9 research outputs found
Microscopic Investigation on Morphologies of Bilayer Gel Structure in the Mixed Polyoxyethylene-Type Nonionic Surfactant Systems
We investigated morphologies of lamellar domains below
the Krafft
temperature in the mixed polyoxyethylene-type nonionic surfactant,
a C<sub>16</sub>E<sub>6</sub>/C<sub>16</sub>E<sub>7</sub>/water system,
by using optical microscopy, confocal microscopy, small/wide-angle
X-ray scattering, and small-angle neutron scattering. We have found
that the morphology discontinuously changes from network structures
of lamellar domains to spherical vesicles with increasing mole fraction
of C<sub>16</sub>E<sub>7</sub>, via the coexistence region of vesicles
and network structures of lamellar domains
Effects of Oscillatory Shear on the Orientation of the Inverse Bicontinuous Cubic Phase in a Nonionic Surfactant/Water System
The
bicontinuous inverse cubic phase (V<sub>2</sub> phase) formed
in amphiphilic systems consists of bilayer networks with a long-range
order. We have investigated effects of oscillatory shear on the orientation
of the V<sub>2</sub> phase with space group <i>Ia</i>3<i>d</i> formed in a nonionic surfactant (C<sub>12</sub>E<sub>2</sub>)/water system by using simultaneous measurements of rheology/small-angle
X-ray scattering. It is shown that grain refining occurs by applying
the large amplitude oscillatory shear (LAOS) with a strain amplitude
(Ī³<sub>0</sub>) of ā¼20, which gives the ratio of the
loss modulus (<i>G</i>ā³) to the storage modulus (<i>G</i>ā²) (<i>G</i>ā³/<i>G</i>ā² = tan Ī“) of ā¼100. On the other hand, orientation
of the cubic lattice occurs when the small amplitude (Ī³<sub>0</sub> ā 0.0004) oscillatory shear (SAOS) in the linear regime
is applied to the sample just after the LAOS. Interestingly, the orientation
is strongly enhanced by the āmedium amplitudeā (Ī³<sub>0</sub> ā 0.05) oscillatory shear (āMAOSā) after
the SAOS. When the MAOS is applied before applying the LAOS, orientation
to a particular direction is not observed, indicating that the grain
refining process by the LAOS is necessary for the orientation during
the MAOS. The results of additional experiments show that the shear
sequence āLAOSāMAOSā is effective for the orientation
of the cubic lattice. When the LAOS and MAOS are applied to the sample
alternatively, grain refining and orientation occur during the LAOS
and MAOS, respectively, indicating reversibility of the orientation.
It is shown that (i) the degree of the orientation is dependent on
Ī³<sub>0</sub> and the frequency (Ļ) of the MAOS and (ii)
relatively higher orientation can be obtained for the combination
of Ī³<sub>0</sub> and Ļ, which gives tan Ī“ = 2ā3.
The lattice constant does not change throughout all the shearing processes
and is equal to that before shearing within the experimental errors,
indicating that the shear melting does not occur. These results suggest
a possibility to control the orientation of the cubic lattice only
by changing the conditions of oscillatory shear without using the
epitaxial transition from other anisotropic phases, such as the hexagonal
and lamellar phases
Electrolyte Effect on Lamellar Domain Morphology in a Nonionic Surfactant Solution below the Krafft Temperature
In our previous papers, we have studied
the lamellar domain morphology
in aqueous solutions of nonionic surfactants C<sub>16</sub>E<sub>6</sub> and C<sub>16</sub>E<sub>7</sub> below the Krafft temperature. In
this study, electrolyte effects on lamellar domain morphology have
been investigated by means of DSC, confocal microscope, small/wide-angle
X-ray scattering (SAXS/WAXS). It has been found that vesicles in C<sub>16</sub>E<sub>7</sub> solution are transformed to network structures
by adding chaotropic ion Cl<sup>ā</sup>, F<sup>ā</sup> and CH<sub>3</sub>COO<sup>ā</sup>, whereas the network structures
in C<sub>16</sub>E<sub>6</sub> solution are gradually changed to the
vesicles with increasing kosmotropic ion SCN<sup>ā</sup> concentration.
Especially, we focused on the SCN<sup>ā</sup> ion effects on
the C<sub>16</sub>E<sub>6</sub> system, and found that the characteristic
morphology of cylinder-like domains were formed in a certain specific
concentration range. In the SAXS observation in nm scale, we have
also found that the repeat distance of lamellar structures in the
C<sub>16</sub>E<sub>6</sub>/NaSCN solution is anomalously swollen
when adding 1.2ā2 mol/kg NaSCN, where the cylinder-like domains
are formed. We have concluded that the cylindrical vesicles could
be explained by the osmotic pressure difference due to the addition
of NaSCN
Pressure-Induced Transition of Bilayers in a Nonionic Surfactant Solution
Pressure effects on the bilayers
of polyoxyethylene type nonionic
surfactant in water have been investigated by means of small- and
wide-angle X-ray scattering. It has been found that the Krafft transition
from the micellar phase to the lamellar gel phase (L<sub>Ī²</sub>) is induced by pressure. By further pressurizing, the lamellar structural
parameters, such as the repeat distance <i>d</i> and CailleĢ
parameter Ī·, discontinuously decrease after taking a maximum.
All the SAXS and WAXS results revealed that the L<sub>Ī²</sub> phase is transformed into the higher-ordered lamellar crystal phase
(L<sub>c</sub>). On the basis of these observations, we have made
the <i>T</i>ā<i>C</i> and <i>T</i>ā<i>P</i> phase diagrams
Re-entrant Lamellar/Onion Transition with Varying Temperature under Shear Flow
We have found for the first time the reentrant lamellar/onion
(lamellarāonionālamellar)
transition with varying temperature under constant shear rate by using
simultaneous measurements of shear stress and small-angle X-ray scattering
(Rheo-SAXS) for a nonionic surfactant (C<sub>14</sub>E<sub>5</sub>)/water system, which exhibits the lamellar phase in a wide temperature
range from 15ā75 Ā°C. The onion state exists in a closed
region in the temperatureāconcentration diagram at a constant
shear rate. Temperature dependence of the lamellar repeat distance
(<i>d</i>) at rest has also been measured at several concentrations.
It is shown that the increase of <i>d</i> with increasing
temperature is necessary for the existence of the lower transition.
We have investigated the change in the lamellar orientation in the
lamellar-to-onion and onion-to-lamellar transition processes near
the upper and lower transition temperatures. For all four kinds of
transition processes, the following change in the lamellar orientation
is observed; lamellar state (oriented to the velocity gradient direction)
ā further enhancement of the orientation to the velocity gradient
direction ā enhancement of the orientation to the neutral direction
ā onion state
Additional file 1: Table S1. of Effects of preoperative cinacalcet hydrochloride treatment on the operative course of parathyroidectomy and pathological changes in resected parathyroid glands
Characteristics of patients with or without adhesion lesions in resected PTGs. (PPTX 54ĆĀ kb
Additional file 3: of Optimising first- and second-line treatment strategies for untreated major depressive disorder Ć¢ĀĀ the SUNĆ¢ĀÅD study: a pragmatic, multi-centre, assessor-blinded randomised controlled trial
SUNĆ¢ĀÅD Investigators and committee members. (DOCX 17 kb
Additional file 2: of Optimising first- and second-line treatment strategies for untreated major depressive disorder Ć¢ĀĀ the SUNĆ¢ĀÅD study: a pragmatic, multi-centre, assessor-blinded randomised controlled trial
Figure S1. Schedule of the assessments. Table S1. Incidence of suicidality, manic switches or any serious adverse events up to week 9 for step 1 randomisation. Table S2. Incidence of suicidality, manic switches or any serious adverse events up to week 25 for step 1 randomisation. Table S3. Two pre-specified subgroup analyses for step 1 randomisation. Table S4. Four pre-specified sensitivity analyses for step 1 randomisation. Table S5. Incidence of suicidality, manic switches or any serious adverse events up to week 9 for step 2 randomisation. Table S6. Incidence of suicidality, manic switches or any serious adverse events up to week 25 for step 2 randomisation. Table S7. Three pre-specified subgroup analyses for step 2 randomisation. (DOCX 32 kb
Additional file 1: of Optimising first- and second-line treatment strategies for untreated major depressive disorder Ć¢ĀĀ the SUNĆ¢ĀÅD study: a pragmatic, multi-centre, assessor-blinded randomised controlled trial
Blinded data analyses statement of interpretation. (PDF 336 kb