bluuebunny/crossref_metadata_2025_split huggingface dataset:
Capped Bimetallic and Trimetallic Nanoparticles for Catalysis and Information Technology
Authors: Toshima Naoki 
Published: September 2008

AbstractSummary: 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

AbstractWe 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

AbstractThe 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

AbstractThe 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

AbstractFusion 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

AbstractPolyaniline/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

AbstractSummary: 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

AbstractPhotocatalytic 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

AbstractMicroporous 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

AbstractHighly 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

AbstractWater‐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

AbstractA 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

AbstractNovel 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

AbstractThe 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

AbstractPolymer 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

AbstractSummary: 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

AbstractBiological 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

AbstractPhloretin (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

AbstractHeterotopic 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.