Amplification of Chirality at Solid Surfaces

Symmetry-breaking phenomena in two-dimensional crystallization at surfaces are reviewed and the potential impact to chiral amplification in three-dimensional systems in connection with the origin of homochirality in the biomolecular world is discussed. Adsorption of prochiral molecules leads to two-dimensional conglomerates, i.e., on a local scale spontaneously to homochiral crystal structures. Small enantiomeric excess or chiral impurities in this environment install homochirality on a global scale, that is, on the entire surfac

Intermediate structures in two-dimensional molecular self-assembly

We discuss the occurrence of transition structures observed in molecular self-assembly at surfaces. The increasing surface coverage transitions from low coverage structures to high coverage structures are a common phenomenon. However, often observed and not perfectly understood is the formation of intermediate structures, sometimes with lower lateral density than the initial phase. We will present different examples from our recent work and discuss the possible mechanisms of intermediate phase formation. In addition, we present intermediate structures occurring due to temperature-controlled reversible phase transition

Surface Explosion Chemistry of Malic Acid on Cu(110)

The thermal decomposition chemistry of malic acid adsorbed on a copper(110) surface was studied with thermal desorption spectroscopy, reflection-absorption infrared spectroscopy, low-energy electron diffraction and X-ray photoelectron spectroscopy in ultrahigh vacuum. In contrast to tartaric acid on Cu(110), no differences between racemate and pure enantiomers have been identifie

Status-quo-Analyse: Datenauswertung zur Fütterungssituation und zum Leistungsgeschehen von Milchkühen im ökologischen Landbau - Weiterentwicklung von Fütterungsempfehlungen

In der vorliegenden Arbeit wurden Daten aus ökologischen Milchviehbetrieben des Rheinlandes und aus Westfalen ausgewertet, um Milchleistungen in diesen Betrieben der jeweiligen Fütterungssituation zuordnen zu können. Als Datengrundlage dienten hierfür zum einen die Ergebnisse der Milchleistungsprüfung über den Zeitraum von Januar 2003 bis März 2006 und zum anderen die Sammelmilchproben der Betriebe aus jeder Milchabholung durch die Molkerei. Die Zahl der Betriebe, zu denen Milchdaten verfügbar waren, betrug 68. Als Basis der Daten zur Fütterungssituationen dienten Aufzeichnungen der Landwirtschaftskammer Nordrhein-Westfalen in Münster. Diese Aufzeichnungen enthielten Angaben über den Weideanteil im Sommer, die Einsatzmengen an Kraftfutter pro Kuh und Jahr und die anteiligen Mengen verschiedener Pflanzen an der Hauptfutterfläche. Diese Angaben waren von 49 Betrieben verfügbar, bezogen sich jedoch immer auf die gesamte Herde und den Jahresdurchschnitt, so dass genaue Zuordnungen von konkreten Rationen zu den dazugehörenden Milchleistungen oder Milchinhaltsstoffen nicht möglich waren. Es wurde versucht, durch die Auswahl von Betrieben mit besonders hohen beziehungsweise niedrigen Leistungen oder Inhaltsstoffen, Unterschiede bezüglich der eingesetzten Futtermittel oder des Weideanteiles im Sommer darzustellen. Weiterhin wurden Betriebe ausgewählt, die im Vergleich zum Mittel aller Betriebe extreme Futtergrundlagen einsetzten. Diese Fütterungsschwerpunkte wurden dann mit den erzielten Milchleistungen in Verbindung gebracht und ausgewertet

National technology policies and international friction: Theory, evidence, and policy options

Economic theory and empirical evidence suggest that governments might usefully intervene in high-technology competition in two ways: First, they could act as a neutral agent that creates the necessary credibility, commitment and mutual trust among private companies so as to facilitate cooperation in high-risk, high-volume R&D. Second, if — in view of the externalities involved — an element of subsidization is to be added, this could be done in a nondiscriminatory fashion. A favourable tax treatment of R&D expenditures may be the most appropriate tool to achieve this task. In practice, governments do engage in targeted industrial and technology policies, whether justified on economic grounds or not. As a consequence, the string of trade conflicts in hightech industries that began in the 1980s is unlikely to end in the near future, unless substantial reforms are undertaken in some crucial areas of the international trade order. Above all, appropriate reform steps should be made with a view to the regulations on (i) subsidies, (ii) structural impediments, and (iii) dumping and anti-dumping. To mitigate the frictions that arise from a subsidization of domestic firms, a new set of rules should be established. The rules should provide that all plans to grant or to alter existing subsidies are to be notified to and approved by the WTO. Moreover, all subsidies should be ranked according to their potential distortional effects on competition and trade. For each category, quantitative limits that constrain the provision of subsidies to a certain fraction of the subsidy base should be set. To facilitate further liberalization steps, a country should be allowed to exceed these limits, if a national subsidy program offers an open access to firms located in third markets. Besides restrictive business practices of private firms, government regulations and technical standards are the most important structural impediments to trade. Existing GATT Articles already offer a multilateral route to conflict resolution in cases of structural impediments. However, this route has not been used by complainants up to now. The so-called "non-violation" clause of Article 23 GATT provides access to a multilateral dispute settlement even if the defending country has not explicitly violated GATT rules. This route should be tested and, if necessary, improved. To reduce the potential for a protectionist abuse of existing anti-dumping regulations, explicit reference to the state of competition in the relevant exporting and importing country markets should be made in anti-dumping investigations. To meet specific anti-trust concerns in hightech competition — notably with respect to network externalities, systems leverage, standardization, and innovation cartels — one might consider adopting the Draft International Antitrust Code (DIAC) that has recently been proposed by an international group of legal experts. --

Condensation of Fivefold-Symmetric Molecules in Two Dimensions

We report the formation of a two-dimensional glass by solidification of a two-dimensional gas of fivefold-symmetric molecules on a copper surface upon cooling. Direct observation with scanning tunneling microscopy allows a detailed insight into the implications of a symmetry mismatch between molecular geometry and crystal lattice

Preface: Special Topic on Supramolecular Self-Assembly at Surfaces

Supramolecular self-assembly at surfaces is one of the most exciting and active fields in Surface Science today. Applications can take advantage of two key properties: (i) versatile pattern formation over a broad length scale and (ii) tunability of electronic structure and transport properties, as well as frontier orbital alignment. It provides a new frontier for Chemical Physics as it uniquely combines the versatility of Organic Synthesis and the Physics of Interfaces. The Journal of Chemical Physics is pleased to publish this Special Topic Issue, showcasing recent advances and new directions