bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel route to pure and composite fibers of polypyrrole
Authors: Han Gaoyi , Shi Gaoquan 
Published: November 2006

AbstractAn organic salt (FeAOT) is synthesized by the reaction of sodium 1,4‐bis(2‐ethylhexyl)sulfosuccinate (AOT) and ferric chloride. It is fabricated into fibers by manual drawing and electrospinning. Long polypyrrole (PPy) fibers are obtained for the first time by a vapor deposition reaction of pyrrole on the FeAOT fibers, and this technique is extended to the synthesis of PPy composite fibers with multiwalled carbon nanotubes (PPy–MWCNT fibers). The PPy and PPy–MWCNT fibers have a nanoporous morphology, a conductivity of 10–15 S cm−1, and a tensile strength of 12–43 MPa. The electrochemistry and current–voltage characteristics of the PPy fibers are also studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1490–1494, 2007
Fire‐resistant effect of nanoclay on intumescent nanocomposite coatings
Authors: Wang Zhen‐yu , Han En‐hou , Ke Wei 
Published: November 2006

AbstractThe aim of the study is the development of an intumescent nanocomposite coating to provide fire protection for the metallic substrate. Acrylic nanocomposites containing nanoclay and relative intumescent nanocoatings are prepared. The effect of nanoclay on the thermal degradation of an intumescent nanocomposite coating is analyzed by using differential thermal analysis, thermogravimetry, and X‐ray diffraction. The influence of the added content of nanoclay on fire performance is studied by a fire protection test and measurements of the limiting oxygen index and effective thermal conductivity. The distribution of nanoparticles in the acrylic nanocomposite is characterized by transmission electron microscopy. The flame‐retardant efficiency of the intumescent nanocomposite coating is improved by 1.5% well‐distributed nanoclay particles. However, 3% nanoclay produces a negative effect on the fire performance of the coating. Fire protection tests and scanning electron microscopy observations reveal that the fire‐retardant property of a conventional intumescent coating is destroyed by aging, whereas the nanocomposite coating modified with 1.5% nanoclay demonstrates good aging and fire resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1681–1689, 2007
Deposition of polymer complex layers onto nonwoven textiles
Authors: Połowiński S. 
Published: November 2006

AbstractPolymeric complex layers are deposited onto polypropylene and polyester nonwoven fabrics via the layer by layer method. It is found that grafting after previous surface activation with an aqueous ammonium persulfate solution is a beneficial method to form the first acidic layer. In order to form polymer complexes, poly (acrylic acid), poly(itaconic acid), poly(allylamine hydrochloride), and poly(N‐dimethylaminoethyl methacrylate) are used. The deposition of subsequent layers to form polymer complexes modifies the properties of nonwovens. Moreover, it is found that the deposited layers can be microreactors for chemical processes such as polymerization of aniline and formation of polymers and copolymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1700–1705, 2007
Moisture absorption modeling using design of experiments
Authors: Yong Virginia , Hahn H. Thomas 
Published: November 2006

AbstractThe effect of temperature and humidity on equilibrium moisture content of laminates was studied by response surface design. Two glass fabric‐reinforced laminated composite materials with different epoxy matrix resins, laminates A and B, were studied. Laminates A and B used are cyanate ester and polyphenylene oxide modified epoxy based laminate, respectively. The results show that the response surface profiles of moisture absorption for the two laminate materials are similar though their amounts of moisture absorption are different. The temperature‐humidity interaction effect and the quadratic effect of temperature are significant for laminate A. However, only the linear effects of temperature and humidity are significant for laminate B. Predictive models relating the important factors to the equilibrium moisture content were proposed in the article. The models developed can be used to predict and assess the reliability of the laminates for moisture related failures. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1539–1543, 2007
Strain rate mediated microstructure evolution for extruded poly(vinylidene fluoride) polymer films under uniaxial tension
Authors: Fang F. , Zhang M. Z. , Yang W. 
Published: November 2006

AbstractThe deformation and fracture mechanism during uniaxial tension under controlled strain rates are investigated for extruded poly(vinylidene fluoride) (PVDF) polymer films at room temperature. It was found that both the longitudinal and transversal film‐samples exhibited pronounced strain rate effect, that is, the yield stress increases while the fracture strain decreases with the increasing of strain rates. For the longitudinal film samples, phase transformation from the nonpolar α‐phase to the polar β‐phase occurs during the uniaxial tension, and the extent of the phase transformation enhances when the strain rate decreases. For the transversal film samples, no phase transformation was detected in all tested strain rates. By combining the stress–strain behavior and the X‐ray results, it can be inferred that the conformational change from α to β phase during uniaxial tension contributes to the higher fracture strain of the longitudinal films than that of the transversal films. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1786–1790, 2007
Synthesis of poly(aniline‐co‐o‐toluidine) coatings and their corrosion‐protection performance on low‐carbon steel
Authors: Pawar Pritee , Sainkar S. R. , Patil P. P. 
Published: November 2006

AbstractStrongly adherent poly(aniline‐co‐o‐toluidine) coatings were synthesized on low‐carbon‐steel substrates by the electrochemical copolymerization of aniline with o‐toluidine with sodium tartrate as the supporting electrolyte. These coatings were characterized with cyclic voltammetry, ultraviolet–visible absorption spectroscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and scanning electron microscopy. The formation of the copolymer with the mixture of monomers in the aqueous sodium tartrate solution was ascertained by a critical comparison of the results obtained from the polymerizations of the individual monomers, aniline and o‐toluidine. The optical absorption spectrum of the copolymer was drastically different from the spectra of the respective homopolymers, polyaniline and poly(o‐toluidine). The extent of the corrosion protection offered by poly(aniline‐co‐o‐toluidine) coatings to low‐carbon steel was investigated in aqueous 3% NaCl solutions by open‐circuit‐potential measurements and a potentiodynamic polarization technique. The results of the potentiodynamic polarization measurements showed that the poly(aniline‐co‐o‐toluidine) coatings provided more effective corrosion protection to low‐carbon steel than the respective homopolymers. The corrosion rate depended on the feed ratio of o‐toluidine used for the synthesis of the copolymer coatings. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103:1868–1878, 2007
Halide‐Anion Binding by Singly and Doubly N‐Confused Porphyrins
Authors: Maeda Hiromitsu , Morimoto Tatsuki , Osuka Atsuhiro , Furuta Hiroyuki 
Published: November 2006

AbstractThe halide‐binding properties of N‐confused porphyrin (NCP, 1) and doubly N‐confused porphyrins (trans‐N2CP (2), cis‐N2CP (3)) were examined in CH2Cl2. In the free‐base forms, cis‐N2CP (3) showed the highest affinity to each anion (Cl−, Br−, I−) with association constants Ka=7.8×103, 1.9×103, and 5.8×102 M−1, respectively. As metal complexes, on the other hand, trans‐N2CP 2–Cu exhibited the highest affinity to Cl−, Br−, and I− with Ka=9.0×104, 2.7×104, and 1.9×103 M−1, respectively. The corresponding Ka values for cis‐N2CP 3–Cu and NCP 1–Cu were about 1/10 and 1/2, respectively, of those of 2–Cu. With the help of density functional theory (DFT) calculations and complementary affinity measurements of a series of trisubstituted N‐confused porphyrins, the efficient anion binding of NCPs was attributed to strong hydrogen bonding at the highly polarized NH moieties owing to the electron‐deficient C6F5 groups at meso positions as well as the ideally oriented dipole moments and large molecular polarizability. The orientation and magnitude of the dipole moments in NCPs were suggested to be important factors in the differentiation of the affinity for anions.
Synthesis of Murisolin, (15R, 16R, 19R, 20S)‐Murisolin A, and (15R, 16R, 19S, 20S)‐16,19‐cis‐Murisolin and Their Inhibitory Action with Bovine Heart Mitochondrial Complex I
Authors: Hattori Yasunao , Kimura Yuka , Moroda Aki , Konno Hiroyuki , Abe Masato , Miyoshi Hideto , Goto Tetsuhisa , Makabe Hidefumi 
Published: November 2006

AbstractThe asymmetric total synthesis of murisolin, (15R, 16R, 19R, 20S)‐murisolin A, and (15R, 16R, 19S, 20S)‐16,19‐cis‐murisolin was performed by using an epoxy alcohol as a versatile chiral building block for synthesizing the stereoisomers of mono‐THF annonaceous acetogenins. The inhibitory activity of these murisolin compounds was examined with bovine heart mitochondrial complex I, and they showed almost the same activity.
Fluorescent Analysis of Translesion DNA Synthesis by Using a Novel, Non‐natural Nucleotide Analogue
Authors: Lee Irene , Berdis Anthony 
Published: November 2006

AbstractThe replication of damaged DNA is a promutagenic process that can lead to disease development. This report evaluates the dynamics of nucleotide incorporation opposite an abasic site, a commonly formed DNA lesion, by using two fluorescent nucleotide analogues, 2‐aminopurine deoxyribose triphosphate (2‐APTP) and 5‐phenylindole deoxyribose triphosphate (5‐PhITP). In both cases, the kinetics of incorporation were compared by using a 32P‐radiolabel extension assay versus a fluorescence‐quenching assay. Although 2‐APTP is efficiently incorporated opposite a templating nucleobase (thymine), the kinetics for incorporation opposite an abasic site are significantly slower. The lower catalytic efficiency hinders its use as a probe to study translesion DNA synthesis. In contrast, the rate constant for the incorporation of 5‐PhITP opposite the DNA lesion is 100‐fold faster than that for 2‐APTP. Nearly identical kinetic parameters are obtained from fluorescence quenching or the 32P‐radiolabel assay. Surprisingly, distinct differences in the kinetics of 5‐PhITP incorporation opposite the DNA lesion are detected when using either bacteriophage T4 DNA polymerase or the Escherichia coli Klenow fragment. These differences suggest that the dynamics of nucleotide incorporation opposite an abasic site are polymerase‐dependent. Collectively, these data indicate that 5‐PhITP can be used to perform real‐time analyses of translesion DNA synthesis as well as to functionally probe differences in polymerase function.
Pd0.213Cd0.787 and Pd0.235Cd0.765 Structures: Their Long c Axis and Composite Crystals, Chemical Twinning, and Atomic Site Preferences
Authors: Schmidt Joshua Teal , Lee Stephen , Fredrickson Daniel C. , Conrad Matthias , Sun Junliang , Harbrecht Bernd 
Published: November 2006

AbstractWe present single‐crystal studies of Pd0.213Cd0.787 and Pd0.235Cd0.765, synchrotron powder studies of Pd1−xCdx, 0.755≥x≥0.800, and LDA‐DFT and extended Hückel (eH) calculations on these or related phases. The two single‐crystal structures have a, b, and c axis lengths of 9.9013(7), 14.0033(10), 37.063(24) and 9.9251(3), 14.0212(7), 60.181(3) Å, respectively and they crystallize in the space groups Ccme and F2mm, respectively (solved as (3+1)‐dimensional crystals their most convenient superspace group is Xmmm(00γ)s00). The structures have two different structural components each with their own separate axis parameters. Powder data shows that the ratio of these separate axes (S/L) varies from 1.615 to 1.64, values near the golden mean (1.618). For Pd0.213Cd0.787, different Pd and Cd site occupancies lead to variation in the R factor from 2.6–3.6 %. The site occupancy pattern with the lowest R factor (among the 26 820 variants studied) is the exact site occupancy pattern predicted by LDA‐DFT parameterized eH Mulliken charge populations. The phases can be understood through a chemical twinning principle found in γ‐brass, the parent structure for the above phases (a relation with the MgCu2 Laves phase is also noted). This twinning principle can be used to account for Cd and Pd site preferences. At the same time there is a clean separation among the Cd and Pd atoms for the two separate chain types at height b=0 and 1/2. These results indicate that Cd:Pd stoichiometry plays a role in phase stability.
Tris‐Cyclometalated Iridium(III) Complexes of Carbazole(fluorenyl)pyridine Ligands: Synthesis, Redox and Photophysical Properties, and Electrophosphorescent Light‐Emitting Diodes
Authors: Bettington Sylvia , Tavasli Mustafa , Bryce Martin R. , Beeby Andrew , Al‐Attar Hameed , Monkman Andrew P. 
Published: November 2006

AbstractUsing ligands synthesized by Suzuki cross‐coupling methodology, new phosphorescent homoleptic tris‐cyclometalated complexes have been obtained, namely fac‐[Ir(Cz‐2‐FlnPy)3] (1 d–f) and fac‐[Ir(Cz‐3‐FlnPy)3] (2 d–f), which are solution‐processible triplet emitters (Cz denotes N‐hexylcarbazole, n is the number of 9,9′‐dihexylfluorene (Fl) units (n=0,1,2) and Py is pyridine). In all cases, Py and Fl are substituted at the 2‐ and 2,7‐positions, respectively, and Cz moieties are substituted by either Py or Fl at the 2‐ or 3‐positions, in series 1 and 2, respectively. The oxidation potential of 1 d studied by cyclic voltammetry (${E{{{\rm ox}\hfill \atop 1/2\hfill}}}$=0.14 V, versus Ag/AgNO3, CH2Cl2) is less positive (i.e. raised HOMO level) compared to that of the isomer 2 d (${E{{{\rm ox}\hfill \atop 1/2\hfill}}}$=0.30 V), where the Cz‐nitrogen is meta to the Ir center. Ligand‐centered oxidations occur at more positive potentials, leading to 7+ oxidation states with good chemical reversibility and electrochemical quasi‐reversibility, for example, for 2 f ${E{{{\rm ox}\hfill \atop {\rm pa}\hfill}}}$ =0.45 (1e), 0.95 (3e), 1.24 V (3e). Striking differences are seen in the solution‐state photophysical data between complexes [Ir(Cz‐2‐Py)3] (1 d) and [Ir(Cz‐3‐Py)3] (2 d), in which the Cz moiety is bonded directly to the metal center: for the latter there is an 85 nm blue‐shift in emission, a decrease in the luminescence lifetime and an increase in the PLQY value. Organic light emitting devices were made by spin‐coating using polyspirobifluorene:bis(triphenyl)diamine (PSBF:TAD) copolymer as host and the complexes 1 d or 2 d as dopants. Turn‐on voltages are low (3–4 V). With 1 d orange light is emitted at λmax=590 nm with an EQE of 1.3 % (at 7.5 mA cm−2) and an emission intensity (luminance) of 4354 cd m−2 (at 267 mA m−2). The green emission from 2 d devices (λmax=500 nm) is due to the reduced electron‐donating ability of the carbazole unit in 2 d. Recording the EL spectra of the 1 d device at 6 V (current density, 100 mA cm−2) established that the time to half brightness was about 9 h under continuous operation with no change in the spectral profile, confirming the high chemical stability of the complex.
Latrunculin Analogues with Improved Biological Profiles by “Diverted Total Synthesis”: Preparation, Evaluation, and Computational Analysis
Authors: Fürstner Alois , Kirk Douglas , Fenster Michaël D. B. , Aïssa Christophe , De Souza Dominic , Nevado Cristina , Tuttle Tell , Thiel Walter , Müller Oliver 
Published: November 2006

AbstractDeliberate digression from the blueprint of the total syntheses of latrunculin A (1) and latrunculin B (2) reported in the accompanying paper allowed for the preparation of a focused library of “latrunculin‐like” compounds, in which all characteristic structural elements of these macrolides were subject to pertinent molecular editing. Although all previously reported derivatives of1and2were essentially devoid of any actin‐binding capacity, the synthetic compounds presented herein remain fully functional. One of the designer molecules with a relaxed macrocyclic backbone, that is compound44, even surpasses latrunculin B in its effect on actin while being much easier to prepare. This favorable result highlights the power of “diverted total synthesis” as compared to the much more widely practiced chemical modification of a given lead compound by conventional functional group interconversion. A computational study was carried out to rationalize the observed effects. The analysis of the structure of the binding site occupied by the individual ligands on the G‐actin host shows that latrunculin A and44both have similar hydrogen‐bond network strengths and present similar ligand distortion. In contrast, the H‐bond network is weaker for latrunculin B and the distortion of the ligand from its optimum geometry is larger. From this, one may expect that the binding ability follows the order1≥44>2, which is in accord with the experimental data. Furthermore, the biological results provide detailed insights into structure/activity relationships characteristic for the latrunculin family. Thus, it is demonstrated that the highly conserved thiazolidinone ring of the natural products can be replaced by an oxazolidinone moiety, and that inversion of the configuration at C16 (latrunculin B numbering) is also well accommodated. From a purely chemical perspective, this study attests to the maturity of ring‐closing alkyne metathesis (RCAM) catalyzed by a molybdenum alkylidyne complex generated in situ, which constitutes a valuable tool for advanced organic synthesis and natural product chemistry.
Hydroaminomethylation with Novel Rhodium–Carbene complexes: An Efficient Catalytic Approach to Pharmaceuticals
Authors: Ahmed Moballigh , Buch Cathleen , Routaboul Lucie , Jackstell Ralf , Klein Holger , Spannenberg Anke , Beller Matthias 
Published: November 2006

AbstractStarting from [{Rh(cod)Cl}2] and 1,3‐dimesitylimidazole‐2‐ylidenes the novel [RhCl(cod)(carbene)] complexes 1–5 have been synthesized, characterized, and tested in the hydroaminomethylation of aromatic olefins. The influence of different ligands and reaction parameters on the catalytic activity was investigated in detail applying 1,1‐diphenylethylene and piperidine as a model system. The scope and limitations of the novel catalysts is shown in the preparation of 16 biologically active 1‐amino‐3,3‐diarylpropenes. In general, high chemo‐ and regioselectivity as well as good yields of the desired products were achieved.
Kibdelones: Novel Anticancer Polyketides from a Rare Australian Actinomycete
Authors: Ratnayake Ranjala , Lacey Ernest , Tennant Shaun , Gill Jennifer H. , Capon Robert J. 
Published: November 2006

AbstractThe kibdelones are a novel family of bioactive heterocyclic polyketides produced by a rare soil actinomycete, Kibdelosporangium sp. (MST‐108465). Complete relative stereostructures were assigned to kibdelones A–C (1–3), kibdelone B rhamnoside (5), 13‐oxokibdelone A (7), and 25‐methoxy‐24‐oxokibdelone C (8) on the basis of detailed spectroscopic analysis and chemical interconversion, as well as mechanistic and biosynthetic considerations. Under mild conditions, kibdelones B (2) and C (3) undergo a facile equilibration to kibdelones A–C (1–3), while kibdelone B rhamnoside (5) equilibrates to a mixture of kibdelone A–C rhamnosides (4–6). A plausible mechanism for this equilibration is proposed and involves air oxidation, quinone/hydroquinone redox transformations, and a choreographed sequence of keto/enol tautomerizations that aromatize ring C via a quinone methide intermediate. Kibdelones exhibit potent and selective cytotoxicity against a panel of human tumor cell lines and display significant antibacterial and nematocidal activity.
Structural, electrical and optical properties of Ge implanted GaSe single crystals grown by Bridgman technique
Authors: Karaağaç H. , Parlak M. , Karabulut O. , Serincan U. , Turan R. , Akınoğlu B. G. 
Published: November 2006

AbstractStructural, optical and electrical properties of Ge implanted GaSe single crystal have been studied by means of X‐Ray Diffraction (XRD), temperature dependent conductivity and photoconductivity (PC) measurements for different annealing temperatures. It was observed that upon implanting GaSe with Ge and applying annealing process, the resistivity is reduced from 2.1 × 109 to 6.5 × 105 Ω‐cm. From the temperature dependent conductivities, the activation energies have been found to be 4, 34, and 314 meV for as‐grown, 36 and 472 meV for as‐implanted and 39 and 647 meV for implanted and annealed GaSe single crystals at 500°C. Calculated activation energies from the conductivity measurements indicated that the transport mechanisms are dominated by thermal excitation at different temperature intervals in the implanted and unimplanted samples. By measuring photoconductivity (PC) measurement as a function of temperature and illumination intensity, the relation between photocurrent (IPC) and illumination intensity (Φ) was studied and it was observed that the relation obeys the power law, IPC αΦn with n between 1 and 2, which is indication of behaving as a supralinear character and existing continuous distribution of localized states in the band gap. As a result of transmission measurements, it was observed that there is almost no considerable change in optical band gap of samples with increasing annealing temperatures for as‐grown GaSe; however, a slight shift of optical band gap toward higher energies for Ge‐implanted sample was observed with increasing annealing temperatures. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth of ytterbium tartrate trihydrate crystals in silica and agar‐agar gels and their characterization
Authors: Want B. , Ahmad F. , Kotru P. N. 
Published: November 2006

AbstractSingle crystals of ytterbium tartrate trihydrate have been grown by gel method using silica and agar‐agar gels as media of growth. The medium of growth influences the morphology of grown crystals, silica gel yielding single and polycrystalline in the form of spherulites whereas agar‐agar gel leading to growth of single and twinned crystals. Materials grown as single crystals have been characterized by using optical and scanning electron microscopy (SEM), EDAX, XRD, FT‐IR, CHN and thermogravimetric techniques. The stoichiometry of the grown single crystals is suggested to be Yb(C4H4O6) (C4H5O6).3H2O. The FT‐IR spectrum shows the presence of singly as well as doubly ionized tartrate ligands. Results of thermal analysis indicate that the material is thermally stable up to a temperature of 200 °C. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of rhodium incorporation in KTiOPO4 single crystals grown from self‐flux
Authors: Bhaumik I. , Ganesamoorthy S. , Bhatt R. , Karnal A. K. , Sundar R. , Wadhawan V. K. 
Published: November 2006

AbstractThe presence of an impurity like rhodium in the platinum crucible used for the growth of KTiOPO4 (KTP) single crystals can have severe consequences in the performance of devices made from these crystals. In the present study the effect of rhodium incorporation has been investigated. Rhodium‐incorporated KTP crystals have a lower ionic conductivity (1.3 × 10–7 S/cm at 100 kHz) than pure KTP crystals (3.5 × 10–6 S/cm at 100 kHz) along the c‐axis. And the optical absorption in the green‐wavelength regime leads to a detrimental effect on their SHG performance. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)