bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Manufacture of Resorbable Suture Material from Magnesium
Authors: Seitz Jan‐Marten , Wulf Eric , Freytag Patrik , Bormann Dirk , Bach Friedrich‐Wilhelm 
Published: November 2010

AbstractMagnesium alloys present an alternative to medical cases in which polymeric sutures may not be ideal. To date, no efficient and low‐cost manufacturing process for the fabrication of magnesium‐based sutures can be found. To obtain an alternative, the previously characterised magnesium alloys ZEK100 (98% Mg), AX30 (96.2% Mg), AL36 (91% Mg) and MgCa0.8 (99.2% Mg) were cast, extruded into 30 mm diameter bars and extruded into 0.5 mm diameter wires. To determine the mechanical properties of the wires, grain size measurements, tensile tests as well as qualitative bending tests were carried out. The ZEK100 alloy's wires showed the finest microstructure having grains of 1.2 µm in diameter. Coarser microstructures were observed for MgCa0.8, AX30 and AL36. The alloy ZEK100 had the highest tensile stress (367 MPa) also revealing a brittle behaviour due to its fine microstructure. The tensile test, carried out for AX30 as well as AL36, resulted in comparable high fracture strains (10.6%) and tensile stresses (300 MPa). However, MgCa0.8 showed a tensile strength of 315 MPa and a low strain of 1.6%. Within the qualitative bending test wires made of the alloy AL36 were able to form tight knots, which is a key feature for suture applications. The comparison of the magnesium sutures with commercially available polymeric sutures revealed lower strength and elongation for the magnesium alloys. Yet, the wires exhibited mechanical properties that can meet the requirements of a suture material.
Bioactive Ti Metal and its Alloys Prepared by Chemical Treatments: State‐of‐the‐Art and Future Trends
Authors: Kokubo Tadashi , Yamaguchi Seiji 
Published: November 2010

AbstractTitanium metal and its alloys are widely used as various implants in orthopaedic and dental fields, because of their good biocompatibility and high mechanical strength. However, they do not bond to living bone. Here, we review the literature showing that they will spontaneously bond tightly to living bone, if they are treated with an acid or alkaline solution and then subjected to heat treatment. This occurs due to the materials becoming negatively or positively charged on their surfaces in the bodily environment, which induces apatite deposition. Porous Ti metal subjected to such treatment exhibits not only osteoconductivity but also osteoinductivity. Examples and clinical applications are reviewed.
Correlation Between Surface Chemistry and Electrocatalytic Properties of Monodisperse PtxNi1‐x Nanoparticles
Authors: Wang Chao , Chi Miaofang , Wang Guofeng , van der Vliet Dennis , Li Dongguo , More Karren , Wang Hsien‐Hau , Schlueter John A. , Markovic Nenad M. , Stamenkovic Vojislav R. 
Published: November 2010

AbstractMonodisperse and homogeneous PtxNi1‐x alloy nanoparticles of various compositions are synthesized via an organic solution approach in order to reveal the correlation between surface chemistry and their electrocatalytic properties. Atomic‐level microscopic analysis of the compositional profile and modeling of nanoparticle structure are combined to follow the dependence of Ni dissolution on the initial alloy composition and formation of the Pt‐skeleton nanostructures. The developed approach and acquired knowledge about surface structure‐property correlation can be further generalized and applied towards the design of advanced functional nanomaterials.
Simultaneous Reduction and Surface Functionalization of Graphene Oxide by Mussel‐Inspired Chemistry
Authors: Kang Sung Min , Park Sungjin , Kim Daewon , Park Sung Young , Ruoff Rodney S. , Lee Haeshin 
Published: November 2010

AbstractThis study presents a method of simultaneous reduction and surface functionalization of graphene oxide by a one‐step poly(norepinephrine) functionalization. The pH‐induced aqueous functionalization of graphene oxide by poly(norepinephrine), a catecholamine polymer inspired by the robust adhesion of marine mussels, chemically reduced and functionalized graphene oxide. Moreover, the polymerized norepinephrine (pNor) layer provided multifunctionality on the reduced graphene oxide that includes surface‐initiated polymerization and spontaneous metallic nanoparticle formation. This facile surface modification strategy can be a useful platform for graphene‐based nano‐composites.
Constrained receding‐horizon experiment design and parameter estimation in the presence of poor initial conditions
Authors: Zhu Yijia , Huang Biao 
Published: November 2010

AbstractAn optimal experiment design assumes the existence of an initial or nominal process model. The efficiency of this procedure depends on how the initial model is chosen. This creates a practical dilemma as estimating the model is precisely what the experiment tries to achieve. A novel approach to experiment design for identification of nonlinear systems is developed, with the purpose of reducing the influence of poor initial values. The experiment design and the parameter estimation are conducted iteratively under a receding‐horizon framework. By taking steady‐state prior knowledge into account, constraints on the parameters can be derived. Such constraints help reduce influence of poor initial models. The proposed algorithm is illustrated through examples to demonstrate its efficiency. © 2010 American Institute of Chemical Engineers AIChE J, 2011
Preparation and properties of core–shell nanosilica/poly(methyl methacrylate–butyl acrylate–2,2,2‐trifluoroethyl methacrylate) latex
Authors: Wei Zheng , Ling He , Junyan Liang , Gang Chang , Na Wang 
Published: November 2010

AbstractA core–shell nanosilica (nano‐SiO2)/fluorinated acrylic copolymer latex, where nano‐SiO2 served as the core and a copolymer of butyl acrylate, methyl methacrylate, and 2,2,2‐trifluoroethyl methacrylate (TFEMA) served as the shell, was synthesized in this study by seed emulsion polymerization. The compatibility between the core and shell was enhanced by the introduction of vinyl trimethoxysilane on the surface of nano‐SiO2. The morphology and particle size of the nano‐SiO2/poly(methyl methacrylate–butyl acrylate–2,2,2‐trifluoroethyl methacrylate) [P(MMA–BA–TFEMA)] core–shell latex were characterized by transmission electron microscopy. The properties and surface energy of films formed by the nano‐SiO2/P(MMA–BA–TFEMA) latex were analyzed by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy/energy‐dispersive X‐ray spectroscopy, and static contact angle measurement. The analyzed results indicate that the nano‐SiO2/P(MMA–BA–TFEMA) latex presented uniform spherical core–shell particles about 45 nm in diameter. Favorable characteristics in the latex film and the lowest surface energy were obtained with 30 wt % TFEMA; this was due to the optimal migration of fluorine to the surface during film formation. The mechanical properties of the films were significantly improved by 1.0–1.5 wt % modified nano‐SiO2. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Optimizing the step‐by‐step forming processes for fabricating a poly(DL‐lactic‐co‐glycolic acid)‐sandwiched cell/hydrogel construct
Authors: Wang Xiaohong , Sui Shaochun , Liu Chang 
Published: November 2010

AbstractA poly(DL‐lactic‐co‐glycolic acid) (PLGA)‐sandwiched cell/fibrin construct was fabricated to overcome the weak mechanical properties of cell/hydrogel mixtures. This construct was formed with a step‐by‐step mold/extraction method to generate a middle smooth muscle layer of natural blood vessels. A desired three‐layer construct, as an integrated entity with optimized inner structures, was achieved by the control of the size of the molds, the concentration of the polymer systems, and the temperature of the extraction and polymerization processes. The constructs were fabricated with the following dimensions: length = 10–25 mm, diameter >2 mm, and wall thickness = 0.6–2 mm. Different microstructures in different layers of the sandwiched structure resulted in different functions. The pore structure in the inner PLGA and middle fibrin layers was beneficial for nutrient transference, whereas the solid structure without pores in the outmost surface of the outer PLGA layer could prevent fluid from leaking during in vitro culturing and in vivo implantation. This study showed that this can be a promising approach for the fabrication of synthetic‐polymer‐sandwiched viable cell/hydrogel constructs for wide potential application in complex organ manufacturing. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Electronic Transfer and Phase Transitions in Cationic Intercalation Chemistry in Low‐Dimensional Chalcogenides
Authors: Rouxel Jean 
Published: November 2010

AbstractBesides their striking physical properties, low‐dimensional solids have also a very rich chemical reactivity, of which the redox intercalation‐disintercalation processes represent an essential part. The intercalation of cations is the result of a coupled ion‐electron transfer reaction. The geometrical features associated to the ions are well known at present. However the role of the electron is oftentime restricted to a modification of the physical properties of the host structure. In this contribution it will be shown that the electronic transfer plays an essential role concerning the ability to intercalate and, also, largely governs the phase transitions that can be observed. Such phase transitions concern either the position taken by the intercalated cations or the host framework itself. They can be also related to a strong ion‐electron coupling.
Schichtkristalle Bi2Te3 und Sb2Te3 — Punktdefekte, Bindungspolarität und einige Transporteigenschaften
Authors: Stary Z. , Horak J. 
Published: November 2010

AbstractThe present paper deals with the determination of changes in bond polarity of Sb2‐xBixTe3 mixed crystals as a function of composition. In addition, the relation between the bond polarization and the concentration of antisite defects is investigated. A model is proposed, in order to evaluate the concentration of Sb'Te and Bi'Te antisite defects in terms of the composition variable x. Consequences for the design of p‐n‐junctions are indicated.
The Correlation Between Diffusion Behaviour and Phonon Softening in BCC Metals
Authors: Herzig Chr. 
Published: November 2010

AbstractA new approach is proposed to explain the wide spread of self diffusion behaviour and the curvature of the Arrhenius plots in bcc metals by typical diffusion‐relevant low‐energy phonon modes. In bcc transition metals the activation enthalpy and the energy of the LA 2/3 (111) phonon mode decrease systematically with decreasing d‐electron concentration, while the diffusivity and the degree of curvature increase. The migration enthalpy HM is related to the frequency of this mode, i.e. to the amplitude of atomic displacements in the 〈111〉 nearest neighbour jump direction. On the basis of experimental results a good correlation between the square of this phonon frequency and the activation enthalpy is obtained. The curvatures of the Arrhenius plots are explained by a decrease of HM with decreasing temperature due to the temperature dependence of the soft T1A 1/2 〈110〉 mode, which causes a “breathing” motion of the saddle point atoms. Thus the model of phonon‐assisted diffusion jumps via monovacancies yields a uniform explanation for the main features of diffusion in bcc metals.
Organische Festkörper. Anwendungsmöglichkeiten in der Optik und Elektronik
Authors: Sixl H. 
Published: November 2010

AbstractSome fundamental aspects of basic principles and applications of organic solids will be presented in this lecture. A special focus is given on present optoelectronic research activities at Hoechst AG related to physico‐chemical and physico‐technical material research. The first part is concerned with the actual research on polymer optical fibers. The second part is concerned with basic principles and properties of non‐linear optical devices. Finally the third part refers to the fundamentals of electrical conducting polymers.
Demixing in Trivalent Doped Transition Metal Oxides Exposed to an Oxygen Potential Gradient
Authors: Martin M. , Schmackpfeffer R. 
Published: November 2010

AbstractA formal treatment is given for demixing in a trivalent doped transition metal oxide which is exposed to a stationary oxygen potential gradient. Various disorder types are discussed for the doped oxide, and an analysis is given of the influence of solute‐vacancy interaction on the demixing behavior. The solute can be enriched either at the low or at the high oxygen potential side of the sample depending on the average oxygen potential at which the demixing experiment is carried out and on the strength of the solute‐vacancy interaction.
Zur Hyperfeinstruktur von 111Cd in Metalloxiden
Authors: Bolse W. , Bartos A. , Kesten J. , Lieb K. P. , Uhrmacher M. 
Published: November 2010

AbstractThe Perturbed Angular Correlation method was applied to measure the hyperfine interaction of the 111Cd‐nucleus after implantation of its radioactive mother isotope 111ln (≈ 1012 ions at E ≈ 400 keV) into various metal‐oxides (NiO, CuO, AgO, Cu2O, Ag2O, Al2O3, Cr2O3, In2O3, Rh2O3). In most cases we were able to identify 111Cd on substitutional sites in a defect‐free oxide surrounding by proper thermal annealing of our samples. The capability of the PAC method to resolve small changes in the microsurrounding will be demonstrated by the results of our experiments on In2O3. Exemplary, the application of the technique to the observation of magnetical, structural and chemical phase transitions in NiO, Rh2O3, AgO and CuO will be discussed. By comparing the experimental values with a simple point charge model, a systematic behaviour of the electric field gradients was found.
Methyl Group Quantum Rotation in Various Methyl Group‐IVa Halides, (CH3)4‐nMIVXn with M = Sn, Pb; X = F, Cl, Br
Authors: Prager Michael , Zhang Da , Weiss Alarich 
Published: November 2010

AbstractRotational tunnelling and librations of the methyl groups in various methyl group‐IVa halides, (CH3)3SnX, X = F, Cl, Br; (CH3)3PbX, X = Cl; (CH3)2SnX2, X = Br; CH3SnX3, X = Cl, Br have been studied using inelastic neutron scattering (INS) technique. The INS results are discussed with respect to the known crystal structures. All compounds investigated show weak rotational potentials but no systematic trends connected to the chemical composition were observed. The large electronegativity of the halogen atoms and the resulting stronger molecular polarity are taken as the reason for the variety of the crystal structures in these solids and the individual CH3‐group rotational behaviour observed.
Coupled Methyl Quantum Rotation and its Influence on the NMR Spin‐Lattice Relaxation
Authors: van Wüllen L. , Müller‐Warmuth W. 
Published: November 2010

Abstract1H NMR spin‐lattice relaxation rates T−11 have been measured at 15 and 30 MHz and various temperatures in powdered molecular crystals of (CH3)2SnCl2 and (CH3)2SnCl2 in a (CD3)2SnCl2 matrix. In the second case T−11 can be interpreted in terms of quantum tunnelling as usual, though it cannot be explained by the motion of the CH3 group in a single particle V3 — V6‐potential. In the first case, however, the presence of coupled pairs of rotating methyl groups changes in addition the frequency and temperature dependences of T−11. The results can be explained on the basis of a quantum mechanical treatment of the coupled system, which leads to the occurrence of 4 rotator and 18 magnetic sublevels in the groundstate instead of 2 and 6. Three of the tunnelling transition frequencies are of comparable size, one is substantially smaller and modifies the relaxation rate.
The Diffusion of Li in Poco Graphite and Glassy Carbon at Low Concentrations and High Temperatures
Authors: Jungblut B. , Hoinkis E. , Döbler V. , Meyerheim H. L. 
Published: November 2010

AbstractX‐ray diffraction and angle dependent X‐ray absorption near edge structure (XANES) measurements were carried out in order to characterize a Poco graphite and a glassy carbon with respect to their long range and short range orders. Poco graphite is a well graphitized polycrystalline material. Glassy carbon has, by contrast, hardly any long range order, but XANES spectra reveal the graphite‐like short range order. The diffusion of 7Li in Poco graphite and in glassy carbon was investigated at Li atomic fractions between 0.1 ppm and 300 ppm and temperatures in the range from 1000 K to 1400 K using a mass spectrometric method. Li was found to be released from Poco graphite mainly via intragranular diffusion and not by Knudsen diffusion through the open interconnected pores. The inaccessible porosity of glassy carbon is equal to the total porosity i.e. open pores are not present. The Arrhenius equations for the diffusion coefficients of Li in Poco graphite and in glassy carbon are D = 3 · 104 · exp(‐2.27 eV/kT) cm2/s and D = 1.5 · 106 · exp(‐3.1 eV/kT) cm2/s.
57Fe‐ und 119Sn‐Mößbauerspektroskopie an gesinterten Eisen‐Zinn‐Pulvermischungen
Authors: Meyer Christian , Nagorny Klaus 
Published: November 2010

AbstractIron‐tin powder mixtures in different compositions have been sintered at temperatures of 500°C up to 950°C. The results of 57Fe‐ und 119Sn‐Mößbauer‐measurements of the samples have been compared with the iron‐tin phase diagram. The samples are a mixture of different FeSn‐phases. We have found: α‐Fe, γ‐Fe, β‐Sn, α‐FeSn solid solutions, Fe3Sn, Fe3Sn2, Fe5Sn3 and FeSn. Kinetic measurements have been made to investigate the sintering behaviour of the iron‐tin powders.
In‐situ Mößbauerspectroscopic Investigations of Phase Transformations in Iron Oxide Layers Below Organic Coatings
Authors: Hoffmann K. , Stratmann M. 
Published: November 2010

AbstractPhase transformations in oxide layers below organic coatings have been investigated by in‐situ Mößbauer spectroscopy. During wetting of preoxidized iron surfaces iron can further corrode without diffusion of O2 through the polymer film. The anodic iron dissolution is compensated by cathodic rust reduction. The reactive rust component γ‐FeOOH can be reduced to the spinel‐phase Fe3 — γO4 changing the rust morphology and causing the loss of adhesion of the organic coating. This reaction is controlled by the ionic conductivity below the organic coating which is caused e.g. by impurities adsorbed from the atmosphere before the application of the organic coating. — In order to retard the redox reactions in oxide scales below organic coatings the oxide surface has been chemically modified e.g. by silanes, phosphates and phosphor‐organic compounds. This decreases the rate of rust reduction significantly.
N‐acetylcysteine modulates doxorubicin‐induced oxidative stress and antioxidant vitamin concentrations in liver of rats
Authors: Koçkar M. Cem , Nazıroğlu Mustafa , Çelik Ömer , Tola H. Tahsin , Bayram Dilek , Koyu Ahmet 
Published: November 2010

AbstractDoxorubicin (DOX) is a chemotherapeutic agent, and is widely used in cancer treatment. The most common side effect of DOX was indicated on cardiovascular system by experimental studies. There are some studies suggesting oxidative stress‐induced toxic changes on liver related to DOX administration. The aim of the present study was to evaluate whether antioxidant N‐acetylcysteine (NAC) relieves oxidative stress in DOX‐ induced liver injury in rat. Twenty‐four male rats were equally divided into three groups. First group was used as a control. Second group received single dose of DOX. NAC for 10 days was given to constituting the third group after giving one dose of DOX. After 10 days of the experiment, liver tissues were taken from all animals. Lipid peroxidation (LP) levels were higher in the DOX group than in control whereas LP levels were lower in the DOX + NAC group than in control. Vitamin C and vitamin E levels were lower in the DOX group than in control whereas vitamin C and vitamin E levels were higher in the DOX + NAC group than in the DOX group. Reduced glutathione levels were higher in the DOX + NAC group than in control and DOX group. Glutathione peroxidase, vitamin A and β‐carotene values were not changed in the three groups by DOX and NAC administrations. In histopathological evaluation of DOX group, there were mononuclear cell infiltrations, vacuolar degeneration, hepatocytes with basophilic nucleus and sinusoidal dilatations. The findings were totally recovered by NAC administration. In conclusion, N‐acetylcysteine induced modulator effects on the doxorubicin‐induced hepatoxicity by inhibiting free radical production and supporting the antioxidant vitamin levels. Copyright © 2010 John Wiley & Sons, Ltd.
Hydrogen Bonding Versus van der Waals Interactions: Competitive Influence of Noncovalent Interactions on 2D Self‐Assembly at the Liquid–Solid Interface
Authors: Mali Kunal S. , Lava Kathleen , Binnemans Koen , De Feyter Steven 
Published: November 2010

AbstractThe structures of the self‐assembled monolayers of various 4‐alkoxybenzoic acids physisorbed at the liquid–solid interface were established by employing scanning tunnelling microscopy (STM). This study has been essentially undertaken to explore the competitive influence of van der Waals and hydrogen‐bonding interactions on the process of two‐dimensional self‐assembly. These acid derivatives form hydrogen‐bonded dimers as expected; however, the dimers organise themselves in the form of relatively complex lamellae. The characteristic feature of these lamellae is the presence of regular discommensurations or kinks along the lamella propagation direction. The formation of kinked lamellae is discussed in light of the registry mechanism of the alkyl chains with the underlying graphite substrate. The location of the kinks along a lamella depends on the number (odd or even) of carbon atoms in the alkyl chain. This result indicates that concerted van der Waals interactions of the alkyl chain units introduce the odd/even chain‐length effect on the surface‐assembled supramolecular patterns. The odd/even effects are retained even upon complexation with a hydrogen‐bond acceptor. However, as the solvent is changed from 1‐phenyloctane to 1‐octanoic acid, the kinked lamellae as well as the odd/even effects disappear. This solvent‐induced convergence of supramolecular patterns is attained by means of co‐crystallisation of octanoic acid molecules in the 2D crystal lattice, which is evident from high‐resolution STM images. The solvent co‐adsorption phenomenon is discussed in terms of competing van der Waals and hydrogen‐bonding interactions.
Synthesis and Biological Properties of the Cytotoxic 14‐Membered Macrolides Aspergillide A and B
Authors: Díaz‐Oltra Santiago , Angulo‐Pachón César A. , Murga Juan , Falomir Eva , Carda Miguel , Marco J. Alberto 
Published: November 2010

AbstractTotal, stereoselective syntheses of the naturally occurring, cytotoxic macrolides aspergillide A and B are described. Olefin metatheses and asymmetric allylations were key steps in the synthetic sequences. Cytotoxicity assays against several tumor cell lines have been performed for the two aspergillides and some of the intermediates or side products of the synthetic sequence. One of these intermediates has been found markedly active against the human leukemia cancer cell line HL‐60, with an IC50 value comparable with that of the clinical drug fludarabine.