Thermal Robustness of Entanglement in a Dissipative Two-Dimensional Spin System in an Inhomogeneous Magnetic Field

Recently new novel magnetic phases were shown to exist in the asymptotic steady states of spin systems coupled to dissipative environments at zero temperature. Tuning the different system parameters led to quantum phase transitions among those states. We study, here, a finite two-dimensional Heisenberg triangular spin lattice coupled to a dissipative Markovian Lindblad environment at finite temperature. We show how applying an inhomogeneous magnetic field to the system at different degrees of anisotropy may significantly affect the spin states, and the entanglement properties and distribution among the spins in the asymptotic steady state of the system. In particular, applying an inhomogeneous field with an inward (growing) gradient toward the central spin is found to considerably enhance the nearest neighbor entanglement and its robustness against the thermal dissipative decay effect in the completely anisotropic (Ising) system, whereas the beyond nearest neighbor ones vanish entirely. The spins of the system in this case reach different steady states depending on their positions in the lattice. However, the inhomogeneity of the field shows no effect on the entanglement in the completely isotropic (XXX) system, which vanishes asymptotically under any system configuration and the spins relax to a separable (disentangled) steady state with all the spins reaching a common spin state. Interestingly, applying the same field to a partially anisotropic (XYZ) system does not just enhance the nearest neighbor entanglements and their thermal robustness but all the long-range ones as well, while the spins relax asymptotically to very distinguished spin states, which is a sign of a critical behavior taking place at this combination of system anisotropy and field inhomogeneity.     

In vitro evaluation of the impact of ultrasound scanner settings and contrast bolus volume on time-intensity curves

The objective of this study was to assess in vitro the impact of ultrasound scanner settings and contrast bolus volume on time-intensity curves formed from dynamic contrast-enhanced ultrasound image loops. An indicator-dilution experiment was developed with an in vitro flow phantom setup used with SonoVue contrast agent (Bracco SpA, Milan, Italy). Imaging was performed with a Philips iU22 scanner and two transducers (L9-3 linear and C5-1 curvilinear). The following ultrasound scanner settings were investigated, along with contrast bolus volume: contrast-specific nonlinear pulse sequence, gain, mechanical index, focal zone depth, acoustic pulse center frequency and bandwidth. Four parameters (rise time, mean transit time, peak intensity, and area under the curve) were derived from time-intensity curves which were obtained after pixel by pixel linearization of log-compressed data (also referred to as video data) included in a region of interest. Rise time was found to be the parameter least impacted by changes to ultrasound scanner settings and contrast bolus volume; the associated coefficient of variation varied between 0.7% and 6.9% while it varied between 0.8% and 19%, 12% and 71%, and 9.2% and 66%, for mean transit time, peak intensity, and area under the curve, respectively. The present study assessed the impact of ultrasound scanner settings and contrast bolus volume on time-intensity curve analysis. One should be aware of these issues to standardize their technique in each specific organ of interest and to achieve accurate, sensitive, and reproducible data using dynamic contrast-enhanced ultrasound. One way to mitigate the impact of ultrasound scanner settings in longitudinal, multi-center quantitative dynamic contrast-enhanced ultrasound studies may be to prohibit any adjustments to those settings throughout a given study. Further clinical studies are warranted to confirm the reproducibility and diagnostic or prognostic value of time-intensity curve parameters measurements in a particular clinical scenario of interest, for example that of cancer patients undergoing vascular targeting therapies.     

Soft mechanical treatments of recycled fibers using a high-shear homogenizer for tissue and hygiene products

Cellulose - This study introduces an innovative approach for developing high strength-high softness recycled fibers through soft mechanical treatment. Recycled fibers from old corrugated containers...     

Effects of modifications of the heteroatoms on fine-tuning the photophysical proprieties of A-π-D-π-A small molecules for photovoltaic applications

An effective way to enhance the photovoltaic properties of a small molecule is to modify the side groups into donor units. Herein three news small molecules A-π-D-π-A, denoted Dye1-3, have been designed, from experimentally reported one noted (R), by insertion of various heteroatoms (S, O, Se) on the electron-donating benzodithiophene (Donor (D = BDT)) part. From the calculated results, the dihedral angle between BDT and side-chain affects the distribution of density on the ground state, gap energy, and intramolecular charge transfer of Dyes. In particular, the Dye3 compound, with the smaller dihedral angle, shows that the furan groups in the side chain of D, participates in the distribution of density on the ground state and consequently the charge transfer is improved. Additionally, Dye3 has the lower reorganization energy revealing that this material exhibits better charge mobility. Using the Scharber diagram, Dye3-PCBM heterojunction shows a power conversion efficiency of around 7%. Overall, this work suggests that the photovoltaic properties can be affected by the modification of heteroatoms on side groups of donor parts in small molecules.