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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 5087-5090 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A study of the water self-diffusion in polycrystalline lamellar systems, by pulsed field gradient spin-echo (PFG-SE) nuclear magnetic resonance (NMR) experiments, is reported here. Our analysis confirmed the validity of previous equations for bidimensional water self-diffusion in lamellar lyomesophases and clarified their applicability limits. Depending on the diffusion experimental time range, two different procedures can be built up; for wide amplitude windows, the experimental diffusion coefficients are correlated to the fraction of bound water, whereas for short times it has been possible to point out the "obstruction factor'' to diffusion. Experimental support for the theoretical findings was inferred by investigation of the lamellar mesophase of the binary system water/sodium-bis-2-ethylhexyl sulfosuccinate (AOT). It confirmed the existence of some defects in the lamellae at water concentration higher than 70 wt. %.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Langmuir 11 (1995), S. 1116-1121 
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 139 (1986), S. 396-402 
    ISSN: 0006-291X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 139 (1986), S. 396-402 
    ISSN: 0006-291X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1435-1536
    Keywords: Key words Poly(ethylene oxide) ; poly(propylene oxide) ; poly(ethylene oxide) ; Micellar solutions ; Hexagonal and lamellar mesophases ; Pulsed field gradient spin-echo nuclear magnetic resonance experiments ; Micellar self-diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Water-soluble poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO–PPO–PPO) triblock copolymers are high-molecular-weight nonionic copolymers and form micellar solutions and liquid-crystalline mesophases in water. We studied the temperature dependence of polymer and water self-diffusion in solutions and lyotropic mesophases of the PEO13 PPO30 PEO13/water and PEO21 PPO47 PEO21/water binary systems. The self-diffusion measurements were performed by means of the pulsed field gradient spin-echo NMR method. The analysis of the water mobility was realised using “the obstruction factor” and “the two-site model”, which consider the reduction of the water self-diffusion due to the microstructure of the lyotropic aggregates and to the presence of one part of the solvent bound to the polymer aggregate surfaces. We calculated the water obstruction factors and the hydration numbers as a function both of the polymer composition and of the temperature. The results are compared with the data obtained in mesophases formed by classical surfactants.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 19 (1989), S. 100-104 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Experimental studies of mass transfer were conducted in stacked screens with a gas-liquid mixture flowing through the bed. Depending on the gas and liquid flow rates and on the geometric characteristics of the screens, different flow regimes are obtained. In the heterogeneous flow regime the gas phase controls mass transfer, meanwhile in the transition and bubbling flow regimes the influence of the liquid flow prevails. Appropriate dimensionless groups correlate the mass transfer coefficients with the pertinent variables for the different regimes.
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Solid State Ionics 72 (1994), S. 147-151 
    ISSN: 0167-2738
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1041
    Keywords: Key words Prostaglandin ; Type-2 diabetes mellitus ; Plasminogen activator inhibitor type-1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objectives: Iloprost, an analogue of prostacyclin, is often utilised in subjects with diabetes mellitus complicated by macroangiopathy. Methods: The effects of iloprost infusion on plasminogen activator inhibitor type-1 (PAI-1), glucometabolic control and cardiovascular equilibrium in patients with type-2 diabetes mellitus and peripheral arterial occlusive disease were investigated. Thirteen (7 men/6 women) normal-weight, normotensive and non-smoker type-2 diabetic patients (63.8 ± 3.4 years, mean ± SD) with peripheral arterial occlusive disease, stage-II according to Fontaine classification, were enrolled. Eight (four men/four women) patients underwent three study designs, each separated by a 1-week interval: study I, infusion of iloprost (3 ng kg−1 min−1 for 5 h) for 1 day alone (short-term treatment); study II, infusion of saline (for 5 h) for 1 day (control treatment); study III, infusion of iloprost (3 ng kg−1 min−1 for 5 h) over a period of 28 days (long-term treatment). The remaining five (three men/two women) patients underwent study IV only, infusion of saline over a period of 28 days (placebo treatment). Plasma levels of glucose, plasminogen, PAI-1 activity and fibrinogen, blood pressure and heart rate were determined in all studies, while plasma insulin levels, blood HbA1c, walking distance and Winsor index only in studies III and IV. Results: Both short- and long-term treatments with iloprost significantly reduced PAI-1 activity (baseline vs end: 17.4 ± 1.9 AU/ml vs 15.0 ± 1.6 AU/ml, P 〈 0.02; 20.5 ± 7.6 AU/ml vs 7.9 ± 2.1 AU/ml, P 〈 0.002, respectively). Long-term treatment with iloprost significantly increased walking distance (baseline vs end: 325 ± 41 m vs 496 ± 52 m, P 〈 0.0001), but not Winsor index. Neither glucometabolic control nor cardiovascular equilibrium were affected by short- and long-term treatments with iloprost. Control and placebo treatments did not cause any significant modifications in the parameters evaluated. Conclusion: If confirmed by further investigations, the results of this pilot study suggest that iloprost, infused for both brief and long periods, is able to reduce the cardiovascular risk factor PAI-1, increases free walking capacity and does not affect glucometabolic control and blood pressure in type-2 diabetic patients complicated by macroangiopathy.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 272 (1994), S. 1289-1294 
    ISSN: 1435-1536
    Keywords: Ionic strength ; DPPC ; multilayer ; ESR ; DSC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effects of salinity on the lateral headgroup interactions of dipalmitoylphosphatidylcholine (DPPC) molecules in fully hydrated multilayers have been investigated by spin label electron spin resonance (ESR) spectroscopy and differential scanning calorimetry (DSC). By increasing the NaCl concentration from 0 to 3 M in the multilayers' dispersion medium, the ESR measurements performed with the 5-stearic acid spin label and di-tert-butyl-nitroxide show an increase in the orientational degree of order of the lipid molecules, mainly in the gel phase, and a decrease of the membrane permeability. An upward shift from 31.5° to 36.5°C and from 40.5° to 41.9°C of the pre- and main DPPC phase transition temperatures, respectively, is observed with 5-SASL, while slightly higher values are detected with DTBN. Small effects are evident on the properties of the liquid crystalline phase of the DPPC multilayers. The DSC measurements also reveal an upward shift of the pre- and main transition temperatures. The shifts, however, are more marked if compared to the ones observed with the ESR technique. The findings suggest an increase in the packing density of the DPPC molecules in the multilayers in presence of high salt concentration. Dehydration of the DPPC interfacial region with a variation of the lateral electrostatic interactions between phospholipid polar heads trigger the phenomena observed.
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