An integrated fiber-based optical trap for single airborne particles

We present a compact fiber-based optical airborne particle trap that is integrated on a microscope slide. Light guided in a short glass capillary is used to inject micron-sized droplets into an optical trap formed by the same light and a counterpropagating beam emanating from a single-mode optical fiber. The glass capillary ensures separation of trapped particles from remaining aerosol in the injection chamber. Permanent alignment of the fibers and the capillary allows for adjustment-free operation. Mie resonances arising in the radiation pressure exerted on trapped droplets are detected via a position stabilization feedback loop and are used to precisely determine the size evolution of trapped glycerol–water droplets.     

Phase equilibria and excess properties for binary systems in reactive distillation processes Part I. Methyl acetate synthesis

Isothermal vapor–liquid equilibrium (VLE) and excess enthalpy (H^E) data were measured for binary systems required for the design of reactive distillation processes for the methyl acetate production. The isothermal P–x data were measured with the help of a computer-operated static apparatus. A commercial isothermal flow calorimeter was used for the determination of the heats of mixing. Temperature-dependent interaction parameters for the UNIQUAC model were fitted simultaneously to the experimental data from this work and other authors.     

Generalizing the Keller�CSegel Model: Lyapunov Functionals, Steady State Analysis, and Blow-Up Results for Multi-species Chemotaxis Models in?the?Presence of Attraction and Repulsion Between Competitive Interacting Species

In this paper we extend the famous Keller–Segel model for the chemotactic movement of motile species to some multi-species chemotaxis equations. The presented multi-species chemotaxis models are more general than those introduced so far and also include some interaction effects that have not been studied before. For example, we consider multi-species chemotaxis models with attraction and repulsion between interacting motile species. For some of the presented new models we give sufficient conditions for the existence of Lyapunov functionals. These new results are related to those of Wolansky (Scent and sensitivity: equilibria and stability of chemotactic systems in the absence of conflicts, preprint, 1998; Eur. J. Appl. Math. 13:641–661, 2002). Furthermore, a linear stability analysis is performed for uniform steady states, and results for the corresponding steady state problems are established. These include existence and nonexistence results for non-constant steady state solutions in some special cases.     

Gasanalyse

Ohne Zusammenfassung     

Boundedness vs. blow-up in a chemotaxis system

We determine the critical blow-up exponent for a Keller-Segel-type chemotaxis model, where the chemotactic sensitivity equals some nonlinear function of the particle density. Assuming some growth conditions for the chemotactic sensitivity function we establish an a priori estimate for the solution of the problem considered and conclude the global existence and boundedness of the solution. Furthermore, we prove the existence of solutions that become unbounded in finite or infinite time in that situation where this a priori estimate fails.     

Localization of cold atoms in state-dependent optical lattices via a Rabi Pulse

We propose a novel realization of Anderson localization in nonequilibrium states of ultracold atoms in an optical lattice. A Rabi pulse transfers part of the population to a different internal state with infinite effective mass. These frozen atoms create a quantum superposition of different disorder potentials, localizing the mobile atoms. For weakly interacting mobile atoms, Anderson localization is obtained. The localization length increases with increasing disorder and decreasing interaction strength, contrary to the expectation for equilibrium localization.