Characterization of Fractal Structures by Spray Flame Synthesis Using X-ray Scattering

In this work, we take on an in-depth characterization of the complex particle structures made by spray flame synthesis. Because of the resulting hierarchical aggregates, very few measurement techniques are available to analyze their primary particle and fractal properties. Therefore, we use small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) to investigate the influence of the precursor concentration on the fractal structures of zirconia nanoparticles. The combination of information gained from these measurement results leads to a detailed description of the particle system, including the polydispersity and size distribution of the primary particles. Based on our findings, unstable process conditions could be identified at low precursor concentrations resulting in the broadest size distribution of primary particles with rough surfaces. Higher precursor concentrations lead to reproducible primary particle sizes almost independent of the initial precursor concentration. Regarding the fractal properties, the typical shape of aggregates for aerosols is present for the investigated range of precursor concentrations. In conclusion, the consistent results for SAXS and TEM show a conclusive characterization of a complex particle system, allowing for the identification of the underlying particle formation mechanism

Russia and Germany in Europe: recent trends of political and economic relations

'Die Beziehungen zwischen Deutschland und Rußland bilden ein wichtiges und unverzichtbares Element gesamteuropäischer Zusammenarbeit. Sowohl Bundeskanzler Kohl als auch Präsident Jelzin charakterisierten das jeweils andere Land wiederholt als 'wichtigsten Partner in Europa'. Dies trifft in unterschiedlicher Weise sicher zu. So ist Deutschland für Rußland der weltweit stärkste Handelspartner, während umgekehrt Rußland für Deutschland (und den Westen insgesamt) unverzichtbar ist, wenn es um die Neuordnung in Ostmitteleuropa geht. Dennoch gibt es in den deutsch-russischen Beziehungen auch Probleme, wozu kriegsbedingte Altlasten ebenso gehören wie unterschiedliche Vorstellungen über eine neue europäische Sicherheitsordnung und unzureichende Rahmenbedingungen in Rußland für ausländische Wirtschaftsaktivitäten. Der vorliegende Bericht befaßt sich mit Chancen und Problemen der Beziehungen Deutschland - Rußland in ihrer bi- und multilateralen Dimension. Dabei stützt er sich auf Originalquellen, wissenschaftliche Literatur und Beiträge aus der Publizistik beider Länder.' (Autorenreferat)'Relations between Germany and Russia constitute an important and indispensable element of European co-operation. Both Chancellor Kohl and President Yeltsin have on a number of occasions described each other's country as their 'most important partner in Europe'. This is certainly true, albeit in different ways for each country. Whereas Germany is Russia's most important world-wide trading partner, Russia is essential for Germany (and indeed for the West as a whole) in the establishment of a new order in East Central Europe. Nevertheless, the relationship is also a troubled one that is burdened both by unresolved issues outstanding from World War II as well as by differing ideas about the new European security arrangements and by the unsatisfactory conditions for foreign economic activity in Russia. The present report examines the problems of and prospects for German-Russian relations in both their bi- and multilateral dimensions. It draws on original sources, scholarly literature and press materials from both countries.' (author's abstract

Coupled vortex oscillations in spatially separated permalloy squares

We experimentally study the magnetization dynamics of pairs of micron-sized permalloy squares coupled via their stray fields. The trajectories of the vortex cores in the Landau-domain patterns of the squares are mapped in real space using time-resolved scanning transmission x-ray microscopy. After excitation of one of the vortex cores with a short magnetic-field pulse, the system behaves like coupled harmonic oscillators. The coupling strength depends on the separation between the squares and the configuration of the vortex-core polarizations. Considering the excitation via a rotating in-plane magnetic field, it can be understood that only a weak response of the second vortex core is observed for equal core polarizations

Water-in-Fluorocarbon Nanoemulsions Stabilized by Phospholipids and Characterized for Pharmaceutical Applications

Fluorocarbons are one of the most promising hydrophobic phases for future pharmaceutical production processes and various biomedical applications. Yet, because of their specific characteristics such as high density and refractive index similar to water, analysis of water‐in‐fluorocarbon (w/fc) nanoemulsions remains a challenge. The present work examines w/fc nanoemulsions stabilized with phospholipids as natural emulsifiers and tackles the measuring problems of photon correlation spectroscopy (PCS) when used for investigation of fluorocarbon nanoemulsions. These emulsions are suitable to form liposomes via centrifugation and thus, are required to meet certain criteria such as stability and size. The results imply a stability of up to 4 weeks with an average size of 180 nm. The intensity mean diameter gained from PCS measurements shows large scattering directly after sonication which is due to gas bubbles from sonication. The number mean is not influenced by gas bubbles and gives a more accurate depiction of the produced nanoemulsions. These findings are supported by small‐angle X‐ray scattering data, which are additionally applied for liposome analysis measuring a size of approximately 60 nm

Magnetic antivortex-core reversal by circular-rotational spin currents

Topological singularities occur as antivortices in ferromagnetic thin-film microstructures. Antivortices behave as two-dimensional oscillators with a gyrotropic eigenmode which can be excited resonantly by spin currents and magnetic fields. We show that the two excitation types couple in an opposing sense of rotation in the case of resonant antivortex excitation with circular-rotational currents. If the sense of rotation of the current coincides with the intrinsic sense of gyration of the antivortex, the coupling to the Oersted fields is suppressed and only the spin-torque contribution locks into the gyrotropic eigenmode. We report on the experimental observation of purely spin-torque induced antivortex-core reversal. The dynamic response of an isolated antivortex is imaged by time-resolved scanning transmission x-ray microscopy on its genuine time and length scale

Mechanical and hydrologic basis for the rapid motion of a large tidewater glacier 2. Interpretation

The data presented in part 1 of this paper (Meier et al., this issue) are here used to assess the role of water input/output, water storage, and basal water pressure in the rapid movement of Columbia Glacier, Alaska. Consistently high basal water pressures, mostly in the range from 300 kPa below to 100 kPa above the ice overburden pressure, are responsible in an overall way for the high glacier flow velocities (3.5–9 m d^−1), which are due mainly to rapid basal sliding caused by the high water pressure. Diurnal fluctuation in basal water pressure is accompanied by fluctuation in sliding velocity in what appears to be a direct causal relation at the upglacier observation site. The water pressure fluctuation tracks the time-integrated water input (less a steady withdrawal), as expected for the diurnally fluctuating storage of water in the glacier far from the terminus. At the downglacier site, the situation is more complex. Diurnal peaks in water level, which are directly related to intraglacial water storage as well as to basal water pressure, are shifted forward in time by 4 hours, probably as a result of the effect of diurnal fluctuation in water output from the glacier, which affects the local water storage fluctuations near the terminus. Because of the forward shift in the basal water pressure peaks, which at the downglacier site lead the velocity peaks by 6 hours, a mechanical connection between water pressure and sliding there would have to involve a 6-hour (quarter period) delay. However, the nearly identical nature of the diurnal fluctuations in velocity at the two sites argues for a single, consistent control mechanism at both sites. The velocity variations in nondiurnal “speed-up events” caused by extra input of water on the longer timescale of several days are only obscurely if at all correlated with variations in basal water pressure but correlate well with water storage in the glacier. It appears that small variations in water pressure (≤100 kPa) sufficient to produce the observed velocity variations (15–30%) are mostly masked by pressure fluctuations caused by spontaneous local reorganizations of the basal water conduit system on a spatial scale much smaller than the longitudinal coupling length over which basal water pressure is effectively averaged in determining the sliding velocity. At the achieved level of observation the clearest (though not complication free) control variable for the sliding velocity variations is basal water storage by cavitation at the glacier bed

Präsidentschaftswahlen in Rußland: Westliche Unterstützungsmaßnahmen im Vorfeld des ersten Wahlgangs

Die westliche Unterstützung, die Rußland und insbesondere El'cin im Vorfeld der Präsidentschaftswahlen gewährt worden ist, besteht einerseits aus multi- und bilateralen Finanzhilfen, andererseits aus Maßnahmen zur außenpolitischen Einbindung des Landes und zu seiner internationalen Aufwertung. Vor allem die neuerlichen Finanztransfers sind sowohl in Rußland als auch in den Geberländern umstritten. Es ist in jedem Fall in Rechnung zu stellen, daß jede Hilfe für Rußland, insbesondere eine konditionierte wie die des Internationalen Währungsfonds, von den Kontrahenten El'cins als Ausduck russischer Abhängigkeit interpretiert und politisch- propagandistisch gegen ihn instrumentalisiert wird. (BIOst-Mrk

Rußland und der Westen im Jahr der Präsidentschaftswahlen: Interessen, Perzeptionen, Formen der Zusammenarbeit

'Die Präsidentschaftswahlen in Rußland, die in zwei Durchgängen am 16. Juni und 3. Juli 1996 stattgefunden haben, lösten im Westen ein beträchtliches Echo aus und veranlaßten die internationalen Wirtschafts- und Finanzorganisationen sowie die G7-Staaten, zur Unterstützung Jelzins aktiv zu werden. Auf der Grundlage offizieller Dokumente sowie der laufenden Berichterstattung der russischen und internationalen Presse umreißt der vorliegende Bericht Interessen und Rußland-Perzeptionen der westlichen Politik, beschreibt die getroffenen Hilfsmaßnahmen, analysiert die politische und wirtschaftliche Lage Rußlands vor und nach den Präsidentschaftswahlen und erörtert Perspektiven zukünftiger Kooperation. Die Ergebnisse des Weltwirtschaftsgipfels von Lyon (27.-29.6.1996) werden dabei besonders berücksichtigt.' (Autorenreferat)'The presidential elections in Russia, which took place in two rounds on 16th June and 3rd July 1996, triggered a considerable echo in the West and prompted the international economic and financial organisations and the G7 governments to come out in support of Yeltsin. The present report takes official documents and the ongoing coverage in the Russian and international press as its basis for outlining Western political interests concerning and perceptions of Russia, describing the forms of assistance rendered to Yeltsin, analysing Russia's political and economic situation before and after the presidential elections, and discussing prospects for future cooperation. The report pays particular attention to the Lyon world economic summit (27th-29th June 1996).' (author's abstract

Fortschreibung statt Innovation: Halifax - 'G7-Gipfel der Bescheidenheit'

Seit dem Pariser Weltwirtschaftsgipfel von 1989 steht die Unterstützung des politisch-ökonomischen Transformationsprozesses im Osten Europas auf der Tagesordnung der G7-Spitzenkonferenzen. Nach einem vielversprechenden Auftakt löste sich der tatsächliche Verlauf der Unterstützung allerdings bald vom Rhythmus der G7- Gipfel ab. Zunehmend verstärkte sich ein Trend zur 'Routinisierung' der Hilfsmaßnahmen, vor allem durch die Verlagerung der Unterstützungsaktivitäten auf die internationalen Wirtschafts- und Finanzorganisationen. Ein Abgehen vom Prinzip 'Fortschreibung statt Innovation' ist auch für die Zukunft kaum zu erwarten. (BIOst-Mrk