Teucrium polium (L.): Phytochemical Screening and Biological Activities at Different Phenological Stages

The aim of the present study was to investigate the changes in the content of phytochemical compounds and in vitro antioxidant, antibacterial, and anti-inflammatory activities of Teucrium polium L. aerial parts and root methanolic extracts at different phenological stages (vegetative, flowering, and seeding). The T. polium extracts were analyzed using gas chromatography–mass spectrometry (GC-MS), and their antioxidant properties were tested with the 2,2-diphenyl-1-picrylhydrazyl (DPPH), nitric oxide (NO), ferrous ions (Fe²⁺), and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) methods. Forty-nine compounds were identified with the majority of germacrene D, t-cadinol, β-pinene, carvacrol, bicyclogermacrene, α-pinene, and limonene. The results show that the extracts significantly differ between different phenological stages of the plant material used in terms of the phytochemical composition (total phenolic compounds, total flavonoids, total alkaloids, and total saponin contents) and bioactivities (antioxidant, antibacterial, and anti-inflammatory) (p < 0.05). The highest total contents of phenolics (72.4 ± 2.5 mg gallic acid equivalent (GAE)/g dry weight), flavonoids (36.2 ± 3.1 mg quercetin equivalent (QE)/g dry weight), alkaloids (105.7 ± 2.8 mg atropine equivalent (AE)/g dry weight), and saponins (653 ± 6.2 mg escin equivalent (EE)/g dry weight), as well as antioxidant, antibacterial, and anti-inflammatory activities, were measured for the extract of the aerial parts obtained at the flowering stage. The minimum inhibitory concentration (MIC) values for the extracts were varied within 9.4–300 µg/mL, while the minimum bactericidal concentration (MBC) values were varied within 18.75–600 µg/mL. In addition, they were more active on Gram-positive bacteria than Gram-negative bacteria. The data of this work confirm that the T. polium extracts have significant biological activity and hence can be used in the pharmaceutical industry, clinical applications, and medical research, as well as cosmetic and food industries.     

Thermal conductance of nanofluids: is the controversy over?

Over the last decade nanofluids (colloidal suspensions of solid nanoparticles) sparked excitement as well as controversy. In particular, a number of researches reported dramatic increases of thermal conductivity with small nanoparticle loading, while others showed moderate increases consistent with the effective medium theories on well-dispersed conductive spheres. Accordingly, the mechanism of thermal conductivity enhancement is a hotly debated topic. We present a critical analysis of the experimental data in terms of the potential mechanisms and show that, by accounting for linear particle aggregation, the well established effective medium theories for composite materials are capable of explaining the vast majority of the reported data without resorting to novel mechanisms such as Brownian motion induced nanoconvection, liquid layering at the interface, or near-field radiation. However, particle aggregation required to significantly enhance thermal conductivity, also increases fluid viscosity rendering the benefit of nanofluids to flow based cooling applications questionable.     

Cryopreservation of Prunus avium L. embryogenic tissues

Embryogenic tissues from wild cherry (Prunus avium L.) were successfully cryopreserved by using a one-step freezing procedure. Cryoprotection consisted of a pretreatment on solid medium with increasing sucrose concentrations (0.25 M for 1 day, 0.5 M for 1 day, 0.75 M for 2 days, and 1.0 M for 3 days), followed by air desiccation to about 20 percent moisture content (fresh weight basis). This method was compared with a pretreatment on solid medium containing 5 percent DMSO and 2 percent proline, followed by immersion in a modified PVS2 cryoprotective solution. Pretreatment on solid medium with increasing concentrations of sucrose led to regrowth of frozen embryogenic tissues, and after 6 weeks of culture, growth was comparable to that of non-dehydrated and non-frozen tissues. By contrast, no regrowth was observed when embryogenic tissues were submitted to the solid/liquid pretreatment with DMSO/proline and a modified PVS2 solution.     

Information Theories with Adversaries,Intrinsic Information,and Entanglement

There are aspects of privacy theory that are analogous to quantum theory. In particular one can define distillable key and key cost in parallel to distillable entanglement and entanglement cost. We present here classical privacy theory as a particular case of information theory with adversaries, where similar general laws hold as in entanglement theory. We place the result of Renner and Wolf—that intrinsic information is lower bound for key cost—into this general formalism. Then we show that the question of whether intrinsic information is equal to key cost is equivalent to the question of whether Alice and Bob can create a distribution product with Eve using I_M bits of secret key. We also propose a natural analogue of relative entropy of entanglement in privacy theory and show that it is equal to the intrinsic information. We also provide a formula analogous to the entanglement of formation for classical distributions. It is our pleasure to dedicate this paper to Asher Peres on the occasion of his seventieth birthday.     

Model-Independent Normalization Condition for Gamow Vectors

Two comments on the theory of Gamow states are presented. First, it is shown that Gamow states may be viewed as two resonating states which correspond to two different eigenproblems for the same real value of energy. Second, a universal normalization condition for all Gamow states is derived.     

On biharmonic maps and their generalizations

We give a new proof of regularity of biharmonic maps from four-dimensional domains into spheres, showing first that the biharmonic map system is equivalent to a set of bilinear identities in divergence form. The method of reverse Hölder inequalities is used next to prove continuity of solutions and higher integrability of their second order derivatives. As a byproduct, we also prove that a weak limit of biharmonic maps into a sphere is again biharmonic. The proof of regularity can be adapted to biharmonic maps on the Heisenberg group, and to other functionals leading to fourth order elliptic equations with critical nonlinearities in lower order derivatives.Received: 6 February 2003, Accepted: 12 March 2003, Published online: 16 May 2003Mathematics Subject Classification (2000): 35J60, 35H20Pawel Strzelecki: Current address (till September 2003): Mathematisches Institut der Universität Bonn, Beringstr. 1, 53115 Bonn, Germany (email: strzelec@math.uni-bonn.de). The author is partially supported by KBN grant no. 2-PO3A-028-22;he gratefully acknowledgesthe hospitality of his colleagues from Bonn,and the generosity of Humboldt Foundation.     

Ranking Beta Sheet Topologies with Applications to Protein Structure Prediction

One reason why ab initio protein structure predictors do not perform very well is their inability to reliably identify long-range interactions between amino acids. To achieve reliable long-range interactions, all potential pairings of β-strands (β-topologies) of a given protein are enumerated, including the native β-topology. Two very different β-topology scoring methods from the literature are then used to rank all potential β-topologies. This has not previously been attempted for any scoring method. The main result of this paper is a justification that one of the scoring methods, in particular, consistently top-ranks native β-topologies. Since the number of potential β-topologies grows exponentially with the number of β-strands, it is unrealistic to expect that all potential β-topologies can be enumerated for large proteins. The second result of this paper is an enumeration scheme of a subset of β-topologies. It is shown that native-consistent β-topologies often are among the top-ranked β-topologies of this subset. The presence of the native or native-consistent β-topologies in the subset of enumerated potential β-topologies relies heavily on the correct identification of β-strands. The third contribution of this paper is a method to deal with the inaccuracies of secondary structure predictors when enumerating potential β-topologies. The results reported in this paper are highly relevant for ab initio protein structure prediction methods based on decoy generation. They indicate that decoy generation can be heavily constrained using top-ranked β-topologies as they are very likely to contain native or native-consistent β-topologies.     

Synthesis and characterization of hyperbranched polyesters from glycerol‐based AB2 monomer

This article describes the synthesis of a new glycerol‐based AB₂ type monomer—ethyl{3‐[2‐hydroxy‐1‐(hydroxymethyl)ethoxy]propyl}thioacetate ( 4 ) and its application for the preparation of hyperbranched polyesters. The polycondensation of 4 has been performed over a wide range of catalysts and reaction conditions leading to polymers containing solely primary hydroxyl groups. The polycondensation progress has been monitored by means of ¹H NMR. The degree of branching of the polymers showed to be in the range of 0.5 ± 0.03. The obtained polyesters easily undergo hydrolysis or alcoholysis and may be of interest as recycled materials. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3860–3868, 2009     

A note on wavelet density deconvolution for weakly dependent data

In this paper we investigate the performance of a linear wavelet-type deconvolution estimator for weakly dependent data. We show that the rates of convergence which are optimal in the case of i.i.d. data are also (almost) attained for strongly mixing observations, provided the mixing coefficients decay fast enough. The results are applied to a discretely observed continuous-time stochastic volatility model.