Analysing observed star cluster SEDs with evolutionary synthesis models: systematic uncertainties

The definitive version is available at www.blackwell-synergy.com. Copyright Blackwell Publishing DOI : 10.1111/j.1365-2966.2004.07197.xWe discuss the systematic uncertainties inherent to analyses of observed (broad-band) Spectral Energy Distributions (SEDs) of star clusters with evolutionary synthesis models. We investigate the effects caused by restricting oneself to a limited number of available passbands, choices of various passband combinations, finite observational errors, non-continuous model input parameter values, and restrictions in parameter space allowed during analysis. Starting from a complete set of UBVRIJH passbands (respectively their Hubble Space Telescope/WFPC2 equivalents) we investigate to which extent clusters with different combinations of age, metallicity, internal extinction and mass can or cannot be disentangled in the various evolutionary stages throughout their lifetimes and what are the most useful passbands required to resolve the ambi- guities. We find the U and B bands to be of the highest significance, while the V band and near-infrared data provide additional constraints. A code is presented that makes use of luminosities of a star cluster system in all of the possibly available passbands, and tries to find ranges of allowed age-metallicity-extinction-mass combinations for individual members of star cluster systems. Numerous tests and examples are pre- sented. We show the importance of good photometric accuracies and of determining the cluster parameters independently without any prior assumptions.Peer reviewe

Phase Control on Surface for the Stabilization of High Energy Cathode Materials of Lithium Ion Batteries.

The development of high energy electrode materials for lithium ion batteries is challenged by their inherent instabilities, which become more aggravated as the energy densities continue to climb, accordingly causing increasing concerns on battery safety and reliability. Here, taking the high voltage cathode of LiNi0.5Mn1.5O4 as an example, we demonstrate a protocol to stabilize this cathode through a systematic phase modulating on its particle surface. We are able to transfer the spinel surface into a 30 nm shell composed of two functional phases including a rock-salt one and a layered one. The former is electrochemically inert for surface stabilization while the latter is designated to provide necessary electrochemical activity. The precise synthesis control enables us to tune the ratio of these two phases, and achieve an optimized balance between improved stability against structural degradation without sacrificing its capacity. This study highlights the critical importance of well-tailored surface phase property for the cathode stabilization of high energy lithium ion batteries

ZIF-67 In Situ Grown on Attapulgite: A Flame Retardant Synergist for Ethylene Vinyl Acetate/Magnesium Hydroxide Composites.

ZIF-67@ATP was prepared by the in situ growth of the zeolite imidazole frame (ZIF-67) on the surface of attapulgite (ATP). The structure and surface morphology of ZIF-67@ATP were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Different mass fractions of ATP and ZIF-67@ATP were added to ethylene vinyl acetate (EVA)/magnesium hydroxide (MH) composites as flame retardant synergists. The flame retardancy of EVA composites was evaluated by the limiting oxygen index (LOI) test, UL-94 test and cone calorimeter test. Composites containing 3 wt% of ZIF-67@ATP reached an LOI value of 43% and a V-0 rating in the UL-94 test, and the ignition time of the composite increased from 38 s to 56 s. The tensile strength and impact strength of the composites did not change significantly, but the elongation at break increased greatly. Typically, for composites containing 4 wt% of ZIF-67@ATP, the elongation at break of the composites increased from 69.5% to 522.2% compared to the samples without the synergist. This study provides novel insights into the application of attapulgite in the field of flame retardant polymer materials.post-print3999 K

Curcumin Blocks Small Cell Lung Cancer Cells Migration, Invasion, Angiogenesis, Cell Cycle and Neoplasia through Janus Kinase-STAT3 Signalling Pathway

Curcumin, the active component of turmeric, has been shown to protect against carcinogenesis and prevent tumor development. However, little is known about its anti-tumor mechanism in small cell lung cancer (SCLC). In this study, we found that curcumin can inhibit SCLC cell proliferation, cell cycle, migration, invasion and angiogenesis through suppression of the STAT3. SCLC cells were treated with curcumin (15 µmol/L) and the results showed that curcumin was effective in inhibiting STAT3 phosphorylation to downregulate of an array of STAT3 downstream targets ,which contributed to suppression of cell proliferation, loss of colony formation, depression of cell migration and invasion. Curcumin also suppressed the expression of proliferative proteins (Survivin, Bcl-XL and Cyclin B1), and invasive proteins (VEGF, MMP-2, MMP-7 and ICAM-1).Knockdown of STAT3 expression by siRNA was able to induce anti-invasive effects in vitro. In contrast, activation of STAT3 upstream of interleukin 6 (IL-6) leads to the increased cell proliferation ,cell survival, angiogenesis, invasion, migration and tumor growth. Our findings illustrate the biologic significance of IL-6/JAK/STAT3 signaling in SCLC progression and providenovel evidence that the pathway may be a new potential target for therapy of SCLC. It was concluded that curcumin is a potent agent in the inhibition of STAT3 with favorable pharmacological activity,and curcumin may have translational potential as an effective cancer therapeutic or preventive agent for SCLC

Biomechanical evolution of the Tkachev on uneven bars in female gymnastics

The development of joint kinematics and kinetics is fundamental to the successful performance of complex flight skills in gymnastics bar routines. Biomechanical understanding of these skills can provide coaches and scientists with key information to make training safe and effective. The Tkachev is a complex and popular gymnastics skill with many different variations. Recently, a new version has been performed, which has become popular with elite female performers. This study examined the key biomechanical characteristics of this skill and contrasted these to the earlier versions reported. Elite female gymnasts (n = 5) were recorded and manually digitised using twin video cameras (50 Hz) at the 2007 World Gymnastics Championships. Three-dimensional (3D) DLT was used to reconstruct the real world coordinates. Individualised inertia characteristics were calculated and used to determine mass centre kinematics. Inverse dynamics analysis was used to calculate joint kinetics at the hips and shoulders from the known values at the toes. The results of this study showed an increased flight time and rotational capacity during the aerial phase for the toe-on Tkachev, as well as a more simple movement pattern and joint kinetic demand with single power impulses at the hips and shoulders compared with previous versions. The key finding of this study was that the toe-on version appeared to be less physically demanding than that the inward and outward techniques, and provide the opportunity to perform more complex aerial phase body positions. These results can help coaches to physically prepare their gymnasts and biomechanists in terms of understanding the demands of these skills

Study on the One-Proton Halo Structure in 23^{23}Al

The Glauber theory has been used to investigate the reaction cross section of proton-rich nucleus $^{23}$Al. A core plus a proton structure is assumed for $^{23}$Al. HO-type density distribution is used for the core while the density distribution for the valence proton is calculated by solving the eigenvalue problem of Woods-Saxon potential. The transparency function in an analytical expression is obtained adopting multi-Gaussian expansion for the density distribution. Coulomb correction and finite-range interaction are introduced. This modified Glauber model is apt for halo nuclei. A dominate s-wave is suggested for the last proton in $^{23}$Al from our analysis which is possible in the RMF calculation.Comment: 4 pages, 4 figure