Class separation of mutagenic polycyclic organic material in grilled and smoked foods

Zusammenfassung Es wird über ein Verfahren zur Abtrennung der in gegrillten und geräucherten Lebensmitteln enthaltenen mutagenen polycyclischen organischen Stoffe in einzelne Klassen berichtet. Das Verfahren umfaßt eine erste Extraktion mit Aceton, das Abscheiden von Fett und Proteinen durch Ausfällung bei –55 °C und eine Säure-Base-Extraktion. Die weitere Fraktionierung erfolgte durch Gelfiltration und Silicagel-Chromatographie. Bei vier Proben von gegrillten Würsten waren 80 bis 90% der extrahierten Mutagenität (TA98 + S9) in den basischen Fraktionen enthalten. Die in der Flamme gegrillten Würste hatten eine höhere Mutagenität als die auf Holzkohle gegrillten. Bei den geräucherten Fischen war die Mutagenität gering und verteilte sich gleichmäßig auf die basischen und die neutralen/sauren Fraktionen. Einige Proben zeigten schwache Direktmutagenität in den neutralen/sauren Fraktionen. Die Anwesenheit von Nitrit in den gegrillten Würsten hatte keinen erheblichen Einfluß auf die Mutagenität. Die Gaschromatographie, Selektive Ionregistrierung-Technik, wurde erfolgreich zur Identifizierung mehrerer PAH-Verbindungen eingesetzt, und mit ihr konnten mehrere Nitro-PAH und oxydierte Verbindungen vorläufig identifiziert werden. Der Nachweis der Mutagene in den basischen Fraktionen gestaltete sich jedoch wegen Peak-Schweifbildung und mit-eluierenden Materials kompliziert.Summary A method for class separation of mutagenic polycyclic organic material in grilled and smoked foods is described. The procedure involves an initial extraction with acetone, removal of fat and proteins by precipitation at –55 °C, and an acid-base extraction. Further fractionation was carried out by gel filtration and silica gel chromatography. In four samples of grilled sausages, 80%–90% of the extracted mutagenicity (TA98 + S9) was contained in the basic fractions. Flame-grilled sausages showed higher mutagenicity than charcoal-grilled ones. In a smoked fish sample, the mutagenicity was low and evenly distributed between the basic and the neutral/acidic fractions. A few samples showed a weak direct-acting mutagenicity in the neutral/acidic fractions. The presence of nitrite in grilled sausages did not influence the mutagenicity markedly. Gas chromatography-selected ion monitoring was used to successfully identify a number of polycyclic aromatic hydrocarbons (PAHs) and tentatively identify several nitro-PAHs and oxygenated compounds. However, the identification of mutagens in the basic fractions was complicated by peak tailing and the presence of co-eluting material.

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Abtrennung mutagenen polycyclischen organischen Materials in gegrillten und geräucherten Lebensmitteln

     

Structural and compositional analysis of (InGa) (AsSb)/GaAs/GaP Stranski–Krastanov quantum dots

We investigated metal-organic vapor phase epitaxy grown (InGa)(AsSb)/GaAs/GaP Stranski–Krastanov quantum dots (QDs) with potential applications in QD-Flash memo...     

Phase and morphology evolution of calcium carbonate precipitated by carbonation of hydrated lime

Phase and morphology evolution of CaCO₃ precipitated during carbonation of lime pastes via the reaction Ca(OH)₂ + CO₂ → CaCO₃ + H₂O has been investigated under different conditions (pCO₂ ≈ 10^−3.5 atm at 60 % RH and 93 % RH; pCO₂ = 1 atm at 93 % RH) using XRD, FTIR, TGA, and SEM. Simulations of the pore solution chemistry for different stages and conditions of carbonation were performed using the PHREEQC code to investigate the evolution of the chemistry of the system. Results indicate initial precipitation of amorphous calcium carbonate (ACC) which in turn transforms into scalenohedral calcite under excess Ca²⁺ ions. Because of their polar character, { 21[`3]4 } \left\{ {21\bar{3}4} \right\} scalenohedral faces (type S) interact more strongly with excess Ca<sup>2+</sup> than non-polar { 10[`1]4 } \left\{ {10\bar{1}4} \right\} rhombohedral faces (type F), an effect that ultimately favors the stabilization of { 21[`3]4 } \left\{ {21\bar{3}4} \right\} faces. Following the full consumption of Ca<sup>2+</sup> ions and further dissolution of CO<sub>2</sub> leading to a pH drop of the pore solution, { 21[`3]4 } \left\{ {21\bar{3}4} \right\} scalenohedra are subjected to dissolution. This eventually results in re-precipitation of { 10[`1]4 } \left\{ {10\bar{1}4} \right\} rhombohedra at close-to-neutral pH. This crystallization sequence progresses through the carbonated depth with a strong dependence on the degree of exposure to CO₂, which is controlled by the carbonated pore structure governing the diffusion of CO₂. Both the carbonation process and the scalenohedral-to-rhombohedral transformation are kinetically favored under high RH and high pCO₂. Supersaturation plays a critical role on the nucleation density and size of CaCO₃ crystals. These results have important implications in understanding the behavior of ancient and modern lime mortars for applications in architectural heritage conservation.     

Effect of free water removal from early-age hydrated cement pastes on thermal analysis

In order to follow the progress of cement hydration by analytical techniques, the ongoing hydration reactions must be stopped by complete removal of free water. A comparison between solvent exchange, oven drying and vacuum drying, using thermal analysis, is presented for early-age hydrated cement pastes. Results show that oven drying at 105 °C accelerates hydration, causes dehydration of some hydrated cement phases and favours carbonation. Solvent exchange with ethanol, ether and methanol results in a strong absorption and an incomplete removal of solvents. FT-IR and XRD gave evidence of the formation of carbonate-like phases due to an interaction upon heating, i.e. during thermal analysis, between the strongly absorbed solvents and the cement compounds or hydrates. Vacuum drying reveals reliable results as no interaction products can be formed and the Ca(OH)₂ content, determined by thermal analysis, gives a good approximation of the real amount of Ca(OH)₂.     

A priori vs. a posteriori normalisation of citation indicators. The case of journal ranking

Two paradigmatic approaches to the normalisation of citation-impact measures are discussed. The results of the mathematical manipulation of standard indicators such as citation means, notably journal Impact Factors, (called a posteriori normalisation) are compared with citation measures obtained from fractional citation counting (called a priori normalisation). The distributions of two subfields of the life sciences and mathematics are chosen for the analysis. It is shown that both methods provide indicators that are useful tools for the comparative assessment of journal citation impact.     

Shape and size control of InAs/InP (113)B quantum dots by Sb deposition during the capping procedure

The role of Sb atoms present on the growth front during capping of InAs/InP (113)B quantum dots (QDs) is investigated by cross-sectional scanning tunnelling microscopy, atomic force microscopy, and photoluminescence spectroscopy. Direct capping of InAs QDs by InP results in partial disassembly of InAs QDs due to the As/P exchange occurring at the surface. However, when Sb atoms are supplied to the growth surface before InP capping layer overgrowth, the QDs preserve their uncapped shape, indicating that QD decomposition is suppressed. When GaAs(0.51)Sb(0.49) layers are deposited on the QDs, conformal growth is observed, despite the strain inhomogeneity existing at the growth front. This indicates that kinetics rather than the strain plays the major role during QD capping with Sb compounds. Thus Sb opens up a new way to control the shape of InAs QDs.     

Patent evolution in relation to public/private R&D investment and corporate profitability: Evidence from the United States

Summary In this paper we analyze the (historical) co-evolution of technological development and economic progress (by relating public and private R&D investment, patenting, and corporate profitability). We relate to the work ofSchmookler(1966),Griliches(1990),Pakes&Griliches(1980) andPakes(1986) who all have studied the techno-economic interplay by considering patents as in indicator of technological performance. We use United States industry and government data over the period 1953-1998 (45 years). Co-evolution analysis over this period reveals a strong interdependency among the variables. Patent evolution is strongly related to the development of private R&D and corporate profitability; the levels of public and private R&D expenditure in combination with the level of technological output (i.e. patents) have a strong predictive and explanatory power towards corporate profitability (R² value of 94.9%). Causality tests reveal a joint determination between R&D investment and corporate profitability (L=2; p<0.01).     

Science cited in patents: A geographic "flow" analysis of bibliographic citation patterns in patents

The interplay and cross-fertilization between science and technology, but also the specific role of science for technological development, have received ample attention in both the research and the policy communities. It is in this context that the concepts of absorptive capacity and knowledge spillovers play an important role. We operationalize the science-technology link by quantifying and modeling bibliographic references to the scientific literature as they occur in patents. This approach allows exploring the associative patterns between science creation (as emerging from the scientific literature) and technology development (as emerging from the patent literature). In the current paper, we focus on an analysis of the geographic distribution of the science citation patterns in patents, singling out two fields of (different) technological development, namely biotechnology and information technology. In both fields, the science citation flows from the European, Japanese and US science bases into USPTO and EPO-patents are explored and modeled. Intensive geographic citation flows between the regions are identified, pointing (amongst others) to the strength of both the US and the European science bases as sources for technological activity and creativity around the world.     

Organizing for Continuous Innovation: On the Sustainability of Ambidextrous Organizations

Organizing for innovation does not present itself as a straightforward exercise. The complexities entailed when implementing an innovation strategy can be related directly to the multitude of objectives it comprises. Recently, several scholars have advanced the notions of semi‐ or quasi‐structures and ambidextrous organizations to handle these multiple requirements. These organizational forms imply the simultaneous presence of different activities, exhibiting differences in technology and market maturation. As a consequence, financial returns will reflect this diversified resource allocation pattern. Moreover, as higher levels of complexity are being introduced; ambidextrous organizations will encounter additional, organizational, costs. Compared to organizations that focus on the most profitable part of the portfolio, ambidextrous organizations – ceteris paribus – tend to be inferior in terms of financial returns. Within this contribution we explore under which conditions ambidextrous organizations can outperform focused firms; considered a prerequisite for their sustainability. In order to do so, we develop an analytical framework depicting the differential value dynamics, focused and ambidextrous firms can enact. Our findings reveal the relevancy of adopting extended time frames as well as introducing interface management practices aimed at cross‐fertilization. Finally, the synergetic potential of (underlying) technologies comes to the forefront as necessary in order for ambidextrous organizations to become sustainable.