Interpolation property for bicartesian closed categories

Summary We show that proofs in the intuitionistic propositional logic factor through interpolants-in this way we prove a stronger interpolation property than the usual one which gives only the existence of interpolants.Translating that to categorical terms, we show that Pushouts (bipushouts) of bicartesian closed categories have the interpolation property (Theorem 3.2).     

Effects of electrolyte concentration and pH on the coalescence stability of beta-lactoglobulin emulsions: experiment and interpretation

Experimental results are presented about the effects of ionic strength and pH on the mean drop-size after emulsification and on the coalescence stability of emulsions, stabilized by a globular protein beta-lactoglobulin (BLG). The mean drop-size is determined by optical microscopy, whereas the coalescence stability is characterized by centrifugation. In parallel experiments, the zeta-potential and protein adsorption on drop surface are determined. The experiments are performed at two different BLG concentrations, 0.02 and 0.1 wt%. The electrolyte concentration in the aqueous phase, C(EL), is varied between 1.5 mM and 1 M, and pH is varied between 4.0 and 7.0. The experiments show that the mean drop-size after emulsification depends slightly on C(EL), at fixed protein concentration and natural pH = 6.2. When pH is varied, the mean drop-size passes through a maximum at fixed protein and electrolyte concentrations. A monolayer protein adsorption is registered in the studied ranges of C(EL) and pH at low BLG concentration of 0.02 wt%. In contrast, a protein multilayer is formed at higher BLG concentration, 0.1 wt%, above a certain electrolyte concentration (C(EL) > 100 mM, natural pH). The experimental results for the emulsion coalescence stability are analyzed by considering the surface forces acting between the emulsion drops. The electrostatic, van der Waals, and steric interactions are taken into account to calculate the barriers in the disjoining pressure isotherm at the various experimental conditions studied. The comparison of the theoretically calculated and the experimentally determined coalescence barriers shows that three qualitatively different cases can be distinguished. (1) Electrostatically stabilized emulsions, with monolayer protein adsorption, whose stability can be described by the DLVO theory. (2) Sterically stabilized emulsions, in which the drop-drop repulsion is created mainly by overlapping protein adsorption multilayers. A simple theoretical model is shown to describe emulsion stability in these systems. (3) Sterically stabilized emulsions with a monolayer adsorption on drop surface.     

On the irreducible representations of the lorentz group

All continuous irreducible representations of the SL(2, C) group (as given by Naimark) are obtained by means of methods developed by Harish-Chandra and Kihlberg. The analysis is done in the SU(2) basis and a single closed expression for the matrix elements of the noncompact generators for an arbitrary irreducible representation of SL(2, C) is given. For the unitary irreducible representations the scalar product for each irreducible Hilbert space is found explicitly. The connection between the unitary irreducible representations of SL(2, C) and those of

is discussed by means of Inönü and Wigner contraction procedure and the Gell-Mann formula. Finally, due to physical interest, the addition of a four-vector operator to SL(2, C) unitary irreducible representations in a minimal way is considered; and all group extensions of the parity and time reversal operators by SL(2, C) are explicitly obtained and some aspects of their representations are treated.     

High level of low-density lipoprotein receptors enhance hypericin uptake by U-87 MG cells in the presence of LDL

The dependence of the uptake of hypericin (Hyp) by human glioma U-87 MG cells on the level of expression of low-density lipoprotein (LDL) receptors has been studied in this work. A special role of the LDL receptor-pathway for Hyp delivery to U-87 MG cells in the presence of LDL was revealed by the substantial increase of Hyp uptake in the situation, when the number of LDL receptors on the cell surface was elevated. Moreover, the colocalization experiments showed the lysosomal localization of Hyp following the uptake and that the concentration of Hyp in these organelles was enhanced in the cells with elevated number of LDL receptors when the incubation medium contained LDL. Both these findings suggest that LDL and LDL receptor-pathway play an important role in the delivery and accumulation of Hyp into the cells.     

Integrable wide-free-spectral-range Fabry-Perot optical filters using free-standing LiNbO3 thin films

We demonstrate the use of free-standing thin films of a complex oxide for chip-scale optical filtering. The films are used as low-order etalons with very large free spectral ranges that exceed 6.78 THz (> 50 nm at 1550 nm) and use a small chip area (< 500 microm2) when they are integrated. The films are produced by crystal ion slicing; this process exfoliates a micrometers-thin layer of single-crystal optical material from a bulk parent by means of high-energy-ion implantation. The etalons, which are 10 microm thick with Ag deposited on both surfaces, are integrated into a silica-on-silicon waveguide block.     

Large Values of Eigenfunctions on Arithmetic Hyperbolic 3-Manifolds

We prove that, on a distinguished class of arithmetic hyperbolic 3-manifolds, there is a sequence of L ²-normalized high-energy Hecke–Maass eigenforms f_j{\phi_{j}} which achieve values as large as l^1/4+o(1)_j{\lambda^{1/4+o(1)}_{j}}, where ( D+l_j ) f_j = 0{( \Delta+\lambda_{j} ) \phi_{j} = 0}. Arithmetic hyperbolic 3-manifolds on which this exceptional behavior is exhibited are, up to commensurability, precisely those containing immersed totally geodesic surfaces. We adapt the method of resonators and connect values of eigenfunctions to the global geometry of the manifold by employing the pre-trace formula and twists by Hecke correspondences. Automorphic representations corresponding to forms appearing with highest weights in the optimized spectral averages are characterized both in terms of base change lifts and in terms of theta lifts from GSp₂.     

Surface shear rheology of saponin adsorption layers

Saponins are a wide class of natural surfactants, with molecules containing a rigid hydrophobic group (triterpenoid or steroid), connected via glycoside bonds to hydrophilic oligosaccharide chains. These surfactants are very good foam stabiliziers and emulsifiers, and show a range of nontrivial biological activities. The molecular mechanisms behind these unusual properties are unknown, and, therefore, the saponins have attracted significant research interest in recent years. In our previous study (Stanimirova et al. Langmuir2011, 27, 12486-12498), we showed that the triterpenoid saponins extracted from Quillaja saponaria plant (Quillaja saponins) formed adsorption layers with unusually high surface dilatational elasticity, 280 ± 30 mN/m. In this Article, we study the shear rheological properties of the adsorption layers of Quillaja saponins. In addition, we study the surface shear rheological properties of Yucca saponins, which are of steroid type. The experimental results show that the adsorption layers of Yucca saponins exhibit purely viscous rheological response, even at the lowest shear stress applied, whereas the adsorption layers of Quillaja saponins behave like a viscoelastic two-dimensional body. For Quillaja saponins, a single master curve describes the data for the viscoelastic creep compliance versus deformation time, up to a certain critical value of the applied shear stress. Above this value, the layer compliance increases, and the adsorption layers eventually transform into viscous ones. The experimental creep-recovery curves for the viscoelastic layers are fitted very well by compound Voigt rheological model. The obtained results are discussed from the viewpoint of the layer structure and the possible molecular mechanisms, governing the rheological response of the saponin adsorption layers.     

Synthesis of Planar Chiral Iridacycles by Cationic Metal π‐Coordination: Facial Selectivity,and Conformational and Stereochemical Consequences

Facial selectivity during the π‐coordination of pseudo‐tetrahedral iridacycles by neutral (Cr(CO)₃), monocationic (Cp*Ru⁺), and biscationic (Cp*Ir²⁺) metal centers was directly influenced by the coulombic imbalance in the coordination sphere of the chelated Ir center. We also showed by using theoretical calculations that the feasibility of the related metallacycles that displayed metallocenic planar chirality was dependent to the presence of an electron‐donating group, such as NMe₂, which contributed to the overall stability of the complexes. When the π‐bonded moiety was the strongly electron‐withdrawing Cp*Ir²⁺ group, the electron donation from NMe₂ resulted in major conformational changes, with a barrier to rotation of about 17 kcal mol^?1 for this group that became spectroscopically diastereotopic (high‐field ¹H NMR spectroscopy). This peculiar property is proposed as a means to introduce a new type of constitutional chirality at the nitrogen center: planar chirality at tertiary aromatic amines.     

Unexpected formation of a cyclic vinylene sulfate in the synthesis of ethynyl-substituted acenes

(E)-2-Styrylanthracene derivatives containing triisopropylsilylacetylene groups at the 9 and 10 positions were synthesized and characterized. The electronic properties have been studied by DFT calculations, spectroscopy and electrochemistry, revealing asymmetric resonance stabilization effects that result in the regioselective formation of an unusual cyclic vinylene sulfate.     

Solving pure yang-mills theory in dimensions

We analytically compute the spectrum of the spin zero glueballs in the planar limit of pure Yang-Mills theory in 2 + 1 dimensions. The new ingredient is provided by our computation of a new nontrivial form of the ground state wave functional. The mass spectrum of the theory is determined by the zeroes of Bessel functions, and the agreement with large lattice data is excellent.