Synthesis of N,N‐Bis(dialkoxyphosphinoylmethyl)‐ and N,N‐Bis(diphenylphosphinoylmethyl)‐β‐ and γ‐amino acid Derivatives by the Microwave‐Assisted Double Kabachnik–Fields Reaction

The title compounds were synthesized by the microwave‐assisted, mostly solvent‐free bis Kabachnik–Fields condensation of β‐alanine and γ‐aminobutyric acid or their esters with formaldehyde and >P(O)H species, such as dialkyl phosphites and diphenylphosphine oxide.     

Bestimmung der Corticosteroide im Harn mit Hilfe der Tetrazoliumblau-Reaktion

Zusammenfassung Mit Hilfe der Tetrazoliumblau-Reaktion wurde eine einfache Methode zur Bestimmung der Corticosteroide im Harn ausgearbeitet. Hierbei wird der Harn mit -Glucuronidase hydrolysiert, dann mit Äther-Äthylacetat extrahiert, mit Natriumcarbonatlösung gereinigt und eingedampft. Die mit Tetrazoliumblau-Reagens gebildete Färbung wird mit Grünfilter colorimetriert (entsprechend dem Absorptionsmaximum bei 510 nm). Es ergab sich eine Harncorticosteroidausscheidung bei Männern von 9–18 mg/24 Std und bei Frauen von 6–15 mg/24 Std.

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Summary A simple method for the determination of corticosteroids in urine has been worked out using the tetrazolium blue reaction. The urine sample is hydrolised by -glucuronidase, extracted with ether-ethyl acetate, purified with sodium carbonate solution and evaporated. The colour formed with tetrazolium blue reagent is measured by help of a green filter (corresponding to an absorption maximum of 510 nm). The normal values of corticosteroid excretion in urine have been found to be 9–18 mg/24 hrs. in the case of men and 6–15 mg/24 hrs. for women.

     

Effect of the reaction temperature on the morphology of nanosized HAp

The main purpose of this study is numerically investigating the flow and heat transfer of nanofluid flow inside a microchannel with L-shaped porous ribs as well as studying the effect of porous media properties on the performance evaluation criterion (PEC) of the fluid. In the present paper, in addition to the pure water fluid, the effect of using water/CuO nanofluid on the PEC of microchannel was investigated. The flow was simulated in four Reynolds numbers and two different volume fractions of nanoparticles in laminar flow regime. The investigated parameters are the thermal conductivity and the porosity rate of porous medium. The results indicate that with the existence of porous ribs, the nanofluid does not have a significant effect on heat transfer increase. By using porous ribs in flow with Reynolds number of 1200, the heat transfer rate increases up to 42% and in flow with Reynolds number of 100, this rate increases by 25%.

     

Ground state phase diagram of the infinite dimensional Hubbard model: A variational study

We use the Gutzwiller variational method to study the ground state phase diagram of the infinite dimensional Hubbard model, paying special attention to features associated with the Gaussian form of the tight binding band density of states. We only consider trial states for which the validity of the Gutzwiller approximation has been proven, i.e., the paramagnetic, ferromagnetic, and two-sublattice antiferromagnetic states. We map out the phase diagram numerically, and give approximate analytic arguments to explain the behaviour in the small-U, and large-U limits. We give two versions of the phase diagram: one restricted to homogeneous phases, and another when phase separation is allowed. In the latter case, a homogeneous antiferromagnetic state is found only at exact half-filling, where the state is also insulating. Off half-filling, four different regions are found: pure paramagnetic, and ferromagnetic states, as well as antiferromagnetic-paramagnetic, and antiferromagnetic-ferromagnetic mixed phases.Dedicated to Professor W. Brenig on the occasion of his 60th birthdayResearch performed within the program of the Sonderforschungsbereich 341 supported by the Deutsche Forschungsgemeinschaft     

Quality assurance features of “HYPERMET-PC”

The γ-ray spectrum analysis code HYPERMET-PC has been significantly upgraded since its introduction in the firstk ₀-Users Workshop (1992). Some aspects of the implemented procedures in the new version 5.0, such as the novel approach to handle tandem LFC spectra and the benefit of using ortho-normal polynomials for fitting efficiency curves will be outlined. Having realized the importance of quality assurance in applied γ-ray spectrometry, additional utilities have been incorporated for checking system parameters: nonlinearity, energy resolution, etc. The new Nuclide Identification routine makes the program suitable for qualitative analysis both of NAA and PGAA type.     

Synthetic strategies and porphyrin building blocks for unsymmetrical multichromophores

A sequential use of halogenation, S_NAr, Sonogashira and/or Suzuki couplings together with the use of either mono-5-, 5,15- or 5,10-di-meso-substituted porphyrins allows the facile construction of unsymmetrical porphyrin dimers and trimers with different spatial orientation. The protocols established allow a convenient entry into multichromophores suitable for application in nonlinear optics and biomedicine.     

On the spectrum of singlet excitations of the S = 12 linear Heisenberg antiferromagnet

We note that available numerical data for the spectrum of small antiferromagnetic Heisenberg rings with nearest neighbour interaction, and $\text{S}\text{=}\text{1}\text{2}$ facilitate an extrapolation giving some idea of the form of the lower edge of the spectrum of singlet excitations for the infinite system. The result we obtain is radically different from the one given by Ovchinnikov in two respects: the singlet excitations are roughly equally distributed over the whole Brillouin zone, and the shape is better approximated by the formula valid for the triplet spectrum. A proof that there is a continuum of singlet excitations for every wave number is given.