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21.
Dirk Pfefferkorn Sven Sonntag Samuel O. Kyeremateng Zofia Funke Hans‐Werner Kammer Jörg Kressler 《Journal of Polymer Science.Polymer Physics》2010,48(17):1893-1900
The pressure–volume–temperature behavior of miscible blends of poly(ethylene oxide) (PEO) and poly(methyl acrylate) (PMA) was studied over extended ranges of temperature and pressure. From pressure–volume–temperature data, the reduction parameters for the Flory‐Orwoll‐Vrij equation‐of‐state were determined. It was found that reduction parameters as well as density, thermal expansion coefficient, and isothermal compressibility vary with composition in a nonlinear manner. The surface tension of the blends in the molten state was measured over the whole composition range using the sessile drop method. The surface tension was found to display negative deviation from additivity pointing toward a remarkable surface excess of PMA. Moreover, surface tension displays a minimum in the range of low PEO content at weight fraction of ~0.19. In addition, the temperature coefficient of surface tension shows negative deviation from linearity. It stays constant when PMA is in excess. Results are discussed in terms of equation‐of‐state thermodynamics. The minimum of surface tension can be well explained by weak self‐association of PEO in the bulk. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1893–1900, 2010 相似文献
22.
Ohne ZusammenfassungDie Mikroanalysen wurden im Institut für Pharmazeutische Chemie durch Herrn Dr.Fritz Stimler ausgeführt.Meinem Lehrer Prof. Dr.Alois Zinke sage ich an dieser Stelle für wertvolle Anregungen während meiner Arbeit den herzlichsten Dank. 相似文献
23.
L. Funke J. Döring P. Kemnitz P. Ojeda R. Schwengner E. Will G. Winter A. Johnson L. Hildingsson Th. Lindblad 《Zeitschrift für Physik A Hadrons and Nuclei》1986,323(2):127-137
Projectile and targetK-vacancy production probabilities in 4.6-, 5.8- and 7.3-MeV/a.m.u. U+U and U+Pb collisions are reported for impact parameters between 10 and 85 fm. These probability measurements are compared with available theory. 相似文献
24.
DSC measurements on full thickness mice skin 总被引:1,自引:0,他引:1
Highly lipophilic basic drugs, the antiestrogens AE1 and AE2 shall be delivered transdermally. DSC as an additional tool in
combination with classic investigation techniques should be used to clarify permeation enhancement. Skin treatment with pure
solvents, polyethyleneglycol (PG) and dimethylisosorbide (DMI), slightly changed the phase transition temperatures. Formulations
containing lauric acid markedly shifted these transitions to lower temperatures, indicating a lipid-fluidising action of lauric
acid. In those cases an additional endothermic peak was observed around 40°C, which is attributed to the melting of crystalline
lauric acid. Since the DSC program started at -20°C, it is very likely that lauric acid in the skin samples crystallized.
A formulation of polyethyleneglycol and lauric acid leads to significantly higher deposition of lauric acid into the skin,
in opposition to dimethylisosorbide/lauric acid formulation. These findings correspond to the results from our in-vitro permeation
studies, where a significantly higher transdermal steady-state flux of lauric acid from polyethyleneglycol-formulation in
comparison to dimethylisosorbide-formulation was observed. By this unique combination of polyethyleneglycol and lauric acid,
the barrier is obviously modified in a way, which allows the highly lipophilic antiestrogens to permeate easily through the
skin. So, from this formulation steady-state fluxes of AE-1 were observed, representing approximately the same value compared
to the unhindered permeation through skin without stratum corneum. The grade of temperature shift on the skin lipids to lower
temperatures can be correlated with softening effects and the enhancement potential of the formulation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
25.
High Ethene/Ethane Selectivity in 2,2′‐Bipyridine‐Based Silver(I) Complexes by Removal of Coordinated Solvent 下载免费PDF全文
Dr. Matthew G. Cowan William M. McDanel Prof. Hans H. Funke Dr. Yuki Kohno Prof. Douglas L. Gin Prof. Richard D. Noble 《Angewandte Chemie (International ed. in English)》2015,54(19):5740-5743
Following removal of coordinated CH3CN, the resulting complexes [AgI(2,2′‐bipyridine)][BF4] ( 1 ) and [AgI(6,6′‐dimethyl‐2,2′‐bipyridine)][OTf] ( 2 ) show ethene/ethane sorption selectivities of 390 and 340, respectively, and corresponding ethene sorption capacities of 2.38 and 2.18 mmol g?1 when tested at an applied gas pressure of 90 kPa and a temperature of (20±1) °C. These ethene/ethane selectivities are 13 times higher than those reported for known solid sorbents for ethene/ethane separation. For 2 , ethene sorption reached 90 % of equilibrium capacity within 15 minutes, and this equilibrium capacity was maintained over the three sorption/desorption cycles tested. The rates of ethene sorption were also measured. To our knowledge, these are the first complexes, designed for olefin/paraffin separations, which have open silver(I) sites. The high selectivities arise from these open silver(I) sites and the relatively low molecular surface areas of the complexes. 相似文献
26.
On the Mechanism of the Formations of Chromium(IV)oxide from Chromyl Chloride The decomposition of chromyl chloride in the temperature range from 380 to 400°C leads with increasing oxygen pressure to chromium oxides containing up to nearly 90% of CrO2. The interaction with the chlorine prevents a quantitative formation of CrO2. Up to 315°C during the decomposition of chromyl chloride chromium oxides of higher valencies are formed separating chlorine and taking up oxygen simultaneously. By working in flowing oxygen it could be proved that the decomposition goes at lower temperatures via the nondetectable CrO3. By heating gradually and by removing the chlorine as far as possible stoichiometric CrO2 at oxygen pressures above 60 atm could be obtained. 相似文献
27.
The frequency dependent far-infrared conductivity of ßAg3SI, determined by measurement of transmittance and reflectivity, provides dynamic evidence for a non-periodic local motion of the silver ions. This motion takes place in the areas at the centers of the iodine-cube faces where the cationic potential is known to be flat. The experimental far-infrared conductivity is compared with conductivity spectra calculated on the basis of the following simple single-particle models: diffusion on a ring, statistical hopping between nearest-neighbor tetrahedral sites, and Brownian motion in a two-dimensional harmonic potential. 相似文献
28.
29.
The high-spin states of 95Tc have been studied in the reaction 93Nb(α, 2n)95Tc using inbeam spectroscopy of both γ-rays and conversion electrons. A new sequence of negative-parity states extending up to angular momentum was found to exist within an excitation energy interval of 4.1 MeV. The positive-parity states are in remarkable agreement with the predictions of a simplified shell-model approach on the basis of coupled excitations of proton and as well as neutron configurations. A similar analysis for the negative-parity states shows qualitative agreement with the experimental results. 相似文献
30.
F. Dubbers L. Funke P. Kemnitz G. Winter S. Elfström Th. Lindblad C. G. Lindén 《Zeitschrift für Physik A Hadrons and Nuclei》1978,287(2):165-169
The doubly-odd nucleus176Ta is investigated by means of in-beamγ-ray spectroscopy techniques using the reactions (α, 3n), (d, 2n) and (p, n). Life-time measurements in thens-region yield low-lying isomeric states withT 1/2=13±1 ns and 30.5±1 ns, while measurements in the ms-region show the existence of a 1.1±0.1 ms isomeric state. A rotational sequence, withK=5 or 6 for the band-head, is also observed. 相似文献