495 research outputs found
Mass and generalized Thiele equation of the magnetic skyrmion
An analytical expression is obtained to the mass of an isolated magnetic
skyrmion and its linearized equation of motion. The magnetic skyrmion is viewed
as a topologically protected spin-wave soliton in the magnetic ultrathin films
stabilized by the interfacial-Dzyaloshinskii-Moriya interaction. The equations
of motion are derived from the Landau-Lifshitz-Gilbert equation for both the
skyrmion charge and magnetization centers. They are generalized Thiele
equations, including gyro-term, dissipation term, external force, an
acceleration term with the tensorial mass, and time derivatives of the external
forces. The equation of motion of the center of the skyrmion charge essentially
shows the massless nature of the skyrmion. In contrast, the equation of motion
for the magnetization center results in a finite mass that is in the same order
as the Doring mass density for the linear domain wall. Furthermore, the time
derivative of the external force predominantly contributes to the immediate
response of the skyrmion motion, i.e., the mass-less property remains even
after the skyrmion acquires its kinetic mass.
A micromagnetic simulation based on the LLG equation was performed for
various magnetic parameters. Obtained trajectories at 0 K are compared with the
theoretical predictions.Comment: 28 pages, 3 figure
Manipulating 1-dimensinal skyrmion motion by external magnetic field gradient
We have investigated an analytic formula of the 1-dimensional magnetic
skyrmion dynamics under external magnetic field gradient. We find excellent
agreement between the analytical model and micromagnetic simulation results for
various magnetic parameters such as the magnetic field gradient, Gilbert
damping constant. We also observe much faster velocity of the chiral domain
wall (DW) motion. The chiral DW is exist with smaller interfacial
Dzyaloshinskii-Moriya interaction energy density cases. These results provide
to develop efficient control of skyrmion for spintronic devices.Comment: 15 pages, 5 figures, 1 tabl
Improvement of the SOD activity of the Cu2+ complexes by hybridization with lysozyme and its hydrogen bond effect on the activity enhancement
We prepared L-amino acids (L-valine and L-serine, respectively) based on the Schiff base Cu2+ complexes CuSV and CuSS in the absence/presence of hydroxyl groups and their imidazole-bound compounds CuSV-Imi and CuSS-Imi to reveal the effects of hydroxyl groups on SOD activity. The structural and spectroscopic features of the Cu2+ complexes were evaluated using X-ray crystallography, UV-vis spectroscopy, and EPR spectroscopy. The spectroscopic behavior upon addition of lysozyme indicated that both CuSV and CuSS were coordinated by the imidazole group of His15 in lysozyme at their equatorial position, leading to the formation of hybrid proteins with lysozyme. CuSS-Imi showed a higher SOD activity than CuSV-Imi, indicating that the hydroxyl group of CuSS-Imi played an important role in the disproportionation of O2− ion. Hybridization of the Cu2+ complexes CuSV and CuSS with lysozyme resulted in higher SOD activity than that of CuSV-Imi and CuSS-Imi. The improvements in SOD activity suggest that there are cooperative effects between Cu2+ complexes and lysozyme
Metastases of soft tissue sarcoma to the liver: A Historical Cohort Study from a Hospital-based Cancer Registry
Background: Hepatic metastasis of soft tissue sarcoma is rare compared to lung metastasis, and the literature is scarce. We examined the risk of hepatic metastasis according to the site of occurrence and histological type. Methods: From a Hospital-based Cancer Registry, 658 patients registered between 2007 and 2017 with soft tissue sarcomas were evaluated. The exclusion criteria were gastrointestinal stromal tumors, tumors of unknown origin, and follow-up periods of less than 1 month. SPSS 25 was used for statistical analysis. Results: The risk of hepatic metastasis was significantly higher in the retroperitoneum (HR, 5.981; 95% CI, 2.793-12.808) and leiomyosarcoma (HR, 4.303; 95% CI, 1.782-10.390). Multivariate analysis showed that the risk of hepatic metastasis as first distant metastasis was high in leiomyosarcoma (HR, 4.546; 95% CI, 2.275-9.086) and retroperitoneal onset (HR, 4.588; 95% CI, 2.280-9.231). The 2-year survival rate after hepatic metastasis was 21.7%. Conclusions: The onset of hepatic metastasis indicates a poor prognosis. However, hepatic metastasis from retroperitoneal sarcoma and leiomyosarcoma may be the first distant metastasis in some cases. For retroperitoneal sarcoma and leiomyosarcoma, additional screening for hepatic metastasis such as contrast CT should be considered during staging and follow-up after treatment.ArticleCancer medicine 17(17) : 6159-6165(2020)journal articl
- …