Visualization of facet-dependent pseudo-photocatalytic behavior of TiO2 nanorods for water splitting using In situ liquid cell TEM

We report an investigation of the pseudo-photocatalytic behavior of rutile TiO2 nanorods for water splitting observed with liquid cell transmission electron microscopy (TEM). The electron beam serves as a “light” source to initiate the catalytic reaction and a “water-in-salt” aqueous solution is employed as the electrolyte. The observation reveals that bubbles are generated preferentially residing near the {110} facet of a rutile TiO2 nanorod under a low electron dose rate (9.3–18.6 e-/Å2·s). These bubbles are ascribed to hydrogen gas generated from the pseudo-photocatalytic water splitting. As the electron beam current density increases to 93 e-/Å2 ·s, bubbles are also found at the {001} and {111} facets as well as in the bulk liquid solution, demonstrating the dominant effects of water electrolysis by electron beam under higher dose rates. The facet-dependent pseudo-photocatalytic behavior of rutile TiO2 nanorods is further validated using density functional theory (DFT)calculation. Our work establishes a facile liquid cell TEM setup for the study of pseudo-photocatalytic water splitting and it may also be applied to investigation of other photo-activated phenomena occurring at the solid-liquid interfaces

The mineralogy of newly formed dust in active galactic nuclei

The tori around active galactic nuclei (AGN) are potential formation sites for large amounts of dust, and they may help resolve the so-called dust budget crisis at high redshift. We investigate the dust composition in 53 of the 87 Palomar Green (PG) quasars showing the 9.7 micron silicate feature in emission. By simultaneously fitting the mid-infrared spectroscopic features and the underlying continuum, we estimate the mass fraction in various amorphous and crystalline dust species. We find that the dust consists predominantly of alumina and amorphous silicates, with a small fraction in crystalline form. The mean crystallinity is 8 +/- 6%, with more than half of the crystallinities greater than 5%, well above the upper limit determined for the Galaxy. Higher values of crystallinity are found for higher oxide fractions and for more luminous sources.Comment: 24 pages, 9 figures, accepted for publication in Planetary and Space Scienc

Injury Severity Score coding: Data analyst v. emerging m-health technology

Background. The cost of Abbreviated Injury Scale (AIS) coding has limited its utility in areas of the world with the highest incidence of trauma. We hypothesised that emerging mobile health (m-health) technology could offer a cost-effective alternative to the current goldstandard AIS mechanism in a high-volume trauma centre in South Africa.Methods. A prospectively collected sample of consecutive patients admitted following a traumatic injury that required an operation during a 1-month period was selected for the study. AISs and Injury Severity Scores (ISSs) were generated by clinician-entered data using an m-health application (ISS eTHR) as well as by a team of AIS coders at Vancouver General Hospital, Canada (ISS VGH). Rater agreements for ISSs were analysed using Bland-Altman plots with 95% limits of agreement (LoA) and kappa statistics of the ISSs grouped into ordinal categories. Reliability was analysed using a two-way mixed-model intraclass correlation coefficient (ICC). Calibration and discrimination of univariate logistic regression models built to predict in-hospital complications using ISSs coded by the two methods were also compared.Results. Fifty-seven patients were managed operatively during the study period. The mean age of the cohort was 27.2 years (range 14 - 62), and 96.3% were male. The mechanism of injury was penetrating in 93.4% of cases, of which 52.8% were gunshot injuries. The LoA fell within –8.6 - 9.4. The mean ISS difference was 0.4 (95% CI –0.8 - 1.6). The kappa statistic was 0.53. The ICC of the individual ISS was 0.88 (95% CI 0.81 - 0.93) and the categorical ISS was 0.81 (95% CI 0.68 - 0.87). Model performance to predict in-hospital complications using either the ISS eTHR or the ISS VGH was equivalent.Conclusions. ISSs calculated by the eTHR and gold-standard coding were comparable. Emerging m-health technology provides a costeffective alternative for injury severity scoring

Dynamics of a faceted nematic-smectic B front in thin-sample directional solidification

We present an experimental study of the directional-solidification patterns of a nematic - smectic B front. The chosen system is C_4H_9-(C_6H_{10})_2CN (in short, CCH4) in 12 \mu m-thick samples, and in the planar configuration (director parallel to the plane of the sample). The nematic - smectic B interface presents a facet in one direction -- the direction parallel to the smectic layers -- and is otherwise rough, and devoid of forbidden directions. We measure the Mullins-Sekerka instability threshold and establish the morphology diagram of the system as a function of the solidification rate V and the angle theta_{0} between the facet and the isotherms. We focus on the phenomena occurring immediately above the instability threshold when theta_{0} is neither very small nor close to 90^{o}. Under these conditions we observe drifting shallow cells and a new type of solitary wave, called "faceton", which consists essentially of an isolated macroscopic facet traveling laterally at such a velocity that its growth rate with respect to the liquid is small. Facetons may propagate either in a stationary, or an oscillatory way. The detailed study of their dynamics casts light on the microscopic growth mechanisms of the facets in this system.Comment: 12 pages, 19 figures, submitted to Phys. Rev.

Mass changes of southern and northern inylchek glacier, Central Tian Shan, kyrgyzstan, during ∼1975 and 2007 derived from remote sensing data

Glacier melt is an essential source of freshwater for the arid regions surrounding the Tian Shan. However, the knowledge about glacier volume and mass changes over the last decades is limited. In the present study, glacier area, glacier dynamics and mass changes are investigated for the period ∼1975-2007 for Southern Inylchek Glacier (SIG) and Northern Inylchek Glacier (NIG), the largest glacier system in Central Tian Shan separated by the regularly draining Lake Merzbacher. The area of NIG increased by 2.0 ± 0.1 km2 (∼1.3%) in the period ∼1975-2007. In contrast, SIG has shrunk continuously in all investigated periods since ∼1975. Velocities of SIG in the central part of the ablation region reached ∼100-120 m a-1 in 2002/2003, which was slightly higher than the average velocity in 2010/2011. The central part of SIG flows mainly towards Lake Merzbacher rather than towards its terminus. The measured velocities at the distal part of the terminus downstream of Lake Merzbacher were below the uncertainty, indicating very low flow with even stagnant parts. Geodetic glacier mass balances have been calculated using multioral digital elevation models from KH-9 Hexagon (representing the year 1975), SRTM3 (1999), ALOS PRISM (2006) and SPOT-5 high-resolution geometrical (HRG) data (2007). In general, a continuous mass loss for both SIG and NIG could be observed between ∼1975 and 2007. SIG lost mass at a rate of 0.43 ± 0.10 m w.e. a-1 and NIG at a rate of 0.25 ± 0.10 m w.e. ag-1 within the period ∼1975-1999. For the period 1999-2007, the highest mass loss of 0.57 ± 0.46 m w.e. ag-1 was found for NIG, whilst SIG showed a potential moderate mass loss of 0.28 ± 0.46 m w.e. a-1. Both glaciers showed a small retreat during this period. Between ∼1975 and 1999, we identified a thickening at the front of NIG with a maximum surface elevation increase of about 150 m as a consequence of a surge event. In contrast significant thinning (>0.5 m a-1) and comparatively high velocities close to the dam of Lake Merzbacher were observed for SIG, indicating that Lake Merzbacher enhances glacier mass loss.Publisher PDFPeer reviewe

Injury Severity Score coding: Data analyst v. emerging m-health technology

Background. The cost of Abbreviated Injury Scale (AIS) coding has limited its utility in areas of the world with the highest incidence of trauma. We hypothesised that emerging mobile health (m-health) technology could offer a cost-effective alternative to the current gold-standard AIS mechanism in a high-volume trauma centre in South Africa.Methods. A prospectively collected sample of consecutive patients admitted following a traumatic injury that required an operation during a 1-month period was selected for the study. AISs and Injury Severity Scores (ISSs) were generated by clinician-entered data using an m-health application (ISS eTHR) as well as by a team of AIS coders at Vancouver General Hospital, Canada (ISS VGH). Rater agreements for ISSs were analysed using Bland-Altman plots with 95% limits of agreement (LoA) and kappa statistics of the ISSs grouped into ordinal categories. Reliability was analysed using a two-way mixed-model intraclass correlation coefficient (ICC). Calibration and discrimination of univariate logistic regression models built to predict in-hospital complications using ISSs coded by the two methods were also compared.Results. Fifty-seven patients were managed operatively during the study period. The mean age of the cohort was 27.2 years (range 14 - 62), and 96.3% were male. The mechanism of injury was penetrating in 93.4% of cases, of which 52.8% were gunshot injuries. The LoA fell within –8.6 - 9.4. The mean ISS difference was 0.4 (95% CI –0.8 - 1.6). The kappa statistic was 0.53. The ICC of the individual ISS was 0.88 (95% CI 0.81 - 0.93) and the categorical ISS was 0.81 (95% CI 0.68 - 0.87). Model performance to predict in-hospital complications using either the ISS eTHR or the ISS VGH was equivalent.Conclusions. ISSs calculated by the eTHR and gold-standard coding were comparable. Emerging m-health technology provides a cost-effective alternative for injury severity scoring.