This study investigated the characteristics and drug release properties of membranes of chitosan and alginate prepared via a casting/solvent evaporation technique. Membranes of chitosan and alginate with silver sulfadiazine as model drug incorporated in different concentrations and different membrane compositions were obtained. The polyblend solution viscosity reached to the highest at the composition polyblends of (1:1). This chitosan/alginate membranes showed pH- and ionic strength-dependent water uptake properties and had the WVTR rang from 442 to 618 g/m(2)/day. The maximum value of the dry membrane of breaking strength was 52.16 MPa and the maximum value of the wet membrane breaking elongation was 46.28%. The results of controlled release studies showed that the silver sulfadiazine release rate was the fastest when the alginate content was 50%. On the basis of the requisite physical properties, the chitosan-alginate PEC membrane can be considered for potential wound dressing or controlled release application.

No abstract

The impacts of different meridional structures of tropical sea surface temperature (SST) on the Hadley circulation (HC) in the annual mean are investigated during the period 1948–2013. By decomposing the variations in SST and the HC into two components—that is, the equatorially asymmetric (SEA for SST, and HEA for HC) and the equatorially symmetric (SES for SST, and HES for HC) parts—it is shown that the long-term variability in SEA and SES captures well the temporal variations in equatorially asymmetric and symmetric variations in SST. The variation in HEA is closely linked to that of SEA, and the variation in HES is connected with that of SES. However, the response of HEA to a given amplitude variation in SEA is stronger (by ~5 times) than that of HES to the same amplitude variation in SES. This point is further verified by theoretical and numerical models, indicating that the meridional structure of SST plays a crucial role in determining the anomalies in HC. This result may explain why the principal mode of HC is dominated by an equatorially asymmetric mode in its long-term variability.

Fast radio bursts (FRBs) are short duration (∼millisecond) radio transients with cosmological origin. The simple sharp features of the FRB signal have been utilized to probe two fundamental laws of physics, namey, testing Einstein's weak equivalence principle and constraining the rest mass of the photon. Recently, Hessels et al. (2018) found that after correcting for dispersive delay, some of the bursts in FRB 121102 have complex time-frequency structures that include sub-pulses with a time-frequency downward drifting property. Using the delay time between sub-pulses in FRB 121102, here we show that the parameterized post-Newtonian parameter γ is the same for photons with different energies to the level of |γ 1 − γ 2 | < 2.5 × 10 −16 , which is 1000 times better than previous constraints from FRBs using similar methods. We also obtain a stringent constraint on the photon mass, m γ < 5.1 × 10 −48 g, which is 10 times smaller than previous best limits on the photon mass derived through the velocity dispersion method.

The recent intensification of trade winds over the tropical Pacific is the strongest ever observed in the past hundred years. This strengthening trend is of great interest in recent research, but the causes are still unclear. Using two relatively long‐term surface wind data sets, the present research shows that there is an overall strengthening trend of the trades in the western equatorial Pacific and an overall weakening trend in the eastern equatorial Pacific. This long‐term trend pattern can be primarily attributed to the cold tongue mode (CTM) rather than to the impact of El Niño–Southern Oscillation (ENSO), El Niño Modoki, or Interdecadal Pacific Oscillation (IPO). The CTM, the second empirical orthogonal function mode of the sea surface temperature anomalies (SSTA) in the tropical Pacific, represents a strong long‐term trend of tropical Pacific background state under global warming. According to the Gill‐Matsuno theory, the easterly winds over the western equatorial Pacific are induced by the equatorial Pacific cooling and warming SSTA associated with the CTM, while the westerly winds over the eastern equatorial Pacific is primarily due to the eastern equatorial Pacific cooling SSTA associated with the CTM. Ultimately, an alternative explanation of past and future changes of the trades is expected to lead to improved understanding of the global climatic impacts of the enhanced trades in tropical Pacific under global warming.

No abstract

No abstract

Sphingosine kinase 1 (SphK1) expression is elevated in various cancers and is associated with shorter survival times for patients. However, the molecular mechanism of SphK1 up-regulation in triple-negative breast cancer (TNBC) remains unclear. In this study, we assayed the expression level of SphK1 in TNBC tissues by qRT-PCR and immunohistochemistry. The level of S1P was quantified by ELISA in the serum of TNBC patients. Our results found that the levels of SphK1 and S1P were significantly increased in TNBC patients compared with normal control. Furthermore, knockdown of SphK1 with siRNA decreased TNBC cell proliferation and inhibited cell migration/invasion. These data suggest that SphK1 has an important role in TNBC and presents an attractive therapeutic target for the treatment for TNBC.