Carbocations and the Complex Flavor and Bouquet of Wine: Mechanistic Aspects of Terpene Biosynthesis in Wine Grapes.

Computational chemistry approaches for studying the formation of terpenes/terpenoids in wines are presented, using five particular terpenes/terpenoids (1,8-cineole, α-ylangene, botrydial, rotundone, and the wine lactone), volatile compounds (or their precursors) found in wine and/or wine grapes, as representative examples. Through these examples, we show how modern computational quantum chemistry can be employed as an effective tool for assessing the validity of proposed mechanisms for terpene/terpenoid formation

New developments in the theory of Groebner bases and applications to formal verification

We present foundational work on standard bases over rings and on Boolean Groebner bases in the framework of Boolean functions. The research was motivated by our collaboration with electrical engineers and computer scientists on problems arising from formal verification of digital circuits. In fact, algebraic modelling of formal verification problems is developed on the word-level as well as on the bit-level. The word-level model leads to Groebner basis in the polynomial ring over Z/2n while the bit-level model leads to Boolean Groebner bases. In addition to the theoretical foundations of both approaches, the algorithms have been implemented. Using these implementations we show that special data structures and the exploitation of symmetries make Groebner bases competitive to state-of-the-art tools from formal verification but having the advantage of being systematic and more flexible.Comment: 44 pages, 8 figures, submitted to the Special Issue of the Journal of Pure and Applied Algebr

Robotic Deployment of Extraterrestrial Seismic Networks

Manual installation of seismic networks in extraterrestrial environments is risky, expensive and error-prone. A more reliable alternative is the automated deposition with a light-weight robot manipulator. However, inserting a spiked sensor into soil is a challenging task for a robot since the soil parameters are variable and difficult to estimate. Therefore, we investigate an approach to accurate insertion and positioning of geophones using a Cartesian impedance controller with a feed-forward force term. The feed-forward force component of the controller is either estimated using the Fundamental Earth-Moving Equation, the Discrete Element Method or empirically. For the first time, both the geological aspects of the problem as well as the aspects of robotic control are considered. Based on this consideration, the control approach is enhanced by predicting the resistance force of the soil. Experiments with the humanoid robot Rollin’ Justin inserting a geophone into three different soil samples validate the proposed method

Elektronische Wechselwirkung zwischen aufgedampften Germaniumfilmen und Sauerstoff

Ge films of thicknesses within the p-boundary layer thickness are precipitated under ultra high vacuum conditions, at 77 °K. They are investigated either in the disordered state (before annealing at a higher temperature) or in the ordered state (after annealing). The electric resistance R and the photoelectric work function & are measured before and after the influence of known amounts of oxygen. R is plotted as a function of time and coverage n, Φ as a function of n. Small amounts of oxygen cause R to increase without changing Φ, large amounts result in a succeeding decrease of R and cause Φ to increase by 0.1 to 0.2 V. The results are discussed by means of a band model. At small coverages oxygen acts as an electron donator, at higher coverages as an electron acceptor. © 1963, Walter de Gruyter. All rights reserved

Wrought Al - Cast Al compound casting based on zincate treatment for aluminum wrought alloy inserts

AbstractThe surface properties of solid inserts are critical to the development of a reaction zone in compound castings. In contrast to prior works (based on Al99.5) the goal of this paper is to apply the zincate treatment to different aluminum wrought alloys. This enables the possibility to create compound structures with enhanced mechanical properties. During zincate treatment the aluminum oxide layers are dissolved and a thin layer of zinc (<500nm) prevents reoxidation. Coating parameters are optimized especially for compound castings: maximum coverage of the surface and high coating adhesion implemented by double zincate treatment. The pretreated inserts are embedded in an aluminum component by high pressure die casting. A sound metallic bonding between both aluminum alloys develops due to diffusion and reaction zones. Mechanical tests confirm a sound metallic bonding. Depending on the integrated wrought alloy enhanced mechanical properties of the compound structure can be achieved. Microprobe and fracture analysis provide detailed information about the interface properties of the compound structure, which can be enhanced by thermal treatment