Photon correlation spectroscopy for molecular self-assembly investigations

Conference (2013, April 11)

The molecular self-assembly performance is among the most important functionalities of amphiphilic compounds in colloidal system areas. This aptitude is required in numerous applications, depending on ... [more ▼]

The molecular self-assembly performance is among the most important functionalities of amphiphilic compounds in colloidal system areas. This aptitude is required in numerous applications, depending on solubilization, hydrotropy, rheology, separation, loading and delivery, encountered in biological and industrial processes. The main physicochemical parameter predicting the capacity of amphiphiles to self-assembly in bulk liquid, aqueous (normal micelles) or non-aqueous phase (reverse micelles), is the pair critical micelle concentration (CMC) and temperature (CMT). A variety of methods based on surface tension, spectral changes, and electrical conductivity are commonly used for determining the value of CMC. The choice usually depends on the ionic or non-ionic nature of the amphiphilic compounds. In this communication, a standard Photon Correlation Spectroscopy (PCS), also known Light Scattering-based technique for CMC determination will be theoretically and practically described in details. Its particular interest for measuring the performance of non-ionic and very high hydrophobic tail, mono or disubstituted carbohydrate-based compounds, from C16 alkyl chain, will be demonstrated. Such a method is advantageous regarding the time, amount, and resolution required, but also for additional information on micelle size, aggregate number, and stability it may provide, compared to surface tension and electrical conductivity-based measurements. [less ▲]

Photoperiodic control of testosterone metabolism, plasma gonadotrophins, cloacal gland growth, and reproductive behavior in the Japanese quail.

in General and Comparative Endocrinology (1979), 39(2), 222-35

Photophysical investigation of Rose Bengal in aqueous sodium taurocholate solutions

in Journal of Photochemistry & Photobiology B : Biology (1993), 17(1), 47-56

The photophysics of rose bengal has been studied in aqueous sodium taurocholate solutions with or without 0.6 mol NaCl dm−3. The ground and first excited singlet states solubilize only in the aggregates ... [more ▼]

The photophysics of rose bengal has been studied in aqueous sodium taurocholate solutions with or without 0.6 mol NaCl dm−3. The ground and first excited singlet states solubilize only in the aggregates formed by sodium taurocholate, whereas the first triplet state solubilizes both in the bulk phase and in the aggregates. A lower limit of the corresponding entry and exit rate constants ke and ks, respectively has been estimated: ke ≥ 5 X 106 dm3 mol−1 s−1 (2x107 dm3 mol−1 s−1 with 0.6 mol NaCl dm−3) and ks ≥ 105 s−1. The triplet state as well as the semioxidized radical react with the taurocholate anion. The former reaction leads to the formation of semireduced dye. The latter is responsible for the detection of only semioxidized radicals which move freely in the aqueous phase. The results are compared with those obtained previously in aqueous sodium dodecyl sulphate solutions and the possible biological implication is discussed. [less ▲]

Photophysique et couleur cutanée.

in Revue Médicale de Liège (2005), 60 Suppl 1

The optical properties of skin and of chromophores orientate and absorbe light. The resulting skin colour can be assessed by visual inspection or by objective methods. Spectrophotometry, tristimulus ... [more ▼]

The optical properties of skin and of chromophores orientate and absorbe light. The resulting skin colour can be assessed by visual inspection or by objective methods. Spectrophotometry, tristimulus colorimetry and computerized image analysis are well codified methods. Epidermal melanisation is detected with great sensitivity under ultraviolet light illumination. [less ▲]

PHOTOREDUCTION OF PROTOCHLOROPHYLLIDE IN DARK-GROWN BEAN COTYLEDONS AS A FUNCTION OF AGE

in Murata, N (Ed.) Research in Photosynthesis (1992)

The photorefractive effect at large modulation depth in semiconductors with multiple defect levels

in Applied Physics B : Lasers & Optics (2002), 74

The photorefractive effect in semiconducting mate- rials with multiple defects is studied in the case of modulation depth m = 1. The basic equations are Poisson's equation and the continuity equations for ... [more ▼]

The photorefractive effect in semiconducting mate- rials with multiple defects is studied in the case of modulation depth m = 1. The basic equations are Poisson's equation and the continuity equations for electrons, holes and occupied defect levels. They include all recombination and optical generation mechanisms between the defect levels and valence and conduc- tion bands. Their explicit numerical solution yields microscopic quantities such as space- and time-dependent electrical field profiles, carrier concentrations, as well as generation and re- combination rates. The fundamental Fourier component of the electric field yields the two-wave-mixing gain. Application is made for InP with two levels in the forbidden gap, for which steady-state and transient resulting quantities are shown. The re- sulting features at large modulation depth are of non-sinusoidal shape. Due to the complexity of the system, the final results strongly depend on all parameters intervening in the models used, as is illustrated for several typical cases. [less ▲]

Photorefractive ZnTe grown by traveling heater method

in Trends in Optics and Photonics (2003), 87

Photos + annonce de Colloque International, U. Lg

in Soul Bag (1991), (124),

1) PHOTO DE COUVERTURE Johnny Heartman 2) Photos Ann PEEBLES , Otis CLAY , Lynn WHITE ; Hasselt Nov. 1989 3) Annonce de la Conférence Internationale de Septembre 1991 à l' Université de Liège ( The ... [more ▼]

1) PHOTO DE COUVERTURE Johnny Heartman 2) Photos Ann PEEBLES , Otis CLAY , Lynn WHITE ; Hasselt Nov. 1989 3) Annonce de la Conférence Internationale de Septembre 1991 à l' Université de Liège ( The secular in religious music and the sacred in secular music" [less ▲]

Photosensitized generation of hydroxyl radical by eught new sulfur and selenium analogs of psoralen

in Journal of Photochemistry & Photobiology B : Biology (1996), 35

comparative study by ESR of the hydroxyl radical generation by 8 eight new sulfur and selenium analogs of psoralen

The "photosphere-wind connection" in Wolf-Rayet stars: simultaneous photometry and spectroscopy of EZ CMa

in Liege International Astrophysical Colloquia (1996)

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