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11.
Francis D. de Kőrösy 《Mikrochimica acta》1989,97(1-2):25-29
Donor or acceptor compounds in apolar organic solvents become charged at a high-field strength electrode and are driven to a surrounding low-field strength electrode of opposite sign. At 10 kV per cm the solutions conduct 3–7 times better when the highly charged electrode is positive in donor solutions. The opposite situation occurs in acceptor solutions. 相似文献
12.
B. Hlavőček J. Šestők L. Koudelka P. Mošner J. J. Mareš 《Journal of Thermal Analysis and Calorimetry》2005,80(2):271-283
Summary The forms of vibrations and displacements of particles in amorphous structures have been investigated. The particles, moving on highly non-linear amplitude, are responsible for the creation of disordered structures of amorphous bodies. The non-linear oscillators, even if 'few' in concentration, are characterized by unpredictable trajectories in phase space. The non-linear oscillators are fully developed in the liquid state above the crossover temperature Tcr and between Tcr and Tg their number decreases. Under Tg they completely disappear. The interconnection between the linear oscillators in blocks plays the most important role in the characteristic time spectra in liquid state. Using the additive properties of elements polarizibilities, the number of acoustical units in individual blocks at Tcr is estimated to be about 600 units. The diameter of blocks at Tcr was estimated to be about 1.8 nm. Even if the non-linear high amplitude motions disappear at solidification, the remnants of structural irregularity remain and the disordered structure of glass is formed. 相似文献
13.
T. Lohner E. Kótai F. Pászti A. Manuaba M. Fried J. Gyulai 《Journal of Radioanalytical and Nuclear Chemistry》1984,83(1):75-81
It is demonstrated that the information obtained by Rutherford backscattering spectrometry and channeling technique can substantially help in the construction of a realistic optical model for the ellipsometry of ion-implanted silicon. In the case of fully amorphous ion-bombarded layers, the ellipsometry is a fast, non-destructive and contactless method to estimate the thickness of these films. For buried and partially disordered layers a qualitative interpretation of different trajectories in the - plance can be given on the basis of channeling measurements. 相似文献
14.
Aranka Pilbáth Ilona Felhősi Gyula Tolnai Erika Kálmán 《Journal of Solid State Electrochemistry》2006,10(9):721-729
Due to the toxic and carcinogenic properties of hexavalent chromium ion, the corrosion protection with chromating technique needs replacement. Several environmentally friendly alternative metal pretreatments have already been proposed. One of these methods is the application of self-assembling molecules to form mono- or multilayers on the metal surfaces. These layers can prevent metal dissolution due to their dense and stable structure. The objective of our studies was to protect zinc surface against corrosion, with a thin phosphonate layer. Aqueous solutions of diphosphonic acid with different alkyl chain lengths were applied with different treatment times. The layer formation, stability, and corrosion protection of these films were monitored by electrochemical impedance spectroscopy and the effect of 1,5-diphosphono-pentane (DPP) on zinc was studied by polarization curves. The wetting properties were determined by static contact angle measurement. 1,5-Diphosphono-pentane forms a thin layer, with a pronounced protective ability in neutral aqueous solutions. The application of self-assembling molecules can be a promising method to replace the chromating technique on zinc surface. 相似文献
15.
The macroradical decay in poly(methyl methacrylate) samples with different thermal histories was investigated in the temperature interval 20–100 °C using ESR spectroscopy and the second order kinetic model. The rate constants exhibit two different regimes with the transitions atT
tr=68±1°C which are independent of thermal treatment. ForT<T
tr andT>T
tr the rate constants as well as the corresponding activation parameters are sensitive to history because of different physical microstructures. The compensation law, i.e., the linear relation between lnk
o, eff andE
eff, was analyzed in terms of the so-called compensation quantitiesk
c andT
c and a proximity betweenT
c=T
tr andT
o=53±3 °C — Vogel temperature for -segmental dynamics was found. A comparison of kinetic and dynamic data suggests that the decay of terminal macroradicals in the low-temperature region is controlled by secondary relaxations and that the -mobility contributes to a more rapid decay at higher temperatures belowT
g. 相似文献
16.
J. Kőmives S. Gál K. Tomor Gy. Kovács 《Journal of Thermal Analysis and Calorimetry》1983,27(2):315-324
Thermogravimetry was applied in studies of aluminium foils for electrolytic capacitors. Scanning electron microscopy, X-ray diffraction and surface area determination were also used in the interpretation of the results. Both the specific surface area and the capacity of the foils showed a linear relationship to the height of the oxidation step measured by TG, which was found suitable for following the processes of anodic oxidation and thermal treatment of the foils as well. 相似文献
17.
Albert Lévai Gábor Tóth Áron Szőllősy Tibor Timár 《Monatshefte für Chemie / Chemical Monthly》1990,121(5):403-411
Summary Arylsulfonyloxy-2,2-dimethyl-2H-chromenes (26–35) have been synthesized by reduction of arylsulfonyloxy-2,2-dimethyl-4-chromanones (6–15) followed by dehydration.
Synthese von Benzopyranderviaten. 15. Mitt.: Darstellung von Arylsulfonyloxy-2,2-dimethyl-2H-chromenen
Zusammenfassung Reduktion von Arylsulfonyloxy-2,2-dimethyl-4-chromanonen (6–15) und anschließende Dehydratisierung liefert Arylsulfonyloxy-2,2-dimethyl-2H-chromene (26–35).相似文献
18.
While the basic fermented (sour) milk products, such as yogurt and kefir can be produced only in live flora version, the post
heat-treatment is preferred in their flavored variations to increase the storage time. Casein being in sour coagulum precipitates
during heat-treatment; therefore protective colloids surrounding the protein should be used to prevent it. Protective colloids
are plant extracts, the most known of them are pectin and amylopectin. Basic requirement of protective colloid effect is the
lower swelling temperature of hydrocolloid than the temperature of precipitation of sour coagulum. In this work we have examined
the precipitation of sour coagulum as a function of the type of lactic acid bacteria cultures applied during fermentation
as well as the swelling of heat protective plant hydrocolloids as a function of the composition (mainly of sugar content)
of medium. To investigate the precipitation of fermented coagulum skimmed milk was fermented with mesophilic butter culture,
thermophilic yogurt culture as well as with exopolysaccharide (EPS)-producing Prebiolact-2 culture. Precipitation was indicated
in the increase of great extent of viscosity. Amylopectin was dispersed into aqueous solution of pH 4.5, the saccharose concentration
of which was changed during the investigation of the swelling of heat protective hydrocolloids. A definite exothermic peak
was assigned to the swelling of hydrocolloids during the DSC experiments. We could conclude that the precipitation temperature
was increasing in the mesophilic-thermophilic-EPS producing microbes line, i.e. the heat stability and swelling temperature
of hydrocolloids depend on the saccharose content of aqueous medium and they increase with rising the concentration of saccharose. 相似文献
19.
Free radicals were generated in a rigid rod-like copolymer via mechanical route and by gamma radiation. The (EPR) method was used for studying free radicals formed at 123 K. The spectra of free radicals observed and the influence of molecular motions on the transport of radical centers in the fracture surface layer are discussed. 相似文献
20.
Optical yields obtained in the hydrogenation of acetophenone with cationic and in situ rhodium complex catalysts depend on the P/Rh ratio and on the ionic or non-ionic character of the active species. The enantioselectivity of the in situ catalyst containing (+)-DIOP is reversed by addition of achiral tri-n-alkyl-phosphines. On the basis of these observations and the amount of H2 consumed in preforming the catalysts, several different mechanisms are suggested: for example: cycles involving cationic rhodium complexes containing two (or three) phosphorus ligands and cycles involving non-ionic rhodium complexes with two phosphorus ligands in cis or trans positions. In the in situ catalyst with a Rh/(+)-DIOP/P-n-Bu3 1/1/1 ratio (+)-DIOP functions as a monodentate ligand. 相似文献