Composition Profiles in Electrodeposited Ceramic Superlattices

Superlattices in the Pb-Tl-O system with layer thicknesses in the 4-6 nm range were electrodeposited from a single aqueous solution by pulsing the applied potential during deposition. The current-time transients that resulted from the potential steps were monitored to both calculate and tailor the composition profiles of the superlattices during growth. The Cottrell method was used to determine that Tl(l) oxidation was diffusion limited at high potentials. The diffusion limitation resulted in a composition profile that was graded throughout the layer with a t-1/2 dependence. Superlattices grown at lower potentials in which both reactants were under kinetic control had square composition profiles

Variants in autophagy-related genes and clinical characteristics in melanoma: a population-based study

Autophagy has been linked with melanoma risk and survival, but no polymorphisms in autophagy-related (ATG) genes have been investigated in relation to melanoma progression. We examined five single-nucleotide polymorphisms (SNPs) in three ATG genes (ATG5; ATG10; and ATG16L) with known or suspected impact on autophagic flux in an international population-based case-control study of melanoma. DNA from 911 melanoma patients was genotyped. An association was identified between (GG) (rs2241880) and earlier stage at diagnosis (OR 0.47; 95% Confidence Intervals (CI) = 0.27-0.81, P = 0.02) and a decrease in Breslow thickness (P = 0.03). The ATG16L heterozygous genotype (AG) (rs2241880) was associated with younger age at diagnosis (P = 0.02). Two SNPs in ATG5 were found to be associated with increased stage (rs2245214 CG, OR 1.47; 95% CI = 1.11-1.94, P = 0.03; rs510432 CC, OR 1.84; 95% CI = 1.12-3.02, P = 0.05). Finally, we identified inverse associations between ATG5 (GG rs2245214) and melanomas on the scalp or neck (OR 0.20, 95% CI = 0.05-0.86, P = 0.03); ATG10 (CC) (rs1864182) and brisk tumor infiltrating lymphocytes (TILs) (OR 0.42; 95% CI = 0.21-0.88, P = 0.02), and ATG5 (CC) (rs510432) with nonbrisk TILs (OR 0.55; 95% CI = 0.34-0.87, P = 0.01). Our data suggest that ATG SNPs might be differentially associated with specific host and tumor characteristics including age at diagnosis, TILs, and stage. These associations may be critical to understanding the role of autophagy in cancer, and further investigation will help characterize the contribution of these variants to melanoma progression

Associations of Cumulative Sun Exposure and Phenotypic Characteristics with Histologic Solar Elastosis

Solar elastosis adjacent to melanomas in histologic sections is regarded as an indicator of sun exposure although the associations of ultraviolet (UV) exposure and phenotype with solar elastosis are yet to be fully explored

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

Scanning Tunneling Microscopy of Nanoscale Electrodeposited Superlattices

Artificially layered superconductor materials based on crystalline multilayer structure are of potential interest due to the unusual quantum effects which could be expected in materials of this type. Scanning tunneling microscopy has recently been used (e.g. see Figure) to measure the modulation wavelength (the bilayer thickness) and to estimate the composition profile in such superlattices

Potential Step Probes of Epitaxial Growth in Electrodeposited BCC Tl₂O₃ Films onto FCC Conducting Metal Oxides

Potential step transients were investigated as an in-situ probe of epitaxial growth for electrodeposited conducting metal oxides of the Tl2O3 and PbaTlbOc systems. Changes in the induction time and growth type were observed for Tl2O3 deposition as a function of the substrate. The substrates studied were glassy carbon and [210]-textured Pb0.8Tl0.2O1.9. Tl2O3 deposited onto the glassy carbon electrode showed a distinct induction time, the magnitude of which was potential dependent. Also the type of growth was characterized as three dimensional with instantaneous nucleation. X-ray diffraction of this film shows a nearly random pattern. The potential step transient for Tl2O3 deposited onto the [210]-textured Pb0.2O1.9 showed the absence of an induction time and elimination of the growth segment. The type of growth was characterized as two dimensional. X-ray diffraction indicated epitaxy was obtained for the Tl2O3 films which grew two dimensionally onto the [210]-textured mixed oxide

Real-time Studies of the Electrocrystallization of Nanoscale Ceramic Superlattices

Electrodeposition is unique among thin film deposition techniques, since the current following a potential step from open circuit to a given overpotential (i.e., driving force) provides a real-time, in situ probe of the deposition process. We have used current-time transients to determine the kinetics and dimensionality of growth, and to calculate the composition profiles of electrodeposited superlattices in the Pb-Tl-O system. The transients are indicative of 2D growth, and the height of the 2D monolayer depends on the orientation of the film. A [100] oriented film has a step height of 0.13 nm and a [210] oriented film has a step height of 0.18 nm. These heights correspond to the (400) and (220) d-spacings, respectively. Using a Cottrell analysis, we were able to both calculate and tailor the composition profile in these superlattices. Superlattices grown by pulsing between 70 and 150 mV have square profiles, while those grown by pulsing between 70 and 230 mV have graded profiles

Cross-sectional Scanning Tunneling Microscopy of Electrodeposited Metal Oxide Superlattices

We have used scanning tunneling microscopy to characterize cleaved cross sections of Pb-Tl-O superlattices. The metal oxide ceramic superlattices were electrodeposited from a single solution, with layer thicknesses as small as 1.5 nm. The lattice parameter of the fcc fluorite-type oxides is approximately 0.536 nm. Modulation wavelengths were determined using Fourier analysis of the STM images and found to be in good agreement with Faraday calculations and x-ray diffraction measurements. The STM is especially well suited for the measurement of modulation wavelengths that are too large to measure by x-ray diffraction, but too small to measure by scanning electron microscopy

Evolution of Crystallinity During the Electrodeposition of Body-centered Cubic Thallium (III) Oxide onto Glassy Carbon

The electrochemical nucleation and growth of crystalline Tl2O3 onto glassy carbon was studied by analyzing current-time transients resulting from potential steps. Stripping voltammetry, x-ray diffraction, and ex situ atomic force microscopy (AFM) were further used to characterize the deposit. The initial layers of Tl2O3 deposited as amorphous material up to a driving-force-dependent critical thickness. The critical thickness was 77 nm at zero driving force, and decreased exponentially as the overpotential was increased. When the critical thickness was exceeded at times greater than the induction time, faceted islands of crystalline material were observed. At the induction time, crystalline islands with an average diameter of 1200 nm were observed by AFM. The increase in current after the induction time is attributed to an increase in the rate of deposition, rather than a simple increase in geometric area. The exchange current densities for amorphous and crystalline Tl2O3 were measured to be 7 × 10-6 and 3 × 10-5 A/cm2, respectively. Crystalline development may proceed by a cooperative process between material depositing from solution and reorganization of amorphous material previously deposited on the surface. Open-circuit measurements showed a 72 mV driving force for this reorganization process