619 research outputs found
Thermodynamics of Surfactants, Block Copolymers and Their Mixtures in Water: The Role of the Isothermal Calorimetry
The thermodynamics of conventional surfactants, block copolymers and their mixtures in water was described to the light of the enthalpy function. The two methodologies, i.e. the van’t Hoff approach and the isothermal calorimetry, used to determine the enthalpy of micellization of pure surfactants and block copolymers were described. The van’t Hoff method was critically discussed. The aqueous copolymer+surfactant mixtures were analyzed by means of the isothermal titration calorimetry and the enthalpy of transfer of the copolymer from the water to the aqueous surfactant solutions. Thermodynamic models were presented to show the procedure to extract straightforward molecular insights from the bulk properties
Neutron scattering studies on ionic diffusion behaviors of superionic -CuSe
We present studies on crystal structure and ionic diffusion behaviors of
superionic CuSe (=0, 0.04, and 0.2) by utilizing neutron
powder diffraction and quasi-elastic neutron scattering. In the superionic
phase, the structural model with Cu ions occupying the Wyckoff sites of 8
and 32 provides the best description of the structure. As the content of Cu
increasing in CuSe, the Cu occupancy increases on the 32 site,
but decreases on the 8 site . Fitting to the quasi-elastic neutron
scattering spectra reveals two diffusion modes, the localized diffusion between
the 8 and 32 sites and the long-range diffusion between the adjacent 8
sites using the 32 site as a bypass, respectively. Between 430 and 650 K, we
measured that the compound with more Cu content exhibits a larger long-range
diffusion coefficient. Temperature in this range does not affect the long-range
diffusion process obviously. Our results suggest the two diffusion modes
cooperative and thus provide a microscopic understanding of the ionic diffusion
of the Cu ions in superionic CuSe.Comment: 6 pages, 3 figure
Application of High-Frequency Oscillations on Scalp EEG in Infant Spasm: A Prospective Controlled Study
ObjectiveWe quantitatively analyzed high-frequency oscillations (HFOs) using scalp electroencephalography (EEG) in patients with infantile spasms (IS).MethodsWe enrolled 60 children with IS hospitalized from January 2019 to August 2020. Sixty healthy age-matched children comprised the control group. Time–frequency analysis was used to quantify γ, ripple, and fast ripple (FR) oscillation energy changes.Resultsγ, ripple, and FR oscillations dominated in the temporal and frontal lobes. The average HFO energy of the sleep stage is lower than that of the wake stage in the same frequency bands in both the normal control (NC) and IS groups (P < 0.05). The average HFO energy of the IS group was significantly higher than that of the NC group in γ band during sleep stage (P < 0.01). The average HFO energy of S and Post-S stage were higher than that of sleep stage in γ band (P < 0.05). In the ripple band, the average HFO energy of Pre-S, S, and Post-S stage was higher than that of sleep stage (P < 0.05). Before treatment, there was no significant difference in BASED score between the effective and ineffective groups. The interaction of curative efficacy × frequency and the interaction of curative efficacy × state are statistically significant. The average HFO energy of the effective group was lower than that of the ineffective group in the sleep stage (P < 0.05). For the 16 children deemed “effective” in the IS group, the average HFO energy of three frequency bands was not significantly different before compared with after treatment.SignificanceScalp EEG can record HFOs. The energy of HFOs can distinguish physiological HFOs from pathological ones more accurately than frequency. On scalp EEG, γ oscillations can better detect susceptibility to epilepsy than ripple and FR oscillations. HFOs can trigger spasms. The analysis of average HFO energy can be used as a predictor of the effectiveness of epilepsy treatment
Coexistence of ferromagnetism, antiferromagnetism, and superconductivity in magnetically anisotropic (Eu,La)FeAs2
Materials with exceptional magnetism and superconductivity usually conceive
emergent physical phenomena. Here, we investigate the physical properties of
the (Eu,La)FeAs2 system with double magnetic sublattices. The parent EuFeAs2
shows anisotropy-associated magnetic behaviors, such as Eu-related moment
canting and exchange bias. Through La doping, the magnetic anisotropy is
enhanced with ferromagnetism of Eu2+ realized in the overdoped region, and a
special exchange bias of the superposed ferromagnetic/superconducting loop
revealed in Eu0.8La0.2FeAs2. Meanwhile, the Fe-related antiferromagnetism shows
unusual robustness against La doping. Theoretical calculation and 57Fe
M\"ossbauer spectroscopy investigation reveal a doping-tunable dual
itinerant/localized nature of the Fe-related antiferromagnetism. Coexistence of
the Eu-related ferromagnetism, Fe-related robust antiferromagnetism, and
superconductivity is further revealed in Eu0.8La0.2FeAs2, providing a platform
for further exploration of potential applications and emergent physics.
Finally, an electronic phase diagram is established for (Eu,La)FeAs2 with the
whole superconducting dome adjacent to the Fe-related antiferromagnetic phase,
which is of benefit for seeking underlying clues to high-temperature
superconductivity.Comment: 13 pages, 6 figures for the main tex
Synthesis and Properties of LaSrNiO and LaSrNiO
Superconductivity has been realized in films of LaSrNiO. Here
we report synthesis and characterization of polycrystalline samples of
LaSrNiO and LaSrNiO ().
Magnetization and resistivity measurements reveal that LaSrNiO
are paramagnetic metals and LaSrNiO exhibit insulating
behavior. Superconductivity is not detected in bulk samples of
LaSrNiO. The absence of superconductivity in bulk
LaSrNiO may be due to the generation of hydroxide during
reduction or a small amount of nickel impurities. The effect of interface in
films of LaSrNiO may also play a role for superconductivity.Comment: 9 pages, 4 figure
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