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Herein, we present a novel silica-based stationary phase modified with N-propyl-N'-2-pyridylurea selector. Due to the weakly basic properties of the pyridine selector and the presence of residual silanols after selector immobilization, a zwitterionic surface with a pI observed at approximately pH 5.5 was measured by electrophoretic light scattering in pH-dependent ζ-potential determinations. The capability of the new N-propyl-N'-2-pyridylurea-modified silica to serve as mixed-mode stationary phase was investigated. For this purpose, it was characterized under RP and HILIC conditions using test mixtures. Subsequent classification of this stationary phase in comparison to in-house and commercial benchmarks was carried by principal component analysis of resultant retention factors from chromatographic tests. The results show a relatively unique mixed-mode character amongst the tested stationary phases. The chromatographic retention characteristics of acidic compounds matched well the ζ-potential determinations. The application of anion-exchange at low pH values (e.g. pH 5) and ion exclusion chromatography at pH 7 for the separation of uridine 5'-mono-, di- and triphosphate demonstrated a pH-dependent umpolung of the stationary phase surface. The combination of these separation principles in a pH gradient from 5 to 7 gave rise to weak anion-exchange selectivity with a charge-inducted elution due to repulsive interactions at higher pH and resulted in a significant faster separation with improved peak shape under mild elution conditions.

In the present work we propose new variants of chiral stationary phases (CSP) with tert-butylcarbamoylquinine (tBuCQN) as chiral selector molecule. Four tBuCQN-CSPs with distinct bonding chemistries are compared in terms of their pH-dependent surface charge by ζ-potential determinations, by achiral and chiral liquid chromatographic tests and LC-ESI-MS hyphenation. In one embodiment tBuCQN was immobilized on 3-mercaptopropylmethylsilyl-modified silica by thiol-ene click reaction (brush type CSP with selector coverage of 0.38mmol/g). In another embodiment, poly-(3-mercaptopropyl)-methylsiloxane was coated onto vinylized silica particles in presence of tBuCQN and radical initiator. The tBuCQN selector was then immobilized onto the polysiloxane film which in turn was crosslinked to the vinyl-surface in a simultaneous double click reaction leading to a CSP with enhanced stability due to multiple linkages (0.29mmol/g tBuCQN). Aliquots of each of the two CSPs were further modified by oxidation of free residual thiol groups to sulfonic acid functionalities to obtain strongly acidic endcapping groups which act as immobilized counterions of the chiral WAX CSPs (0.2mmol/g sulfonic acid co-ligands for brush type CSP). This caused secondary repulsive interactions, hence balanced interactions of the target analytes (chiral acids) at the WAX site and decreased non-specific interactions. Furthermore, this rendered possible the use of milder elution conditions, i.e. lower ionic strength, for acidic compounds. Separation performance was maintained and slightly improved, respectively, when using polar organic or reversed-phase type elution mode in chiral separations which were significantly accelerated (isoeluotropic conditions could be achieved with ca. factor 40 lower counterion concentration in the mobile phase). Thus, LC-ESI-MS enantiomer separations could be readily performed at very low ionic strength conditions (10mM acetate) which is favorable due to less ion suppression. In addition to this the newly developed stationary phases showed complementary retention profiles in RP- and HILIC-mode which make these type of stationary phases also promising tools for achiral applications in pharmaceutical analysis, especially as orthogonal separation principle e.g. in 2D-LC and impurity profiling.

Micro-fluidized beds represent a novel means of significantly enhancing mixing, mass and heat transfer under the low Reynolds number flows that dominate in micro- devices used in microfluidics and chemical micro-process technologies. This is one way of implementing process intensification. Major differences of micro-fluidized beds from their classical macro-scale counterparts are the critical importance of surface forces and almost unavoidable wall effects due to their small bed size. Surface forces can become dominant over gravity and hydrodynamics forces at the microscale and fluidization could either be hindered or even prevented through the adhesion of particles to the walls of the bed. We have used the acid-base theory of van Oss, Chaudhury and Good combined with the Derjaguin approximation to estimate the wall adhesion forces for comparison with hydrodynamics forces. Our new experiments show interesting fluidization behaviour at the boundary of micro-flow as a result of interplay between the ratio of surface and hydrodynamics forces and wall effects which both influence the minimum fluidization velocity.

Schistose high-grade hematite orebodies (>64 wt % Fe) in the Iron Quadrangle, Minas Gerais, were formed in shear zones by hydrothermal alteration of the Paleoproterozoic Caue BIF during the Transamazonian orogenesis. The ore is comprised of platy hematite (specularite) grains that define the foliation and overprint a relict banded martite-hematite fabric resembling, at first sight, a mylonite. The EBSD analyses of a m-scale schistose orebody from the Pau Branco mine show that specularite grew as elongated plates with the (00.1) plane parallel to the foliation. The population of the measured grain aspect ratio (GAR) is homogenous in different scales, and the longest axes of the crystals align with the stretching lineation (L//X) building continuous domains, or anastomose around stretched iron oxide aggregates and rootless fold hinges. The pole figure of the (00.1) plane shows usually a maximum centered on the pole of the foliation Z often elongated on a girdle perpendicular to the lineation L. The {10.4} pole figure has the configuration of a symmetric cleft girdle and the corresponding {11.0} and {10.0} pole figures present well developed girdles parallel to the foliation with an elongated maximum centered on X. Microstructures associated with crystal-plastic behavior and dynamic recrystallization are missing and the fabric of the orebody probably results from precipitation of strain-controlled oriented hematite plates and anisotropic syntaxial growth of favorably oriented grains with the intervention of hydrothermal fluids during Fe enrichment. The shear zone provided pathways for the percolation of mineralizing fluids under temperatures that varied from 140 to 350 °C or higher, under ductile or ductile–brittle conditions. The orthorhombic fabric and CPO (crystallographic preferred orientation) of the ore nevertheless contrast with the asymmetry of simple shear as observed in the torsion experiments by Siemes et al., 2010 , Siemes et al., 2011 , probably due to volume loss and possibly a flattening component of deformation in the ore zone.

The forthcoming experiments on neutrino mass measurement using beta decay, open a new window to explore the Large Extra Dimension model. The Kaluza-Klein tower of neutrinos in Large Extra Dimension contribute to the Kurie function of beta decay that can be tested kinematically. In addition to providing an alternative approach using just the kinematical properties, we show that KATRIN can probe the compactification radius of extra dimensions down to 0.2 \mu m which is better, at least by a factor of two, than the upper limits from neutrino oscillation experiments., Comment: 4 pages, 4 figures; v2: discussion improved, matches the version published at PLB

We show that the non-standard neutrino interactions can play a role as sub-leading effect on the solar neutrino oscillations. We observe that very small flavor universality violations of order of 0.1-0.2 G_F is sufficient to induce two phenomena: suppression of the eletronic neutrino earth regeneration and a shift of the resonance layer in the sun. We obtain these phenomena even in the absence of any flavor changing interactions. We discuss their consequences and confront with a global analysis of solar+KamLAND results. We conclude that a new compatibility region in the Delta m^2 x tan^2\theta, which we call very low Large Mixing Angle region, is found for Delta m^2 ~ 1e-5 eV^2 and tan^2\theta= 0.45., Comment: references added, small changes in text, some changes in predictions of KamLAND future sensitivity to NSNI parameters

The (3+1)-scheme in which the fourth (predominantly sterile) neutrino is isolated from a block of three flavour neutrinos by the mass gap Δm2L S N D ∼ (0.4 – 10) eV2 is revisited in the light of evidence that the atmospheric (νμ → ντ) and the solar neutrino oscillations (νe → νμ/ντ) are dominantly active to active neutrino transitions, as is indicated by recent data. In this framework, I revisited the (3+1)-scheme and I find that the LSND result can be reconciled with existing bounds on νe- and νμ - disappearance at 95 – 99% C.L..

If active to active neutrino transitions are dominant modes of the atmospheric ( ν μ →ν τ ) and the solar neutrino oscillations ( ν e →ν μ /ν τ ), as is indicated by recent data, the favoured scheme which accommodates the LSND result — the so-called (2+2) -scheme — should be discarded. We introduce the parameters η s atm and η s sun which quantify an involvement of the sterile component in the solar and atmospheric neutrino oscillations. The (2+2) -scheme predicts η s atm +η s sun =1 and the experimental proof of deviation from this equality will discriminate the scheme. In this connection the (3+1) -scheme is revisited in which the fourth (predominantly sterile) neutrino is isolated from a block of three flavour neutrinos by the mass gap Δm 2 LSND ∼(0.4 – 10) eV2. We find that in the (3+1) -scheme the LSND result can be reconciled with existing bounds on ν e - and ν μ -disappearance at 95–99% C.L. The generic prediction of the scheme is the ν e - and ν μ -disappearance probabilities at the level of present experimental bounds. The possibility to strengthen the bound on ν μ -disappearance in the KEK — front detector experiment is studied. We consider phenomenology of the (3+1) -scheme, in particular, its implications for the atmospheric neutrinos, neutrinoless double beta decay searches, supernova neutrinos and primordial nucleosynthesis.

The purpose of the present work was to evaluate the kallikrein-kinin system and effects of hypothermia during renal ischemia and reperfusion. Male C57BL/KSJmdb mice were subjected to 20 or 60 min ischemia for different periods of reperfusion. Our results demonstrate that short periods of ischemia followed by reperfusion did not cause significant alterations in kallikrein activity, Evans Blue (EB) extravasation, prokallikreins, myeloperoxidase activity or plasma creatinine concentration. Edema was evident at 1 h reperfusion in the treated mice, but returned to basal values after 24 h reperfusion. Kallikrein activities and EB extravasation showed a significant increase in 60 min ischemic mice. Myeloperoxidase activity in the kidney of the mice confirmed net infiltration in the group with 60 min ischemia and 24 h reperfusion. The generation of kinins and activation of matrix degrading enzymes by tissue kallikrein, liberated from both renal and infiltrated leukocytes, could be responsible at least in part for the damage observed in the kidney of mice subject to 60 min ischemia and reperfusion. The hypothermia significantly reduced the inflammatory process in the 60 min ischemic mice, and did prevent an increase in vascular permeability. Nevertheless, the tissue edema was not shown to change between normothermic and hypothermic ischemic mice.

Sub-diabetogenic doses of streptozotocin (STZ) produce insulitis, β cell destruction and diabetes in mice. Since kinin have been proposed as an inflammatory mediator in several diseases, we decided to evaluate the role of the kallikrein–kinin system in the evolution of insulitis. Male C 57 BL/KsJ mdb mice were injected with STZ (40 mg/kg) for 5 consecutive d. Aprotinin (4000 KIU/d) was injected simultaneously with STZ during 10 d. Plasma and urine samples collected on day 15 were assayed for glucose concentration and proteins, nitrites and kallikrein. Diabetic mice showed hyperglycemia and increased diuresis, marked proteinuria, nitrites and kallikrein. Administration of aprotinin, a potent tissue kallikrein inhibitor, to STZ mice, reduced the hyperglycemia and the altered renal function of the diabetic mice to level no different from normal mice. The present studies are consistent with the hypothesis that the over-production of tissue kallikrein in insulitis could be controlled by the effect of aprotinin.

We study the possible manifestation of the interference between the effects produced in the atmospheric neutrinos due to oscillation driven by the solar parameters parameters $\Delta m^2_{21}$, $\sin^2 2\theta_{21}$ and due to oscillation driven by $U_{e3}$., Comment: 3 pages, 2 figures. to appear in Proc. of TAUP2001 conference, Laboratori Nazionali del Gran Sasso, Sept. 2001

We reexamine the possibility of explaining the latest Super-Kamiokande atmospheric neutrino data including the upward going muon data by means of flavor-changing induced massless neutrino oscillations. We show that the energy independence of such flavor-changing coversion clearly leads to incompatibility between the upward going passing muons and the other samples, unless the flux of passing muons is larger than expected.

We study the phenomenology of the 3+1-scheme is revisited in which the fourth (predominantly sterile) neutrino is isolated from a block of three flavour neutrinos by the mass gap Δ m LSND 2 ∼(0.4–10) eV 2 . The generic prediction of the scheme is the ν e - and ν μ -disappearance probabilities at the level of present experimental bounds.

We propose a phenomenological model of mass varying neutrino (MaVaN) to be applied to supernovae. We consider oscillations of ν ¯ e → ν ¯ s in this MaVaN approach and seek for possible modifications of survival probabilities.