Materials Literature
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Results obtained using the Brunauer-Emmett-Teller method, small-angle x-ray scattering and wide angle x-ray diffraction in the study of porous silicon are compared. The BET method seems to fail when the porosity of samples is smaller than 50%, giving unrealistically large values for the specific surface area, but givi…
This paper reports on materials whose second order nonlinear optical (NLO) properties can be switched by light. We synthesized and studied the properties of a series of substituted N-salicylidene anilines which are noncentrosymmetric and photochromic crystals. All compounds exhibit second harmonic generation (SHG). On…
Effect of alloy elements on corrosion of low alloy steel was studied under simulated offshore conditions. The results showed that the elements Cu, P, Mo, W, V had evident effect on corrosion resistance in the atmosphere zone; Cu, P, V, Mo in the splash zone and Cr, Al, Mo in the submerged zone.
As-spun poly(ethylene-2,6-naphthalate) (PEN) fibers (i.e., precursors) prepared from high molecular weight polymer were drawn and/or annealed under various conditions. Structure and property variations taking place during the treatment process were followed via wide-angle X-ray scattering (WAXS), small-angle X-ray sca…
Composite plates containing pine wood chips and high density polyethylene (HDPE) matrix were prepared and studied for their impact fracture behavior using an instrumented drop weight tester. Maximum load sustained, deflection to maximum load, energy to maximum load and energy for total penetration of the test specimen…
The structure of [Mg(H(2)O)(6)]SO(4) was redetermined at 120 K, confirming the hydrogen-bond pattern found at room temperature [Zalkin et al. (1964). Acta Cryst. 17, 235-240] but showing the librational corrections of bond lengths to be unrealistic.
Single-crystalline α-Al 2 O 3 (0001) surfaces were investigated by low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS) and noncontact-mode atomic force microscopy (NC-AFM). When the α-Al 2 O 3 (0001) surface was annealed in air at 1273 K, terraces of ∼80 nm width and steps of ∼0.2 nm height…
Recent progress in antimicrobial dendrimers is reviewed. Both specific interactions and non-specific interactions can be utilized to design multifunctional (polyvalent) antimicrobial agents, which might be more potent than their mono-functional counterparts. Dendrimers or hyperbranched polymers can also be used to des…
The hydrogen permeation behaviour in austenitic stainless steel (1.4301, AISI 304) was studied between 25 to 85 °C using the electrochemical double cell permeation technique. Influences of parameters like carbon content, grain size and cold work were investigated. Using the current transient plots from the permeation…
A series of silicon-accumulating plants [different Equisetum (horse tail) species, Echium vulgare, and Symphytum officinale] were studied by solid-state 29 Si NMR experiments. For this purpose, selected parts of these plants were freeze-dried and then investigated by solid-state 29 Si VACP/MAS NMR spectroscopy. The 29…
Abstract Vinyl chloride polymerizations are known to be autoaccelerating. The reaction rate increases with conversion. Because of this phenomenon, substantial reactor productivity at early conversion can be lost because the heat‐removal capacity of the reactor is not fully utilized until near the end of the polymeriza…
It is well known that the electrical properties of polymers are significantly influenced by the morphology. High-density polyethylene (HDPE) is a semicrystalline polymer with crystalline and amorphous regions. HDPE specimens with different crystallinities have been prepared by varying the annealing conditions. Based o…
The production technology of carbon-black loaded polyolefins adopted for stress grading purposes in ac cable terminations may impart, in addition to the nonlinear electrical properties, an anisotropic behavior to the material. In this paper a numerical study is presented in order to study the influence of both anisotr…
Polymeric actuator and sensor materials suffer from a low thermal and temporal stability. We report on an attempt to slow down the underlying structural relaxation in polyvinylidenefluoride (PVDF) films by irradiation with electrons of 1.5 MeV. This treatment yielded a dose-dependent crosslinking of the macromolecular…
Abstract Flavylium salts exhibited a reversible thermochromism in an agar-gel matrix. Thus, by the temperature change from −3 to 50 °C, the absorption band around 600 nm of 7-diethylamino-4′-dimethylaminoflavylium perchlorate increased by a factor of ca. 1.5, while the band around 520 nm substantially decreased. Upon…
Abstract The influences of doping the core of TiO 2 pigments with Al 2 O 3 and of various inorganic surface modifications on the rate of poly(vinyl chloride) (PVC) weathering are investigated. The kinetics of loss of gloss are transformed into photooxidation rates by using Weibull statistics of failure, and a scheme o…
Aggregation of methylcellulose in aqueous dilute solution is studied by light and small angle neutron scattering. For temperature T<293.15K, the free chains adopt a swollen conformation. For T>313.15K, a slow aggregation kinetics occurs. At qR g <1, the association number is found to vary as R g 3 . However a…
Results are presented of a complex study of the magnetic and resistive properties, the Hall effect, the thermal emf, and the longitudinal Nernst-Ettingshausen effect of an La 0.8 Ba 0.2 MnO 3 single crystal at temperatures between 77 and 400 K. A maximum was observed near the Curie temperature T c on the temperature d…
The effect of hydrogen bonding on the photochemical cis-trans isomerization is discussed on the basis of the results of absorption and fluorescence spectra as well as of the determination for the efficiencies of photochemical and photophysical processes.
The phase equilibria of the La 2 O 3 –SrO–CaO–Mn 3 O 4 system in air at 1200°C has been studied. Under these conditions, eight univariant four‐phase equilbria were observed. Quaternary phases, as well as liquid phases, were not observed. Perovskite‐structure phases LaMnO 3 , SrMnO 3 , and CaMnO 3 did not form complete…