Dynamic Control Over Electronic Transport in 3D Bulk Nanographene via Interfacial Charging

Electrochemical surface charge‐induced variation of physical properties in interface‐dominated bulk materials is a rapidly emerging field in material science. The recently developed three‐dimensional bulk nanographene (3D‐BNG) macro‐assemblies with ultra‐high surface area and chemical inertness offer new opportunities in this area. Here, the electronic transport in centimeter‐sized 3D‐BNG monoliths can be dynamically controlled via electrochemically induced surface charge density. Specifically, a fully reversible variation in macroscopic conductance up to several hundred percent is observed with ≤1 V applied gate potential. The observed conductivity change can be explained in the light of the electrochemically‐induced accumulation or depletion of charge carriers in combination with a large variation in the carrier mobility; the latter, being highly affected by the defect density modulations resulting from the interfacial charge injection, sharply decreases with an increase in defect concentrations. The phenomenon presented in this study is believed to open the door to novel applications of bulk graphene materials such as, for example, low voltage and high power tunable resistors.     

Applied Regression Analysis (2nd Ed.)

We describe a diagnostic method for assessing the degree to which individual cases and groups of cases influence the Box-Cox likelihood estimate of the transformation parameter for the response variable in linear regression models. We compare the method to a method proposed by Atkinson (1982) and sketch the extension to explanatory variables. We present two examples.     

Electrochemical synthesis and characterization of mixed molybdenum-rhenium oxides

The electrodeposition of Mo_xRe_1−xO_y films (0.6 ≤ x ≤ 1) on indium-tin oxide (ITO) coated glass substrates from acidic peroxo-polymolybdo-perrhenate solutions is described. Trends in film growth were established as a function of potential from +0.4 V to −0.7 V vs Ag/AgCl by analyzing the composition and stoichiometry of the deposit using inductively coupled plasma mass spectrometry (ICPMS) and X-ray photoelectron spectroscopy (XPS). These experiments show that the concentration of rhenium increases linearly with the deposition potential and that the deposits are mixed-valent containing up to five different metal oxidation states (i.e., Mo^IV, Mo^V, Mo^VI, Re⁰, Re^IV). Electroanalytical techniques were used to explore the deposition mechanism, including chronocoulometry, cyclic voltammetry, spectroelectrochemistry, and electrochemical quartz crystal nanogravimetry (EQCN). At potentials positive to −0.26 V, perrhenate (Re^VIIO₄⁻) behaves as a redox mediator to accelerate the deposition of a mixed-valent molybdenum oxide, but at more negative potentials mixed molybdenum-rhenium oxides are produced.     

A Nonlinear Structure Tensor with the Diffusivity Matrix Composed of the Image Gradient

We propose a nonlinear partial differential equation (PDE) for regularizing a tensor which contains the first derivative information of an image such as strength of edges and a direction of the gradient of the image. Unlike a typical diffusivity matrix which consists of derivatives of a tensor data, we propose a diffusivity matrix which consists of the tensor data itself, i.e., derivatives of an image. This allows directional smoothing for the tensor along edges which are not in the tensor but in the image. That is, a tensor in the proposed PDE is diffused fast along edges of an image but slowly across them. Since we have a regularized tensor which properly represents the first derivative information of an image, the tensor is useful to improve the quality of image denoising, image enhancement, corner detection, and ramp preserving denoising. We also prove the uniqueness and existence of solution to the proposed PDE.     

Micro-capacitors based on electrochemically grown vertical arrays of gold nanowires as electrodes

This paper describes the development of micro-capacitors with electrodes based on electrochemically grown vertical gold nanowire arrays. A high aspect-ratio anodized aluminum oxide template integrated on silicon dioxide/silicon substrates was exploited for fabricating a vertical array of nanowires with a high surface to volume ratio. Bismuth ferric oxide thin films were deposited to create high dielectric material between the electrodes using room temperature electrodeposition. This nanofabrication process may be compatible with a complementary metal-oxide-semiconductor (CMOS) process, therefore, this capacitor can be used for protecting and regulating the surge voltage biased to the CMOS circuits. This capacitor achieved a high density capacitance of 3.1 μF/m² at 1 MHz, which was measured using a parallel plate set-up.     

Flexibility as a source of value in the production of alternative fuels: The ethanol case

There is typically a high degree of flexibility associated with the production of alternative fuels due to the ability to source from different input raw materials or to produce different output products based on market conditions. In this paper, we consider the particular example of ethanol and seek to quantify the incremental value from flexibility in its production from sugarcane in Brazil. We accomplish this by first jointly modeling the stochastic processes for the prices of the two relevant commodities, sugar (a food commodity) and ethanol (an energy commodity) in discrete time as a bivariate lattice. This framework allows us to value the option to switch output products based on the respective price signals of the two commodities. However, unlike the usual assumption of geometric Brownian motion stochastic processes, we use the more realistic case of mean reverting commodity price processes. We estimate the parameters for these processes by applying a regression-based procedure to empirical sugar and ethanol data collected during a period from 1998 through 2008. Our results show that the option to switch outputs has significant value, even under the assumption of mean reverting prices, which has implications for both producers and policy-makers alike.     

Calculation of leak sizes in pressurised vessels and pipes according to the leak-before-break criterion

For the consideration of released mass flows and their effects within hazard studies, leakage areas need to be determined which are physically justifiable and which cannot be reasonably excluded. Applying the fracture mechanics the leak-before-break behaviour is verified by the calculation of the propagation of an initial material defect. Consequently, leakage areas of through-cracks are calculated to determine probable and maximum leakage areas. For this purpose, models for the calculation of leak sizes are compared and evaluated. Example calculations are stated for typical pressurised vessels and pipes of the chemical industry in order to check the present estimates of leakage areas. In addition, measures supporting the leak-before-break behaviour are outlined.     

A-sign und a.trust bündeln Aktivitäten

AktuellDivitec Metal

Aufbereitung von Elektro(nik)-Altger?ten