Thermische Ausdehnung von Metallen bei tiefen Temperaturen

The thermal expansion coefficients of the following metals in the temperature region between 1,5° and 12°K have been measured: Al, Pb, Pt, Mo, Ta, W, Mg, Cd, Re, Ti, La, Ce, Nd, Gd, Yb. Except for tantalum all the specimens were polycrystalline. Is is found in accordance with theoretical prediction that the coefficient of thermal expansionβ=1/V (?V/?T) [whereV = volume,T = temperature] at sufficiently low temperatures is composed of an electronic component varying linearly with temperature, and a lattice component varying as the cube of the temperature. The electronic component is strongly modified in the superconducting state (Pb, Ta, La). The rare earth metals Gd, Ce and Nd have negative anomalies in their expansion. These are connected with the ferro- and antiferromagnetism of these substances. The results are discussed on the basis of lattice dynamics and the theory of electrons in metals.     

Frequency doubling and tuning with KB5O8·4H2O and application to NO (A2Σ+) excitation

Frequency doubling by angle tuning with KB₅O₈·4H₂O has been investigated at 217.0–250 nm. The phase matching angle, refractive index and doubling efficiency have been measured. A first application has been made by exciting NO(A²Σ⁺) in the UV.     

A tutorial review of the basic theory for and practical aspects of aerosol chambers

A review of the theory for the separation of large droplets in aerosol chambers related to analytical spectroscopy is given. The theoretical treatment is used for discussing practical aspects and the behaviour of aerosol chambers. It is shown that the theories presented can be used for explaining the characteristics of aerosol chambers. The most likely processes describing the separation of large droplets in aerosol chambers are inertial deposition processes. Cyclone and jet impaction are the most interesting concepts for designing new types of aerosol chambers for atomic spectroscopy.     

Study of an Underexpanded Plasma Jet II. Diagnostics with Microwaves

The properties of the plasma of an underexpanded jet in air were examined by optical and by probe methods as described in a previous paper (Contrib. Plasma Phys. 27 (1987) 203). The jet was produced by an erosion plasmatron with xenon-filling operating in a single-pulse regime. Now, independent measurements of the space-time development of the electron density by microwave interferometry are described. The results of cut-off and phase shift measurements are in agreement with those obtained by probe diagnostics.     

Acylations of 1,10-dilithiophenothiazine. A new synthesis of 1-formylphenothiazine

The synthesis of 1-formyl-, 1-benzyyl-, 1-anisoyl-, and 1-nicotinyl-phenothiazines ( 1–4 ) resulting from the reaction of the corresponding amids with 1,10-dilithiophenothiazine ( 5 ) is reported. The site of attachment on 1,10-dilithiophenothiazine, based on the nature of some different acylating reagents, is also discussed.     

Model-based optimization of a preparative ion-exchange step for antibody purification

A method using a model-based approach to design and optimize an ion-exchange step in a protein purification process is proposed for the separation of IgG from a mixture containing IgG, BSA and myoglobin. The method consists of three steps. In the first step, the model is calibrated against carefully designed experiments. The chromatographic model describes the convective and dispersive flow in the column, the diffusion in the adsorbent particles, and the protein adsorption using Langmuir kinetics with mobile phase modulators (MPM). In the second step, the model is validated against a validation experiment and analyzed. In the third and final step, the operating conditions are optimized. In the optimization step, the loading volume and the elution gradient are optimized with regard to the most important costs: the fixed costs and the feed cost. The optimization is achieved by maximizing the objective functions productivity (i.e. the production rate for a given amount of stationary phase) and product yield (i.e. the fraction of IgG recovered in the product stream). All optimization is conducted under the constraint of 99% purity of the IgG. The model calibration and the analysis show that this purification step is determined mainly by the kinetics, although as large a protein as IgG is used in the study. The two different optima resulting from this study are a productivity of 2.7 g IgG/(s m3) stationary phase and a yield of 90%. This model-based approach also gives information of the robustness of the chosen operating conditions. It is shown that the bead diameter could only be increased from 15 microm to 35 microm with maximum productivity and a 99% purity constraint due to increased diffusion hindrance in larger beads.     

Temperature-programmed packed capillary liquid chromatography coupled to evaporative light-scattering detection and electrospray ionization time-of-flight mass spectrometry for characterization of high-molecular-mass hindered amine light stabilizers

High-molecular weight-hindered amine light stabilizers (HMW-HALSs) are of utmost importance in modern polyolefin stabilization technology and in-depth knowledge about their chemical composition, particularly the oligomers, is essential for development of new and more efficient stabilizers. In the present study, the applicability of temperature-programmed packed capillary LC coupled to miniaturized ELSD and positive mode ESI-TOF-MS for analysis of HMW-HALSs is demonstrated through extensive characterization of two state-of-the-art stabilizers, i.e., HALS-1 and HALS-2. Both stabilizers were individually separated on a 320 microm i.d. x 35 cm long Hypersil 3 microm ODS-100 column using a temperature program from 30 to 120 degrees C and a quaternary mixture of ethylacetate, acetonitrile, triethylamine (TEA) and acetic acid (45.0:44.9:10.0:0.1 (v/v/v/v)) as the mobile phase. The effect of using various amounts of ethylacetate, acetonitrile and triethylamine in the mobile phase on the chromatographic separation is demonstrated. Furthermore, the LC-ESI-TOF-MS analyses revealed that HALS-1 (oligomeric) was highly complex and consisted of at least five different mass series, while HALS-2, which was assumed to be monomeric, contained two different mass series. Chemical structures for nearly all species of both stabilizers are proposed.     

Gromov-Witten invariants on Grassmannians

We prove that any three-point genus zero Gromov-Witten invariant on a type Grassmannian is equal to a classical intersection number on a two-step flag variety. We also give symplectic and orthogonal analogues of this result; in these cases the two-step flag variety is replaced by a sub-maximal isotropic Grassmannian. Our theorems are applied, in type , to formulate a conjectural quantum Littlewood-Richardson rule, and in the other classical Lie types, to obtain new proofs of the main structure theorems for the quantum cohomology of Lagrangian and orthogonal Grassmannians.

     

The monopulsed nature of sperm whale clicks

Traditionally, sperm whale clicks have been described as multipulsed, long duration, nondirectional signals of moderate intensity and with a spectrum peaking below 10 kHz. Such properties are counterindicative of a sonar function, and quite different from the properties of dolphin sonar clicks. Here, data are presented suggesting that the traditional view of sperm whale clicks is incomplete and derived from off-axis recordings of a highly directional source. A limited number of assumed on-axis clicks were recorded and found to be essentially monopulsed clicks, with durations of 100 micros, with a composite directionality index of 27 dB, with source levels up to 236 dB re: 1 microPa (rms), and with centroid frequencies of 15 kHz. Such clicks meet the requirements for long-range biosonar purposes. Data were obtained with a large-aperture, GPS-synchronized array in July 2000 in the Bleik Canyon off Vester?len, Norway (69 degrees 28' N, 15 degrees 40' E). A total of 14 h of sound recordings was collected from five to ten independent, simultaneously operating recording units. The sound levels measured make sperm whale clicks by far the loudest of sounds recorded from any biological source. On-axis click properties support previous work proposing the nose of sperm whales to operate as a generator of sound.     

Removable singularities for analytic functions in BMO and locally Lipschitz spaces

In this paper we study removable singularities for holomorphic functions such that sup_z|f⁽ⁿ⁾(z)|dist(z,)^s<. Spaces of this type include spaces of holomorphic functions in Campanato classes, BMO and locally Lipschitz classes. Dolzhenko (1963), Král (1976) and Nguyen (1979) characterized removable singularities for some of these spaces. However, they used a different removability concept than in this paper. They assumed the functions to belong to the function space on and be holomorphic on \ E, whereas we only assume that the functions belong to the function space on \ E, and are holomorphic there. Koskela (1993) obtained some results for our type of removability, in particular he showed the usefulness of the Minkowski dimension. Kaufman (1982) obtained some results for s=0.In this paper we obtain a number of examples with certain important properties. Similar examples have earlier been obtained for Hardy H^p classes and weighted Bergman spaces, mainly by the author. Because of the similarities in these three cases, an axiomatic approach is used to obtain some results that hold in all three cases with the same proofs. Supported by the Swedish Research Council and Gustaf Sigurd Magnusons fund of the Royal Swedish Academy of Sciences.Mathematics Subject Classification (2000):30B40, 30D45, 30D55, 46E15.