Drag reduction via wall-normal oscillations in turbulent flat plate boundary layer flow at very high Reynolds number

The effects of wall-normal single point oscillations in turbulent boundary layers at very high Reynolds number are investigated by numerical simulation. The impact on the friction drag and on the turbulent structures is analyzed. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Phonon mechanisms and transformation paths in Pu

A long-standing problem in Pu science is the crystallographic mechanism for the delta-->alpha' (fcc-->monoclinic) transformation. Orientation relations between the two structures impose severe restrictions on the possible mechanisms and require the transition to be reconstructive, which we describe as a sequence of three displacive transitions: fcc-->trigonal-->hexagonal-->monoclinic. We predict instabilities along the Lambda and Sigma branches in the phonon dispersion of the delta phase and formulate a free energy to describe the displacement of atoms across the transition. We suggest that the delta-->alpha' transition in Pu lies at the threshold of a change in character of the orientation relationship from lighter to heavier actinides, correlating with changes in electron itinerancy, magnetism, and volume.     

Kinetic modeling of hyperpolarized 13C1-pyruvate metabolism in normal rats and TRAMP mice

PurposeTo investigate metabolic exchange between ¹³C₁-pyruvate, ¹³C₁-lactate, and ¹³C₁-alanine in pre-clinical model systems using kinetic modeling of dynamic hyperpolarized ¹³C spectroscopic data and to examine the relationship between fitted parameters and dose–response.Materials and methodsDynamic ¹³C spectroscopy data were acquired in normal rats, wild type mice, and mice with transgenic prostate tumors (TRAMP) either within a single slice or using a one-dimensional echo-planar spectroscopic imaging (1D-EPSI) encoding technique. Rate constants were estimated by fitting a set of exponential equations to the dynamic data. Variations in fitted parameters were used to determine model robustness in 15 mm slices centered on normal rat kidneys. Parameter values were used to investigate differences in metabolism between and within TRAMP and wild type mice.ResultsThe kinetic model was shown here to be robust when fitting data from a rat given similar doses. In normal rats, Michaelis–Menten kinetics were able to describe the dose–response of the fitted exchange rate constants with a 13.65% and 16.75% scaled fitting error (SFE) for k_pyr→lac and k_pyr→ala, respectively. In TRAMP mice, k_pyr→lac increased an average of 94% after up to 23 days of disease progression, whether the mice were untreated or treated with casodex. Parameters estimated from dynamic ¹³C 1D-EPSI data were able to differentiate anatomical structures within both wild type and TRAMP mice.ConclusionsThe metabolic parameters estimated using this approach may be useful for in vivo monitoring of tumor progression and treatment efficacy, as well as to distinguish between various tissues based on metabolic activity.     

Growth and basic dielectric data of high quality TSCC crystals

Tris-sarcosine calcium chloride (TSCC) single crystals were grown from water solutions by the isothermal evaporation method. The growth solutions contained sarcosine and CaCl₂ either in stoichiometric or nonstoichiometric ratio. The required phase diagram sarcosine–CaCl₂ H₂O at 40 °C was determined by the synthetic method. PFT 400 MHz NMR was used for the analysis of organic impurities in sarcosine and TSCC. The crystals grown from both types of solutions had maximum values of the dielectric permittivity 10 to 200 times larger than those measured by other authors at comparable measuring frequencies and fields. It is discussed in terms of crystal quality.     

Leitfähigkeits- und Halleffektmessungen an Tellur-Epitaxieschichten auf KCl

The temperature dependence of resistivity of epitactixial thin tellurium films grown on (110) KCl is contrary to the results well known from single crystals. For interpretation of this discrepancy a model is proposed which makes use of piezoresistance effects. This model is in qualitative and quantitative agreement with measurements.