Materials Literature
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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…
Dielectric barrier discharge at atmospheric pressure has been applied to prepare diamond-like hydrogenated amorphous carbon films on glass and silicon substrates from CH 4 –H 2 mixtures. The coating with Knoop hardness up to 10 GPa can be deposited under CH 4 -to-H 2 ratio of 1:2 and substrate temperature of 300°C. Th…
The crystal structures of the Tutton salts (NH4)2[Cu(H2O)6](SO4)2, diammonium hexaaquacopper disulfate, formed with normal water and isotopically substituted H2(18)O, have been determined by X-ray diffraction at 9.5 K and are very similar, with Cu-O(7) the longest of the Cu-O bonds of the Jahn-Teller distorted octahed…
A sample of the natural type IIa diamond was pre-irradiated in a nuclear reactor and then annealed under isothermal conditions at 550°C. The experimental data were used to calculate a decrease in concentration of the neutral vacancy defect called GR1, corresponding to a phononless band (PLB) at 741 nm, and an increase…
The effects of substituting chromium for iron and the use of low cost ferrochromium alloys in the production of β-Ti–Fe–Cr alloys have been studied with respect to phase constitution, stability, and mechanical properties, in solution treated and quenched states using resistivity, hardness measurement, X-ray diffractio…
Several methodologies to produce α-terpinyl chloride from “hydrochlorination” of limonene were studied and the best results were obtained by reaction with 0.5 mol equiv. SOCl2 in SiO2 / CH2Cl2. Using this methodology (R)- and (S)-α-terpinyl chloride can easily be prepared in good yields from (R)- and (S)-limonene, res…
Abstract Selective-dissolution techniques by ammonium oxalate (OX), dithionite-citrate-bicarbonate (DCB), and dithionite-ethylenediaminetetraacetic acid (D-EDTA), and X-ray diffraction and Mössbauer spectroscopy were used to identify and characterize iron oxides and oxyhydroxides in the <2-mm, <50-μm, and <2-…
Systematic fatigue experiments, including both high‐cycle axial fatigue ( S – N curves) and fatigue crack growth (FCG, d a /d N –Δ K curves), were performed on a precipitation‐hardening martensitic stainless steel in laboratory air and 3.5 wt% NaCl solution. Specimens were prepared in three tempers, i.e. solution‐anne…