Photoelectrocatalytic performances of nanostructured/decorated TiO 2 electrodes: Effect of wavelength and cell configuration

The behaviour of TiO2 based electrodes was investigated during the photoelectrocatalytic water splitting process. TiO2 nanotubes and compact oxide structures were obtained by electrochemical oxidation of Ti foils. A subsequent hydrothermal process carried out at both the nanotubular and compact oxide structures allowed decorating the structure by TiO2 nanoparticles. The synthesized TiO2 samples worked as photoanodes both in a bulk three electrode cell and in a thin gap cell. The results from measurements of the photocurrent and from electrochemical impedance spectroscopy were used to highlight a combined effect of the wavelength of the incident light and the kind of cell configuration, on the global performance of the systems. The results indicate that the decoration process does not result only in a simple increase of the specific surface, but it also determines a different concentration of the bulk and superficial sites in the electrode. The different response of the sites at different wavelengths, along with the accessibility of the electrolyte to the porous structure are evocated to justify the experimental behaviour observed

Selective Lanthanide Sensing with Gold Nanoparticles and Hydroxypyridinone Chelators.

The octadentate hydroxypyridinone chelator 3,4,3-LI(1,2-HOPO) is a promising therapeutic agent because of its high affinity for f-block elements and noncytotoxicity at medical dosages. The interaction between 3,4,3-LI(1,2-HOPO) and other biomedically relevant metals such as gold, however, has not been explored. Gold nanoparticles functionalized with chelators have demonstrated great potential in theranostics, yet thus far, no protocol that combines 3,4,3-LI(1,2-HOPO) and colloidal gold has been developed. Here, we characterize the solution thermodynamic properties of the complexes formed between 3,4,3-LI(1,2-HOPO) and Au3+ ions and demonstrate how under specific pH conditions the chelator promotes the growth of gold nanoparticles, acting as both reducing and stabilizing agent. 3,4,3-LI(1,2-HOPO) ligands on the nanoparticle surface remain active and selective toward f-block elements, as evidenced by gold nanoparticle selective aggregation. Finally, a new colorimetric assay capable of reaching the detection levels necessary for the quantification of lanthanides in waste from industrial processes is developed based on the inhibition of particle growth by lanthanides

Spitzer Mid-Infrared Photometry of 500 - 750 K Brown Dwarfs

Mid-infrared data, including Spitzer warm-IRAC [3.6] and [4.5] photometry, is critical for understanding the cold population of brown dwarfs now being found, objects which have more in common with planets than stars. As effective temperature (T_eff) drops from 800 K to 400 K, the fraction of flux emitted beyond 3 microns increases rapidly, from about 40% to >75%. This rapid increase makes a color like H-[4.5] a very sensitive temperature indicator, and it can be combined with a gravity- and metallicity-sensitive color like H-K to constrain all three of these fundamental properties, which in turn gives us mass and age for these slowly cooling objects. Determination of mid-infrared color trends also allows better exploitation of the WISE mission by the community. We use new Spitzer Cycle 6 IRAC photometry, together with published data, to present trends of color with type for L0 to T10 dwarfs. We also use the atmospheric and evolutionary models of Saumon & Marley to investigate the masses and ages of 13 very late-type T dwarfs, which have H-[4.5] > 3.2 and T_eff ~ 500 K to 750 K.Comment: To be published in the on-line version of the Proceedings of Cool Stars 16 (ASP Conference Series). This is an updated version of Leggett et al. 2010 ApJ 710 1627; a photometry compilation is available at http://www.gemini.edu/staff/slegget

Statistical Confirmation of a Stellar Upper Mass Limit

We derive the expectation value for the maximum stellar mass (m_max) in an ensemble of N stars, as a function of the IMF upper-mass cutoff (m_up) and N. We statistically demonstrate that the upper IMF of the local massive star census observed thus far in the Milky Way and Magellanic Clouds clearly exhibits a universal upper mass cutoff around 120 - 200 M_sun for a Salpeter IMF, although the result is more ambiguous for a steeper IMF.Comment: PDF, 5 pages, 4 figures. Accepted to the Astrophysical Journal Letter

H2_2 Emission Nebulosity Associated with KH 15D

An H$_2$ emission filament is found in close proximity to the unique object KH 15D using the adaptive optics system of the Subaru Telescope. The morphology of the filament, the presence of spectroscopic outflow signatures observed by Hamilton et al., and the detection of extended H$_2$ emission from KH 15D by Deming, Charbonneau, & Harrington suggest that this filament arises from shocked H$_2$ in an outflow. The filament extends about 15" to the north of KH 15D.Comment: 11 pages, 3 figures, 1 table. Astrophysical Journal Letters, in pres

Numerical simulation of three-phase flow in an external gear pump using immersed boundary approach

This paper presents a three-phase fully compressible model applied along with an immersed boundary model for predicting cavitation occurring in a two dimensional gear pump in the presence of non-condensable gas (NCG). Combination of these models is capable of overcoming numerical challenges such as modelling the contact between the gears and simulating the effect of NCG in cavitation. The model accounting for the effect of NCG also has broader applicability, since gas dissolved in liquids can come out of the solution when exposed to low pressures; this plays a significant role in the pump performance and cavitation erosion. Here the simulation results are presented for the gear pump at different operating conditions including the contact between gear, gear RPM and % of NCG; their effects on performance and cavitation is demonstrated. The results suggest that modelling the contact between the gears play a role in the cavitation prediction inside the gear pump. An increase in cavitation is observed when the contact is modelled even for the small pressure difference considered between the inlet and outlet. An increase in the RPM of the gears also results in increased cavitation within the pump, whereas an increase in the percentage of NCG content by a small amount can reduce the cavitation to a greater extent. This reduction is due to the expansion of the gas at a lower pressure which recovers the pressure and prevents or delays the phase-change process of the working fluid. The fluctuations in the outflow rate is also found to increase when the gears are in contact and also with increasing gas content

ULAS J141623.94+ + 134836.3 - a faint common proper motion companion of a nearby L dwarf. Serendipitous discovery of a cool brown dwarf in UKIDSS DR6

New near-infrared large-area sky surveys (e.g. UKIDSS, CFBDS, WISE) go deeper than 2MASS and aim at detecting brown dwarfs lurking in the Solar neighbourhood which are even fainter than the latest known T-type objects, so-called Y dwarfs. Using UKIDSS data, we have found a faint brown dwarf candidate with very red optical-to-near-infrared but extremely blue near-infrared colours next to the recently discovered nearby L dwarf SDSS J141624.08$+$134826.7. We check if the two objects are co-moving by studying their parallactic and proper motion and compare the new object with known T dwarfs. The astrometric measurements are consistent with a physical pair ($sep$$\approx$75 AU) at a distance $d$$\approx$8 pc. The extreme colour ($J$$-$$K$$\approx$$-$1.7) and absolute magnitude ($M_J$=17.78$\pm$0.46 and $M_K$=19.45$\pm$0.52) make the new object appear as one of the coolest (T$_{eff}$$\approx$600 K) and nearest brown dwarfs, probably of late-T spectral type and possibly with a high surface gravity (log $g$$\approx$5.0).Comment: accepted for publication as a Letter in Astronomy and Astrophysics, 4 pages, 7 figures, changed subtitle and discussion, former Fig. 4 removed, new Figs. 2, 6, and

マトリックスメタロプロテアーゼと膵疾患

Matrix metalloproteinases (MMPs) is a family of collagenolytic enzymesand are associated with many pathological conditions. Especially, MMPs have a strong relation with tumor progression and invasion. In this review, we focused on association of MMPs and pancreatic diseases, and a potential treatment of MMPs inhibitors for pancreatic cancer.マトリックスメタロブロテアーゼ（MMP）は，コラーゲン分解能を有し，種々の疾患との関連性が示唆されている。とりわけ,癌の浸潤，転移には密接な関係があるとされている。また，MMP阻害剤を癌の治療に用いる試みもなされている。本稿ではMMPと膵疾患の関連性，MMP阻害剤の膵癌への応用の可能性について総説する

The hydration state of HO−^-(aq)

The HO$^-$(aq) ion participates in myriad aqueous phase chemical processes of biological and chemical interest. A molecularly valid description of its hydration state, currently poorly understood, is a natural prerequisite to modeling chemical transformations involving HO$^-$(aq). Here it is shown that the statistical mechanical quasi-chemical theory of solutions predicts that $\mathrm{HO\cdot[H_2O]_3{}^-}$ is the dominant inner shell coordination structure for HO$^-$(aq) under standard conditions. Experimental observations and other theoretical calculations are adduced to support this conclusion. Hydration free energies of neutral combinations of simple cations with HO$^-$(aq) are evaluated and agree well with experimental values.Comment: 10 pages, 1 figur