Direct evidence for dynamic intramolecular double proton exchange in carboxylic acid dimers in the solid is obtained from NMR measurements. For the p-toluic acid dimer, an asymmetric double minimum potential with an energy difference ΔG = 1.0 kJ/mol and an activation energy of Ea = 4.8 kJ/mol between the two tautomeric forms is found. The equilibrium position of the carboxylic proton pair at low temperature is derived from the corresponding dipolar coupling tensor. The importance of double proton tunneling at low temperature is discussed.

We consider the situation of a heavier fluid placed above a lighter one in a vertically arranged Hele-Shaw cell. The two fluids are miscible in all proportions. For this configuration, experiments and nonlinear simulations recently reported by Fernandez et al. (2002) indicate the existence of a low-Rayleigh-number (Ra) ‘Hele-Shaw’ instability mode, along with a high-Ra ‘gap’ mode whose dominant wavelength is on the order of five times the gap width. These findings are in disagreement with linear stability results based on the gap-averaged Hele-Shaw approach, which predict much smaller wavelengths. Similar observations have been made for immiscible flows as well (Maxworthy 1989).In order to resolve the above discrepancy, we perform a linear stability analysis based on the full three-dimensional Stokes equations. A generalized eigenvalue problem is formulated, whose numerical solution yields both the growth rate and the two-dimensional eigenfunctions in the cross-gap plane as functions of the spanwise wavenumber, an ‘interface’ thickness parameter, and Ra. For large Ra, the dispersion relations confirm that the optimally amplified wavelength is about five times the gap width, with the exact value depending on the interface thickness. The corresponding growth rate is in very good agreement with the experimental data as well. The eigenfunctions indicate that the predominant fluid motion occurs within the plane of the Hele-Shaw cell. However, for large Ra purely two-dimensional modes are also amplified, for which there is no motion in the spanwise direction. Scaling laws are provided for the dependence of the maximum growth rate, the corresponding wavenumber, and the cutoff wavenumber on Ra and the interface thickness. Furthermore, the present results are compared both with experimental data, as well as with linear stability results obtained from the Hele-Shaw equations and a modified Brinkman equation.

We study the photon-echo attenuation by various dynamical processes in rare-earth-ion-doped crystals. The experimental investigations concentrate on a Pr 3ϩ :Eu 3ϩ :Nd 3ϩ codoped Y 2 SiO 5 crystal at low temperatures. Two-pulse photon-echo intensities are measured as a function of the pulse intensities when either the Pr 3ϩ or the Eu 3ϩ ions are excited. For the quantitative interpretation we consider primarily excitation-induced frequency shifts ͑EFS͒ by diagonal and off-diagonal interactions and show that for the systems under consideration EFS are dominated by diagonal interactions. The observed echo attenuation by EFS is compared with the predictions calculated from independent Stark-field measurements and reasonable agreement is obtained. The broadening by spin-ion interactions, by nonequilibrium phonons and the dependence of the echo attenuation on the frequency position in the inhomogeneously broadened band are further investigated.

Willi, B. et al. (2016) non-epizootic infection associated with skin ulceration and edema are presented. 32Samples from eleven symptomatic cats, four in-contact cats and 27 cats with no 33 contact with symptomatic cats were collected and tested for FCV, feline herpesvirus-34

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Bileaflet MHVs were demonstrated to be only slightly sensitive to rotation regarding the washout performance of the TAH. The proposed numerical washout model proved to be an adequate tool to quantitatively compare different configurations and designs of the artificial organ regarding the potential for blood stagnation where experimental measurements are limited.

Hemocompatibility of blood pumps is a crucial parameter that has to be ensured prior to in vivo testing. In contrast to rotary blood pumps, a standard for testing a pulsatile total artificial heart (TAH) has not yet been established. Therefore, a new mock circulation loop was designed to investigate hemolysis in the left ventricle of the ReinHeart TAH. Its main features are a high hemocompatibility, physiological conditions, a low priming volume, and the conduction of blood through a closed tubing system. The mock circulation loop consists of a noninvasive pressure chamber, an aortic compliance chamber, and an atrium directly connected to the ventricle. As a control pump, the clinically approved Medos-HIA ventricular assist device (VAD) was used. The pumps were operated at 120 beats per minute with an aortic pressure of 120 to 80 mm Hg and a mean atrial pressure of 10 mm Hg, generating an output flow of about 5 L/min. Heparinized porcine blood was used. A series of six identical tests were performed. A test method was established that is comparable to ASTM F 1841, which is standard practice for the assessment of hemolysis in continuous-flow blood pumps. The average normalized index of hemolysis (NIH) values of the VAD and the ReinHeart TAH were 0.018 g/100 L and 0.03 g/100 L, respectively. The standard deviation of the NIH was 0.0033 for the VAD and 0.0034 for the TAH. Furthermore, a single test with a BPX-80 Bio-Pump was performed to verify that the hemolysis induced by the mock circulation loop was negligible. The performed tests showed a good reproducibility and statistical significance. The mock circulation loop and test protocol developed in this study are valid methods to investigate the hemolysis induced by a pulsatile blood pump.

SummaryESR. spectra of the chlorine substituted phenoxy radicals listed in Table 1, which were produced by photo-oxidation of the parent phenols in aprotic solvents, are reported. In most cases the chlorine splittings could be resolved and analysed in detail. Experimental data as well as quantum chemical calculations were used for assignment of all measured chlorine couplings and determination of their relative signs.Spin density distributions and polarization parameters for chlorine are discussed and compared with the results from current semiempirical molecular orbital theories.Chlorine couplings associated with the larger splittings are found positive in sign, whereas signs of small couplings appear difficult to establish. Limitations in the applicability of McConnell or Karplus-Fraenkrl type relations to chlorine substituted aromatic radicals will be discussed and related to peculiar properties of the spin density matrix of such systems.1. Introduction. -The number of reported coupling constants for chlorine substituents in radicals is at present rather limited [I]. In the ca:je of aromatic radicals in particular this has to be traced back to a number of factors, e.g. small hyperfine splittings, overlapping of spectra of isotopic modifications, nuclear quadrupole effects and chemical instability. As a consequence of these difficulties the theory which should explain the chlorine splittings is much less developed than the theory for corresponding fluorinated aromatic radicals [I] [2]. In this work ESR. spectra of a series of chlorine substituted phenoxy radicals were investigated with the aim to obtain sufficient experimental data for an unambiguous assignment of observed hyperfine splittings, in particular for the chlorine substituent. This in turn should provide a basis for testing spin density values as obtained from different MO theories and, eventually, lead to a determination of polarization constants for the chlorine substituent in an aromatic radical.