Sticky behavior of fluid particles in the compressible Kraichnan model

We consider the compressible Kraichnan model of turbulent advection with small molecular diffusivity and velocity field regularized at short scales to mimic the effects of viscosity. As noted in ref.[5], removing those two regularizations in two opposite orders for intermediate values of compressibility gives Lagrangian flows with quite different properties. Removing the viscous regularization before diffusivity leads to the explosive separation of trajectories of fluid particles whereas turning the regularizations off in the opposite order results in coalescence of Lagrangian trajectories. In the present paper we re-examine the situation first addressed in ref.[6] in which the Prandtl number is varied when the regularizations are removed. We show that an appropriate fine-tuning leads to a sticky behavior of trajectories which hit each other on and off spending a positive amount of time together. We examine the effect of such a trajectory behavior on the passive transport showing that it induces anomalous scaling of the stationary 2-point structure function of an advected tracer and influences the rate of condensation of tracer energy in the zero wavenumber mode.Comment: latex, 35 page

Adipocyte-Like Differentiation in a Posttreatment Embryonal Rhabdomyosarcoma.

We describe a 16-year-old boy with rhabdomyosarcoma, consistent with embryonal subtype, of the lower extremity who received systemic neoadjuvant chemotherapy and subsequent excision. Microscopic sections of the postchemotherapy excision demonstrated diffuse, prominent, and immature adipocyte-like differentiation, in addition to skeletal muscle differentiation. Adipocyte-like differentiation was confirmed by a combination of positive Oil Red O and adipophilin immunohistochemical staining. To our knowledge, this represents the first report of an unusual phenomenon of differentiation of a soft tissue rhabdomyosarcoma into adipocyte-like cells after chemotherapy

Molekuláris lenyomatot tartalmazó polimerek vizsgálata = Study of molecularly imprinted polymers

A nem-kovalens MIP-ek, többek között a kompozit szilikagél-MIP-ek, kromatográfiás tulajdonságait vizsgálva általánosítottuk azt a megállapítást, hogy a MIP állófázisokon tapasztalt aszimmetrikus, széles csúcsok a nemlineáris adszorpciós izoterma következményei. Ezért jellemzésükre nem alkalmasak a MIP irodalomban általánosan használt mennyiségek (retenciós tényező, szelektivitás, imprintelési tényező). Helyettük az izoterma megadását javasoltuk, illetve a könnyen mérhető megoszlási hányadost. Három alapreceptúra alapján állítottunk elő sok célvegyületre MIP-eket kis mennyiségben és teszteltük szelektivi-tásukat. Ily módon lerövidíthető a MIP-ek fejlesztése új vegyületekre. A polimer szintézis és tesz-telés további felgyorsítására kidolgoztunk egy nagyáteresztőképességű módszert, amely párhuzamosan sok MIP előállítását teszi lehetővé mindössze két nap alatt, szemben a korábbi egy-két- héttel. A polimereket egy mikroszűrő tálca szűrőin állítottuk elő vékony rétegben, így polimerizáció után a templát nagyon gyorsan eltávolítható. Viszkózus polimerizációs oldószer használatával sikerült tömény oldatban mikronméretű szemcsés MIP-eket előállítani a szokásos tömbpolimer helyett, ami sok alkalmazásnál (HPLC, SPE, ligandumkötő assay) előnyös. Nano- és mikroreaktorokban vizes közegből történő elektropolimerizációval felületi kötőhelyekkel rendelkező MIP nano/mikrorudakat állítottunk elő proteinek imprintelésével. A mikrorudakat sikeresen alkalmaztuk fehérjék szelektív meghatározására. | Non-covalent MIPs and composite silica-MIPs were studied as chromato-graphic stationary phases. It has been proved that the asymmetric broad peaks obtained on these sorbents are generally due to their nonlinear adsorption isotherm. Therefore they cannot be characterized by the usual parameters used in the MIP literature, like retention factor, selectivity and imprinting factor. Instead the isotherm or the easily measurable distribution coefficient is proposed for the evaluation of MIPs. Large numbers of templates were imprinted with three widely applied basic recipes in small quantities and were tested for their selectivity. With this approach the development of new MIPs can be accelerated. To further speed up MIP synthesis and testing we have set up a new high throughput system that allows parallel preparation of many MIPs within only two days as opposed to 1-2 weeks required by the earlier method. Polymers were synthetized on the filter fibers of a filterplate in very thin layers enabling fast and easy template removal. Micrometer sized MIP particles were obtained at high monomer concentrations instead of a block polymer when viscous polymerization solvents were used. This format is advantageous in many applications like HPLC, SPE and ligand binding assay. MIP nano/microrods were prepared by electropolymerization in aqueous solution in nano/microreactors. The polymer rods possess selective surface binding sites for template proteins and were applied in protein assays

Relationship between Individual and Competitive Adsorption Isotherms on Molecularly Imprinted Polymers

Molecularly imprinted polymers (MIP) are a new generation of selective adsorbents. In practical applications of MIPs simultaneous adsorption of at least two compounds occurs. Simultaneous (typically competitive) adsorption on MIPs has not yet been quantitatively analyzed. This paper shows that with a typical type of MIP the individual isotherms of two compounds coincide with their competitive isotherms in the logD-logq isotherm plot, where D is the distribution coefficient and q is the adsorbed concentration. Based on this observation the usual competitive isotherm, i.e., the (c1,c2 ) to (q1,q2 ) mapping can be established from the two individual isotherms. (The c-s are the respective solution phase equilibrium concentrations.) Batch separation experiments can be easily designed and the selectivity of the MIPs is also easily determined without the tedious measurement of the full competitive isotherm.

Microscopic origin of the surface tension anomaly of water

We investigate the hydrogen bonding percolation threshold of water molecules at the surface of the liquid-vapor interface. We show that the percolation temperature agrees within statistical accuracy with the high-temperature inflection point of the water surface tension. We associate the origin of this surface tension anomaly of water with the sudden breakup of the hydrogen bonding network in the interfacial molecular layer