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Selected AbstractsAssociation between serum bicarbonate and death in hemodialysis patients: Is it better to be acidotic or alkalotic?HEMODIALYSIS INTERNATIONAL, Issue 1 2005D.Y.J. Wu The optimal acid base status for survival in maintenance hemo-dialysis (MHD) patients (pts) remains controversial. According to some reports acidosis is associated with improved survival in MHD pts, i.e., reverse epidemiology. We examined associations between baseline (first 3-month averaged) serum bicarbonate (HCO3), divided into 12 categories, and 2-yr mortality in 56,376 MHD pts across the US after controlling for confounding effects of malnutrition-inflammation complex syndrome (MICS). Three sets of Cox regression models were evaluated to estimate hazard ratios (HR) of death and 95% confidence intervals (CI): (1) Unadjusted; (2) Multivariate adjusted for case-mix (age, gender, diabetes, race, insurance, marital status, vintage, standardized mortality ratio, residual renal function, dialysate HCO3, and Kt/V); and (3) Additional adjustments for 8 markers of MICS (body mass index, serum albumin, creatinine, ferritin, TIBC, dietary protein intake, WBC and lymphocyte counts). See Figure for HR and 95% CI: We conclude that, although high HCO3 levels appear to be associated with increased mortality in MHD pts, this paradoxical effect is almost entirely due to the overwhelming impact of MICS on survival. [source] Vitrified Silica-Nanofiber Mats as Reinforcements for Epoxy ResinsADVANCED ENGINEERING MATERIALS, Issue 5 2009Oliver Weichold The effects of vitrified, electrospun silica nanofiber mats on the tensile and bending strength (see Figure) of epoxy resins are presented. The mats consist of randomly oriented, amorphous filaments of 600,800,nm diameter. The effects of annealing conditions and surface functionalization on the fiber/matrix adhesion is discussed. The results are compared to those of reference materials. [source] Synthesis of Cobalt/Polymer Multilayer Nanotubes,ADVANCED ENGINEERING MATERIALS, Issue 4 2005K. Nielsch Cobalt/polymer multilayer nanotubes (see Figure) are formed by wetting of alumina and silicon membranes by polystyrene containing a metallo,organic precursor, followed by a thermal decomposition process. This article describes the fabrication and magnetic properties of high quality, thin-walled ferromagnetic nanotubes. They might be very attractive for a broad range of potential applications ranging from biotechnology to magnetic storage devices. [source] Effect of Hypervelocity Impact on Microcellular Ceramic Foams from a Preceramic PolymerADVANCED ENGINEERING MATERIALS, Issue 11 2003P. Colombo A promising material for hypervelocity impact shields in spacecraft and satellites has been found in lightweight microcellular SiOC foams. The foam stops the projectile and the debris from the impacted bumper facesheet within a few millimeters (see Figure for a cross-section of the crater) at speeds up to 5.1 km,s,1. The impacted SiOC ceramic did not react with incoming debris, and no phase transformation or compositional change was observed. [source] Preparation and Characterization of Uniformly Sized Sub-micrometer Spherical Silica/Organic Polymer Hybrid ParticlesADVANCED ENGINEERING MATERIALS, Issue 9 2003X.-s. Xing Hybrid particles with a core-shell structure, consisting of a silica core and a polyvinyl alcohol (PVA) shell, (see Figure for an SEM image of a particle material of this type), were fabricated via a two-step sol-gel process. The PVA molecular chains are probably physically adsorbed onto the surface of silica cores by hydrogen bonds and van der Waals forces. [source] Recrystallization and Texture in a Ferritic Stainless Steel: an EBSD Study,ADVANCED ENGINEERING MATERIALS, Issue 8 2003C.W. Sinclair The recrystallization behavior of laboratory-processed AISI409 ferritic stainless steel sheet has been studied with a focus on texture inhomogeneity and "sluggish" recrystallization kinetics, mainly using EBSD in the scanning electron microscope. Pronounced texture gradients were observed in some grain orientations (see Figure for a TEM image of the , versus ,-grain border region) and correlated to the deformation-induced substructure. The strong pinning of some boundaries has been linked not only to textural effects, but also to the precipitation of fine titanium carbonitrides. [source] Automated Evaluation of Kikuchi Patterns by Means of Radon and Fast Fourier Transformation, and Verification by an Artificial Neural Network,ADVANCED ENGINEERING MATERIALS, Issue 8 2003R.A. Schwarzer Automated crystal orientation measurement (ACOM) in the SEM by interpreting backscatter Kikuchi patterns (see Figure) has become a standard tool of quantitative texture analysis in materials science during the last decade. A Radon transformation of the diffraction pattern, in combination with a 1D fast Fourier transformation, enables the fast extraction of the positions of Kikuchi bands. The high-frequency coefficients of the 1D FFT are used to define pattern quality as a measure of lattice imperfection and residual stress of the real crystal structure. [source] Beneficial Effects of AlN as Sintering Aid on Microstructure and Mechanical Properties of Hot-pressed ZrB2,ADVANCED ENGINEERING MATERIALS, Issue 7 2003F. Monteverde Higher density of ZrB2 ceramics than with the pure material is achieved when 4.6,% of aluminum nitride are added before hot-pressing as a sintering aid. AlN supports densification and prevents grain coarsening, mainly by virtue of its ability to remove the boron oxide layer that otherwise covers ZrB2 particles. The new material (see Figure for an SEM image of a polished section) has outstanding mechanical properties, e.g. strength values of 600 and 200 MPa at 25 and 1500,°C. [source] Predicting the Mircostructure in Semi-Crystalline Thermoplastics using Software for the Simulation of Recrystallization in Metals,ADVANCED ENGINEERING MATERIALS, Issue 3 2003W. Michaeli A software for the simulation of spherulite growth during the cooling of a quiescent melt has been developed and tested vs. experimental data by the authors. The tests have verified good qualitative results: the calculated crystal microstructure and distribution (see Figure for a simulated pattern close to the mold surface) correspond well with the real morphology. [source] Out-of-Equilibrium Self-Assembly of Binary Mixtures of NanoparticlesADVANCED MATERIALS, Issue 5 2006G. Sztrum A coarse-grained lattice-gas model is developed to study the drying-mediated self-assembly of binary mixtures of nanoparticles (NPs). Three model systems are considered, corresponding to equilibrium phase separation between two NPs (A and B), to an amorphous state, and to an ordered, checkerboard-like superstructure (see Figure; red: NPA; green: NPB; blue: solvent). The mechanism for self-ordering depends on the nature of the equilibrium superstructure and on the dynamic coupling to the evaporating solvent. [source] Control of Morphology and Helicity of Chiral Mesoporous Silica,ADVANCED MATERIALS, Issue 5 2006H. Jin Chiral ordered mesoporous silica has been synthesized by using a chiral surfactant (N -myristoyl- L -alanine sodium salt) as a template, 3-aminopropyltriethoxysilane as a co-structure directing agent, and tetraethoxylsilane as an inorganic source. The helicity and the morphology of the mesoporous silica are determined by the stirring rate during the chiral surfactant self-assembly (see Figure), providing new insight into the chiral self-assembly of molecules. [source] Alumina-Template Synthesis of Fluorescent RuO2 Nanotubes Derived from Ru3(CO)12 Clusters,ADVANCED MATERIALS, Issue 5 2006H. Tan RuO2 nanotubes with diameters of 15,25,nm and up to 3,,m in length have been prepared by the thermal decomposition of Ru3(CO)12 inside alumina templates. The RuO2 (110) planes grow along the long axis of the straight crystalline nanotubes. The growth of these fluorescent nanotubes appears to have proceeded via mononuclear ruthenium carbonyl intermediates (see Figure). [source] Silica-Incorporated Polyelectrolyte-Complex Fibers as Tissue-Engineering Scaffolds,ADVANCED MATERIALS, Issue 5 2006Fibers of polyelectrolyte complexes incorporated in silica are synthesized by combining the polymerization of hydrolyzed tetraethylorthosilicate with the process of interfacial polyelectrolyte complexation. The resulting fibers are hydro-entangled to successfully produce porous scaffolds that act as a platform for the immobilization of biological molecules for tissue engineering (see Figure). [source] Photoluminescence Quenching Control in Quantum Dot,Carbon Nanotube Composite Colloids Using a Silica-Shell Spacer,ADVANCED MATERIALS, Issue 4 2006M. Grzelczak One-dimensional nanocomposite colloids are prepared by means of electrostatic self-assembly of CdTe nanocrystals on both carbon nanotubes (CNTs) and silica-coated CNTs (see Figure). The dense coverage of these linear nanoparticle assemblies minimizes the spacing between the nanocrystals, thereby facilitating efficient electronic and energy transfer along the nanotubes. [source] Complexation of C60 on a Cyclothiophene Monolayer Template,ADVANCED MATERIALS, Issue 4 2006E. Mena-Osteritz Highly ordered monolayers of macrocyclic oligothiophene C[12]T (see Figure) can be used as veritable templates to epitaxially grow 3D nanoarchitectures with C60 -fullerenes. Due to submolecularly resolved STM images, 1:1 complexes consisting of a ring-shaped p-type semiconductor (C[12]T) and a spherical n-type semiconductor (C60) can be investigated in terms of dynamics and complexation sites. [source] Metallodielectric Photonic Crystals Assembled from Monodisperse Spherical Colloids of Bismuth and Lead,ADVANCED MATERIALS, Issue 4 2006Y. Wang Monodisperse metallic and metallodielectric spherical colloids have been synthesized in large quantities and explored as building blocks for fabricating three-dimensional metallodielectric photonic crystals. Both measurements and calculations revealed large photonic bandgaps covering optical wavelengths from the visible up to the near-IR region for the metallic (Bi and Pb) and metallodielectric (with a silica coating) colloids (see Figure). [source] "Supercritical Carbon Dioxide in Water" Emulsion-Templated Synthesis of Porous Calcium Alginate Hydrogels,ADVANCED MATERIALS, Issue 4 2006S. Partap Controlled-porosity alginate hydrogels are synthesized via a novel organic solvent-free method, "reactive emulsion templating", which utilizes dense-phase carbon dioxide as a reagent and as a templating agent to produce well-defined hydrogels with a narrow macropore-size distribution and high degrees of porosity and interconnectivity (see Figure). These hydrogels may find use in the biomedical field as drug delivery devices, wound dressings, or as supports for tissue engineering applications. [source] An Azotolane Liquid-Crystalline Polymer Exhibiting Extremely Large Birefringence and Its Photoresponsive BehaviorADVANCED MATERIALS, Issue 4 2006K. Okano A liquid-crystalline polymer (LCP) containing an azotolane group in the mesogenic moeity has been synthesized (see Figure). A homogeneously aligned film of the LCP exhibits an extremely large birefringence in a wide wavelength range. Upon irradiation by a pump laser beam, a large change in birefringence is quickly induced as a result of destruction of the homogeneous alignment of the azotolane moieties. [source] Efficient Near-Infrared Emission from Sodalite Derivatives,ADVANCED MATERIALS, Issue 3 2006M. Lezhnina The use of nanoporous host materials for luminescent guests has been extended into the near-infrared (NIR) regime using sodalite derivatives containing rare earth ions and the tungstate group (see Figure). The emission intensities obtained for Nd3+ meet or even surpass commercial Nd glasses. While Nd3+ -tungstate-modified zeolites do not yield significant luminescence, NIR emission occurs in the sodalites due to the low phonon frequencies involved and the exclusion of water in particular. [source] Highly Bendable, Transparent Thin-Film Transistors That Use Carbon-Nanotube-Based Conductors and Semiconductors with Elastomeric Dielectrics,ADVANCED MATERIALS, Issue 3 2006Q. Cao Transparent flexible thin-film transistors (see Figure) have been made using single-walled carbon nanotube networks of high and moderate coverages as the conducting and semiconducting layers. Electrical (e.g., good performance on plastic), optical (e.g. transparency to visible wavelengths), and mechanical (e.g. extreme flexibility) characteristics that would be difficult, or impossible, to achieve with conventional materials are reported. [source] Molecular Origin of the Temperature-Dependent Energy Migration in a Rigid-Rod Ladder-Phenylene Molecular Host,ADVANCED MATERIALS, Issue 3 2006H. Wiesenhofer Excitation diffusion is studied in a molecular host doped with a luminescent guest. An atomistic model based on the coupling of the electronic excitations to low-frequency intramolecular vibrations reproduces remarkably well the measured temperature-dependent host-to-guest energy transfer efficiency (see Figure). [source] Hybrid Inorganic/Organic Semiconductor Heterostructures with Efficient Non-Radiative Energy Transfer,ADVANCED MATERIALS, Issue 3 2006G. Heliotis An inorganic/organic hybrid semiconductor heterostructure is reported, in which an InGaN quantum well is non-radiatively coupled to a semiconducting polymer overlayer (see Figure). This architecture has the potential to take advantage of the complementary attributes of the two types of semiconductor that it contains, and may lead to devices with highly efficient emission across the entire visible spectrum. [source] Low-Temperature Synthesis of Star-Shaped PbS Nanocrystals in Aqueous Solutions of Mixed Cationic/Anionic Surfactants,ADVANCED MATERIALS, Issue 3 2006N. Zhao Uniform, well-defined star-shaped PbS nanocrystals with tunable sizes (40,100,nm, see Figure), as well as octahedral PbS nanocrystals, have been readily synthesized in aqueous solutions containing a mixture of the surfactants cetyltrimethylammonium bromide/ sodium dodecyl sulfate (CTAB/SDS) at low temperature (80,°C). The size of the PbS nanostars can be accurately controlled by adjusting the reaction time. This result may open new avenues for the green chemical synthesis of shape-controlled semiconductor nanocrystals. [source] Integration of Erbium-Doped Lithium Niobate Microtubes into Ordered Macroporous Silicon,ADVANCED MATERIALS, Issue 3 2006L. Zhao Er3+ -doped LiNbO3 microtubes have been prepared by the infiltration of ordered macroporous silicon with Er:LiNbO3 melts (see Figure). The microtubes consist of single-crystalline segments and exhibit the characteristic photoluminescence of Er3+, which coincides with the transmittance maximum of silica-based optical components. [source] Highly Periodic Fullerene Nanomesh,ADVANCED MATERIALS, Issue 2 2006N. Néel Fullerene nanomesh: Fullerene islands with rectangular shapes organize themselves on a vicinal gold surface in an extraordinarily well-ordered mesh with unprecedented periodicity and low defect density (see Figure). This adsorbate system is a promising candidate for guiding subsequent deposition of functional units. [source] Tapered Carbon Nanotubes from Activated Carbon Powders,ADVANCED MATERIALS, Issue 2 2006Q. Hu Tapered carbon nanotubes (TCNTs) are produced from activated carbon powders via simple thermal catalytic reactions in which the carbon nanotubes grow though a Sn-catalyzed vapor,liquid,solid growth process. The tapered nanotubes are well aligned and have a length of several tens of micrometers (see Figure). [source] Direction-Dependent Homoepitaxial Growth of GaN Nanowires,ADVANCED MATERIALS, Issue 2 2006H. Li GaN nanowires with vastly different morphologies depending upon the growth direction are produced by direct nitridation and vapor transport of Ga in disassociated ammonia. Nanowires grown homoepitaxially along the c -direction develop hexagonal-prism island morphologies (see Figure, left, and Cover), while wires grown along the a -direction form uniform, belt-shaped morphologies (Figure, right). A "ballistic" transport phenomenon for adatoms is proposed to explain the observed prismatic island morphologies. [source] Synthesis of Mesoporous Organosilicate Films in Supercritical Carbon Dioxide,ADVANCED MATERIALS, Issue 2 2006A. Pai Uniform, well-ordered, mesoporous organosilicate films (see Figure) have been synthesized by efficient direct and post-synthesis functionalization methods in supercritical carbon dioxide and characterized using spectroscopic, microscopy, and diffraction techniques. These materials have numerous potential applications, including in sensors, low- k dielectrics, separations, and catalysis. [source] Experimental Evidence for Grain-Boundary Sliding in Ultrafine-Grained Aluminum Processed by Severe Plastic Deformation,ADVANCED MATERIALS, Issue 1 2006Q. Chinh Evidence for grain boundary sliding in ultrafine-grained aluminum after processing with equal channel angular pressing (ECAP) is presented (see Figure). Pure aluminum is used as a model material; depth sensing indentation testing and atomic force microscopy are used to measure the nature of the displacements around indentations for samples in an annealed and work-hardened condition, and after processing using ECAP. [source] Biofunctionalized pH-Responsive Microgels for Cancer Cell Targeting: Rational Design,ADVANCED MATERIALS, Issue 1 2006M. Das The design of a drug-delivery system based on bioconjugated, pH-responsive microgels is demonstrated. Microgels loaded with the anticancer drug Doxorubicin are introduced into the HeLa tumor cells by means of receptor- mediated endocytosis. Changes in pH within the intracellular environment induce shrinkage of microgels, triggering the drug release into the cells. The microgel described in this work shows enhanced cytotoxicity to HeLa cells (see Figure). [source] | ||||||||||||||||