| 1. |
- Linpé, W., et al.
(författare)
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An electrochemical cell for 2-dimensional surface optical reflectance during anodization and cyclic voltammetry
- 2020
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 91:4
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Tidskriftsartikel (refereegranskat)abstract
- We have developed an electrochemical cell for in situ 2-Dimensional Surface Optical Reflectance (2D-SOR) studies during anodization and cyclic voltammetry. The 2D-SOR signal was recorded from electrodes made of polycrystalline Al, Au(111), and Pt(100) single crystals. The changes can be followed at a video rate acquisition frequency of 200 Hz and demonstrate a strong contrast between oxidizing and reducing conditions. Good correlation between the 2D-SOR signal and the anodization conditions or the cyclic voltammetry current is also observed. The power of this approach is discussed, with a focus on applications in various fields of electrochemistry. The combination of 2D-SOR with other techniques, as well as its spatial resolution and sensitivity, has also been discussed.
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| 2. |
- Price, KM, et al.
(författare)
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Hypothesis-driven genome-wide association studies provide novel insights into genetics of reading disabilities
- 2022
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Ingår i: Translational psychiatry. - : Springer Science and Business Media LLC. - 2158-3188. ; 12:1, s. 495-
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Tidskriftsartikel (refereegranskat)abstract
- Reading Disability (RD) is often characterized by difficulties in the phonology of the language. While the molecular mechanisms underlying it are largely undetermined, loci are being revealed by genome-wide association studies (GWAS). In a previous GWAS for word reading (Price, 2020), we observed that top single-nucleotide polymorphisms (SNPs) were located near to or in genes involved in neuronal migration/axon guidance (NM/AG) or loci implicated in autism spectrum disorder (ASD). A prominent theory of RD etiology posits that it involves disturbed neuronal migration, while potential links between RD-ASD have not been extensively investigated. To improve power to identify associated loci, we up-weighted variants involved in NM/AG or ASD, separately, and performed a new Hypothesis-Driven (HD)–GWAS. The approach was applied to a Toronto RD sample and a meta-analysis of the GenLang Consortium. For the Toronto sample (n = 624), no SNPs reached significance; however, by gene-set analysis, the joint contribution of ASD-related genes passed the threshold (p~1.45 × 10–2, threshold = 2.5 × 10–2). For the GenLang Cohort (n = 26,558), SNPs in DOCK7 and CDH4 showed significant association for the NM/AG hypothesis (sFDR q = 1.02 × 10–2). To make the GenLang dataset more similar to Toronto, we repeated the analysis restricting to samples selected for reading/language deficits (n = 4152). In this GenLang selected subset, we found significant association for a locus intergenic between BTG3-C21orf91 for both hypotheses (sFDR q < 9.00 × 10–4). This study contributes candidate loci to the genetics of word reading. Data also suggest that, although different variants may be involved, alleles implicated in ASD risk may be found in the same genes as those implicated in word reading. This finding is limited to the Toronto sample suggesting that ascertainment influences genetic associations.
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| 3. |
- Bertuccio, Giuseppe, et al.
(författare)
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Ultra Low Noise Epitaxial 4H-SiC X-Ray Detectors
- 2009
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Ingår i: Materials Science Forum. - : Trans Tech Publications Inc.. - 0255-5476 .- 1662-9752. ; 615-617, s. 845-848
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Tidskriftsartikel (refereegranskat)abstract
- The design and the experimental results of some prototypes of SiC X-ray detectors are presented. The devices have been manufactured on top of 2 inch 4H-SiC wafer with 115 μm thick undoped high purity epitaxial layer, which constitutes the detection’s active volume. Pad and pixel detectors based on Ni-Schottky junctions have been tested. The residual doping of the epi-layer was found tobe extremely low, 3.7 x 1013 cm-3, allowing to achieve the highest detection efficiency and the lower specific capacitance of the detectors. At 22 °C and in operating bias condition, the reverse current densities of the detector’s Schottky junctions have been measured to be between J = 0.3 pA/cm2 and J = 4 pA/cm2; these values are more than two orders of magnitude lower than those of state of the art silicon detectors. With such low leakage currents, the equivalent electronic noise of SiC pixel detectors is as low as 0.5 electrons r.m.s at room temperature, which represents a new state of the art in the scenario of semiconductor radiation detectors.
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| 4. |
- Grespi, A., et al.
(författare)
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Probing the electrode-liquid interface using operando total-reflection X-ray absorption spectroscopy
- 2024
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Ingår i: Surface Science. - : Elsevier B.V.. - 0039-6028 .- 1879-2758. ; 748
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Tidskriftsartikel (refereegranskat)abstract
- Traditional methods to study electrochemical (EC) processes, although successful, are based on current/voltage measurements, providing information about performances rather than offering a direct observation of chemical and structural changes occurring at the electrode surface. These processes are localized at the electrode-electrolyte interface, the structure of which is the main determinant of their behavior, but most surface sensitive experimental techniques are limited to ex situ conditions, owing to the need for an ultra-high vacuum environment. In this contribution, we report operando X-ray absorption spectroscopy in total external reflection geometry (Refle-XAFS) at P64 beamline (DESY, Hamburg), using a simple and versatile EC flow cell designed for multimodal surface sensitive studies with hard X-ray scattering and spectroscopy techniques. We show that the Refle-XAFS method can be used to study chemical surface changes of industrial alloys and model electrodes in harsh electrochemical environments, without being limited to thin film samples. The surface passive film development and breakdown of a corrosion-resistant Ni-Cr-Mo alloy and the electro-oxidation of polycrystalline gold (poly-Au), relevant for fundamental studies on water electrolysis, were investigated. Despite the strong attenuation of the beam by the electrolyte and the PEEK walls of the EC cell, nanoscale surface oxide films were detected using beam energies down to 8 keV. The passivity breakdown region of Ni alloy 59 in 1 M NaCl at pH 7 and pH 12 was identified, showing differences in the composition of the surface oxides during anodic polarization. The electro-oxidation of poly-Au in 0.05 M H2SO4 was observed, showing a progression from two-dimensional Au1+/3+ to three-dimensional thick Au3+ surface oxide/hydroxide during OER.
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