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Density modulated tungsten (W) thin films with nanoscale porosity contents of 7% to 40% by volume were grown on Si substrates through magnetron sputter deposition. Process parameters were selected according to the structure zone model, which resulted in film thicknesses between 105 nm and 520 nm. Nanomechanical properties of samples were investigated by means of instrumented nanoindentation. Reduced-χ2 analysis was carried out to assess four models formulated through differential effective medium approach. The model that factored in both the crowding effect and the maximum random packing of pores successfully captured the experimental trends. Attempts to breach the auxetic barrier resulted in large-scale pulverization or spontaneous conversion into WO3. Porosity corrected yield strength calculations underlined the possibility of defining a porosity threshold beyond which the compressive yield strength of density modulated nanoporous metallic thin films would drop abruptly due to aggravated geometric slenderness effects in agreement with earlier hypotheses.
Major depressive disorder (MDD) is moderately heritable, however genome-wide association studies (GWAS) for MDD, as well as for related continuous outcomes, have not shown consistent results. Attempts to elucidate the genetic basis of MDD may be hindered by heterogeneity in diagnosis. The Center for Epidemiological Studies Depression (CES-D) scale provides a widely used tool for measuring depressive symptoms clustered in four different domains which can be combined together into a total score but also can be analysed as separate symptom domains.
We performed a meta-analysis of GWAS of the CES-D symptom clusters. We recruited 12 cohorts with the 20- or 10-item CES-D scale (32 528 persons).
One single nucleotide polymorphism (SNP), rs713224, located near the brain-expressed melatonin receptor (MTNR1A) gene, was associated with the somatic complaints domain of depression symptoms, with borderline genome-wide significance (pdiscovery = 3.82 × 10−8). The SNP was analysed in an additional five cohorts comprising the replication sample (6813 persons). However, the association was not consistent among the replication sample (pdiscovery+replication = 1.10 × 10−6) with evidence of heterogeneity.
Despite the effort to harmonize the phenotypes across cohorts and participants, our study is still underpowered to detect consistent association for depression, even by means of symptom classification. On the contrary, the SNP-based heritability and co-heritability estimation results suggest that a very minor part of the variation could be captured by GWAS, explaining the reason of sparse findings.
In this work, we demonstrate a new density modulated multilayered silicon thin film anode approach that can provide a robust high capacity electrode for Li-ion batteries. These films have the ability to tolerate large volume changes due to their controlled microstructure. Silicon films with alternating layers of high/low material density were deposited using a DC sputtering system. Density of the individual layers was controlled by simply changing the working gas pressure during sputtering. Samples of Si films having thicknesses of 460 nm with different number of high/low density layers have been deposited on Cu current collectors. The electrochemical performance of the multilayered anode material was evaluated using a galvanostatic battery testing system at C/10 rate. After reaching a stabilized phase the battery cell showed a high coulombic efficiency of 96% to 99% and reversible specific capacity of 666 mAh g-1 (after 100 cycles). Low-density layers are believed to be acting as compliant sheets during volume expansion making the films more durable compared to conventional Si film anodes. The results indicate that density modulated multilayer Si thin films can be used to improve the mechanical properties of Li-ion battery anodes leading to high reversible capacity values even after high number of cycles.
Al was thermally evaporated onto the conjugated semiconductor polymer, poly(2-methoxy-5,2′- ethyl-hexyloxy-phenylene vinylene) (MEH-PPV) in successive steps. Interface formation and chemical interactions between the polymer and Al were investigated by X-ray Photoelectron Spectroscopy (XPS) and synchrotron source Ultraviolet Photoelectron Spectroscopy (UPS). XPS analyses (angle resolved and sputtering depth profile) proved the formation of an insulating aluminum oxide layer at the polymer metal interface. The C-O bonds in the polymer decreased as more Al was evaporated on the MEH-PPV. Also reaction between Al and the carbon backbone of the polymer leading to the creation of carbon-metal bonds was observed. UPS analysis suggested the possibility of Al reacting with the phenylene ring of the polymer.
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