Hydraulic Transport Across Hydrophilic and Hydrophobic Nanopores: Flow Experiments with Water and n-Hexane

We experimentally explore pressure-driven flow of water and n-hexane across nanoporous silica (Vycor glass monoliths with 7 or 10 nm pore diameters, respectively) as a function of temperature and surface functionalization (native and silanized glass surfaces). Hydraulic flow rates are measured by applying hydrostatic pressures via inert gases (argon and helium, pressurized up to 70 bar) on the upstream side in a capacitor-based membrane permeability setup. For the native, hydrophilic silica walls, the measured hydraulic permeabilities can be quantitatively accounted for by bulk fluidity provided we assume a sticking boundary layer, i.e. a negative velocity slip length of molecular dimensions. The thickness of this boundary layer is discussed with regard to previous capillarity-driven flow experiments (spontaneous imbibition) and with regard to velocity slippage at the pore walls resulting from dissolved gas. Water flow across the silanized, hydrophobic nanopores is blocked up to a hydrostatic pressure of at least 70 bar. The absence of a sticking boundary layer quantitatively accounts for an enhanced n-hexane permeability in the hydrophobic compared to the hydrophilic nanopores.Comment: 15 pages, 7 figures, in press, Physical Review E 201

Gender in Community Consultations

Landmine removal within Cambodia has been an important, unsolved problem for many years. This article focuses on mine-action strategies for gender mainstreaming in the community consultations carried out in rural, mine-affected areas in Cambodia

Molecular dynamics of n-hexane: A quasi-elastic neutron scattering study on the bulk and spatially nanochannel-confined liquid

We present incoherent quasi-elastic neutron scattering measurements in a wavevector transfer range from 0.4 AA^{-1} to 1.6AA^{-1} on liquid n-hexane confined in cylindrical, parallel-aligned nanochannels of 6 nm mean diameter and 260 micrometer length in monolithic, mesoporous silicon. They are complemented with, and compared to, measurements on the bulk system in a temperature range from 50K to 250K. The time-of-flight spectra of the bulk liquid can be modeled by microscopic translational as well as fast localized rotational, thermally-excited, stochastic motions of the molecules. In the nano-confined state of the liquid, which was prepared by vapor condensation, we find two molecular populations with distinct dynamics, a fraction which is immobile on the time scale of 1ps to 100ps probed in our experiments and a second component with a self-diffusion dynamics slightly slower than observed for the bulk liquid. No hints of an anisotropy of the translational diffusion with regard to the orientation of the channels' long axes have been found. The immobile fraction amounts to about 5% at 250K, gradually increases upon cooling and exhibits an abrupt increase at 160K (20K below bulk crystallization), which indicates pore freezingComment: 10 pages, 7 figure

Melting and freezing of argon in a granular packing of linear mesopore arrays

Freezing and melting of Ar condensed in a granular packing of template-grown arrays of linear mesopores (SBA-15, mean pore diameter 8 nanometer) has been studied by specific heat measurements C as a function of fractional filling of the pores. While interfacial melting leads to a single melting peak in C, homogeneous and heterogeneous freezing along with a delayering transition for partial fillings of the pores result in a complex freezing mechanism explainable only by a consideration of regular adsorption sites (in the cylindrical mesopores) and irregular adsorption sites (in niches of the rough external surfaces of the grains, and at points of mutual contact of the powder grains). The tensile pressure release upon reaching bulk liquid/vapor coexistence quantitatively accounts for an upward shift of the melting/freeezing temperature observed while overfilling the mesopores.Comment: 4 pages, 4 figures, to appear as a Letter in Physical Review Letter

Capillary rise of water in hydrophilic nanopores

We report on the capillary rise of water in three-dimensional networks of hydrophilic silica pores with 3.5nm and 5nm mean radii, respectively (porous Vycor monoliths). We find classical square root of time Lucas-Washburn laws for the imbibition dynamics over the entire capillary rise times of up to 16h investigated. Provided we assume two preadsorbed strongly bound layers of water molecules resting at the silica walls, which corresponds to a negative velocity slip length of -0.5nm for water flow in silica nanopores, we can describe the filling process by a retained fluidity and capillarity of water in the pore center. This anticipated partitioning in two dynamic components reflects the structural-thermodynamic partitioning in strongly silica bound water layers and capillary condensed water in the pore center which is documented by sorption isotherm measurements.Comment: 4 pages, 3 figure

Ethische Perspektiven einer entwicklungsgerechten Weltwirtschaft

Der Verfasser formuliert ethische Perspektiven einer am Kriterium gerechter Entwicklung orientierten Weltwirtschaft. Einleitend setzt er sich auf theoretischer wie empirische Ebene mit dem Zusammenhang von Wirtschaftswachstum und Ungleichheit auseinander. Danach wird eine spezifische Interpretation von Gerechtigkeit und Entwicklungszielen entworfen, die auf die Identifizierung und Überwindung von Ungerechtigkeit orientiert ist. Auf dieser Basis werden grundlegende ethische Standards, Verantwortungsniveaus und Akteure einer entwicklungsgerechten Weltwirtschaft diskutiert. (ICEÜbers)"This paper seeks to outline some ethical perspectives of a global economy fitting a just development after introducing some elementary considerations and empirical facts on the linkage between economic growth and inequality. A specific interpretation of justice and of development aims at identifying and overcoming patent injustice. Based on this, fundamental ethical standards, levels of responsibility and actors of a global economic order doing justice to development are spelled out." (author's abstract

Provisional and protective measures in the Draft of the New Hungarian Civil Procedure

This paper presents and analyzes the rules of provisional and protective measures as laid down in the current Draft of the New Hungarian Civil Procedure. It focuses on the purposes and contents of the provisional measures and devotes a separate section to the function of the security that the applicant has to deposit if ordered by the court. The paper concludes that provisional measures have a special mixed character in the sense that they are simultaneously and tightly connected to substantive law and procedural law. The security is regulated in accordance with this mixed character

Wirtschaftsethik

"Die Wirtschaftswissenschaft und die Ethik werden in der öffentlichen Diskussion heute weitgehend als kaum vermittelbare Disziplinen wahrgenommen. Dabei gerät allerdings häufig in Vergessenheit, dass wirtschaftliches Denken ursprünglich aus philosophischen Überlegungen heraus entwickelt wurde. So gab Aristoteles der Ökonomie ihren Namen und Adam Smith, der als Begründer der modernen Nationalökonomie gilt, lehrte im 18. Jahrhundert als Moralphilosoph an der Universität Glasgow. Als Reaktion auf offensichtliche moralische Defizite modernen Wirtschaftens, wie etwa dem wachsenden Wohlstandsgefälle zwischen Armen und Reichen oder der fortschreitenden Gefährdung der natürlichen Lebensgrundlagen, hat sich seit etwa 25 Jahren zunächst in den USA und dann auch in Europa die Wirtschaftsethik als eigenständige Forschungsrichtung etabliert. Ihr geht es ganz allgemein um eine Vermittlung dieser beiden scheinbar widersprüchlichen Disziplinen und dabei vor allem um eine methodische Reflexion des Verhältnisses von ökonomischer Logik und moralischen Ansprüchen. In der gegenwärtigen wirtschaftsethischen Debatte können drei verschiedene, teilweise miteinander konkurrierende Richtungen unterschieden werden, von denen nachstehend jeweils ein Ansatz kurz vorgestellt wird. Diese werden in einem zweiten Teil anhand einiger ausgewählter Fragestellungen diskutiert." (Autorenreferat

Wirtschaftliches Handeln, Well-being und Glück: Impulse der ökonomischen Glücksforschung für die Wirtschaftsethik

"Die Frage nach dem Glück als einer relevanten Perspektive für die Wirtschaftsethik mag auf den ersten Blick verwundern. Persönliche Vorstellungen von Glück, Sinnerfüllung oder vom gelingenden Leben werden in unseren hochgradig arbeitsteiligen und anonymen Gesellschaften meist dem Privatbereich zugeordnet. Darüber hinaus wird Glück bestenfalls als 'weicher Faktor' angesehen, da der wirtschaftliche Alltag von ökonomischen Sachzwängen und Kosten-Nutzen-Kalkülen bestimmt zu sein scheint. Konsequenterweise meidet die gängige Wirtschaftstheorie den Begriff des Glücks und spricht von Nutzen oder Präferenzen, die eher in einem formalen Sinn verstanden werden. Dabei wird meist stillschweigend vorausgesetzt, dass höheres Vermögen oder Einkommen den Nutzen und damit auch das individuelle Wohlergehen (well-being) mehrt. In der Ethik ist Glück dagegen immer ein zentraler Begriff gewesen. Warum sollte Glück dann nicht auch relevant sein für die Wirtschaftsethik?" (Autorenreferat)"Luck as a relevant perspective for business ethics may be surprising at first blush. Personal ideas of luck, eudemonism or successful life are usually allocated to the private area in our highly labor-divided and anonymous societies. In addition luck is at best considered a 'soft factor' because the economic weekday seems to be determined by economic practical necessities and cost-benefit calculations. Consequently current economic theory avoids the term 'luck' and talks of benefit or preferences generally in a formal sense. In this context it is widely assumed that greater assets or higher income increases the benefit and thus also the individual well-being. On the other hand, luck has always been a central term in ethics. Why then should luck not also be relevant for business ethics, asks the author." (author's abstract