1,722,042 research outputs found
Replication data for: Patents, Data Exclusivity and the Development of New Drugs
No full textGaessler, Fabian, and Wagner, Stefan, (2022) “Patents, Data Exclusivity, and the Development of New Drugs.” Review of Economics and Statistics 104:3, 571–586
Conduction mechanisms during the growth of Pd thin films: Experiment and model
No full textThe conduction mechanisms in different growth stages of Pd thin films are investigated in detail. Special attention is paid to the transition regions between the different stages of film growth and the dominant conduction mechanisms. Mechanisms of thermally activated tunneling, percolation conduction, and continuous film conduction are considered and a consistent set of model parameters is deduced. This is done by also varying the substrates. Activation energies of tunneling on the order of 50 meV, percolation thresholds p(c)=0.70 +/- 0.01, and conduction exponents mu=2.43 +/- 0.12 were achieved. The physical meaning of the model parameters is discussed and connected mechanisms are proposed. The minimal film thicknesses of continuous RT-sputtered Pd films were found to be on the order of 1.5 nm
Integrating state machine analysis with system-theoretic process analysis
No full textSafety becomes a critical aspect for software-intensive systems in different applications areas. Many hazard analysis techniques are proposed and used to investigate system design models to elicit hazards and design flaws. STPA (System- Theoretic Process Analysis) is a modern hazard analysis technique, which is based on a new systems-theoretic model of accidents for large and complex systems. With STPA, the system is viewed as interacting control loops and the accidents are considered as results from inadequate enforcement of safety constraints in design, development and operation. STPA still needs appropriate diagrammatic notations to represent the relation between the process model variables, control actions and hazards. For this purpose, we propose to integrate state machine analysis with STPA to provide a suitable notation of arguments between the states of controllers, control actions and hazards
Electrical resistivity and hydrogen solubility of PdHc thin films
No full textDuring hydrogen gas loading, Pd thin films exhibit an anomalous reduction of resistivity change with decreasing film thickness. In this paper we show that this effect can mainly be attributed to a stress-dependent reduction of hydrogen solubility at a given hydrogen pressure. Different stress states of the thin films result from different bonding to a rigid substrate. Strongly buckled thin films show bulk-like pressure-resistivity isotherms. The resistivity changes as a function of hydrogen concentration appear to be independent of film thickness. The apparent Sieverts' constant seems to be larger for thin films compared to bulk, and increases with cycling of the thin films. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved
Quasi-thermodynamic model on hydride formation in palladium-hydrogen thin films: Impact of elastic and microstructural constraints
No full textThe impact of elastic and microstructural constraints on structural phase transitions is investigated by using (10-300) nm Pd-H films of different microstructures. Hydrogen induced stress mainly arises from the film's adhesion to a substrate. Stress changes the hydrogens' chemical potential mu(H), modifying the hydride phase stability. Microstructural constraints channel stress release in films. A thermodynamic model is proposed to deduce the H-H interaction energy E-HH and an effective critical temperature T-c(eff) of hydride formation in films. It allows for occasionally observed sloped plateaus of mu(H) below T-c(eff). EHH (between 15 and 30 kJ/mol(H)) and T-c(eff) (340 K to 490 K) are reduced by up to 50% compared to bulk (E-HH = 36.8 kJ/mol(H), T-c = 563 K), for all films. Concentration-dependent contributions of substrate-induced stress (of about (2-5) kJ/mol(H)) and microstructure (of about (5-8) kJ/mol(H)) are separated. For all films phase separation is still found at 300 K. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Deutsche Forschungsgemeinschaft [PU 131/7-2, PU 131/9-1
Delamination-supported growth of hydrides in Pd thin films studied by electrochemical hydrogenography
No full textHydride nucleation and growth is studied by electrochemical hydrogenography on Pd-thin films with modified adhesion between the film and the glass substrate. Modification was controlled by a Nb-adhesive. A clear influence of the adhesion on the hydride formation was found. The adhering films showed small hydrides far beyond the resolution limit of the method. Contrary to this, the weak-adhering films showed low nucleation densities and large separated hydrides extending in the mu m-range. The difference was attributed to enhanced hydride formation in quasi stress-free volumes and an easily propagating delamination front that supports hydride growth. (C) 2014 Elsevier B.V. All rights reserved
In-situ STM and XRD studies on Nb-H films: Coherent and incoherent phase transitions
No full textHydride precipitation in 25 nm and 40 nm epitaxial Nb-films was studied by ScanningTunnelling Microscopy (STM) supported by X-Ray diffraction (XRD) measurements. Incombination, these methods yield information about the phase transition, the coherency state,the hydride precipitates' density and size as well as their lateral distribution, at 293 K. Forboth film thicknesses, hydride formation was detected with STM; it can be easily missed byXRD. While the 25 nm film showed a coherent phase transition, the phase transition wasincoherent for the 40 nm film. This is in good accordance with theory. The phase transitionfeatures are found to strongly depend on the coherency state: a large number of small hydridesappear in the coherent regime while a small number of large hydrides evolve in the incoherentregime
Mechanical stress impact on thin Pd1−xFex film thermodynamic properties
No full textThermodynamic properties of thin films deviate strongly from those of bulk. The deviations are reported to originate from microstructure and from mechanical stress, whereas the contribution of both is unknown in particular. Focussing on the mechanical stress contribution and by using Pd(1-x)Fe(x)-H as a model system, it is shown that mechanical stress strongly changes phase transition pressures. The measured loading pressures shift up to 400 mbars in contrast to 18 mbars for bulk. These shifts relate to the film bonding to the substrate and can be affected by film detachment. (c) 2008 American Institute of Physics
- …
