Search results for "angle"
showing 10 items of 1921 documents
Propolis-Based Nanofiber Patches to Repair Corneal Microbial Keratitis
2021
In this research, polyvinyl-alcohol (PVA)/gelatin (GEL)/propolis (Ps) biocompatible nanofiber patches were fabricated via electrospinning technique. The controlled release of Propolis, surface wettability behaviors, antimicrobial activities against the S. aureus and P. aeruginosa, and biocompatibility properties with the mesenchymal stem cells (MSCs) were investigated in detail. By adding 0.5, 1, and 3 wt.% GEL into the 13 wt.% PVA, the morphological and mechanical results suggested that 13 wt.% PVA/0.5 wt.% GEL patch can be an ideal matrix for 3 and 5 wt.% propolis addition. Morphological results revealed that the diameters of the electrospun nanofiber patches were increased with GEL (from…
COX-2 and sPLA2 inhibitory activity of aqueous extract and polyphenols of Rhizophora mangle (red mangrove)
2006
The aqueous extract of Rhizophora mangle bark and its polyphenolic fractions showed remarkable in vitro antiinflammatory activity in a preliminary study. The low molecular weight fraction exhibited cyclooxygenase-2 inhibitory activity while the total aqueous extract and the low molecular weight fraction showed secretory phospholipase A(2) inhibitory activity.
The effect of β-methylation on the conformation of α, β-dehydrophenylalanine: a DFT study
2009
Dehydroamino acids are non-coded amino acids that offer unique conformational properties. Dehydrophenylalanine (ΔPhe) is most commonly used to modify bioactive peptides to constrain the topography of the phenyl ring in the side chain, which commonly serves as a pharmacophore. The Ramachandran maps (in the gas phase and in CHCl3 mimicking environments) of ΔPhe analogues with methyl groups at the β position of the side chain as well as at the C-terminal amide were calculated using the B3LYP/6-31 + G** method. Unexpectedly, β-methylation alone results in an increase of conformational freedom of the affected ΔPhe residue. However, further modification by introducing an additional methyl group a…
Small angle neutron scattering studies of critical phenomena in a three-component microemulsion
2007
Critical density fluctuations of a ``water-in-oil`` microemulsion consisting of water, benzene, and BHDC (benzyldimethyl-n-hexadecyl ammonium chloride) were observed near the phase boundary by SANS. Observed profiles were well described by product of a form factor of spherical droplets and a structure factor, consisting of a term describing the inter-droplet correlations and also an Ornstein- Zernike component describing the droplet density fluctuations. Allowance was also made fro droplet polydispersity,though the width of the distribution turned out to be very small (1-2%). Observed temperature dependence of osmotic compressibility was fitted using the crossover function proposed by Belya…
Active locking and entanglement in type II optical parametric oscillators
2018
Type II optical parametric oscillators are amongst the highest-quality sources of quantum-correlated light. In particular, when pumped above threshold, such devices generate a pair of bright orthogonally-polarized beams with strong continuous-variable entanglement. However, these sources are of limited practical use, because the entangled beams emerge with different frequencies and a diffusing phase-difference. It has been proven that the use of an internal wave-plate coupling the modes with orthogonal polarization is capable of locking the frequencies of the emerging beams to half the pump frequency, as well as reducing the phase-difference diffusion, at the expense of reducing the entangl…
Structure features and phase behaviour of amphiphilic N-tetradecyl-β-hydroxy-propionic acid amide monolayers
1997
Abstract Two phase transitions of N-tetradecyl-β-hydroxy-propionic acid amide monolayers at the air/water interface were studied by means of pressure/surface area ( π A ) isotherms, Brewster angle microscopy (BAM) and synchrotron X-ray grazing-incidence diffraction (GID). At T≤15 °C the π A isotherms show two plateau regions indicating two first-order phase transitions. In the first main transition from the lowdensity fluid-like phase to a condensed phase, dendritic growth of condensed phase domains with six main growth directions was observed by BAM. A second transition from a condensed phase with large tilt angle to a condensed phase with smaller tilt angle and a denser arrangement of mol…
Phase Transitions in Prequenched Mesomorphic Isotactic Polypropylene during Heating and Annealing Processes As Revealed by Simultaneous Synchrotron S…
2011
Time-resolved simultaneous synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) technique was used to investigate the phase transitions in prequenched mesomorphic isotactic polypropylene (iPP) samples during heating and annealing processes, respectively. For the heating process, it is shown that the mesomorphic-to-monoclinic phase transition is relatively faster for the mesomorphic iPP sample obtained with the high quenching rate than that with the low quenching rate. For the former, the stability of α-monoclinic crystals formed during heating is relatively higher. As for the annealing process, WAXD and SAXS data illustrate that the higher the annealing te…
Static and MAS 35CI NMR and Molecular Motions of ClO −4 Ions in the Various Phases of Multimethylammonium Perchlorates
1986
Static and MAS*) 35CI NMR data of CIO−4 ions in the low-, intermediate- and high-temperature phases of trimethylammonium, dimethylammonium and monomethylammonium perchlorates are reported. The observed solid-solid phase transitions are interrelated with the motional state of the perchlorate ions. In the low-temperature phase III of trimethylammonium perchlorate there is an anisotropic motion of the ClO−4 ions with a constant quadrupole frequency of 185 kHz and an increasing value of the asymmetry parameter when approaching phase transition III-II. The activation energy for this motion is found to be 44.3 kj/mol. At the transition III-II the ClO−4 ions gain orientational degrees of freedom m…
Quantum Critical Scaling under Periodic Driving
2016
Universality is key to the theory of phase transition stating that the equilibrium properties of observables near a phase transition can be classified according to few critical exponents. These exponents rule an universal scaling behaviour that witnesses the irrelevance of the model's microscopic details at criticality. Here we discuss the persistence of such a scaling in a one-dimensional quantum Ising model under sinusoidal modulation in time of its transverse magnetic field. We show that scaling of various quantities (concurrence, entanglement entropy, magnetic and fidelity susceptibility) endures up to a stroboscopic time $\tau_{bd}$, proportional to the size of the system. This behavio…
LaAg x In1?x
1980
The phonon dispersion of LaAg x In1−x (x=1, 0.89, 0.8) has been studied by inelastic neutron scattering in the cubic high temperature phase. A soft mode behaviour was observed at theM-point. The doubling and the cubic to tetragonal deformation of the elementary cell was observed through the phase transition. The measurements of the elastic constants were extended to 450 K and their magnetic field dependence was investigated.