Plasma-Enhanced ALD of TiO2 Thin Films on SUS 304 Stainless Steel for Photocatalytic Application

Plasma-enhanced atomic layer deposition (PE-ALD) of TiO2 thin films using Ti(NMe2)(4) [tetrakis(dimethylamido) Ti] and O-2 plasma were prepared on stainless steel to show the self-cleaning effect. The TiO2 thin films deposited on stainless steel have high growth rate, large surface roughness, and low impurities. The film deposited below 200 degrees C was amorphous, while the films deposited at 300 and 400 degrees C showed anatase and rutile phases, respectively. The contact angle measurements on crystalline PE-ALD TiO2 thin films exhibited superhydrophilicity after UV irradiation. The TiO2 thin film with anatase phase deposited at 300 degrees C showed the highest photocatalytic efficiency, which is higher than on Activ glass or thermal ALD TiO2 films. We suggest that anatase structure and large surface area of TiO2 thin film on stainless steel are the main factors for the high photocatalytic efficiency. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3095515] All rights reserved.X117sciescopu

Family composition and age at menarche: findings from the international Health Behaviour in School-Aged Children Study

This research was funded by The University of St Andrews and NHS Health Scotland.Background Early menarche has been associated with father absence, stepfather presence and adverse health consequences in later life. This article assesses the association of different family compositions with the age at menarche. Pathways are explored which may explain any association between family characteristics and pubertal timing. Methods Cross-sectional, international data on the age at menarche, family structure and covariates (age, psychosomatic complaints, media consumption, physical activity) were collected from the 2009–2010 Health Behaviour in School-aged Children (HBSC) survey. The sample focuses on 15-year old girls comprising 36,175 individuals across 40 countries in Europe and North America (N = 21,075 for age at menarche). The study examined the association of different family characteristics with age at menarche. Regression and path analyses were applied incorporating multilevel techniques to adjust for the nested nature of data within countries. Results Living with mother (Cohen’s d = .12), father (d = .08), brothers (d = .04) and sisters (d = .06) are independently associated with later age at menarche. Living in a foster home (d = −.16), with ‘someone else’ (d = −.11), stepmother (d = −.10) or stepfather (d = −.06) was associated with earlier menarche. Path models show that up to 89% of these effects can be explained through lifestyle and psychological variables. Conclusions Earlier menarche is reported amongst those with living conditions other than a family consisting of two biological parents. This can partly be explained by girls’ higher Body Mass Index in these families which is a biological determinant of early menarche. Lower physical activity and elevated psychosomatic complaints were also more often found in girls in these family environments.Publisher PDFPeer reviewe

Scaling of nestedness in complex networks

Nestedness characterizes the linkage pattern of networked systems, indicating the likelihood that a node is linked to the nodes linked to the nodes with larger degrees than it. Networks of mutualistic relationship between distinct groups of species in ecological communities exhibit such nestedness, which is known to support the network robustness. Despite such importance, quantitative characteristics of nestedness is little understood. Here we take graph-theoretic approach to derive the scaling properties of nestedness in various model networks. Our results show how the heterogeneous connectivity patterns enhance nestedness. Also we find that the nestedness of bipartite networks depend sensitively on the fraction of different types of nodes, causing nestedness to scale differently for nodes of different types.Comment: 9 pages, 4 figures, final versio

Laser treatment of Ag@ZnO nanorods as long-life-span SERS surfaces.

This is the accepted manuscript. The final version is available from ACS at http://pubs.acs.org/doi/abs/10.1021/am506622x.UV nanosecond laser pulses have been used to produce a unique surface nanostructuration of Ag@ZnO supported nanorods (NRs). The NRs were fabricated by plasma enhanced chemical vapor deposition (PECVD) at low temperature applying a silver layer as promoter. The irradiation of these structures with single nanosecond pulses of an ArF laser produces the melting and reshaping of the end of the NRs that aggregate in the form of bundles terminated by melted ZnO spherical particles. Well-defined silver nanoparticles (NPs), formed by phase separation at the surface of these melted ZnO particles, give rise to a broad plasmonic response consistent with their anisotropic shape. Surface enhanced Raman scattering (SERS) in the as-prepared Ag@ZnO NRs arrays was proved by using a Rhodamine 6G (Rh6G) chromophore as standard analyte. The surface modifications induced by laser treatment improve the stability of this system as SERS substrate while preserving its activity.We thank the Junta de Andalucía (TEP8067, FQM-6900 and P12-FQM-2265) and the Spanish Ministry of Economy and Competitiveness (Projects CONSOLIDER-CSD 2008-00023, MAT2011-28345-C02-02, MAT2013-40852-R, MAT2013-42900-P and RECUPERA 2020) for financial support. The authors also thank the European Union Seventh Framework Programme under Grant Agreements 312483-ESTEEM2 (Integrated Infrastructure Initiative-I3) and REGPOT-CT-2011-285895-Al-NANOFUNC, and the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC grant agreement 291522 - 3DIMAGE. R. J. Peláez acknowledges the grant JCI-2012_13034 from the Juan de la Cierva program

Insulin-Like Growth Factors Promote Vasculogenesis in Embryonic Stem Cells

The ability of embryonic stem cells to differentiate into endothelium and form functional blood vessels has been well established and can potentially be harnessed for therapeutic angiogenesis. However, after almost two decades of investigation in this field, limited knowledge exists for directing endothelial differentiation. A better understanding of the cellular mechanisms regulating vasculogenesis is required for the development of embryonic stem cell-based models and therapies. In this study, we elucidated the mechanistic role of insulin-like growth factors (IGF1 and 2) and IGF receptors (IGFR1 and 2) in endothelial differentiation using an embryonic stem cell embryoid body model. Both IGF1 or IGF2 predisposed embryonic stem to differentiate towards a mesodermal lineage, the endothelial precursor germ layer, as well as increased the generation of significantly more endothelial cells at later stages. Inhibition of IGFR1 signaling using neutralizing antibody or a pharmacological inhibitor, picropodophyllin, significantly reduced IGF-induced mesoderm and endothelial precursor cell formation. We confirmed that IGF-IGFR1 signaling stabilizes HIF1α and leads to up-regulation of VEGF during vasculogenesis in embryoid bodies. Understanding the mechanisms that are critical for vasculogenesis in various models will bring us one step closer to enabling cell based therapies for neovascularization

Electrically Guiding Migration of Human Induced Pluripotent Stem Cells

A major road-block in stem cell therapy is the poor homing and integration of transplanted stem cells with the targeted host tissue. Human induced pluripotent stem (hiPS) cells are considered an excellent alternative to embryonic stem (ES) cells and we tested the feasibility of using small, physiological electric fields (EFs) to guide hiPS cells to their target. Applied EFs stimulated and guided migration of cultured hiPS cells toward the anode, with a stimulation threshold of <30 mV/mm; in three-dimensional (3D) culture hiPS cells remained stationary, whereas in an applied EF they migrated directionally. This is of significance as the therapeutic use of hiPS cells occurs in a 3D environment. EF exposure did not alter expression of the pluripotency markers SSEA-4 and Oct-4 in hiPS cells. We compared EF-directed migration (galvanotaxis) of hiPS cells and hES cells and found that hiPS cells showed greater sensitivity and directedness than those of hES cells in an EF, while hES cells migrated toward cathode. Rho-kinase (ROCK) inhibition, a method to aid expansion and survival of stem cells, significantly increased the motility, but reduced directionality of iPS cells in an EF by 70–80%. Thus, our study has revealed that physiological EF is an effective guidance cue for the migration of hiPS cells in either 2D or 3D environments and that will occur in a ROCK-dependent manner. Our current finding may lead to techniques for applying EFs in vivo to guide migration of transplanted stem cells