Variance of additive functions defined on random assemblies

We establish an inequality for the variance of an additive function defined on random decomposable structures called assemblies. The result generalizes estimates obtained earlier in the cases of permutations and mappings of a finite set into itself. It is analogous to the Turán–Kubilius inequality for additive number-theoretic functions.     

PICOSECOND ABSORPTION STUDIES OF Zn-OCTAETHYLPORPHIN π-MONOANIONS

Abstract— Using the example of Zn-octaethylporphin π-monoanion solution in tetrahydrofuran, we studied the dynamics of ultrafast photoprocesses in porphyrin π-anions using a tunable picosecond absorption spectrometer. The deactivation kinetics of the lowest excited electronic (doublet) state of Zn-octaethylporphin iT-monoanion has been determined and was found to be followed by a single exponential function with the characteristic time 135 ps. It is shown that upon picosecond excitation to the long wavelength absorption band (λ_max= 830 nm) the process of two-quantum photoionization of the involved monoanion is easily realized, with the results that the observable kinetics of spectral changes exhibit a strong dependence on the excitation intensity.     

Synthesis and Antibacterial Activity of New Azole,Diazole and Triazole Derivatives Based on p-Aminobenzoic Acid

The p-aminobenzoic acid was applied for the synthesis of substituted 1-phenyl-5-oxopyrrolidine derivatives containing benzimidazole, azole, oxadiazole, triazole, dihydrazone, and dithiosemicarbazide moieties in the structure. All the obtained compounds were evaluated for their in vitro antimicrobial activity against Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Salmonella enteritidis, Escherichia coli, and Pseudomonas aeruginosa by using MIC and MBC assays. This study showed a good bactericidal activity of γ-amino acid and benzimidazoles derivatives. The antimicrobial activity of the most promising compounds was higher than ampicillin. Furthermore, two benzimidazoles demonstrated good antimicrobial activity against L. monocytogenes (MIC 15.62 µg/mL) that was four times more potent than ampicillin (MIC 65 µg/mL). Further studies are needed to better understand the mechanism of the antimicrobial activity as well as to generate antimicrobial compounds based on the 1-phenyl-5-oxopyrrolidine scaffold.     

In vitro and in vivo biocompatibility study on laser 3D microstructurable polymers

Films and microstructured scaffolds have been fabricated using direct laser writing out of different polymers: hybrid organic-inorganic ORMOCORE b59, acrylate-based AKRE23, novel organic-inorganic Zr containing hybrid SZ2080, and biodegradable PEG-DA-258. Adult myogenic stem cells were grown on these surfaces in vitro. Their adhesion, growth, and viability test results suggest good potential applicability of the materials in biomedical practice. Pieces of these polymers were implanted in rat’s paravertebral back tissue. Histological examination of the implants and surrounding tissue ex vivo after 3 weeks of implantation was conducted and results show the materials to be at least as biocompatible as surgical clips or sutures. The applied direct laser writing technique seems to offer good future prospects in a polymeric 3D scaffold design for artificial tissue engineering with autologous stem cells.     

Electrochemical Peroxidase‐Catalase Clark‐Type Biosensor: Computed and Experimental Response

A bioelectrode containing immobilized catalase and peroxidase was built using a Clark‐type oxygen electrode. The bioelectrode responded to hydrogen peroxide (H₂O₂) as well as to acetaminophen (Ac). The sensitivity of the bioelectrode for H₂O₂ was 0.35 mM O₂/mM H₂O₂ and for Ac it was 0.23–1.05 µM O₂/µM Ac at pH 6.6 and 25 °C. The limit of detection of Ac varied from 12 to 44 µM. The half‐time of the bioelectrode response to hydrogen peroxide was 36 s. The modeling of the bioelectrode action was performed digitally at transition and steady‐state conditions using finite difference technique. The calculated half‐time of the bioelectrode response to hydrogen peroxide was 53 % larger and the steady‐state response 11 % less than experimentally determined. The response to Ac was 2–3 times smaller in comparison to the experimental values. The calculated response change correlated with the experimentally determined when the catalase and peroxidase concentrations in the biocatalytical membrane changed 3–4 orders of magnitude. The simulations of the bioelectrode response revealed that the bioelectrode acts in diffusion limiting conditions at almost all enzymes concentrations. The model appears to be promising for optimization of the bioelectrode response.     

Helical Propensity in an Intrinsically Disordered Protein Accelerates Ligand Binding

Many intrinsically disordered proteins fold upon binding to other macromolecules. The secondary structure present in the well‐ordered complex is often formed transiently in the unbound state. The consequence of such transient structure for the binding process is, however, not clear. The activation domain of the activator for thyroid hormone and retinoid receptors (ACTR) is intrinsically disordered and folds upon binding to the nuclear coactivator binding domain (NCBD) of the CREB binding protein. A number of mutants was designed that selectively perturbs the amount of secondary structure in unbound ACTR without interfering with the intermolecular interactions between ACTR and NCBD. Using NMR spectroscopy and fluorescence‐monitored stopped‐flow kinetic measurements we show that the secondary structure content in helix 1 of ACTR indeed influences the binding kinetics. The results thus support the notion of preformed secondary structure as an important determinant for molecular recognition in intrinsically disordered proteins.     

Synthesis, chemical properties, and antimicrobial activity of 2- and 2,3-substituted [(tetrahydro-2,4-dioxopyrimidin-1(2H)-yl)phenoxy]naphthalene-1,4-diones

Abstract  

Mono- and disubstituted [(tetrahydro-2,4-dioxopyrimidin-1(2H)-yl)phenoxy]naphthalene-1,4-diones were synthesized by the reaction of dihydro-1-(3-hydroxy- and 4-hydroxyphenyl)pyrimidine-2,4(1H,3H)-diones and their 5- and 6-methyl derivatives with 2,3-dichloro-1,4-naphthoquinone. Their stability in alkaline and acidic media was investigated. Four of the compounds exhibited good antimicrobial activity against Staphylococcus aureus, Mycobacterium luteum, Candida tenuis, and Aspergillus niger.     

Unicity of Types for Supercuspidal Representations of GLN

Let F be a non-Archimedean local field, with the ring of integerso_F. Let G = GL_N(F), K = GL_N (o_F), and be a supercuspidal representationof G. We show that there exists a unique irreducible smoothrepresentation of K, such that the restriction to K of a smoothirreducible representation ' of G contains if and only if 'is isomorphic to ° det, where is an unramified quasicharacterof F^x. Moreover, we show that contains with the multiplicity1. As a corollary we obtain a kind of inertial local Langlandscorrespondence. 2000 Mathematics Subject Classification 22E50.     

Effects of lipid confinement on insulin stability and amyloid formation

We report on a study of insulin incorporation into cubic phases of mono-olein (MO), using synchrotron small-angle X-ray scattering and FT-IR spectroscopy. We studied the thermal stability and aggregation scenario of insulin as a function of protein concentration in the narrow water channels of the cubic lipid matrix and compared it with data for insulin unfolding and fibrillation in bulk water solutions. The concomitant effect of insulin entrapment on the structure and phase behavior of the lipid matrix itself was also examined. We show that the protein's unfolding behavior and stability are influenced by confinement due to geometrical limitations, and vice versa, the topological properties of the lipid matrix change as well. The addition of insulin already at concentrations as low as 0.1 wt % significantly alters the phase behavior of MO. Surprisingly, new cubic structures are induced by insulin incorporation into the lipid matrix. When insulin begins to partially unfold at higher temperatures, the structure of the new cubic phase changes and finally disappears around 60 degrees C, where the aggregation process sets in. The aggregation in cubo proceeds much faster and leads to the formation of medium-sized oligomers or clusters, while the formation of large fibrillar agglomerates, as observed for bulk insulin aggregation, is largely prohibited. Hence, the results yield valuable information about the use of cubic mesoporous lipid systems as a medium for long-term storage of insulin and aggregation-prone proteins in general. Furthermore, the results provide new insights into the effects of soft-matter confinement on protein aggregation and fibrillation, a situation usually met in natural cell environments.