A scanning mobility particle sizer (SMPS, TSI Model 3934) and a white-light optical particle counter (OPC, as described by Umhauer 1983) are combined. With these two instruments, fast and non-intrusive on-line measurements of particle size distributions in a range of 15 nm up to 15 μm are possible. A filter provides the possibility of taking samples in order to analyse the morphology and chemical composition of the aerosol. Both liquid and solid airborne particles in diluted suspensions can be measured. The complete system is able to cope with particle concentrations of up to 107 particles/cm3 without dilution of the aerosol. Since the measuring principles of the combined devices are based on different physical properties, careful calibration is necessary. Both theoretical calculations and experimental methods are used for calibration purposes. The measuring results of different devices are compared during simultaneous characterisation of several aerosols. The performance of the combined measuring system is demonstrated by means of comparison with a common cascade impactor in the laboratory as well as during industrial application.

We have investigated the one-dimensional spin-1/2 axial next-nearest-neighbour Ising (ANNNI) model in two orthogonal magnetic fields at zero temperature. There are four different possible ground state configurations for the ANNNI model in a longitudinal field, in the thermodynamic limit. The inclusion of a transverse field introduces quantum fluctuations which destroy the existing spin order along certain critical lines. The effects of the fluctuations in three of the four ordered regions were investigated using the finite-size scaling technique. The phase boundaries of the ANNNI model in two orthogonal magnetic fields were thus determined numerically. For certain limits of the Hamiltonian we compared the obtained results with the existing literature and our results were in good agreement with the results in the existing literature.

We compare the thermodynamic entropy of a quantum Brownian oscillator derived from the partition function of the subsystem with the von Neumann entropy of its reduced density matrix. At low temperatures we find deviations between these two entropies which are due to the fact that the Brownian particle and its environment are entangled. We give an explanation for these findings and point out that these deviations become important in cases where statements about the information capacity of the subsystem are associated with thermodynamic properties, as it is the case for the Landauer principle.

We analyze ground state and spectral properties of the one-dimensional half-filled Holstein Hubbard model with respect to the Peierls-insulator to Mott-insulator transition, exploiting Lanczos diagonalization, density matrix renormalization, kernel polynomial expansion, and maximum entropy methods on the Hitachi SR8000-F1 supercomputer.

The elastic properties of SrTiO3 are investigated as function of temperature within an anharmonic electron-phonon interaction model.. Pronounced zone boundary acoustic mode softening with decreasing temperature is observed, which is accompanied by giant elastic instabilities and the formation of microdomains. In the isotope substituted compound (SrTiO3)-O-18 the onset of feroelectricity is marked not only by a divergence of the dielectric constant but also by a distinct anomaly in the elastic properties.

Although it is well known that for hydrogen-bonded ferro- and antiferroelectric systems the replacement of hydrogen by deuterium induces a large isotope effect on the ferroelectric transition temperature T c , similar findings have not been reported for perovskite type ferroelectrics until recently when it has been shown experimentally that the incipient quantum paraelectric SrTiO 3 can be driven to a ferroelectric state by replacing O 16 by its isotope O 18 [Phys. Rev. Lett. 28, 3540 (1999)]. The experimental data have been analyzed within an anharmonic electron–phonon interaction model and consistent quantitative agreement with the corresponding experiment is achieved. In addition, it is shown that the origin of the isotope effect in perovskite type quantum paraelectrics differs substantially from the one observed in hydrogen-bonded systems.

This chapter contains sections titled: Introduction Slave-boson theory for the t-t′-J model SU(2)-invariant slave-particle representation Functional integral formulation Saddle-point approximation Magnetic phase diagram of the t-t′-J model Comparison with experiments Normal-state transport properties Magnetic correlations and spin dynamics Inelastic neutron scattering measurements Summary References

The hydrogen dynamics in the metalhexahydrateperchlorates with Mg, Mn, Fe, Ni, and Zn as metal ions has been investigated with quasielastic neutron scattering. The water molecules perform 180°-flip motions on a picosecond time scale through a series of solid–solid phase transitions. In the highest temperature phase I and the subsequent phase II, rotational barriers of typically Ea=50 meV are found. These values are surprisingly small in view of the low symmetry of H2O molecules. The I → II phase transition has only very small effects on the hydrogen dynamics. At the transition into phase III an increase of the rotational barriers to typically Ea=250 meV is found. This is interpreted as the formation of weak hydrogen bonds. In phase I 180°-flip motions provide a complete description of the observed data. In phases II and III an extension of the dynamical model toward a stronger localization of hydrogen is required. A preference is given to a mechanism leading to a temporary blockade of the flip motions. In phase III of the Fe compound, the existence of crystallographically different sites for water molecules is inferred.

The calibration of an optical particle counter (OPC) by means of the Aerodynamic Particle Sizer APS (TSI, Model 3310) was investigated. The pulse-height distribution and the aerodynamic size distribution were measured by parallel use of an OPC and the APS. A calibration curve was obtained by comparison of the two different cumulative distribution curves. First calibration results are presented for spherical particles (water droplets and glycerine droplets). A comparison of these results with Mie calculations and aerodynamic calibrations by means of sampling cyclones shows good agreement. Furthermore, measurements were carried out with non-spherical particles. Quartz dust was used for these measurements. In order to calibrate the OPC by means of the APS, the behaviour of both devices was investigated.

Due to induced turbulent interactions between particles to be separated and the scrubbing liquid present as droplets, very good collection efficiency down to submicron particle size can be achieved as shown by detailed studies [1]. Assumed are suitable flow conditions, a long residence time and a certain droplet size distribution or a special liquid dispersion system. As the name implies, the cyclone-scrubber basically consists of a cyclone. This cyclone serves as a contact space in which the interaction between dust particles and scrubbing liquid droplets takes place, and as a droplet separator. Thus, under normal conditions, a water saturated but dust- and droplet-free gas stream leaves the cyclone. The droplets are generated by a pneumatic atomization nozzle, arranged at the cyclone inlet in the direction of flow. A complete theoretical description of the three-dimensional, three-phase, nonsteady turbulent flow in the cyclone scrubber has not been possible up to now. The detailed experimental investigations presented in this work, and covering multiple parameters, led to physically based conclusions about the dominant interactions and separation mechanisms involved. Grade efficiencies which did not fall below 0.75, down to a particle size of 0.5 gm, could be measured by an optical particle counter. Collection efficiency of 99.2% was determined by gravimetric analysis of the dust load, according to VDI-guideline 2066, in the raw and clean gas sections of the dust load, according to VDI-guideline 2066, in the raw and clean gas sections of the cyclone scrubber.

The relationship between ferroelectricity and high-temperature superconductivity is investigated. The proposed approach combines an extension of Hirsch's description of the oxygen hole superconductivity and the coupling to an anharmonic lattice. Using standard variational principles, the superconducting order parameter and the static lattice distortion are calculated for certain sets of model parameters. Comparison of the free energies of different possible phases shows to what extent the anharmonic lattice influences superconductivity. This depends mainly on the modulation of the hopping interaction which couples the superconducting subsystem (holes) to the lattice. In particular, the phase boundaries are obtained for different hole concentrations. There is a parameter regime where superconductivity and ferroelectricity coexist. However, both order parameters (the energy gap and the lattice distortion) are reduced as compared to the pure phases. In the paraelectric regime the anharmonic lattice instability supports the superconducting state.

ABSTRACT The “nozzle scrubber” is a wet scrubber in which the scrubbing water is dispersed in the dust laden gas stream by means of one or more pneumatic nozzles. This scrubber is distinguished by an excellent collection efficiency for submicron dust at an unusually low energy and water consumption. No well-defined theory exists for this process. The collection efficiency in the “nozzle scrubber” depends primarily on turbulent diffusion respectively on the interaction of particles and droplets induced by turbulence, and not on inertial separation as in the case of the venturi scrubber. A light scattering device was used to measure the particle distributions. The experimental set-up was built up in a technical scale. The influence of operation parameters, especially water consumption, residence time, and pressurized air, on the grade efficiency has been demonstrated by their systematic variation. The contribution of turbulent diffusion to the collection efficiency has been confirmed.

The experimentally observed broken charge-conjugation symmetry in quasi-one-dimensional systems can be understood in an effective electron-phonon one-band Hamiltonian as a prototype model of these systems.

Chemie Ingenieur TechnikVolume 62, Issue 2 p. 156-157 Wissenschaftliche Forschungsarbeit Partikelabscheidung in kleinen Laborzyklonen als Grundlage für Auslegung von großen Betriebszyklonen Dr.-Ing. habil. Helmut Büttner, Dr.-Ing. habil. Helmut Büttner Lehrstuhl für Mechanische Verfahrenstechnik und Strömungsmechanik, Univ. Kaiserslautern, Erwin-Schrödinger-Straße, 6750 KaiserslauternSearch for more papers by this authorProf. Dr.-Ing. habil. Fritz Ebert, Prof. Dr.-Ing. habil. Fritz Ebert Lehrstuhl für Mechanische Verfahrenstechnik und Strömungsmechanik, Univ. Kaiserslautern, Erwin-Schrödinger-Straße, 6750 KaiserslauternSearch for more papers by this author Dr.-Ing. habil. Helmut Büttner, Dr.-Ing. habil. Helmut Büttner Lehrstuhl für Mechanische Verfahrenstechnik und Strömungsmechanik, Univ. Kaiserslautern, Erwin-Schrödinger-Straße, 6750 KaiserslauternSearch for more papers by this authorProf. Dr.-Ing. habil. Fritz Ebert, Prof. Dr.-Ing. habil. Fritz Ebert Lehrstuhl für Mechanische Verfahrenstechnik und Strömungsmechanik, Univ. Kaiserslautern, Erwin-Schrödinger-Straße, 6750 KaiserslauternSearch for more papers by this author First published: February 1990 https://doi.org/10.1002/cite.330620233AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. Volume62, Issue2February 1990Pages 156-157 RelatedInformation

Angewandte Chemie International Edition in EnglishVolume 28, Issue 5 p. 671-672 Book Review Book Review: Electrons in Solids: An Introductory Survey. By R. H. Bube Helmut Büttner, Helmut Büttner Physikalisches Institut der Universität, Bayreuth (FRG)Search for more papers by this author Helmut Büttner, Helmut Büttner Physikalisches Institut der Universität, Bayreuth (FRG)Search for more papers by this author First published: May 1989 https://doi.org/10.1002/anie.198906711AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume28, Issue5May 1989Pages 671-672 RelatedInformation

AbstractThe “nozzle scrubber” is a wet scrubber in which the scrubbing water is dispersed in dust laden gas stream by means of one or more pneumatic nozzle. This scrubber is distinguished by an excellent collection efficiency for submicron dust at an unusually low energy and water consumption. So far, the physical effects affecting the separation cannot be explained by a well‐defined theory. Therefore, it is sensible to investigate the collection efficiency with regard to the mechanisms of inertial impaction, turbulent diffusion and coalescence induced by turbulence. The experimental equipment is of a very simple design. A light scattering device was used to measure the particle distributions. In addition, electron micrographs were analyzed to obtain information about the submicron particles. The influence of operating parameters on grade efficiency has been demonstrated by their systematic variation. The contribution of turbulent diffusion to the collection efficiency has been confirmed; nevertheless, grade efficiencies were also measured when inertial impaction prevailed.