bluuebunny/crossref_metadata_2025 huggingface dataset:
Macromol. Biosci. 9/2008
Authors: Mandal Biman B. , Kundu Subhas C.
Published: September 2008

Cover: The cover picture shows a uniform growth of cells with spread out cytoskeleton and clear nuclei on the high strength non‐bioengineered silk fibroin protein 3D scaffolds along with different life stages of the silkworm. Being cytocompatible and biodegradable the natural non‐mulberry matrices has potential for biotechnological and tissue engineering applications. Further details can be found in the article by B. B. Mandal and S. C. Kundu on page 807.
Anisotropic Photomechanical Response of Stretched Blend Film Made of Polycaprolactone‐Polyvinyl Ether with Azobenzene Group as Side Chain
Authors: Tanaka Shimon , Kim Hyun‐Kyoung , Sudo Astushi , Nishida Haruo , Endo Takeshi
Published: September 2008

A rapid and reversible anisotropic photomechanical response of polymer film was achieved by using uniaxially stretched blend film composed of polycaprolactone and poly(vinyl ether) with azobenzene moiety (Azo‐PVE) as a side chain. The photomechanical response behavior of the film was studied under a constant tensile stress. The deformation or recovery was rapidly completed within at most 0.1 min of UV + Vis light irradiation being switched on or off, respectively. The anisotropy of deformation was confirmed on a stretched film subjected to light irradiation. The deformation was observed as a contraction in a direction parallel to the stretching direction and as an elongation in the perpendicular direction. The anisotropy of the photoresponse was remarkably observed with increase in the stretching ratio, reflecting the binding between amorphous areas by Azo‐PVE long chains.

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Photoinitiated Cationic Polymerization of Mono and Divinyl Ethers in Aqueous Medium Using Ytterbium Triflate as Lewis Acid
Authors: Kahveci Muhammet U. , Tasdelen M. Atilla , Cook Wayne D. , Yagci Yusuf
Published: September 2008

Photoinitiated cationic polymerization of vinyl ethers in aqueous medium by using diphenyliodonium iodide (DPII) in the presence of a water‐tolerant Lewis acid, ytterbium triflate (Yb(OTf)3), was reported. The polymerizations were performed in heterogeneous systems consisting of an aqueous phase containing Yb(OTf)3 and photoinitiator and an organic phase of acetonitrile containing monomer. The polymerization consists of two‐steps; (i) photoinduced adduct formation and (ii) subsequent propagation with the aid of Yb(OTf)3. The fast polymerization exhibited an explosive character so that the monomer conversion and molecular weights of the resulting polymers are very dependent on the experimental conditions, such as temperature, stirring manner and rate.

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Increased Electrical Conductivity in Poly(3,4‐ethylenedioxythiophene) upon Cross‐Linking
Authors: Mendez James D. , Weder Christoph
Published: September 2008

Cross‐linked poly(3,4‐ethylenedioxythiophene) (PEDOT) films were synthesized by the oxidative polymerization of 3,4‐ethylenedioxythiophene in the presence of five different conjugated and non‐conjugated cross‐linkers. The concentration and structure of the cross‐linker was systematically varied to explore the influence on the electrical conductivity. Optimized compositions displayed an electrical conductivity of up to ≈800 S · cm−1; this corresponds to a conductivity increase of up to 36% compared to linear PEDOT prepared under identical conditions. An increase in the conductivity was only observed for the conjugated cross‐linkers that were incorporated in low concentrations, typically at a level of less than 2 mol‐%. Attempts to incorporate higher concentrations of cross‐linker led to phase separation and crystallization of the cross‐linker and afforded materials in which a significant reduction of the electrical conductivity was observed. The optical properties of the polymer were only marginally affected upon cross‐linking, even at high cross‐linker concentrations.

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Aging Effects on the Phase Composition and Chain Mobility of Isotactic Poly(propylene)
Authors: Hedesiu Cristian , Demco Dan E. , Kleppinger Ralf , Poel Geert Vanden , Remerie Klaas , Litvinov Victor M. , Blümich Bernhard , Steenbakkers Rieky
Published: September 2008

Changes in phase composition and chain mobility in injection‐molded isotactic poly(propylene), crystallized from the melt with slow cooling rate and subsequently quenched, associated with aging at temperature well above Tg for 150 and 1 000 h, are studied using time‐domain 1H solid‐state NMR and XRD. All sample exhibit physical aging when exposed to elevated temperatures, and the physical aging kinetics was observed to depend on the morphology of the homopolymer iPP and aging temperatures. The significant increase in the tensile modulus in time was observed for injection‐molded iPP. The observed property changes induced by aging are attributed to microstructural changes within the semi‐rigid and amorphous fractions.

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Polyurethanes with Narrow‐ and Polydisperse Hard Segment Distributions
Authors: De Debasish , Gaymans Reinoud J.
Published: September 2008

Polyurethanes with narrow‐disperse (ND) and polydisperse (PD) hard segment (HS) distributions were prepared in a two‐step process. First, a poly(propylene oxide) end‐capped with MDI (4,4′methylenebis(phenyl isocyanate) was synthesized. To this prepolymer either a diamine–diamide was added to form ND HSs or a mixture of a diamine–diamide and additional MDI to form PD HSs in the copolymers. The polyurethanes displayed a ribbon‐like crystalline morphology, and it was found that the copolymers with ND HSs were more crystalline, had a higher modulus, a less temperature‐dependant modulus, and a higher melting temperature than their PD counterparts. Overall, the polyurethanes with the narrow‐dispersed HSs displayed superior properties.

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Rheological Features and Flow‐Induced Crystallization of Branched Poly[ethylene‐co‐(1,4‐cyclohexanedimethylene terephthalate)] Copolyesters
Authors: Quintana Robert , de Ilarduya Antxon Martínez , Guerra Sebastián Muñoz , Fernández Mercedes , Muñoz María Eugenia , Santamaría Anton
Published: September 2008

A set of amorphous poly[ethylene‐co‐(1,4‐cyclohexanedimethylene terephthalate)] (PECT) copolymers containing 25 and 30% of 1,4‐cyclohexane dimethylene (CHDM) units and small amounts of branching agent pentaerythritol (PER) is investigated. The level of long chain branching was estimated by analyzing the positive deviation from $\eta _0 \sim\overline M _{\rm w}^{3.54}$ law. Branching also produced melt elasticity enhancement which is desirable for certain processing methods. Capillary extrusion experiments at 180 °C generated flow‐induced crystallization in PECT containing 25% of CHDM. Crystallization increased with the amount of PER added, which was explained by the favorable effect of branching to increase elongational rate at the entrance of the capillary. Linear and branched PECTs containing 30% of CHDM did not crystallize.

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Novel in situ NMR Measurement System for Evaluating Molecular Mobility during Drawing from Highly Entangled Polyethylene Melts
Authors: Kakiage Masaki , Uehara Hiroki , Yamanobe Takeshi
Published: September 2008

A novel in situ measurement system for evaluating molecular mobility during uniaxial drawing of polymeric materials was established by introducing drawing and stress‐detecting devices into a 1H pulse nuclear magnetic resonance spectrometer. In this study, we analyze the changes in molecular motion of amorphous chains during melt‐drawing of ultra‐high molecular weight polyethylenes (UHMW‐PEs) with different molecular weight distributions. In the initial stage of drawing, a three‐component resolution was possible for the relaxation decay curve, which includes “rigid”, “intermediate”, and “mobile” amorphous components. The quality and quantity changes in these components demonstrated that this intermediate amorphous component could be regarded as the index of the change in molecular entanglement characteristics during the orientation of PE chains.

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Thermoreversible Contraction and Extension of Layer Spacing in Smectic Phase of Side Chain Liquid Crystal Poly(fumarate)s
Authors: Michinobu Tsuyoshi , Fujii Nozomu , Tokita Masatoshi , Watanabe Junji , Shigehara Kiyotaka
Published: September 2008

Two types of liquid crystal poly(fumarate)s having cyanobiphenyl mesogen in side chain were prepared by radical polymerization of disubstituted fumarate monomers in bulk. The mesogen is thus connected via alkyl spacer to every carbon atom in the main chain. The liquid crystalline temperature range expands with an increase in the molecular weight and with alkyl chain spacer length. The poly(fumarate)s form a smectic Ad phase whose layer spacing decreases and increases on heating and cooling, respectively. The contraction ratio is up to 15.2%. This significantly large change in the layer spacing corresponds to temperature dependence of the orientational order parameter. It may be connected to high density of the mesogen hanging from the main chain.

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Taking Advantage of Tailored Electrostatics and Complementary Hydrogen Bonding in the Design of Nanostructures for Biomedical Applications
Authors: Hunley Matthew T. , Karikari Afia S. , McKee Matthew G. , Mather Brian D. , Layman John M. , Fornof Ann R. , Long Timothy E.
Published: September 2008

Four‐armed, star‐shaped poly(D,L‐lactide) (PDLLA) was synthesized and terminally‐functionalized with either adenine or thymine complementary hydrogen bonding groups (PDLLA‐A and PDLLA‐T, respectively). The strong hydrogen bonding led to increased viscosity below the dissociation temperature of the hydrogen bonds. Rheology confirmed that these bonds were thermally reversible, with a sharp reduction in viscosity near 100 °C. PDLLA, PDLLA‐A, and PDLLA‐T were melt electrospun with no significant change in fiber diameter (all between 3.6 and 4.0 µm). However, a blend of PDLLA‐A and PDLLA‐T formed fibers with an average diameter of 9.8 ± 2.0 µm, resulting from the hydrogen bond associations. Also, the phospholipid 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphoethanolamine (POPE) was melt electrospun at 200 °C and formed uniform fibers with average fiber diameter of 6.5 ± 2.0 µm.
Supramolecular Assembly and Hybridization in Giant Nanomembranes
Authors: Kunitake Toyoki
Published: September 2008

We demonstrated recently that large nanomembranes became available from inorganic, organic/inorganic and totally organic precursors. Spin coating of mixtures of acrylate monomers and zirconium butoxide (or tetraethoxysilane), when combined with simultaneous radical polymerization and sol‐gel reaction, gave 10–30 nm thick, free‐standing nanomembranes composed of metal oxides and crosslinked acrylates as interpenetrating network. This approach was extended to thermosetting resins (epoxy, melamine and phthalic resins), to fabricate robust, free‐standing nanomembranes. Mechanical properties of the nanomembranes as measured by the bulge test and by a compression method were comparable to those of the corresponding macroscopic resins.

The hybrid nanomembrane was subsequently prepared by supramolecular assembly of the nanofilm with surfactants and lipids. These amphiphiles produced adsorbed monolayers on the nanomembrane and some of the assemblies were stably kept in water.
Self‐Assembly of Inorganic Nanocrystals: Emergence of a New Physics
Authors: Pileni M. P.
Published: September 2008

In this paper we demonstrate that ordering of nanocrystals on long distance in 3D superlatices called supra crystals permit to emerge of collective intrinsic properties, which was not expected. The shape of the organization at the mesoscopic scale also induces new physical properties.
Capped Bimetallic and Trimetallic Nanoparticles for Catalysis and Information Technology
Authors: Toshima Naoki
Published: September 2008

Summary: Polymer‐capped metal nanoparticles can be recognized as a kind of macromolecule‐metal nanoparticle complexes. Here the preparations of the capped bimetallic and trimetallic nanoparticles, in which each particle contains two and three elements of metal, respectively, are presented. They may have a random alloy, a core/shell, or other kinds of structure depending on the preparation method and the combination of elements. The core/shell structure is advantageous to electronically control the activity of metal catalysts. The triple core/shell structured trimetallic nanoparticles were found to have higher catalytic activity than the corresponding monometallic and bimetallic nanoparticles in three cases. Capped metal nanoparticles were also used as a dopant to liquid crystals. Liquid crystal displays, fabricated by metal nanoparticle‐doped liquid crystals, showed faster response than those without dopants. Bimetalization could increase the long‐term stability in the doped liquid crystal displays. Thus, metal nanoparticles can improve the electronic display system, which occupies an important position in information technology. In addition, SmCo5 nanomagnets were successfully prepared by a chemical method, possibly providing a new building block for information technology. The prepared SmCo5 nanoparticles have a coercivity of 1500 Oe at room temperature. The bimetallic nanoparticles may open a new field in super‐high‐density magnetic memories.
Functional Columnar Liquid Crystalline Phases From Ionic Complexes of Dendronized Polymers and Sulfate Alkyl Tails
Authors: Canilho Nadia , Kasëmi Edis , Schlüter A. Dieter , Ruokolainen Janne , Mezzenga Raffaele
Published: September 2008

We describe how cationic dendronized polymers of generations 1, and 2 and anionic monoalkyl tails can be combined by supramolecular ionic complexation into comb‐like liquid crystalline polymers. The final structures in bulk of these supramolecular complexes were studied by differential scanning calorimetry (DSC), cross‐polarized optical microscopy (CPOM), small angle x‐rays scattering (SAXS) and transmission electron microscopy (TEM). The combination of these techniques allowed elucidating (i) that these complexes exhibit thermotropic behaviour, (ii) that various liquid crystalline structures in the 3–5 nm length scale can be obtained such as columnar rectangular, columnar tetragonal, columnar hexagonal and lamellar, depending both on alkyl tail length and polymer generation, (iii) that although the alkyl tails represent the majority phase in the columnar phases, they form the cylindric domains, and the dendronized polymers occupy the continuous domains. Therefore, upon selective cleavage of the alkyl tails in the columnar phases, the present self‐assembly approach may constitute an efficient strategy towards the formation of porous organic matrices with ultra‐dense pore size in the range of 2 to 4 nm.
Computer Study of Stimuli‐Responsive Polyelectrolyte Micelles in Aqueous Media. Comparison of Monte Carlo and Self‐Consistent Field Approaches
Authors: Jelínek Karel , Uhlík Filip , Limpouchová Zuzana , Procházka Karel
Published: September 2008

The behavior of polyelectrolyte micelles with kinetically frozen hydrophobic cores in aqueous solutions was studied by Monte Carlo (MC) simulations and self‐consistent field (SCF) calculations. Some results have already been published. The structure of water‐soluble shells formed by weak polyelectrolytes, both pure and containing a low fraction of strongly hydrophobic units arranged either in a short sequence or distributed uniformly in the shell‐forming chains was studied in detail. In the case of sequenced system, the analysis of concentration profiles of individual species reveals strong segregation and important self‐organization of hydrophobic units in the shell. A comparison and critical analysis of results of MC and SCF methods is presented.
Bisthiol‐Assisted Multilayers' Self‐Assembly of Gold Nanoparticles: Synthesis, Characterization, Size Control and Electrocatalytic Applications
Authors: Abdelrahman Ahmed I. , Mohammad Ahmad M. , El‐Deab Mohamed S. , Okajima Takeyoshi , Ohsaka Takeo
Published: September 2008

The layer‐by‐layer (LBL) approach has been utilized to self‐assemble multilayers films of citrate‐stabilized gold nanoparticles (AuNPs) on polycrystalline gold (poly‐Au) substrates. 1,4‐benzenedimethanethiol (BDMT) was used as a cross linker to bind every two successive AuNPs layers. The transmission electron microscopy (TEM), and X‐ray photoelectron spectroscopy (XPS) techniques were employed to confirm the existence of the alternative layers of AuNPs and BDMT in the self‐assembled multilayers film. The AuNPs modified poly‐Au electrode showed a significant electrocatalysis towards the reduction of oxygen (a positive potential shift of about 100 mV was observed in the reduction peak potential compared to that obtained at the bare poly‐Au electrode). The AuNPs tend to aggregate during their assembling to different extent which markedly depends on the substrate geometry and roughness. An effort was dedicated to understand and control the aggregation phenomenon.
Fusion and Growth Behavior of Gold Nanoparticles Stabilized by Allylmercaptane
Authors: Shirahata Naoto , Yonezawa Tetsu , Matsushita Yoshihiro , Masuda Yoshitake , Koumoto Kunihito
Published: September 2008

Fusion and growth behavior of gold nanoparticles in a relatively low temperature range were studied using a transmission electron microscopy (TEM). Using allylmercaptane (AM: 2‐propene‐1‐thiol, HSCH2CHCH2) as a particle stabilizer, a colloidal suspension of AM‐terminated gold nanoparticles was prepared with a two‐phase system. TEM observation revealed that the adjacent nanoparticles formed a particulate neck to give fused nanoproducts even at lower than 65 °C. Such fusion behavior allowed a non‐spherical growth of the adjacent nanoparticles. Interestingly, the nanoparticle fused to form a nanowire‐type structure when the thermal radical reaction occurred between the terminal double carbon bond of the stabilizer and the hydrogen terminated surface of silicon wafer.
Versatile Synthesis of Polyaniline/Pd Nanoparticles and Catalytic Application
Authors: Amaya Toru , Saio Daisuke , Hirao Toshikazu
Published: September 2008

Polyaniline/Pd nanoparticles were synthesized through two approaches. “Direct reduction approach” was revealed to be a simple method to prepare small (2–7 nm) and dispersed polyaniline/Pd nanoparticles via reduction with sodium borohydride. On the other hand, “template approach” was developed to provide a versatile route to small and well‐dispersed nanoparticles (1–4 nm, average diameter = 2.4 nm) with high Pd density due to pre‐organization of Pd(II) species on polyaniline into the corresponding d,π‐conjugated complex. Thus‐obtained nanoparticles worked as an efficient redox catalyst for oxidative coupling reaction of 2,6‐di‐t‐butylphenol.
Polymerization and Catalytic Properties of Cluster‐Containing Monomers and Polymers
Authors: Pomogailo Svetlana I. , Dzhardimalieva Gulzhian I. , Pomogailo Anatolii D.
Published: September 2008

Summary: Cluster‐containing monomers were obtained and characterized. Mono‐ and disubstituted products were obtained under mild conditions via the interaction of Rh6(CO)16 with 4‐vinylpyridine (4‐VPy). Substitution of labile acetonitrile ligand in Rh6(CO)15NCMe by allyldiphenylphosphine (AlPPh2) yields Rh6(CO)14(µ,η2‐PPh2CH2CHCH2) with formation of π‐complex. The copolymerization of cluster‐containing monomers synthesized with traditional monomers has been studied. It was found that Rh6‐ containing monomers change neither the ligand surroundings nor the structure of cluster monomer framework during polymerization reaction. Polymer‐immobilized clusters were found to be active in hydrogenation reactions of cyclohexene.
Photocatalytic Reduction of Ag2SO4 by Dawson‐Derived Sandwich Complex
Authors: Ruhlmann Laurent , Costa‐Coquelard Claire , Sorgues Sébastien , Lampre Isabelle
Published: September 2008

Photocatalytic reduction of AgI2SO4 from aqueous solutions is observed in the presence of Dawson‐derived sandwich type polyoxometalates (POMs) [M4(P2W15O56)2]16−, M = Co2+, Ni2+ and Zn2+ as photocatalyst and an organic substrate (propan‐2‐ol) as sacrificial electron donor. The direct photochemical excitation of the Dawson‐derived sandwich type polyoxometalates in the presence of propan‐2‐ol leads to its reduction. That first reduction step induces electron transfer to Ag+ ions to give Ag0 metal atoms which then form by aggregation colloidal metal nanoparticles stabilized by POM. In the case of [Co4(P2W15O56)2]16−, TEM experiments reveal that the Agn particles obtained with a slight excess of Ag+ are almost spherical with size in the range 20 – 50 nm. However, in a large excess of Ag+, the obtained colloids are more oblate and assembled together to give larger aggregates.
Nanoporous Networks of Si‐, Al‐, P‐Oxygen Tetrahedra with Encapsulated Dyes as New Composite Materials
Authors: Wöhrle D. , Schulz‐Ekloff G. , Bräuchle C. , Laeri F.
Published: September 2008

Microporous and mesoporous molecular sieves like zeolite faujasites, AlPO4‐5 and Si‐MCM‐41 are obtained by polycondensation of oxygen containing tetrahedra of the metal aluminium, the semimetal silicon and the non‐metal phosphorus by conventional or microwave‐assisted hydrothermal synthesis. The encapsulation of dyes after different methods is described. Monomolecular distribution of dyes in the framework of the hosts is obtained. The encapsulated dyes show high absorption and fluorescence intensities which is interesting for photochromic switches, optical sensors and lasing. The location of a dye is identified after single molecule spectroscopy.
Study on the Zn(II)‐Doped CdS Luminescent Nanoparticles Formation on the Chelating Polymer Microsphere
Authors: Wang Cheng‐Chien , Wu Shu‐Yuan , Yuan Ling‐Ya
Published: September 2008

Highly photoluminescent hybrid Zn(II)‐doped CdS nanocluster/copolymer nanocomposites latex were prepared by using the chelating copolymer, poly(methyl methacrylate‐co‐methyl acrylate‐co‐2‐methyl acrylic acid 3‐(bis‐carboxymethyl amino)‐2‐hydroxyl‐propyl ester), with in‐situ chemical precipitation method. The morphology and photoluminescence property of the hybrid Zn(II)‐doped CdS nanocluster/copolymer nanocomposites latex was examined by TEM and photoluminescence analyzer (PL), respectively. The photoluminescent intensity of the hybrid CdS nanocluster/copolymer nanocomposites could be enhanced by Zn(II) doped treatment from the PL measurement. Furthermore, these hybrid nanocomposite latex could be easily manufactured into the transparent nanocomposite membrane without losing their photoluminescence property as they were cured at 60 °C. Interestingly, the photoluminescence property of the hybrid Zn(II)‐doped CdS nanocluster/copolymer nanocomposite membranes would be influenced by amino compounds due to the surface passivation effect. When the secondary amine compounds were used as the surface passivation materials, the photoluminescent intensity of the hybrid nanocomposite membrane would be enhanced. On the contrary, the hybrid nanocomposite membranes would descend their photoluminescent intensity as the primary amine compounds were used as surface passivation materials.
Water‐soluble Polyelectrolytes Contaning Sulfonic Acid Groups with Metal Ion Binding Ability by Using the Liquid Phase Polymer Based Retention Technique
Authors: Rivas Bernabé L. , Maureira Antonio
Published: September 2008

Water‐soluble polyelectrolytes from 2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (APSA) were obtained by radical polymerization with different comonomers which contain weak acid and neutral groups. These copolymers were investigated as polyelectrolytes and polychelatogens, in view of their metal ion binding properties using the liquid‐phase polymer‐based retention (LPR) technique under different experimental conditions. The metal ions investigated were: Ag(I), Co(II), Cu(II), Zn(II), Cd(II), and Pb(II). APSA allowed increase metal ion interaction of weak acid, meanwhile did not improve the metal ion interaction of neutral monomers at these experimental conditions. Results indicated that retention capability depended strongly on the structure of the polyelectrolyte, arrangement of comonomers at main chain, pH, and the filtration factor, Z.
Synthesis of an Anthraquinone‐Bridged bis(terpyridine) Ligand and its Use in the Stepwise Fabrication of Complex Oligomer Wires on Gold
Authors: Utsuno Mitsuya , Toshimitsu Fumiyuki , Kume Shoko , Nishihara Hiroshi
Published: September 2008

A new bis(terpyridine) ligand with an anthraquinone linker was synthesized. Stepwise coordination reactions at the gold surface using this ligand gave homo‐metal oligomer wires up to pentamer, [nFeL1] (n = 1–5), and hetero‐metal oligomer wires with ferrocene as the terminal group, [1FeL11FeL2Fc]. Electrochemical properties of these modified electrodes were examined.
Conjugated Polymers for Optoelectronic Applications
Authors: Xu Shengang , Liu Yingliang , Cao Shaokui
Published: September 2008

Novel conjugated polymers containing carbazole, phenothiazine or triphenylamine units in the main chain were designed and synthesized via Wittig, Knovenagel or Heck condensations respectively. A majority of them have good solubility in common organic solvents, high thermal stability and good hole‐injection ability. Their diluted solutions in THF showed strong absorption with the absorption maximum in the range of 294∼470 nm and the optic band gaps located in the range of 1.90∼2.75 eV. When irradiated by ultraviolet or visible light, the diluted solutions in THF of the polymers emitted light from purple to yellow color with the emission maximum in the range of 347∼597 nm and the full width at half maximum located in the range of 59∼119 nm. Several polymeric light‐emitting diodes (PLEDs) devices were fabricated using these polymers as light‐emitting materials, and a double‐layer device composed of ITO/PEDOT:PSS/PQTN/Mg:Ag showed a good performance, in which the maximum brightness was measured as 2434.0 cd/m2 under a 11.0 V forward bias voltage. Photovoltaic devices were also investigated using these polymers as an active layer, and a device composed of ITO/PNB/PTCDI‐C13/Al showed a good performance, which was estimated to have external quantum efficiency at around 1% at 330 nm. From these preliminary experimental results, we may infer that these polymers are good light‐emitting materials for PLEDs; while for photovoltaic applications, their absorption spectra need to be further improved to match the solar illumination.
Enhanced Photocurrent Generation in Self‐Assembled Monolayers Formed at Plasmonic Gold Nanostructures
Authors: Akiyama Tsuyoshi , Nakada Masato , Sugawa Kosuke , Yamada Sunao
Published: September 2008

The effect of localized surface plasmon resonance (SPR) appearing at the surfaces of gold nanoparticles (AuPs) was successfully applied for the enhancement of photocurrents from porphyrin (Po) immobilized on AuPs. The electrode consisting of AuPs with different sizes (∼15 or ∼35 nm) was prepared using the AuP film formed at the liquid/liquid interface, and then Po was self‐assembled on the gold surface. The SPR effect for the AuP film was verified from the attenuated total reflection SPR and absorption measurements. Photocurrents from the modified electrodes were compared with the corresponding planar electrode. Appreciable enhancement of photocurrents was observed.
Preparation and Optical Properties of New Metal/Macromolecule Architectures
Authors: Bernabò Marco , Ciardelli Francesco , Pucci Andrea , Ruggeri Giacomo
Published: September 2008

Polymer nanocomposite films with unusual and anisotropic optical properties were obtained by the controlled in‐situ generation of noble metal nanoparticles (NPs). Poly(vinyl alcohol) (PVA) and poly(ethylene‐co‐vinylalcohol) (EVAl) nanocomposites containing gold and silver NPs were efficiently produced by a photo‐reduction or thermal process both operating directly in the solid state and resulted efficiently stabilized by the presence of polymer hydroxyl groups, which prevent particles agglomeration. Uniaxial drawing of the NPs/polymer composites promoted anisotropic packing of the embedded particles along the stretching direction of the film, resulting in a shift of the surface plasmon resonance well above 40 nm and thus producing a well‐defined polarization‐dependent colour change. Such nanostructured materials when are obtained in the form of thin films can be applied to several fields, from sensor to photonics (i.e., macromolecular strain sensor, linear absorbing polarizer).
Heme Pocket Architecture in Human Serum Albumin: Regulation of O2Binding Affinity of a Prosthetic Heme Group by Site‐Directed Mutagenesis
Authors: Komatsu Teruyuki , Nakagawa Akito , Tsuchida Eishun
Published: September 2008

Summary: We present the O2binding properties of recombinant human serum albumin (rHSA) mutants complexed with an iron(II) protoporphyrin IX as a prosthetic heme group. Iron(III) protoporphyrin IX (hemin) is bound within subdomain IB of HSA with weak axial coordination by Tyr‐161. In order to confer O2binding capability to this naturally occurring hemoprotein: (i) a proximal histidine was introduced into position Ile‐142; and (ii) the coordinated Tyr‐161 was replaced with hydrophobic Leu using site‐directed mutagenesis. It provided a recombinant HSA double‐mutant [rHSA(I142H/Y161L) = rHSA(HL)]. The rHSA(HL)–heme formed a ferrous five‐coordinate high‐spin complex with axial ligation of His‐142 under an Ar atmosphere. This artificial hemoprotein binds O2at room temperature. Laser flash photolysis experiments demonstrated that O2rebinidng to rHSA(HL)–heme displays monophasic kinetics, whereas the CO recombination process obeyed a double‐exponential pattern. This might be attributable to the two different geometries of the axial imidazole coordination arising from the two orientations of the porphyrin plane in the heme pocket. The O2binding affinity of rHSA(HL)–heme was considerably lower than those of R‐state hemoglobin (Hb) and myoglobin (Mb), principally because of the high O2dissociation rate constant. The third mutations have been introduced into the distal side of the heme (at position Leu‐185 or Arg‐186) to increase the O2binidng affinity. The rHSA(HL/L185N)–heme showed high O2binding affinity ($P_{1/2}^{{\rm O}_2 } $: 1 Torr), which is 18‐fold greater than that of the original double mutant rHSA(HL)–heme and which is rather close to those of Hb (R‐state) and Mb. Furthermore, replacement of polar Arg‐186 with Leu or Phe adjusted the O2binding affinity ($P_{1/2}^{{\rm O}_2 } $) to 10 Torr, which is almost equivalent to value for human red blood cells.
Medicinal Applications of Metal Complexes Binding to Biological Macromolecules
Authors: Reedijk Jan
Published: September 2008

Biological macromolecules present in living organisms, like proteins, DNA, have many metal‐binding sites. As a consequence, coordination compounds can react with such cellular components, displaying possible toxic effects, or they also may have beneficial applications. So metal ions and compounds not only are essential for life in e.g. dioxygen transport, or biocatalysis, but they can also be used for controlled toxicity in medicinal applications. Well‐known examples are the application of gold compounds in arthritis treatment, bismuth compounds for ulcer healing, and silver compounds for open skin protection. However, only in a few cases details of the mechanist are known, and if so, the biological macromolecules play a key role. Transition‐metal coordination compounds that have metal‐ligand exchange rates comparable to cell‐division processes, i.e. in particular Pt and Ru, often appear to be highly active in killing cancers, as seen from the study of several cancer cell lines. Classical examples, like cisplatin, and new examples of Pt and Ru compounds will be discussed in some detail, with a focus on their binding to the DNA biomacromolecule. The classical compoundcis‐diamminedichloridoplatinum(II), often abbreviated as cisplatin, and its first‐generation derivatives are known to bind to several biomacromolecules in a specific way, and eventually bind at DNA. Four important examples are shown in the figure. However, on its way to DNA other cellular components, like proteins and peptides might be intermediates before the final target is reached. Other metal‐containing drugs, like Ru compounds, that show anti‐cancer activity have a less well‐known mode of action. Molecular‐based mechanistic studies may result in improved clinical administration protocols.
Apple polyphenol phloretin potentiates the anticancer actions of paclitaxel through induction of apoptosis in human hep G2 cells
Authors: Yang Kuo‐Ching , Tsai Chia‐Yi , Wang Ying‐Jan , Wei Po‐Li , Lee Chia‐Hwa , Chen Jui‐Hao , Wu Chih‐Hsiung , Ho Yuan‐Soon
Published: September 2008

Phloretin (Ph), which can be obtained from apples, apple juice, and cider, is a known inhibitor of the type II glucose transporter (GLUT2). In this study, real‐time PCR analysis of laser‐capture microdissected (LCM) human hepatoma cells showed elevated expression (>5‐fold) of GLUT2 mRNA in comparison with nonmalignant hepatocytes. In vitro and in vivo studies were performed to assess Ph antitumor activity when combined with paclitaxel (PTX) for treatment of human liver cancer cells. Inhibition of GLUT2 by Ph potentiated the anticancer effects of PTX, resensitizing human liver cancer cells to drugs. These results demonstrate that 50–150 µM Ph significantly potentiates DNA laddering induced in Hep G2 cells by 10 nM PTX. Activity assays showed that caspases 3, 8, and 9 are involved in this apoptosis. The antitumor therapeutic efficacy of Ph (10 mg/kg body weight) was determined in cells of the SCID mouse model that were treated in parallel with PTX (1 mg/kg body weight). The Hep G2‐xenografted tumor volume was reduced more than fivefold in the Ph + PTX‐treated mice compared to the PTX‐treated group. These results suggest that Ph may be useful for cancer chemotherapy and chemoprevention. © 2008 Wiley‐Liss, Inc.
Assessment of graft function in rodent models of heart transplantation
Authors: Martins Paulo Ney Aguiar
Published: September 2008

Heterotopic heart transplantation in rats and mice is the most commonly used model to study allograft immune response and to test immunosuppressive drugs and tolerance induction protocols. Standardization of both the surgical procedure and the evaluation of graft function is essential for data interpretation. The most popular way to monitor graft function has been the palpation method. However, there are some proposal for more objective assessment methods like electrocardiogram and echocardiogram. Although, complementary tests might add some relevant information when assessing minor effects of immunosuppressive therapy, palpation by an experienced investigator is very predictive and so far the simplest method to determine heart allograft function. Minor complications during the surgical procedure and unreliable assessment can have a major impact on the interpretation of experiment results. Here, the author reviews the literature and presents some suggestions that help eliminating biases on the assessment of heart allograft function. © 2008 Wiley‐Liss, Inc. Microsurgery, 2008.
Intercostal nerve transfer in infants with obstetric brachial plexus palsy
Authors: El‐Gammal Tarek A. , Abdel‐Latif Mohamed M. , Kotb Mohamed M. , El‐Sayed Amr , Ragheb Yasser Farouk , Saleh Waleed Riad , Geith Mohamed A. , Abdel‐Ghaffar Hala S.
Published: September 2008

The use of intercostal nerve (ICN) transfer to repair brachial plexus lesions associated with root avulsions is a well known procedure in adults. However, there is a paucity of reports on the use of ICN in infants with obstetrical brachial plexus palsy (OBPP). This study included 46 infants with obstetric brachial plexus palsy who underwent 62 neurotization procedures. Clinically, 2 cases had upper trunk injury, 19 had upper‐middle trunk injury, 3 had lower trunk injury, and 22 had total palsy. The average age at surgery was 14 months. Twelve patients underwent surgery younger than 6 months of age, 11 patients at 6 to <9 months, 9 patients at 9–12 months, and 14 patients at >12 months. The average follow‐up period was 49 months. ICN transfer resulted in 76% satisfactory (good and excellent) outcome, and was best for restoration of elbow flexion (93.5%). Functional results were best when the operation was done before the age of 9 months; however, the difference between age groups was statistically insignificant. Functional results were also independent of the extent of the original injury. Nine children had preoperative and postoperative CT chest scans. All the nine children developed basal pulmonary atelectasis postoperatively. Pulmonary atelectasis was mostly ipsilateral and was not correlated to the patient age (months), or the duration of anesthesia (in minutes). We conclude that, intercostals nerve transfer is an effective procedure for restoration of function in infants with OBPP and root avulsions. The procedure is associated with variable degree of ipsilateral pulmonary atelectasis. © 2008 Wiley‐Liss, Inc. Microsurgery, 2008.
Selenium and the prevention of prostate and colorectal cancer
Authors: Peters Ulrike , Takata Yumie
Published: September 2008

Prostate and colorectal cancers are among the most common cancers and identifying modifiable risk factors are important steps to reduce the burden of these severe diseases. Results from several but mostly small observational studies as well as the secondary analysis of an intervention trial provide support for a chemopreventive effect of selenium on prostate and colorectal cancers. Results suggest effect modification by gender and smoking, but this interpretation is limited by the statistical power of previous studies. Several cancer preventive mechanisms have been described and it is likely that selenium acts through multiple pathways. In particular, the anti‐oxidative and anti‐inflammatory effects mediated through activity of selenoenzymes are discussed, given the relevance of oxidative stress and inflammation in these cancers. Genetic variation in selenoenzymes may modify the potential chemopreventive effect of selenium and need to be further investigated. Additional large observational studies using biomarkers of selenium intake and intervention trials, such as the Selenium and Vitamin E Cancer Prevention Trial, will be important to further evaluate the potential chemopreventive effect of selenium. Furthermore, characterization of functional effects of polymorphisms in selenoenzymes is needed.
Structural determination of three new eudesmanolides from Inula helenium
Authors: Ma Xiao‐Chi , Liu Ke‐Xin , Zhang Bao‐Jing , Xin Xiu‐Lan , Huang Jian
Published: September 2008

Ten sesquiterpenens were isolated from Inula helenium. Among them, three eudesmanolides: 15‐hydroxy‐11βH‐eudesm‐4‐en‐8β,12‐olide (1), 3α‐hydroxy‐11βH‐eudesm‐5‐en‐8β,12‐olide (2) and 2β, 11α‐dihydroxy‐eudesm‐5‐en‐8β,12‐olide (3) are new compounds. Their chemical structures were determined by spectral methods including 2D NMR. Copyright © 2008 John Wiley & Sons, Ltd.
New results on the convergence of the conjugate gradient method
Authors: Bouyouli R. , Meurant G. , Smoch L. , Sadok H.
Published: September 2008

This paper is concerned with proving theoretical results related to the convergence of the conjugate gradient (CG) method for solving positive definite symmetric linear systems. Considering the inverse of the projection of the inverse of the matrix, new relations for ratios of the A‐norm of the error and the norm of the residual are provided, starting from some earlier results of Sadok (Numer. Algorithms 2005; 40:201–216). The proofs of our results rely on the well‐known correspondence between the CG method and the Lanczos algorithm. Copyright © 2008 John Wiley & Sons, Ltd.
Quadrilateral membrane elements with analytical element stiffness matrices formulated by the new quadrilateral area coordinate method (QACM‐II)
Authors: Cen Song , Chen Xiao‐Ming , Li C. F. , Fu Xiang‐Rong
Published: September 2008

A novel strategy for developing low‐order membrane elements with analytical element stiffness matrices is proposed. First, some complete low‐order basic analytical solutions for plane stress problems are given in terms of the new quadrilateral area coordinates method (QACM‐II). Then, these solutions are taken as the trial functions for developing new membrane elements. Thus, the interpolation formulae for displacement fields naturally possess second‐order completeness in physical space (Cartesian coordinates). Finally, by introducing nodal conforming conditions, new 4‐node and 5‐node membrane elements with analytical element stiffness matrices are successfully constructed. The resulting models, denoted as QAC‐ATF4 and QAC‐ATF5, have high computational efficiency since the element stiffness matrices are formulated explicitly and no internal parameter is added. These two elements exhibit excellent performance in various bending problems with mesh distortion. It is demonstrated that the proposed strategy possesses advantages of both the analytical and the discrete method, and the QACM‐II is a powerful tool for constructing high‐performance quadrilateral finite element models. Copyright © 2008 John Wiley & Sons, Ltd.
On the smoothed finite element method
Authors: Zhang H.‐H. , Liu S.‐J. , Li L.‐X.
Published: September 2008

Recently, Liu et al. proposed the smoothed finite element method by using the non‐mapped shape functions and then introducing the strain smoothing operator when evaluating the element stiffness in the framework of the finite element method. However, the theories and examples by Liu et al. are not sufficient for general quadrilateral elements. This paper shows that the non‐mapped shape functions used in the smoothed finite element have disadvantages in existence, linearity, non‐negativity and patch test. Copyright © 2008 John Wiley & Sons, Ltd.
Linking collegiate service‐learning to future volunteerism: Implications for nonprofit organizations
Authors: Tomkovick Chuck , Lester Scott W. , Flunker LaNette , Wells Theresa A.
Published: September 2008

One of the biggest challenges facing nonprofits is attracting and retaining volunteers to help deliver their programs. One way that colleges and universities are attempting to educate students on the importance of community issues and to graduate “good citizens” is through service‐learning (S‐L) programs. Although many scholars argue that collegiate S‐L programs will increase the extent to which students volunteer following graduation (for example, Astin, Sax, and Avalos, 1999; Misa, Anderson, and Yamamura, 2005), more empirical research has been called for to examine this relationship. This article proposes three predictors of future volunteerism for alumni of a collegiate S‐L experience: the amount of personal development experienced during the S‐L project, the perceived value of the S‐L project to the community organization, and the level of volunteerism prior to participation in an S‐L project. Results showed significant effects of all the proposed predictors on postgraduation volunteering. Our findings have implications for nonprofit managers charged with maintaining a sufficient level of volunteers to provide their community services as well as individuals who are responsible for organizing S‐L programs. These managerial implications and directions for future S‐L research are discussed.
Collaboration in foundation grantor‐grantee relationships
Authors: Fairfield Kent D. , Wing Kennard T.
Published: September 2008

Foundations take many forms and wield widespread influence within the nonprofit sector. One aspect of foundations that has received limited research attention is the relationship between the foundation and the grantee. Some authors have encouraged a reframing of this relationship to be more one of equals, where each party brings attributes valuable to the other and where collaboration can germinate and produce more effective philanthropy. This exploratory study suggests that the quality of these relationships varies widely and that it is often difficult to form collaborative ones. It identifies some of the earmarks of fruitful relationships and suggests some ways to replicate those successes.

I hate foundation officers—they're all jerks!

—Experienced nonprofit executive

We care about these [nonprofit] organizations—it is through them that we do our work.

—Senior foundation program officer
Determinants of fraud losses in nonprofit organizations
Authors: Holtfreter Kristy
Published: September 2008

Although fraud research has increased, the nonprofit setting has been ignored in criminology and business ethics. This exploratory study examines occupational fraud in 128 nonprofit agencies. Characteristics of offenders (age, gender, educational background, position in the agency), victims (size of organization and available control mechanisms), and offenses are compared to previous research. Regression analyses indicate that several factors are significant predictors of financial loss. At the individual level, it appears females are responsible for increased dollar losses; however, subsequent analyses demonstrate that organizations with a higher level of internal controls detect fraud committed by males, and it is these offenses that result in more serious losses.
The decline of motivation?: From commitment to dropping out of volunteering
Authors: Yanay Galit Ventura , Yanay Niza
Published: September 2008

This article studies volunteerism through the phenomenon of dropping out. By ascertaining the achievements, difficulties, and dilemmas of volunteers at the Center for Assistance to Victims of Sexual Assault and Domestic Violence, we explored the process of dropping out as an encore to understanding the meaning of volunteerism that ends with abandoning a desired activity. On the basis of a longitudinal study, we argue that dropping out is not always a product of waning motivation—for many volunteers, dropping out was extremely difficult—but rather the outcome of unabridged discrepancies between “ought” and “actual” experiences. Volunteers expect to feel good about themselves. In contrast, the organization expects them to act as free agents who can independently manage feelings of pain and self‐doubt. When such discrepancies between expectations and reality occur, feelings of anger and disappointment set in. As a result, devoted volunteers drop out in order to preserve their positive self‐feeling. It is our contention that in order to understand the nature of volunteers' dropout and perseverance, close attention should be paid to processes of self‐regulation in the context of the specific relations between the volunteers and the organization.
Succession, strategy, culture, and change at Santropol Roulant
Authors: Neville Lukas , Murray Elspeth J.
Published: September 2008

Santropol Roulant is an innovative nonprofit organization in Montreal focused on youth training, food security, and intergenerational community building. Since its inception, the Roulant has delivered more than 250,000 meals to isolated seniors and trained more than sixteen hundred young volunteers. Within a few short months, the Roulant will lose half its board members, five senior staff members, and its dedicated and wellliked executive director. The leadership turnover will be a highstakes test for the Roulant: Can they turn a period of vulnerability into an opportunity for growth and rejuvenation? This teaching case is intended to develop familiarity with key issues related to succession planning, transition management, and organizational change. Students will learn about managing a period of complex, high‐intensity organizational change, develop an understanding of the linkages between organizational form and strategic objectives, and become familiar with the structural and substantive issues facing transition teams.