A5033537024- Surfactants and Colloidal Systems
- Liquid Crystal Research Advancements
- Lipid Membrane Structure and Behavior
- Material Dynamics and Properties
- Spectroscopy and Quantum Chemical Studies
- Molecular spectroscopy and chirality
- Nonlinear Dynamics and Pattern Formation
- Nuclear Physics and Applications
- Characterization and Applications of Magnetic Nanoparticles
- Advanced NMR Techniques and Applications
- Nanopore and Nanochannel Transport Studies
- Electrostatics and Colloid Interactions
- Primate Behavior and Ecology
- Proteins in Food Systems
- Thermodynamic properties of mixtures
- Crystallization and Solubility Studies
- NMR spectroscopy and applications
- Magnetic and Electromagnetic Effects
- Sphingolipid Metabolism and Signaling
- Solid-state spectroscopy and crystallography
- DNA and Nucleic Acid Chemistry
- Nuclear reactor physics and engineering
- Pickering emulsions and particle stabilization
- Micro and Nano Robotics
- Particle accelerators and beam dynamics
Universidade de São Paulo
2010-2023
Brazilian Synchrotron Light Laboratory
1999
Universidade de Santiago de Compostela
1997
University of Florence
1997
Ospedali Riuniti di Ancona
1994
Instituto de Pesquisas Energéticas e Nucleares
1972
Institute of Atomic Energy
1972
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDistance distribution function of sodium dodecyl sulfate micelles by x-ray scatteringR. Itri and L. Q. AmaralCite this: J. Phys. Chem. 1991, 95, 1, 423–427Publication Date (Print):January 1991Publication History Published online1 May 2002Published inissue 1 January 1991https://doi.org/10.1021/j100154a074RIGHTS & PERMISSIONSArticle Views623Altmetric-Citations85LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum full text article...
A study of a magnetically oriented lyomesophase formed by quaternary system (Na decyl sulfate/water/decanol/Na sulfate) is reported. Small angle x-ray diffraction measurements have been performed on unoriented samples and previously subjected to the action magnetic fields (H). Diffraction patterns show diffuse inner halo at 80–140 Å sharp outer ring 38 Å. They reduce spots in equator for with beam parallel H; no figure produced perpendicular H. NMR spectra indicate that director phase...
Specific ion effects in surfactant solutions affect the properties of micelles. Dodecyltrimethylammonium chloride (DTAC), bromide (DTAB), and methanesulfonate (DTAMs) micelles are typically spherical, but some organic anions can induce shape or phase transitions DTA+ Above a defined concentration, sodium triflate (NaTf) induces separation dodecyltrimethylammonium (DTATf) micelles, phenomenon rarely observed cationic This unexpected behavior DTATf/NaTf system suggests that DTATf aggregates...
Aqueous dispersions of the anionic phospholipid dimyristoyl phosphatidylglycerol (DMPG) at pH above apparent pK DMPG and concentrations in interval 70-300 mM have been investigated by small (SAXS) wide-angle X-ray scattering, differential scanning calorimetry, polarized optical microscopy. The order-disorder transition hydrocarbon chains occurs along an about 10 degrees C (between T(m)(on) approximately 20 T(m)(off) 30 C). Such melting regime was previously characterized lower...
At low ionic strength dimyristoylphosphatidylglycerol (DMPG) exhibits a broad phase transition region characterized by several superimposed calorimetric peaks. Peculiar properties, such as sample transparency, are observed only in the region. In this work we use differential scanning calorimetry (DSC), turbidity, and optical microscopy to study narrowing of with increase (0−500 mM NaCl). Upon addition salt, temperature extension is reduced, number peaks decreases until single cooperative...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNematic domain in the sodium lauryl sulfate/water/decanol systemL. Q. Amaral and M. E. Marcondes HeleneCite this: J. Phys. Chem. 1988, 92, 21, 6094–6098Publication Date (Print):October 1, 1988Publication History Published online1 May 2002Published inissue 1 October 1988https://pubs.acs.org/doi/10.1021/j100332a049https://doi.org/10.1021/j100332a049research-articleACS PublicationsRequest reuse permissionsArticle Views265Altmetric-Citations41LEARN...
The paper by Yu and Saupe on the first biaxial nematic phase created excitement for a number of reasons. Some theories phases already existed, but experimental observation was still lacking. discovered in lyotropic system with three components, which theory is difficult. Lyotropic liquid crystals are composed supramolecular assemblies amphiphilic molecules, may change shape size as function concentration temperature. diagram rather complex, region inserted between cylindrical discotic via...
Micellar phases of the sodium dodecyl (lauryl) sulfate (SLS)--water--decanol system have been studied by x-ray scattering in isotropic (I) phase, with emphasis on I\ensuremath{\rightarrow}hexagonal (${\mathit{H}}_{\mathrm{\ensuremath{\alpha}}}$) and I\ensuremath{\rightarrow}nematic-cylindrical (${\mathit{N}}_{\mathit{c}}$) lyotropic liquid-crystal phase transitions. Analysis curves is made through modeling product P(q)S(q), where P(q) micellar form factor S(q) intermicellar interference...
In order to approach the nature of phase transitions, three lipid-water systems (namely PaLPC,
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew nematic lyomesophase of sodium dodecyl sulfateL. Q. Amaral, M. E. Helene, D. R. Bittencourt, and ItriCite this: J. Phys. Chem. 1987, 91, 23, 5949–5953Publication Date (Print):November 1, 1987Publication History Published online1 May 2002Published inissue 1 November 1987https://pubs.acs.org/doi/10.1021/j100307a027https://doi.org/10.1021/j100307a027research-articleACS PublicationsRequest reuse permissionsArticle Views166Altmetric-Citations30LEARN...
The system sodium dodecyl sulphate (SDS)/decanol (DeOH)/water presents, with temperature increase, an unusual phase transition between a stable biaxial and coexistence region of the two uniaxial nematic phases (discotic ND + cylindrical NC). This has been detected previously by several methods for sample water/SDS molar ratio Mw = 36. Here, this is investigated changing to 32, where was reported after discotic phase, without phase. We report now existence NB in range ~2°C, defining both...
Lyotropic nematics consisting of surfactant–cosurfactant water solutions may present a biaxial phase or direct U(+)↔U(−) transitions, in different regions the temperature‐relative concentration diagram, for systems and compositions. We propose that these be related to changes uniaxial micellar form, which occur either smoothly abruptly. Smooth change cylinder‐like into disc‐like shapes requires distribution Maier–Saupe interaction constants we consider two limiting cases forms: single...
The hexagonal cell parameter a of the system sodium dodecyl lauryl sulfate and water as function volume concentration ${\mathit{c}}_{\mathit{v}}$ in phase ${\mathit{H}}_{\mathrm{\ensuremath{\alpha}}}$ shows functional behavior expected for micelles finite length: a\ensuremath{\propto}${\mathit{c}}_{\mathit{v}}^{\mathrm{\ensuremath{-}}1/3}$. interpretation x-ray data based on leads to an alternative description ${\mathit{H}}_{\mathrm{\ensuremath{\alpha}}}$: spherocylindrical constant radius...
Abstract A model of finite planar micelles (platelets) surrounded by water was previously proposed for a type II lyomesophase. In this paper it is shown that X-ray diffraction results lyomesophase are strongly dependent on the container. Results consistent with hypothesis under influence orientational forces platelets aggegate forming macromicelles composed several amphiphilic bilayers slightly swoolen.
Abstract Experimental evidence for the existence of a first order transition between Nc–Nd uniaxial lyonematic phases as function variable M d (number decanol molecules per amphiphilic molecule) is reported. The relevance this to molecular models micellar aggregates discussed. change in symmetry at transition.
The nematic cylindrical (Nc)−nematic discotic (Nd) phase transitions in three amphiphile/decanol/water systems, occurring as a function of the decanol/amphiphile molecular ratio (Md), are correlated with change micellar form from spherocylinder (SC) to square tablet (ST), which occurs geometrically continuous way, an intermediate biaxial object. relative stability these forms is measured by elastic bending energy, calculated surfactant parameter model, quantity p = v/al (where v, l, and...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTBending energy and relative stability of micellar formsG. Taddei L. Q. AmaralCite this: J. Phys. Chem. 1992, 96, 14, 6102–6104Publication Date (Print):July 1, 1992Publication History Published online1 May 2002Published inissue 1 July 1992https://doi.org/10.1021/j100193a083RIGHTS & PERMISSIONSArticle Views131Altmetric-Citations18LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum full text article downloads since November 2008 (both...