Pro-oxidant action of polar triglyceride oligopolymers in edible vegetable oils

The aim of the research was to evaluate the pro-oxidant action of oxidized triglyceride oliogopolymers, a class of oxidation compounds present in refined vegetable oils. Silica gel column chromatography was used to obtain the polar compounds from a thermally oxidized oil and preparative gel permeation chromatography to separate and collect the oxidized triglyceride oligopolymers. A purified oil that was practically free of oxidation and hydrolytic degradation products, pigments and anti-oxidants was prepared in the laboratory to evaluate pro-oxidant activity without interferences. Addition of percent amounts of oxidized triglyceride oligopolymers of 0.25 to 1.0% to both the purified and unpurified oils clearly evidenced the pro-oxidant activity of this class of compounds.     

Identity-creators and image-makers: Using citation analysis and thick description to put authors in their place

We describe the steps involved in constructing authors" citation identities (whom they cite) and citation images (who cites them). Familiarity with the intellectual, social, and institutional connections of these authors over time helps inform the analysis and augment the specificity of citation counts. Our study shows that authors" writing and referencing styles constitute a form of watermark for their scholarly output.     

Enabling the interactive display of large medical volume datasets by multiresolution bricking

In this paper, we present an approach to interactive out-of-core volume data exploration that has been developed to augment the existing capabilities of the LhpBuilder software, a core component of the European project LHDL (). The requirements relate to importing, accessing, visualizing and extracting a part of a very large volume dataset by interactive visual exploration. Such datasets contain billions of voxels and, therefore, several gigabytes are required just to store them, which quickly surpass the virtual address limit of current 32-bit PC platforms. We have implemented a hierarchical, bricked, partition-based, out-of-core strategy to balance the usage of main and external memories. A new indexing scheme is introduced, which permits the use of a multiresolution bricked volume layout with minimum overhead and also supports fast data compression. Using the hierarchy constructed in a pre-processing step, we generate a coarse approximation that provides a preview using direct volume visualization for large-scale datasets. A user can interactively explore the dataset by specifying a region of interest (ROI), which further generates a much more accurate data representation inside the ROI. If even more precise accuracy is needed inside the ROI, nested ROIs are used. The software has been constructed using the Multimod Application Framework, a VTK-based system; however, the approach can be adopted for the other systems in a straightforward way. Experimental results show that the user can interactively explore large volume datasets such as the Visible Human Male/Female (with file sizes of 3.15/12.03 GB, respectively) on a commodity graphics platform, with ease.     

The Juxtaposed approximate PageRank method for robust PageRank approximation in a peer-to-peer web search network

We present Juxtaposed approximate PageRank (JXP), a distributed algorithm for computing PageRank-style authority scores of Web pages on a peer-to-peer (P2P) network. Unlike previous algorithms, JXP allows peers to have overlapping content and requires no a priori knowledge of other peers’ content. Our algorithm combines locally computed authority scores with information obtained from other peers by means of random meetings among the peers in the network. This computation is based on a Markov-chain state-lumping technique, and iteratively approximates global authority scores. The algorithm scales with the number of peers in the network and we show that the JXP scores converge to the true PageRank scores that one would obtain with a centralized algorithm. Finally, we show how to deal with misbehaving peers by extending JXP with a reputation model. Partially supported by the EU within the 6th Framework Programme under contract 001907 “Dynamically Evolving, Large Scale Information Systems” (DELIS).     

Multiple Structure Reconstruction by Dual Dynamic Crosslinking Strategy Inducing Self-Reinforcing and Toughening the Polyurethane/Nanocellulose Elastomers

High-performance elastomers are expected to possess excellent healing and recycling ability, damage resistance in conjunction with high strength and toughness. Herein, a dual dynamic crosslinking strategy is implemented by multiple hydrogen and disulfide bonds to obtain a novel amorphous and transparent polyurethane/nanocellulose elastomer with excellent self-healing, self-reinforcing and toughening performance. First, hydrogen bonds are introduced in TEMPO-oxidized cellulose nanofibers (TCNF) by modification with 2-ureido-4[1H]-pyrimidone (UTCNF), while disulfide bonds (SS) are introduced in the polyurethane (PU) main chain, leading to the formation of dual dynamic cross-linking networks. The PU-SS-UTCNF elastomer can fully self-heal within 4.0 h at 50 °C. Surprisingly, for the first time, the PU-SS-UTCNF elastomer also self-strengthens and self-toughens after multiple hot-pressing, with tensile strength and toughness that increase by up to 401% and 257% compared to original elastomer samples, up to 50.0 MPa and 132.5 MJ m^-3. The self-strength and self-toughening effects are attributed to 1) reconstruction of dual dynamic networks that increase the cross-linking degree during the multiple hot-pressing processes; 2) multiple hydrogen bonds in the system are beneficial to the orientation of highly crystallized UTCNF, as a replacement of stress-induced process in deformation under external tensile force.     

Broad-Spectrum Bactericidal Activity of a Synthetic Random Copolymer Based on 2-Methoxy-6-(4-Vinylbenzyloxy)-Benzylammonium Hydrochloride

Low-molecular-weight organic ammonium salts exert excellent antimicrobial effects by interacting lethally with bacterial membranes. Unfortunately, short-term functionality and high toxicity limit their clinical application. On the contrary, the equivalent macromolecular ammonium salts, derived from the polymerization of monomeric ammonium salts, have demonstrated improved antibacterial potency, a lower tendency to develop resistance, higher stability, long-term activity, and reduced toxicity. A water-soluble non-quaternary copolymeric ammonium salt (P7) was herein synthetized by copolymerizing 2-methoxy-6-(4-vinylbenzyloxy)-benzylammonium hydrochloride monomer with N, N-di-methyl-acrylamide. The antibacterial activity of P7 was assessed against several multidrug-resistant (MDR) clinical isolates of both Gram-positive and Gram-negative species. Except for colistin-resistant Pseudomonas aeruginosa, most isolates were susceptible to P7, also including some Gram-negative bacteria with a modified charge in the external membrane. P7 showed remarkable antibacterial activity against isolates of Enterococcus, Staphylococcus, Acinetobacter, and Pseudomonas, and on different strains of Escherichia coli and Stenotrophomonas maltophylia, regardless of their antibiotic resistance. The lowest minimal inhibitory concentrations (MICs) observed were 0.6–1.2 µM and the minimal bactericidal concentrations (MBC) were frequently overlapping with the MICs. In 24-h time–kill and turbidimetric studies, P7 displayed a rapid non-lytic bactericidal activity. P7 could therefore represent a novel and potent tool capable of counteracting infections sustained by several bacteria that are resistant to the presently available antibiotics.     

Scanning electron microscopy comparison of the resin–dentin interface using different specimen preparation methods

Microscopy has been widely used to complement the data of studies related to dentin bonding; however, different specimen preparation methods may influence the analysis. Aiming to contribute to the reported scenario, this study evaluated the effect of two specimen‐sectioning methods (cleavage and diamond disk cut) on the quality of the scanning electron microscopy (SEM) images. Four crowns of human molars were selected and had an area of approximately 6 mm² of dentin exposed. They were then divided into two groups according to the universal adhesive application: total and self‐etching modes. Then, composite blocks were built up and the specimens were stored in deionized water to allow the postcuring. The specimens were further divided according to the sectioning method: cleavage or diamond disk cut. Four specimens were obtained from each tooth. They were desiccated, placed on aluminum stubs, sputter‐coated with gold, and observed in a scanning electron microscope, with ×2000 of magnification. The quality of the SEM images were evaluated by two calibrated examiners and classified into four scores (1–4). Mann–Whitney test (p < .05) showed that the diamond disk provided significantly higher scores than cleavage, whereas no significant difference was observed when comparing the total‐etching and self‐etching modes of application. The diamond disk cut method is preferable to the cleavage method to ensure the quality of the SEM analysis in studies involving the resin–dentin interface.     

Synthesis and characterization of thermoresponsive N-isopropylacrylamide/methacrylated pullulan hydrogels

Thermosensitive hydrogels were prepared by free radical polymerization starting from a methacrylated pullulan derivative (acting as the cross-linker) and using N-isopropylacrylamide (NIPAAM) as the monomer. Several hydrogels were obtained by changing the monomer to cross-linker ratio. A significant thermosensitivity was observed only when the molar amount of NIPAAM incorporated in the network was at least eight times higher that of methacrylate groups on pullulan. The hydrogel with high amount of NIPAAM deswells more than 80% after the T-jump. The lower critical solution temperature of thermosensitive hydrogels decreases with increasing amount of NIPAAM. The mechanical properties of the hydrogels are strongly affected by the percentage of incorporated NIPAAM and by the temperature.