Light-activated antibacterial surfaces comprise photosensitizers

Antibacterial surfaces were prepared using a base polyethylene sheet topped with a layer containing a mixed powder of poly (vinylidene fluoride) and photosensitizers (PSs). A crimpled stamp was placed on the mixed powder, and then it was passed through a heating and pressing device. The three chosen PSs were rose bengal, toluidine blue O and methylene blue. Scanning electron microscope analysis showed that the PS surface texture was coarse and highly developed. Measurement of the apparent contact angles of the droplets deposited on the PS surfaces using goniometry showed that all three surfaces were hydrophobic. Photodynamic analysis of the surfaces into which the PSs were incorporated indicated significant reactive oxygen species formation after illumination with light fluency rate of 1.46 mW cm(-2) for 30 min. Photodynamic inactivation assays performed in nutrient broth demonstrated more than 4 log reduction of the attached Escherichia coli after illumination (1.46 mW cm(-2)) for 24 h when the inoculum was 10(3) CFU mL(-1). However, more than 4 log reduction of Staphylococcus aureus occurred even when the cultures were illuminated for only 6 h. Our results provide an inexpensive, simple, state-of-the-art method for preparing antibacterial surfaces that may help prevent infections in hospital surroundings and in some medical devices.     

Hydrogel nanoparticles covered by neuroligin-2-derived peptide-protected <Emphasis Type="Italic">β</Emphasis> cells under oxidative stress and increase their proliferation

Protein complexes that mediate secretion and adhesion are located on the plasma membrane of pancreatic β cells. Neuroligins and their binding partners, the neurexins, are among these complexes. β cell maturation and physiologically regulated insulin secretion, as a response to high levels of blood glucose, are dependent on their three-dimensional (3D) arrangement. Both insulin secretion and the proliferation rates of β cells dramatically increase when β cells are co-cultured with clusters of a member of the neuroligin family: NL-2. A membranal protein, such as NL-2, has very limited drugability owing to its low biostability and bioavailability. Thus, based on in silico modeling, a short NL-2 peptide (HSA-28), which was able to mimic NL-2-positive effects on β cells, was designed, as we described in previous publication. However, the peptide was active only as a cluster, created by the covering the maghemite (γ-Fe₂O₃)-based nanoparticles (NPs) with limited biocompatibility. In this brief communication, we will show that conjugation of HSA-28 to biocompatible hydrogel NPs exhibits an impressive protective effect on INS-1E β cells under oxidative stress and induces their proliferation rate via augmentation of PDX1 nuclear translocation. The diameter of coated by the peptide NPs was 206?±?63 nm (DLS) and 114?±?27 nm (cryo-TEM). This significant change in size can be explained by the very hydrophilic character of the proteinoid NPs, inducing adsorption of many water molecules on their surface, which are accounted only by the DLS. The ability of biocompatible hydrogel NPs to prevent apoptosis and increase β cell mass might be used for developing novel β cell protective therapies.

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Graphical abstract Effect of covered by bioactive peptide NPs on PDX1 nuclei translocation.

     

A hasse principle for function fields over pac fields

LetK be a perfect pseudo-algebraically closed field and letF be an extension ofK of relative transcendence degree 1. It is shown that the restriction map Res: Br(F)→Π_p Br(F _p ^h ) is injective, where p ranges over all non-trivialK-places ofF, andF _p ^h is the corresponding henselization. Conversely, the validity of this Hasse principle for all such extensionsF implies a weaker version of pseudo-algebraic closedness. As an application we determine the finitely generated pro-p closed subgroups of the absolute Galois group ofK(t).     

Hybrid composites of monodisperse pi-conjugated rodlike organic compounds and semiconductor quantum particles

Composite materials of quantum particles (Q-particles) arranged in layers within crystalline powders of pi-conjugated, rodlike dicarboxylic acids are reported. The synthesis of the composites, either as three-dimensional crystals or as thin films at the air-water interface, comprises a two-step process: 1) The preparation of the Cd salts 6 (Cd), 8 (Cd) or Pb salts 6 (Pb), 8 (Pb) of the oligo(p-phenyleneethynylene)dicarboxylic acids 6 (H), 8 (H), in which the metal ions are arranged in ribbons and are separated by the long axis of the organic molecules, as demonstrated by X-ray powder diffraction analysis of the solids and grazing incidence X-ray diffraction analysis of the films on water. 2) Topotactic solid/gas reaction of these salts with H(2)S to convert the metal ions into Q-particles of CdS or PbS embedded in the organic matrix that consists of the acids 6 (H) and 8 (H). These hybrid materials have been characterized by X-ray photoelectron spectroscopy and transmission electron microscopy.     

Exact analysis for multiserver queueing systems with cross selling

Annals of Operations Research - Exact analysis of a multi-server Markovian queueing system with cross selling in steady-state is presented. Cross selling attempt is initiated at the end of a...     

A generalization of Marshall's equivalence relation

For prime and for a field containing a root of unity of order , we generalize Marshall's equivalence relation on orderings to arbitrary subgroups of of index . The equivalence classes then correspond to free pro- factors of the maximal pro- Galois group of . We generalize to this setting results of Jacob on the maximal pro- Galois group of a Pythagorean field.

     

Valuations and diameters of milnor <Emphasis Type="Italic">K</Emphasis>-rings

Given a field F and a subgroup S of F ^x containing −1, we define a graph on F ^x/S associated with the relative Milnor K-ring K _* ^M (F)/S. We prove that if the diameter of this graph is at least 4, then there exists a valuation v on F such that S is v-open. This is done by adopting to our setting a construction in a noncommutative setting due to Rapinchuk, Segev and Seitz. We study the behavior of the diameter under important K-theoretic constructions, and relate it to the elementary type conjecture. Finally, we provide an example showing that the above bound 4 is sharp.     

Queues where customers of one queue act as servers of the other queue

We consider a system comprised of two connected M/M/?/? type queues, where customers of one queue act as servers for the other queue. One queue, Q ₁, operates as a limited-buffer M/M/1/N?1 system. The other queue, Q ₂, has an unlimited-buffer and receives service from the customers of Q ₁. Such analytic models may represent applications like SETI@home, where idle computers of users are used to process data collected by space radio telescopes. Let L ₁ denote the number of customers in Q ₁. Then, two models are studied, distinguished by their service discipline in Q ₂: In Model 1, Q ₂ operates as an unlimited-buffer, single-server M/M/1/∞ queue with Poisson arrival rate λ ₂ and dynamically changing service rate μ ₂ L ₁. In Model 2, Q ₂ operates as a multi-server M/M/L ₁/∞ queue with varying number of servers, L ₁, each serving at a Poisson rate of μ ₂. We analyze both models and derive the Probability Generating Functions of the system’s steady-state probabilities. We then calculate the mean total number of customers present in each queue. Extreme cases are indicated.     

On the number of regular vertices of the union of jordan regions

Let \C be a collection of n Jordan regions in the plane in general position, such that each pair of their boundaries intersect in at most s points, where s is a constant. If the boundaries of two sets in \C cross exactly twice, then their intersection points are called regular vertices of the arrangement \A(\C) . Let R(\C) denote the set of regular vertices on the boundary of the union of \C . We present several bounds on |R(\C)| , depending on the type of the sets of \C . (i) If each set of \C is convex, then |R(\C)|=O(n ^1.5+\eps ) for any \eps>0 . (ii) If no further assumptions are made on the sets of \C , then we show that there is a positive integer r that depends only on s such that |R(\C)|=O(n ^2-1/r ) . (iii) If \C consists of two collections \C ₁ and \C ₂ where \C ₁ is a collection of m convex pseudo-disks in the plane (closed Jordan regions with the property that the boundaries of any two of them intersect at most twice), and \C ₂ is a collection of polygons with a total of n sides, then |R(\C)|=O(m ^2/3 n ^2/3 +m +n) , and this bound is tight in the worst case. Received December 4, 1998, and in revised form June 3, 2000. Online publication Feburary 1, 2001.