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An Assessment of the Impact Response of Knit/Knit Stitch Fabric Reinforced Epoxy Composites
Effects of Second Phase Dispersions on Microstructure and Mechanical Properties in MgO/SiC Nanocomposites
Información Bibliográfica
Influence of relative humidity and temperature on-site corrosion rates
When the steel rebar depassivates, the corrosion starts to develop at a rate which mainly depends upon the moisture content in the concrete pores. In natural outdoor exposure conditions, the moisture content will depend not only on the relative humidity of the atmosphere but also upon the temperature cycling occurring…
Degradation of Nylon-6 By Glycolysis. Part 1: Identification of Degradation Products
Glycolysis of nylon-6, in the presence of phosphoric acid at 250°CC, leads to a mixture of low molecular weight compounds. HPLC analysis combined with 1H-NMR and mass spectroscopy showed that the main degradation products were ethylene glycol derivatives of caprolactam and linear oligomers. No cyclic oligomers were fo…
Crystallization and Strength of Natural Rubber and Synthetic cis-1,4-Polyisoprene
Abstract Crosslinked samples of natural rubber (NR, SMR-5L) and a synthetic cis -1,4-polyisoprene (IR, Natsyn 2200, The Goodyear Tire & Rubber Company) were crystallized at −25 °C at various strains, and then slowly melted. Crystallization was somewhat slower for IR under all conditions, taking two to three times…
A New Low‐Brittleness Glass in the Soda‐Lime‐Silica Glass Family
In the soda‐lime‐silica glass family, the effect of each constituent of the composition on the brittleness was first investigated. Vickers indentation was employed to estimate the brittleness (ratio of harness ( H ) to fracture toughness ( K c )) by measuring the C / a ratios (where C and a are the characteristic crac…
Active Sites Imaging for Oxygen Reduction at the La0.9Sr0.1MnO3 − x /Yttria‐Stabilized Zirconia Interface by Secondary‐Ion Mass Spectrometry
Active sites for oxygen reduction were investigated at the interface of (LSM)/yttria‐stabilized zirconia (YSZ). Isotopic oxygen ( 16 O/ 18 O) exchange under cathodic polarization and secondary‐ion mass spectrometry (SIMS) analysis were examined to visualize the oxygen reduction active sites. The LSM mesh pattern elect…
Hertzian‐Crack Suppression in Ceramics with Elastic‐Modulus‐Graded Surfaces
Hertzian (spherical) indentation experiments were carried out in a graded alumina‐glass composite whose Young's modulus increased with depth beneath the indented surface. An in situ processing method involving impregnation of a dense, fine‐grained alumina by an aluminosilicate glass was employed to fabricate such a co…
Adsorption of Anionic Dyes on the Biopolymer Chitin
The adsorption of the anionic dyes orange IV, orange G and xylenol orange on chitin was studied, employing the Langmuir isotherm. The adsorption parameters were determined utilizing various linear regressions of the isotherm. The results showed that the adsorption capacity is dependent on pH. In acid pH, the polymer a…
Malate dehydrogenase: distribution, function and properties.
Malate dehydrogenase (MDH) (EC 1.1.1.37) catalyzes the conversion of oxaloacetate and malate. This reaction is important in cellular metabolism, and it is coupled with easily detectable cofactor oxidation/reduction. It is a rather ubiquitous enzyme, for which several isoforms have been identified, differing in their s…
Monodisperse Enantiomeric Lactic Acid Oligomers: Preparation, Characterization, and Stereocomplex Formation
d - and l -lactic acid oligomers were synthesized by polymerization of d - or l -lactide using 2-(2-methoxyethoxy)ethanol (MEE) and stannous octoate as initiator and catalyst, respectively. The average degree of polymerization (DP av ) of the oligomers could be tailored by the monomer/initiator ratio. HPLC and GPC ana…
Range dependence of interlayer exchange coupling
We have considered the effects of non magnetic impurities and interface roughness on the interlayer coupling between magnetic layers in metallic multilayers. The two types of defects alter the interlayer coupling in quite different ways. Elastic electron scattering by impurities in the non magnetic spacer layers betwe…
Magnetic properties of CoFe2O4 thin films prepared by a sol-gel method
Thin films with cobalt ferrite layers on thermally oxidized silicon wafers were fabricated by a sol-gel method. Magnetic and structural properties of the films were investigated with an x-ray diffractometer, a vibrating sample magnetometer and atomic force microscopy. The crystallization temperature for Co ferrite thi…
Interfacial compositions of solid and liquid in a phase-field model with finite interface thickness for isothermal solidification in binary alloys
We show that a finite interface thickness in an isothermal phase-field model for alloy solidification introduces a chemical potential gradient in the interfacial region and the solute trapping effect, and the relationships between material properties and parameters in the phase-field equation can be determined at a lo…
SERS spectra of poly(3-hexylthiophene) in oxidized and unoxidized states
Surface enhanced Raman scattering (SERS) is being increasingly used for the study of the structural properties of conducting polymer thin films. It is generally accepted that the enhancement process has an electromagnetic origin, arising from the excitation of surface plasmons in the metal support on which the polymer…
Defects and interfaces in epitaxial ZnO/α-Al2O3 and AlN/ZnO/α-Al2O3 heterostructures
We have investigated the nature of epitaxy, defects (dislocations, stacking faults, and inversion domains), and heterointerfaces in zinc oxide films grown on (0001) sapphire and explored the possibility of using it as a buffer layer for growing group III nitrides. High quality epitaxial ZnO films were grown on sapphir…
Quasicontinuum simulation of fracture at the atomic scale
We study the problem of atomic scale fracture using the recently developed quasicontinuum method in which there is a systematic thinning of the atomic-level degrees of freedom in regions where they are not needed. Fracture is considered in two distinct settings. First, a study is made of cracks in single crystals, and…
Permanent magnets based on R-Fe-B and R-Fe-C alloys
A review is given on the basic properties of 2:14:1 hard magnetic phases as well as technological procedures used for manufacturing R-Fe-B and R-Fe-C permanent magnets. First, we analyse the phase diagrams, crystal structure of hard magnetic phases and composition ranges in which these phases form solid solutions, as…