Breakup of Spiral and Concentric Ringed Spherulites in Polymer Crystallization

Recently, the breakup of spiral and concentric ringed spherulites has been observed experimentally in isothermal crystallization of poly(vinylidene fluoride) in its blends with ethylene vinyl acetate copolymer. To elucidate the phenomenon of spiral breakup in polymer spherulites, a theoretical simulation has been undertaken in the framework of the phase field model of solidification based on time-dependent Ginzburg-Landau equations (TDGL model C) pertaining to the conserved concentration and nonconserved phase field order parameters. The concentration order parameter was described in terms of the Landau-type potential, while the crystal order parameter was expressed in terms of an asymmetric double-well potential to account for the nonequilibrium nature (i.e., metastability) of polymer crystallization. After inserting these potentials into the TDGL model C, the resulting coupled time-evolution equations show the emergence of the target and spiral patterns that undergo fragmentation at a very shallow supercooling. It is concluded that the depth of supercooling is the major contributor to the formation of the spirals and subsequent breakup of the spiral arms

Dynamical analysis of fractional-order Mathieu equation

The dynamical characteristics of Mathieu equation with fractional-order derivative is analytically studied by the Lindstedt-Poincare method and the multiple-scale method. The stability boundaries and the corresponding periodic solutions on these boundaries for the constant stiffness δ0=n2 (n = 0, 1, 2, …), are analytically obtained. The effects of the fractional-order parameters on the stability boundaries and the corresponding periodic solutions, including the fractional coefficient and the fractional order, are characterized by the equivalent linear damping coefficient (ELDC) and the equivalent linear stiffness coefficient (ELSC). The comparisons between the transition curves on the boundaries obtained by the approximate analytical solution and the numerical method verify the correctness and satisfactory precision of the analytical solution. The following analysis is focused on the effects of the fractional parameters on the stability boundaries located in the δ-ε plane. It is found that the increase of the fractional order p could make the ELDC larger and ELSC smaller, which could result into the rightwards and upwards moving of the stability boundaries simultaneously. It could also be concluded the increase of the fractional coefficient K1 would make the ELDC and ELSC larger, which could move the transition curves to the left and upwards at the same time. These results are very helpful to design, analyze or control this kind of system, and could present beneficial reference to the similar fractional-order system

Analytically optimal parameters of fractional-order dynamic vibration absorber

In this paper the optimal parameters of the fractional-order Voigt type dynamic vibration absorber (DVA) are analytically studied for two cases, named as H∞ and H2 optimization criteria. At first the approximately analytical solution is obtained by the averaging method when the primary system is subjected to harmonic excitation. Then the optimal fractional coefficient and order are obtained based on H∞ optimization criterion, which is designed to minimize the maximum amplitude magnification factor of the primary system. Based on H2 optimization criterion, the optimal fractional parameters are obtained to reduce the total vibration energy of the primary system over the whole-frequency range. The comparisons of the approximate solutions with the numerical ones in the two cases are fulfilled, and the results verify that the approximately analytical solutions are correct and satisfactorily precise. At last the control performance of the fractional-order Voigt type DVA is compared with the classical integer-order counterpart, and it could be concluded that the fractional-order DVA has superiority in vibration engineering, and fractional-order element could replace the traditional damper and spring simultaneously in some cases

Depression Involved in the Chemotherapy Induced Event-based Prospective Memory Impairment in Breast Cancer Survivors

The aim of this study was to investigate the relationships between depression and occurrence of chemotherapy induced prospective memory impairment in patients with breast cancer (BC).The 63 BC patients before and after chemotherapy were administered with the self-rating depression scale (SDS) and a battery of cognitive neuropsychological tests including event-based and time-based prospective memory (EBPM and TBPM, respectively) tasks. The changes in their prospective memory and cognitive neuropsychological characteristics before and after chemotherapy were compared. Compared with the scores before chemotherapy, the EBPM score exhibited a statistically significant difference after chemotherapy (t = 6.069, P 0.05). Further, compared with the patients without depression, the patients with depression exhibited a statistically significant difference in the EBPM score (t = -4.348, P 0.05). Post-chemotherapy, EBPM and overall cognitive functions in BC patients merged with depression were found to decline, while TBPM did not show a significant change, suggesting that the combination of chemotherapy and depression might be related with the occurrence of post-chemotherapy EBPM impairment

Effect of magnetic nanoparticles on apoptosis and cell cycle induced by wogonin in Raji cells

Traditional Chinese medicine is gradually becoming a new source of anticancer drugs. One such example is wogonin, which is cytotoxic to various cancer cell lines in vitro. However, due to its low water solubility, wogonin is restricted to clinical administration. Recently, the application of drug-coated magnetic nanoparticles (MNPs) to increase water solubility of the drug and to enhance its chemotherapeutic efficiency has attracted much attention. In this study, wogonin was conjugated with the drug delivery system of MNPs by mechanical absorption polymerization to fabricate wogonin-loaded MNPs. It was demonstrated that MNPs could strengthen wogonin-induced cell inhibition, apoptosis, and cell cycle arrest in Raji cells by methylthiazol tetrazolium assay, flow cytometer assay, and nuclear 4′,6-diamidino-2-phenylindole staining. Furthermore, the molecular mechanisms of these phenomena were explored by western blot, in which the protein levels of caspase 8 and caspase 3 were increased significantly while those of survivin and cyclin E were decreased significantly in wogonin-MNPs group. These findings suggest that the combination of wogonin and MNPs provides a promising strategy for lymphoma therapy