The role of oxidation in the protection of sliding metal surfaces

This study is concerned with the mechanisms of growth and wear of protective oxide films formed under various tribological conditions. In the study three different tribological systems are examined in each of which oxidational wear is the dominant equilibrium mode. These are an unlubricated steel on steel system sliding at low and elevated temperatures, a boundary lubricated aluminium bronze on steel system and an unlubricated reciprocating sliding 9% Cr steel system operated at elevated temperature, in an atmosphere of carbon dioxide. The results of mechanical measurements of wear and friction are presented for a range of conditions of load, speed and temper.ature for the systems, together with the results of extensive examinations of the surfaces and sub­ surfaces by various physical methods of analysis. The major part of the thesis, however, is devoted to the development and application of surface models and theoretical quantative expressions in order to explain the observed oxidational wear phenomena. In this work, the mechanisms of formation of load bearing ox ide plateaux are described and are found to be dependent on system geometry and environment. The relative importance of ''in contact" and "out of contact" oxidation is identified together with growth rate constants appropriate to the two situations. Hypotheses are presented to explain the mechanisms of removal of plateaux to form wear debris. The latter hypotheses include the effects of cyclic stressing and dislocation accumulation, together with effects associated with the kinetics of growth and physical properties of the various oxides. The proposed surf ace mode1s have led to the develop­ ment of quantitative expressions for contact temperature, unlubricated wear rates, boundary lubricated wear rates and the wear of rna ter ial during the transition from severe to mild wear. In general theoretical predictions from these expressions are in very good agreement with experimental values.

Erythrocyte antioxidant protection of rose hips (Rosa spp.)

Rose hips are popular in health promoting products as the fruits contain high content of bioactive compounds. The aim of this study was to investigate whether health benefits are attributable to ascorbic acid, phenols, or other rose-hip-derived compounds. Freeze-dried powder of rose hips was preextracted with metaphosphoric acid and the sample was then sequentially eluted on a C18 column. The degree of amelioration of oxidative damage was determined in an erythrocyte in vitro bioassay by comparing the effects of a reducing agent on erythrocytes alone or on erythrocytes pretreated with berry extracts. The maximum protection against oxidative stress, 59.4 ± 4.0% (mean standard deviation), was achieved when incubating the cells with the first eluted meta-phosphoric extract. Removal of ascorbic acid from this extract increased the protection against oxidative stress to 67.9 ± 1.9% . The protection from the 20% and 100% methanol extracts was 20.8 ± 8.2% and 5.0 ± 3.2% , respectively. Antioxidant uptake was confirmed by measurement of catechin by HPLC-ESI-MS in the 20% methanol extract. The fact that all sequentially eluted extracts studied contributed to protective effects on the erythrocytes indicates that rose hips contain a promising level of clinically relevant antioxidant protection. © Copyright 2012 C. Widén et al.

Development, Annotation and Protection of Digital Archive “Bulgarian Folklore Heritage”

The key to prosperity in today's world is access to digital content and skills to create new content. Investigations of folklore artifacts is the topic of this article, presenting research related to the national program „Knowledge Technologies for Creation of Digital Presentation and Significant Repositories of Folklore Heritage” (FolkKnow). FolkKnow aims to build a digital multimedia archive "Bulgarian Folklore Heritage” (BFH) and virtual information portal with folk media library of digitized multimedia objects from a selected collection of the fund of Institute of Ethnology and Folklore Studies with Ethnographic Museum (IEFSEM) of the Bulgarian Academy of Science (BAS). The realization of the project FolkKnow gives opportunity for wide social applications of the multimedia collections, for the purposes of Interactive distance learning/self-learning, research activities in the field of Bulgarian traditional culture and for the cultural and ethno-tourism. We study, analyze and implement techniques and methods for digitization of multimedia objects and their annotation. In the paper are discussed specifics approaches used to building and protect a digital archive with multimedia content. Tasks can be systematized in the following guidelines: * Digitization of the selected samples * Analysis of the objects in order to determine the metadata of selected artifacts from selected collections and problem areas * Digital multimedia archive * Socially-oriented applications and virtual exhibitions artery * Frequency dictionary tool for texts with folklore themes * A method of modern technologies of protecting intellectual property and copyrights on digital content developed for use in digital exposures.

Protection of human erythrocytes against oxidative stress by berries

Berries contain several bioactive compounds that can protect against oxidative stress. In this study we evaluated the protective effect of different sequential extracts (ethyl acetate, ethanol and water) of seven berry species: bilberry (Vaccinium myrtillus), blackcurrant (Ribes nigrum), elderberry (Sambucus nigra), lingonberry (Vaccinium vitis-idaea), rose hips (Rosa sp.), sea buckthorn (Hippohae rhamnoides) and strawberry (Fragaria × ananassa). The protective effect was tested on human erythrocytes and the antioxidant capacity was also evaluated in vitro by the FRAP assay. In the erythrocyte assay all sea buckthorn extracts were superior in antioxidant effect to other berry extracts. The ethyl acetate extract of bilberries, and the ethanol and water extracts of blackcurrants, also protected the erythrocytes from oxidation. In contrast, water extracts of rose hips, bilberries and strawberries had a pro-oxidant effect on erythrocytes. The water extract of rose hips was superior to the other berry extracts in the FRAP assay. Thus, the results of the erythrocyte assay did not correlate with the results of the FRAP assay, but provided additional insights into the potential protective effects of berry extracts against oxidative stress. © 2012 - IOS Press and the authors. All rights reserved.

The Everglades Ecosystem and the Politics of Nature

In this article, I offer an institutional history of the ecosystem concept, tracing shifts in its meaning and application as it has become the key organizing principle for the Everglades restoration program in Florida. Two institutional forms are analyzed here: (1) quasigovernmental organizations, a term I use to describe interagency science collaboratives and community stakeholder organizations, and (2) government bureaucracies, which are the administrative agencies tasked with Everglades restoration planning and implementation. In analyzing these knowledge trajectories, I both document the complex networks of relations that facilitate the ecosystem’s emergence as an object of knowledge and examine the bureaucratic claims to authority that circumscribe the ecosystem’s transformation into policy.