Moderate antioxidative efficiencies of flavonoids during peroxidation of methyl linoleate in homogeneous and micellar solutions

The relative reactivities as well as the stoichiometric coefficients for a number of flavonoids, catechols, and—for comparison—standard phenolic antioxidants were determined by analyzing the kinetics of oxygen consumption in organic and micellar systems, with peroxidation initiated by lipid- and water-soluble azo initiators. The results demonstrated that the flavonoids did not behave as classic phenolic antioxidants such as α-tocopherol, but showed only moderate chain-breaking activities. The results were in line with other structure-activity relationship studies on the importance of the B-ring catechol structure, the 2,3-double bond, and the 3,5-hydroxy groups. The data are discussed in view of possible explanations of the deviations flavonoids reveal in their behavior compared with regular phenolic antioxidants.     

Some soft measures for performance analysis: The “core” dimensions of expert system quality

The post-implementation evaluation of new technologies such as artificial intelligence, multimedia or parallel computing systems which are in operation is a much neglected problem. There is a lack of methods, techniques and tools for the practitioner to analyze the performance such systems. In earlier work, we have presented a framework and methodology that described a socio-technical approach for evaluating expert systems. In short, we determined the features and characteristics of expert systems that are most critical for their “implementation success”. This was the result of empirical evidence from a first-ever field study of expert systems in production. In this paper, specifically tailored to an audience of generalists, we retrospectively put our work into the framework of performance measurement and analysis. The end-result of our investigations is that we have definitional clarity as to how we may alternately evaluate such decision support systems.     

Pressure release of containments during severe accidents in Switzerland

As required by the Swiss Federal Nuclear Safety Inspectorate (HSK) all Switzerland's five nuclear power plants have to install a containment filtered venting system. The integrity of the containment (the last barrier for radioactive releases to the environment) can be threatened by overpressure due to inadequate heat removal. Design requirements have been provided for a specific class of severe accident scenarios. In general the capacity of the system is considered sufficient if it is able to vent the steam production corresponding to a decay heat level of 1% of the thermal reactor power. The mitigation capacity for the reduction of released radioactive material is specified by a retention factor of 1000 for aerosols to prevent or limit a long term ground contamination and a factor of 100 for elementary iodine for prevention or limiting of thyroid doses and to avoid short term evacuation. Besides existing requirements for design, maintenance and operation, additional claims such as passivity and operability at any pressure conditions inside the containment have to be met. Passivity implies that the system can be initiated after a severe accident without any operator action. The system also has to allow early manual venting. Various filtered venting systems are presently available. The nuclear power plants of Beznau, Gosgen, Leibstadt and Muhleberg have already selected such systems and already implemented them or are going to install them step by step. Beznau selected the Sulzer-EWI system which is using a water pool with nozzles-baffle plates and mixing elements to achieve the required filtration of the aerosols. In both Beznau units, the systems are installed and in standby mode. Gosgen, a pressurized water reactor as well as Beznau, is going to implement a filter system developed by Siemens-KWU, known as sliding pressure venting process, combining a venturi scrubber in a water pool and a mesh filter. The boiling water reactor of Leibstadt also selected the same system as Beznau while Müheberg choose the ABB system but not in the common design. The venturi pipes are thereby integrated in the water pool of the outer torus. The system in all five nuclear power plants is fully operable and in standby mode since December 1993.     

Comparison of physical property-porosity behaviour with minimum solid area models

An extensive survey of the porosity dependence of (room temperature) physical properties shows that mechanical properties and electrical and thermal conductivity, i.e. properties dependent on the local flux or fields in the material, follow minimum solid area models. This is shown extensively for elastic properties and tensile (flexure) strength, but consistency with other properties, e.g. compressive strength, hardness, electrical and thermal conductivity is also shown. Although data for ceramics is most extensive, data for rocks, metals, and carbon are included, since the consistency of these, especially of metals with ceramics, provides important support for the minimum solid area concept. While porosity characterization is generally minimal, expected model trends with pore character are corroborated by correlating processing and resultant expected pore character with porosity-property results. It is argued that properties dependent on mass should be better fit by a linear, i.e. rule of mixture, relationship between such properties and porosity. Support for this is shown in dielectric constant-porosity data.     

Absorbability of Calcium From Common Beans

Absorption of calcium from white, red, and pinto beans, labeled with ⁴⁵Ca, was measured in 24 women in a three-way randomized design using a calcium load of 72 mg and milk as the referent. Fractional absorption for the three beans averaged 0.219 ± 0.047 and did not differ by type. Milk calcium absorption at the same load was more than two times higher, 0.451 ± 0.088 (P < 0.001). Oxalate content averaged 0.34%, and phytate averaged 1.7%, a stoichiometric excess relative to calcium. To evaluate the relation of phytate to reduced absorbability, labeled pinto beans were pre-treated with phytase and fed to 10 subjects. Fractional absorption rose, averaging 0.318 ± 0.071, (P <0.01 vs. untreated beans), but was significantly below that of milk. The difference was partly accounted for by phytate, with the remainder probably due to relatively high oxalate.     

CHALLENGE STUDIES WITH CLOSTRIDIUM BOTULINUM TYPE E IN A VALUE-ADDED SURIMI PRODUCT STORED UNDER A MODIFIED ATMOSPHERE

Challenge studies were carried out on raw, cooked, and sterilized surimi nuggets, inoculated with 10⁴ spores/g of C. botulinum type E spores. All products were packaged in air and air with an Ageless SS oxygen absorbent and stored at 4, 12 and 25C. Toxin was not detected in any raw product throughout storage (28 days). The absence of toxigenesis was attributed to the low pH (4.1–4.3) due mainly to the growth of lactic acid bacteria (10⁷CFU/g). Toxin was also not detected in any cooked product after 28 days. Product pH did not decrease as previously (due to the absence of LAB), but counts of C. botulinum still decreased throughout storage.
In sterile nuggets , C. botulinum counts increased to 10⁶ cfu/g at both 12 and 25C, respectively, by 28 days. Lactic acid bacteria and Bacillus spp. were not detected throughout the 28 days storage period. Toxin was detected by days 28 and 14 at 12 and 25C, respectively, and toxigenesis preceded spoilage. The absence of toxin in cooked nuggets was attributed to the anti-botulinal role by Bacillus species, the predominant spoilage bacteria in cooked nuggets.