Materials Literature
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Titanium silicon carbide (Ti3SiC2) is a damage tolerance material that is expected to be used in a number of high temperature applications. In this work, the microstructure and damage tolerance mechanism of Ti3SiC2 was investigated. The result demonstrated that the Ti3SiC2 ceramics prepared by the in-situ hot pressing…
We have developed a high energy resolution electron energy-loss spectroscopy (EELS) microscope, which can take spectra from specified small specimen areas and specified small reciprocal space areas to investigate detailed electronic structures. The EELS microscope is equipped with retarding Wien filters as the monochr…
The concept of the inductive effect is defined in terms of thermodynamics and its quantitative estimation is reviewed. The electrostatic (through-space) and sigma-inductive (through-bond) theories are confronted and experimental proofs evaluated, with the result that both theories are very approximate and neither is i…
Novel silane based metal pretreatments have been developed as cost effective alternatives to the chromating process. The new process is a simple solution dip process, is non-carcinogenic, and has outperformed chromated systems under different test conditions. The system provides superior corrosion and adhesion per for…
Zinc-meso-tetrasulfonatophenyl-porphyrin (ZnTPPS 4- ) spontaneously forms a complex with methyl viologen (MV 2+ ) in aqueous solutions. Both the free porphyrin and its complex with viologen were studied by pump−probe spectroscopy. Excitation in the porphyrin Soret band with a short laser pulse (fwhm = 200 fs) populate…
To understand the complex mechanisms of reaction, solvation, and diffusion that determine the chemistry of silica in solution, it is necessary to study first the silicate clusters that participate in these processes. We have investigated, by ab initio density functional methods, all silica-based clusters of the form S…
This study compared surface characteristics and dissolution behavior of well-crystallized (KGa-1b) and poorly crystallized (KGa-2) kaolinite standards. Atomic force microscopy (AFM) revealed that particles of KGa-1b generally have nicely hexagonal micromorphology and crystallographically controlled microtopographic fe…
A binary poly(L-lactide)/poly(ε-caprolactone) (PLLA/PCL) (70/30 w/w) blend and a ternary PLLA/PCL/PLLA-PCL-PLLA blend of the same composition which contains 4 wt.-% of a triblock PLLA-PCL-PLLA copolyester as compatibilizing agent were prepared by melt mixing at 200°C. Investigation of the thermal and mechanical proper…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSynthesis and Characterization of Stable Stoichiometric Clathrates of Silicon and Germanium: Cs8Na16Si136 and Cs8Na16Ge136Svilen Bobev and Slavi C. SevovView Author Information Department of Chemistry and Biochemistry University of Notre Dame, Notre Dame, Indiana 46556…
A vertex-sharing double square pyramid of cobalt(II) ions (see picture) is present in the nonanuclear complex 1, obtained by treating cobalt acetate with 0.5 equivalents of (py2)CO. The corresponding 1:1 reaction gave 2, which has a central core with a cubane structure. py=pyridine.
A simple method of producing aligned carbon nanotube films and a mechanism for their formation are described. The alignment method is based on the self-organization by surface decomposition of a SiC wafer in a vacuum at a temperature between 1500 and 1700°C. From the results of cross-sectional observations by high-res…
The adsorption of benzotriazole (BTAH) on copper in aqueous electrolytes is examined by means of a vibrational analysis utilizing surface-enhanced Raman spectroscopy (SERS) as a function of solvent deuteration, pH, and electrode potential in order to examine adsorbate speciation, surface bonding, and the potential-dep…
OBJECTIVE: Currently used valve substitutes for valve replacement have certain disadvantages that limit their long-term benefits such as poor durability, risks of infection, thromboembolism or rejection. A tissue engineered autologous valve composed of living tissue is expected to overcome these shortcomings with natu…
Existing experimental data for the antiferroelastic phase transition in strontium titanate are reviewed and analysed using a Landau free energy of the form ΔG = 1/2Aθs (cothθs/ Tc-colb.θ/T)Q2 + 1/4BQ 4 + 1/6CQ 6, with A = 0·6472 J K−1mol−1, B = 29·12 Jmol−1, C = 39·27 Jmol, T c= 105·6 K, θ S = 60·8 K. The temperature…
We report on the temperature dependence of the crystal and magnetic structure of the layered colossal magnetoresistive manganite, ${\mathrm{La}}_{2\ensuremath{-}2x}{\mathrm{Sr}}_{1+2x}{\mathrm{Mn}}_{2}{\mathrm{O}}_{7}, x=0.3$. Neutron-diffraction measurements show that the insulator-metal (IM) transition ${(T}_{\mathr…
In this study, atomistic finite deformation calculations employing the Embedded Atom Method show three items of interest related to continuum field theory. First, a spatial size scale effect on the yield stress is found. In these calculations, mechanical yield point occurred from dislocation initiation at the edge of…
Isothermal transformation kinetics and coarsening rates were studied in unseeded and alpha‐Al 2 O 3 ‐seeded γ‐Al 2 O 3 powders heated in dry air and water vapor. Unseeded samples heated in dry air transformed to alpha‐Al 2 O 3 with an activation energy of 567 kJ/mol. Seeding with alpha‐Al 2 O 3 increased the transform…
The packet-like space-charge behaviour in an oxidized crosslinked polyethylene (XLPE) film doped with antioxidant is discussed through computer simulation. The model is based on the following assumptions, (1) both electrons and holes are injected from the electrodes and they migrate to the opposite electrodes by hoppi…
The mixed ionic‐electronic conductor (LSCF) is a candidate for use as the membrane material in the pressure‐driven air separator. However the long‐term stability of these materials is a major concern for the commercial realization of these devices. In an attempt to assess the stability of the material under realistic…
Cosmo-mimetic carbon microcoils with a three-dimensional helical/spiral structure similar to deoxynucleic acid, having coil diameters of 3–6 μm and coil lengths of 5–8 mm could be obtained by the catalytic pyrolysis of acetylene. A three-dimensional growth model of the carbon coils, based on the anisotropy for the car…