theorists' evaluation reality
Authors: Alkin Marvin C. , Christie Christina A.
Published: July 2005

The volume editors provide a comparative analysis of the evaluation approaches employed by each of the theorists relative to a number of important evaluation issues.
Sol‐gel‐modified titanium with hydroxyapatite thin films and effect on osteoblast‐like cell responses
Authors: Kim Hae‐Won , Kim Hyoun‐Ee , Salih Vehid , Knowles Jonathan C.
Published: July 2005

Titanium (Ti) surface was coated with hydroxyapatite (HA) films via the sol‐gel method. The coating properties, such as crystallinity and surface roughness, were controlled and their effects on the osteoblast‐like cell responses were investigated. The film crystallinity was controlled with different heat treatment temperatures (400, 500, and 600°C): Also the surface roughness was changed by using different heating rates (1 and 50°C/min). The obtained sol‐gel films had a dense and homogeneous structure with a thickness about 1 μm. The film heat‐treated at higher temperature had enhanced crystallinity (600 > 500 ≫ 400°C), while retaining similar surface roughness. When heat‐treated rapidly (50°C/min), the film became quite rough, with roughness parameters being much higher (4–6 times) than that obtained at a low heating rate (1°C/min). The dissolution rate of the film decreased with increasing crystallinity (400 ≫ 500 > 600°C), and the rougher film had slightly higher dissolution rate. The attachment, proliferation, and differentiation behaviors of human osteosarcoma HOS TE85 cells were affected by the properties of the films. On the films with higher crystallinity (heat treated over 500°C), the cells attached and proliferated well and expressed alkaline phosphatase (ALP) and osteocalcin (OC) to a higher degree as compared to the poorly crystallized film (heat treated at 400°C). On the rough film, the cell attachment was enhanced, but the ALP and OC expression levels were similar as compared to the smooth films. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Novel chitosan‐based hyaluronan hybrid polymer fibers as a scaffold in ligament tissue engineering
Authors: Funakoshi Tadanao , Majima Tokifumi , Iwasaki Norimasa , Yamane Shintaro , Masuko Tatsuya , Minami Akio , Harada Kazuo , Tamura Hiroshi , Tokura Seiichi , Nishimura Shin‐Ichiro
Published: July 2005

To clarify the feasibility of using novel chitosan‐based hyaluronan hybrid polymer fibers as a scaffold in ligament tissue engineering, their mechanical properties and ability to promote cellular adhesion, proliferation, and extracellular matrix production were studied in vitro. Chitosan fibers and chitosan‐based 0.05% and 0.1% hyaluronan hybrid fibers were developed by the wet spinning method. Hyaluronan coating significantly increased mechanical properties, compared to the chitosan fibers. Rabbit fibroblasts adhesion onto hybrid fibers was significantly greater than for the control and chitosan fibers. For analysis of cell proliferation and extracellular matrix production, a three‐dimensional scaffold was created by simply piling up each fiber. At 1 day after cultivation, the DNA content in the hybrid scaffolds was higher than that in the chitosan scaffold. Scanning electron microscopy showed that the fibroblasts had produced collagen fibers after 14 days of culture. Immunostaining for type I collagen was clearly predominant in the hybrid scaffolds, and the mRNA level of type I collagen in the hybrid scaffolds were significantly greater than that in the chitosan scaffold. The present study revealed that hyaluronan hybridization with chitosan fibers enhanced fiber mechanical properties and in vitro biological effects on the cultured fibroblasts. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Estrogen provides neuroprotection against activated microglia‐induced dopaminergic neuronal injury through both estrogen receptor‐α and estrogen receptor‐β in microglia
Authors: Liu Xuan , Fan Xiao‐Lan , Zhao Yan , Luo Guang‐Rui , Li Xu‐Ping , Li Rui , Le Wei‐Dong
Published: July 2005

Estrogen provides neuroprotection against neurodegenerative diseases, including Parkinson's disease. Its effects may stem from interactions with neurons, astrocytes, and microglia. We demonstrate here in primary cultures of rat mesencephalic neurons that estrogen protects them from injury induced by conditioned medium obtained from lipopolysaccharide (LPS)‐activated microglia. LPS‐induced nitrite production and tumor necrosis factor‐α up‐regulation in microglia were blocked by estrogen pretreatment. Estrogen neuroprotection was related to microglial activation of estrogen receptors (ERs), insofar as the protective effect of the microglia‐conditioned medium was overridden by pretreatment of microglia with the ER antagonist ICI 182,780. On the other hand, the specific ERα antagonist, MPP dihydrochloride, only partially blocked the effects of estrogen, suggesting that estrogen protection was mediated via both ERα and ERβ. LPS treatment did not change ERα mRNA levels in microglia, astrocytes, and neurons, but it up‐regulated ERβ mRNA levels in microglia and astrocytes. Similarly, increased ERβ protein levels were detected in LPS‐activated microglia. More interesting was that immunocytochemical analysis revealed that ERβ was localized in the cytoplasm of microglia and in the cell nucleus of astrocytes and neurons. In summary, our results support the notion that estrogen inhibits microglial activation and thus exhibits neuroprotective effects through both ERα and ERβ activation. The cytoplasm location of microglial ERβ suggests the possible involvement of nonclassical effects of estrogen on microglia. Changes in microglial ERβ expression levels may modulate such effects of estrogen. © 2005 Wiley‐Liss, Inc.
Front Cover: Macromol. Biosci. 7/2005
Authors: Lee Bae Hoon , Vernon Brent
Published: July 2005

Front Cover: Polymers with time‐dependent LCST properties are dissolved in aqueous buffers at temperatures below the LCST and then gel upon injection at 37 °C. With time the polymers undergo dissolution when the LCST increases above 37 °C. This suggests that they can be cleared by the kidney when dissolved into its individual 30 000 g/mol polymeric chains. Further details can be found in the Full Paper by B. H. Lee, B. Vernon* on page 629.
Back Cover: Macromol. Biosci. 7/2005
Authors: Tsuji Hideto
Published: July 2005

Back Cover: The picture on the cover shows the spherulites (on the upper left side), dried gel (on the upper right side), particulate precipitates (on the lower left and right side), and crystal lattice (in the center) of the poly(lactide) stereocomplexes. Further details can be found in the Review by H. Tsuji on page 569.
Cover Picture: Macromol. Mater. Eng. 7/2005
Authors: Chen Wenping , Zhu Meifang , Song Song , Sun Bin , Chen Yanmo , Adler Hans‐Jürgen P.
Published: July 2005

Cover: The picture on the cover shows that the morphological structures of PMMA/PAN composite particles in nano to submicro size are well characterized by transmission electron microscopy. The selective staining agent is a phosphotungstic acid solution with a pH value of 6.4. Further details can be found in the Full Paper by W. Chen, M. Zhu,* S. Song, B. Sun, Y. Chen, and H.‐J. P. Adler on page 669.
A continuum mechanics‐based framework for optimizing boundary and finite element meshes associated with underground excavations‐framework
Authors: Zsáki Attila M. , Curran John H.
Published: July 2005

Many field problems, from stress analysis, heat transfer to contaminant transport, deal with disturbances in a continuum caused by a ‘source’ (defined by its discrete geometry) and a ‘region of interest’ (where a solution is sought). Depending on the location of ‘regions of interest’ in relation to the ‘sources’, the level of geometric detail necessary to represent the ‘sources’ in a model can vary considerably. A practical application of stress analysis in mining is the evaluation of the effects of continuous excavation on the states of stress around mine openings. Labour intensive model preparation and lengthy computation coupled with the interpretation of analysis results can have considerable impact on the successful operation of an underground mine, where stope failures can cost tens of millions of dollars and possibly lead to closure of the mine.

A framework is proposed based on continuum mechanics principles to automatically optimize the level of geometric detail required for an analysis by simplifying the model geometry using expanded and modified algorithms that originated in computer graphics. This reduction in model size directly translates to savings in computational time. The results obtained from an optimized model have accuracy comparable to the uncertainty in input data (e.g. rock mass properties, geology, etc.). This first paper defines the optimization framework, while a companion paper investigates its efficiency and application to practical mining and excavation‐related problems. Copyright © 2005 John Wiley & Sons, Ltd.
A continuum mechanics based framework for optimizing boundary and finite element meshes associated with underground excavations—accuracy, efficiency and applications
Authors: Zsáki Attila M. , Curran John H.
Published: July 2005

A framework was developed to address the automatic optimization of the level of geometric detail required for stress analysis of underground excavations in mining, which was presented in the companion paper. The motivation for optimizing the mesh geometry stems from the over‐discretization of computational domain as the digital mine model is built while our knowledge of some of the input parameters is quite limited. Thus, the accuracy of the solution is not expected to be increased with a finely discretized mesh, only the computation time does. Therefore, it is acceptable if the results obtained from an optimized model have accuracy comparable to the uncertainty in input data (e.g. rock mass properties, geology, etc.). Although the mesh optimization framework automates the geometry optimization and reduces computation time, the accuracy of the solution from the resulting geometry must be evaluated to ensure the quality of the solution at the ‘region of interest’. Both a priori (mesh quality) and a posteriori (solution quality) measures are employed along with recording the mesh optimization time. Finally, the applicability of the mesh optimization framework is demonstrated by analysing a number of mining and civil engineering underground models. Copyright © 2005 John Wiley & Sons, Ltd.
An approximate planning model for distributed computing networks
Authors: Hollywood John S.
Published: July 2005

We develop an approximate planning model for a distributed computing network in which a control system oversees the assignment of information flows and tasks to a pool of shared computers, and describe several optimization applications using the model. We assume that the computers are multithreaded, and have differing architectures leading to varying and inconsistent processing rates. The model is based on a discrete‐time, continuous flow model developed by Graves [Oper Res 34 (1986), 522–533] which provides the steady‐state moments of production and work‐in‐queue quantities. We make several extensions to Graves' model to represent distributed computing networks. First, we approximately model control rules that are nonlinear functions of the work‐in‐queue at multiple stations through a linearization approach. Second, we introduce an additional noise term on production and show its use in modeling the discretization of jobs. Third, we model groups of heterogeneous computers as aggregate, “virtual computing cells” that process multiple tasks simultaneously, using a judiciously selected control rule. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005.
Firms' collaboration on building a business infrastructure as public goods‐dynamics of common versus firm‐specific benefits
Authors: Kim Bowon , Lee Seungchul
Published: July 2005

In this paper, we investigate under what circumstances firms effectively participate in creating an industry‐wide infrastructure such as an industry standard without incurring opportunistic behaviours. Literature attests that free riding is unavoidable when companies are involved in offering public goods, which will eventually benefit all the members in the industry regardless of whether they actually contributed to making the goods. That is, the steady state equilibrium stocks of capital (investment) for a Markov perfect Nash equilibrium are lower than those in the collusive case, where the companies act like a single entity, not competitors. We postulate that in addition to the non‐discriminating ‘industry‐wide, i.e. common’ benefits, the firm participating in the process can earn another more important type of benefits, firm‐specific benefits, which improve the firm's own internal operations and enhances its performance. If it is indeed possible for the firms to realize there exist both common and firm‐specific benefits in collaboration and to be able to capitalize on both benefits simultaneously, our analysis shows that opportunistic behaviours can be mitigated or even eliminated, meaning economically better solutions can be derived from both the individual firm's and the entire industry's perspective. Copyright © 2005 John Wiley & Sons, Ltd.
Fibroblast growth factor receptor 2, gain‐of‐function mutations, and tumourigenesis: investigating a potential link
Authors: Hansen Ruth MS , Goriely Anne , Wall Steven A , Roberts Ian SD , Wilkie Andrew OM
Published: July 2005

Activating germline mutations in the fibroblast growth factor receptor (FGFR) gene family have been identified in several dominantly inherited skeletal disorders; in the case of FGFR3, the same somatically arising mutations have also been isolated from a variety of tumour tissues. Whilst the role of FGFR2 mutations in congenital syndromes has been well documented, their relationship with cancer has not been clearly defined. Based on evidence that gain‐of‐function mutations in FGFR2 drive positive selection in adult spermatogonia, the present study investigated, by denaturing high‐performance liquid chromatography (DHPLC), DNA sequencing, and restriction digestion, the prevalence of FGFR2 mutations in 58 tumour cell lines of various types, and 29 testicular germ cell tumour samples. Although sequence variations and allelic imbalance were identified in FGFR2, none of the previously documented dominant mutations was detected in any of the tumour types examined. This suggests that gain‐of‐function FGFR2 mutations are not commonly encountered in tumourigenesis and specifically excludes a major contribution in testicular tumours. Copyright © 2005 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Methods for the surface functionalization of γ‐Fe2O3 nanoparticles with initiators for atom transfer radical polymerization and the formation of core–shell inorganic–polymer structures
Authors: Gravano Stefanie M. , Dumas Randy , Liu Kai , Patten Timothy E.
Published: July 2005

Carboxylic acid capped γ‐Fe2O3 nanoparticles were prepared by the standard decomposition of Fe(CO)5 in di‐n‐octyl ether and oleic acid. Two methods were employed to introduce surface functionality to the nanoparticles. First, a thermally stable, tert‐butyldiphenylsilyl‐protected hydroxyl group was incorporated into the carboxylic acid surfactant used during the synthesis. Subsequent deprotection and transformation installed a 2‐bromopropionyl ester group on the particle surface (the functional‐group‐interchange method). The resulting nanoparticles were 4.53 nm in average diameter and were characterized with IR spectroscopy, transmission electron microscopy (TEM), selected area electron diffraction, and elemental analysis. Second, a 2‐bromopropionyl ester group was installed on the particle surface after synthesis via the exchange of the surface oleic acid with a carboxylic acid containing the desired 2‐bromopropionyl ester unit (the ligand‐exchange method). The resulting nanoparticles were 4.30 nm in average diameter and were characterized with IR spectroscopy, TEM, and elemental analysis. Monitoring the percentage of bromine incorporated into the nanoparticle sample versus the ligand‐exchange reaction time indicated that the number of initiator‐containing carboxylic acids that could be exchanged onto the surface was limited, presumably by the steric size of the 2‐bromopropionyl ester group. Styrene was then polymerized directly off γ‐Fe2O3 nanoparticles, and this yielded hybrid core–shell structures. The measurements of the magnetic properties of the samples demonstrated that the magnetism of the core γ‐Fe2O3 nanoparticle did not change during the performance of the chemical transformations. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3675–3688, 2005
Effects of thermal annealing on the viscoelastic properties and morphology of bimodal hard/soft latex blends
Authors: Colombini Didier , Hassander Helen , Karlsson Ola J. , Maurer Frans H. J.
Published: July 2005

The effects of thermal annealing on the viscoelastic properties and morphology of films prepared from bimodal latex blends containing equal weight fractions of soft and hard latex particles with controlled sizes were investigated. The thermal and viscoelastic properties of as‐dried and annealed samples were investigated with differential scanning calorimetry and dynamic mechanical analysis (DMA). Throughout the thermal annealing, the latex blend morphologies were also followed with atomic force microscopy and transmission electron microscopy (TEM). A particulate morphology, consisting of hard particles evenly dispersed in a continuous soft phase, was observed in the TEM micrographs of the as‐dried latex blends and resulted in an enhancement of the mechanical film properties at temperatures between the α relaxations of the soft and hard phases in the DMA thermograms. As soon as the thermal annealing involved temperatures higher than the glass‐transition temperature of the hard phase, the hard particles progressively lost their initial spherical shape and formed a more or less continuous phase in the latex blends. This induced coalescence of the hard particles was confirmed by the association of the experimental viscoelastic data with theoretical predictions, based on self‐consistent mechanical models, which were performed by the consideration of either a particulate or cocontinuous morphology for the bimodal latex blends. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2289–2306, 2005
Viscoelastic properties of bis(phenyl)fluorene‐based cardo polymers with different chemical structure
Authors: Tokumitsu Katsuhisa , Tanaka Akira , Kobori Kana , Kozono Yuji , Yamada Masahiro , Nitta Koh‐Hei
Published: July 2005

Viscoelastic properties of urethane and ester conjugation cardo polymers that contain fluorene group, 9,9‐bis(4‐(2‐hydroxyethoxy)phenyl)fluorene (BPEF), were investigated. As for the urethane‐type cardo polymers containing BPEF in the main chain, it had a high glass‐transition temperature (Tg), which was observed as the α dispersion on viscoelastic measurement, and its temperature depended on the chemical structure of the spacing unit, such as toluene diisocyanate (TDI), 4,4′‐methylene diphenyl diisocyanate (MDI), methylene dicycloexyl diisocyanate (CMDI), and hexamethylene diisocyanate (HDI). Moreover, the Tg of urethane‐type cardo copolymers with various cardo contents increased with an increase of cardo content. Owing to the increase of Tg of cardo polymers, another molecular motion can be measured at the temperature between the α and β dispersion that was assigned to the molecular motion of urethane conjugation unit around 200 K, and it was referred to as the αsub dispersion. The peak temperature of the αsub dispersion was influenced by the chemical structure of the spacing unit, but it did not change for the cardo polymer containing the same spacing unit. Consequently, it was deduced that the αsub dispersion was originated in the subsegmental molecular motions of the cardo polymers. Ester‐type cardo polymer had higher Tg in comparison with noncardo polymer that consisted of dimethyl groups (BPEP) instead of BPEF as well. The αsub dispersion was also measured at the temperature between the α and β dispersion, which was assigned to the molecular motion of ester conjugation unit, around 220 K. For ester cardo polymer, the γ dispersion was measured in a low‐temperature region around 140 K, and it was due to a small unit motion in the ester‐type cardo polymers, such as ethoxyl unit, C2H4O. Moreover, the intensity of the γ dispersion of noncardo polymer was higher than that of cardo polymer, which means the molecular motion was much restricted by the cardo structure of BPEF. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2259–2268, 2005
Functionalized SWNT/polymer nanocomposites for dramatic property improvement
Authors: Ramanathan T. , Liu H. , Brinson L. C.
Published: July 2005

In this paper, we present results for polymer nanocomposites of poly‐ (methyl methacrylate) (PMMA) and amide‐functionalized SWNTs. The results demonstrate that even at very low loadings, 1 wt % (0.5 vol %), the mechanical and electrical properties are significantly improved. The improvement over PMMA properties exceeds the theoretical bounds for composites with the same volume fraction loading of randomly oriented, straight, individually dispersed nanotubes. The modeling and experimental results thus suggest that the nanotube bundles are well dispersed in the polymer matrix, that the functionalization significantly improves interaction with polymer, and that the interphase formed has improved mechanical properties over that of the matrix material. Loss modulus results indicate a significant difference between functionalized and nonfunctionalized tubes in the composite. Functionalized tubes result in a composite in which relaxation mechanisms are shifted by 30 °C from that of the matrix material, indicating extensive interphase regions and absence of PMMA with bulk properties. Unfunctionalized composites demonstrate a broadening of relaxation modes, but still retain the signature of bulk PMMA properties. These data suggest a morphological difference with a discrete interphase layer in unfunctionalized composites and a fully transformed matrix in the case of functionalization. This difference is consistent with electrical and mechanical property data. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2269–2279, 2005
Crystallization behavior of bisphenol A polycarbonate with a simple vacuum process
Authors: Mochizuki Hiroyuki , Mizokuro Toshiko , Tanigaki Nobutaka , Ueno Ichiro , Hiraga Takashi
Published: July 2005

The crystallization behavior of an amorphous polymer, bisphenol A polycarbonate (BAPC), was evaluated. BAPC was crystallized by exposure to diphenylpropane, a component of BAPC, by vapor transportation methods. Furthermore, the surface of BAPC was also crystallized by this method. Crystallized BAPC was employed as a novel simple storage medium, and bit patterns were recorded on its surface by laser irradiation. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2307–2313, 2005
Measurement of the Parameters of Atmospheric‐Pressure Barrier‐Torch Discharge
Authors: Chichina Mariya , Hubicka Zdenek , Churpita Oleksandr , Tichy Milan
Published: July 2005

Summary:The atmospheric plasma jet system was investigated for deposition of oxide layers on polymer (kapton) substrates. The plasma in the system was excited by an RF power source working in pulse modulated mode. This modulation allowed exciting high density plasma in the active part of the duty cycle and simultaneously keeping the neutral gas in the plasma jets at the substrate sufficiently cold, thus protecting the kapton substrate from thermal damage. The atmospheric plasma jet system was tested in two configurations: as single jet system and as linear multi‐jet system with four equivalent jets. The plasma in the system was investigated by means of impedance measurements. A calibrated capacitive voltage probe and a Rogowski current coil were used for direct measurement of voltage and current RF waveforms, respectively. From these data the power deposited in the discharge and the plasma column impedance were estimated. The real part of plasma impedance was used for electron concentrationneestimation. It was found that the electron concentration in the plasma jet was about 2 × 1013cm−3. The atmospheric plasma jet source was used for low temperature deposition of conductive oxide (ZnO) thin films on kapton, silicon and quartz glass substrates. As growth precursors for ZnO films, Zn‐acetylacetonate vapors were used. Deposited ZnO films on both kapton and quartz glass contained hexagonal crystalline phase. They were optically transparent and had an electrical conductivityσ ≈ 10−1–100S · cm−1.

magnified image
Consequences of underwater releases of LNG
Authors: Shaw Stephen , Baik John , Pitblado Robin
Published: July 2005

The potential outcome of marine incidents involving liquefied natural gas (LNG) is of significant interest, but most work has examined above‐waterline releases onto the sea surface. This paper examines the likely discharge rate and changes in hazard zones for underwater releases of LNG compared to surface releases. The discharge rate calculation for underwater LNG releases is more complex than that for the above‐waterline case because of the initial ingress of water into the LNG tank. The entry of water into the LNG storage tank will cause a small positive pressure in the tank and increase the LNG discharge rate through the hole. This report, which identifies some uncertainties, while discussing the sequence of development for such LNG incidents, would support planning for larger‐scale experimental projects. © 2005 American Institute of Chemical Engineers Process Saf Prog, 2005