Advanced water treatment with manganese oxide for the removal of 17alpha-ethynylestradiol (EE2)

Municipal wastewater is supposed to be one of the most important sources of endocrine-disrupting compounds (EDCs) in water. Therefore, advanced treatments and cost-efficient techniques should be developed to prevent the spread of this type of pollution into the environment. In this view, experiments were conducted in which the removal of 17alpha-ethynylestradiol (EE2), a synthetic and persistent estrogen, from water was monitored in three upstream bioreactors (UBRs), filled with, respectively, sand, granulated activated carbon (GAC) and MnO(2) granules. Tap water, spiked with 15,000ngEE2/L was filtered through the reactors with a hydraulic retention time of approximately 1h. The removal of EE2 in the sand, GAC and MnO(2) reactors was, respectively, 17.3%,>99.8% and 81.7%. The removal in the GAC reactor was mainly due to adsorption. The MnO(2) reactor, however, removed significantly more EE2 than could be predicted from its adsorption capacity, probably thanks to its catalytic properties. These catalytic properties could make it a cost-efficient technique for the removal of EE2, but further research at more environmentally relevant concentrations is needed.     

Creating and using the urgent metadata catalogue and thesaurus

The Urban Regeneration and the Environment Research Programme (URGENT) required a system for cataloguing its datasets and enabling its scientific community to discover what data were available to it. This community was multidisciplinary in nature and therefore needed a range of facilities for searching. Of particular importance were facilities to help those unfamiliar with specialist terminology. To meet these needs, four applications were designed and developed: a Metadata Capture Tool for describing datasets in compliance with the National Geospatial Data Framework (NGDF) standard, a Term Entry Tool for creating an ISO compliant thesaurus, a Thesaurus Builder for merging thesauri and a Search Tool. To encourage users to help in cataloguing data, the capture tools were written as stand alone applications, which users could keep and use to build their own metadatabases. The tools contained export and import facilities that allowed the URGENT Data Centre to build a central database and publish it upon the web. During the development work, it was found necessary to extend the NGDF standard as it could not adequately describe time variant or 3-D atmospheric datasets. The four applications met their design objectives. However, a number of ergonomic issues will need to be addressed if the system is to meet the needs of the much larger up coming programmes. The main challenges will be moving from the NGDF standard to the ISO standard, hence bringing the work into line with the recommendations of the INSPIRE Project, and merging the metadatabase with the scientific database, which enable metadata maintenance to be semi-automated.     

Rhizobium meliloti mutants deficient in phospholipid N-methyltransferase still contain phosphatidylcholine

Phosphatidylcholine (PC) is the major membrane-forming phospholipid in eukaryotes. In addition to this structural function, PC is thought to play a major role in lipid turnover and signalling in eukaryotic systems. In prokaryotes, only some groups of bacteria, among them the members of the family Rhizobiaceae, contain PC. To understand the role of PC in bacteria, we have studied Rhizobium meliloti 1021, which is able to form nitrogen-fixing nodules on its legume host plants and therefore has a very complex phenotype. R. meliloti was mutagenized with N-methyl-N'-nitro-N-nitrosoguanidine, and potential mutants defective in phospholipid N-methyltransferase were screened by using a colony autoradiography procedure. Filters carrying lysed replicas of mutagenized colonies were incubated with S-adenosyl-L-[methyl-14C]methionine. Enzymatic transfer of methyl groups to phosphatidylethanolamine (PE) leads to the formation of PC and therefore to the incorporation of radiolabel into lipid material. Screening of 24,000 colonies for reduced incorporation of radiolabel into lipids led to the identification of seven mutants which have a much-reduced specific activity of phospholipid N-methyltransferase. In vivo labelling of mutant lipids with [14C]acetate showed that the methylated PC biosynthesis intermediates phosphatidylmonomethylethanolamine and phosphatidyldimethylethanolamine are no longer detectable. This loss is combined with a corresponding increase in the potential methyl acceptor PE. These results indicate that PC biosynthesis via the methylation pathway is indeed blocked in the mutants isolated. However, mass spectrometric analysis of the lipids shows that PC was still present when the mutants had been grown on complex medium and that it was present in the mutants in wild-type amounts. In vivo labelling with [methyl-14C]methionine shows that in phospholipid N-methyltransferase-deficient mutants, the choline moiety of PC is not formed by methylation. These findings suggest the existence of a second pathway for PC biosynthesis in Rhizobium.     

Microform calibrations in surface metrology

Microform calibrations include the measurement of complex profile forms and position errors of micrometer scale in combination with the measurement of deviations from a specified profile and surface texture of profile segments. Tolerances on the profile form are specified and may correspond geometrically to surface texture parameters. One example of microform calibration is the calibration of Rockwell diamond indenters used for hardness testing of materials. Previously reported measurement techniques do not meet the stringent microfonn calibration requirements for Rockwell diamond indenters. Inadequate microform calibration of hardness indenters may be one factor resulting in significant interlaboratory differences in results from Rockwell hardness tests. By using a stylus instrument, in combination with a series of calibration and check standards and calibration and measurement uncertainty calculation procedures, we have calibrated Rockwell diamond indenters in accordance with the definitions specified in ISO and ASTM standards. Our procedures for conducting microform calibration yield total measurement uncertainties less than ten percent of the tolerance values specified in ISO and ASTM standards. In this paper, the general calibration requirements, calibration and check standards, and calibration and uncertainty procedures that we use in performing microform calibrations are introduced. Some general considerations on stylus radius correction, data fitting, calibration traceability, uncertainty and reproducibility are also discussed.     

Microform Calibration Uncertainties of Rockwell Diamond Indenters

National and international comparisons in Rockwell hardness tests show significant differences. Uncertainties in the geometry of the Rockwell diamond indenters are largely responsible for these differences. By using a stylus instrument, with a series of calibration and check standards, and calibration and uncertainty calculation procedures, we have calibrated the microform geometric parameters of Rockwell diamond indenters. These calibrations are traceable to fundamental standards. The expanded uncertainties (95 % level of confidence) are ±0.3 μm for the least-squares radius; ±0.01° for the cone angle; and ±0.025° for the holder axis alignment calibrations. Under ISO and NIST guidelines for expressing measurement uncertainties, the calibration and uncertainty calculation procedure, error sources, and uncertainty components are described, and the expanded uncertainties are calculated. The instrumentation and calibration procedure also allows the measurement of profile deviation from the least-squares radius and cone flank straightness. The surface roughness and the shape of the spherical tip of the diamond indenter can also be explored and quantified. Our calibration approach makes it possible to quantify the uncertainty, uniformity, and reproducibility of Rockwell diamond indenter microform geometry, as well as to unify the Rockwell hardness standards, through fundamental measurements rather than by performance comparisons.     

Thermal CVD of homoepitaxial diamond using CF/sub 4/ and F/sub 2/

For the first time, diamond has been grown using low-pressure thermal CVD. No additional excitation such as plasmas or filaments was used. The authors report the homoepitaxial growth of diamond on type II-A diamond     

GaAs MIS structures with SiO2 using a thin siliconinterlayer

The introduction of a pseudomorphic Si interlayer, about 1.0 nm thick, is found to dramatically improve the MIS characteristics of the SiO₂-GaAs system. Quasistatic and high-frequency capacitance/voltage data from such a novel capacitor structure on n -GaAs indicate that the surface of the GaAs is swept from inversion to accumulation. X-ray photoelectron spectroscopy and ion scattering spectroscopy confirm the presence of the Si layer and its complete coverage of the GaAs surface. The Si layer minimises the formation of any detrimental native oxides and thus controls the chemical nature of the GaAs surface. This approach has implications in the development of metal-insulator-semiconductor systems in general     

Influence of injection rate shaping on combustion and emissions for a medium duty diesel engine

This paper describes the effects of injection rate shaping on the combustion, fuel consumption and emission of NO_X and soot of a medium duty diesel engine. The focus is on the influence of four different injection rate shapes; square type 1, square type 2, boot and ramp, with a variation of maximum injection pressure and start of injection (SOI). The experiments were carried out on a 1 liter single cylinder research diesel engine equipped with an amplifier-piston common rail injection system, allowing the adjustment of the injection pressure during the injection event and thus injection rate as desired. Two strategies to maintain the injected fuel mass constant were followed. One where rate shaping is applied at constant injection duration with different peak injection pressure and one strategy where rate shaping is applied at a constant peak injection pressure, but with variable injection duration. Injection rate shaping was found to have a large effect on the premixed and diffusion combustion, a significant influence on NO_x emissions and depending on the followed strategy, moderate or no influence on soot emission. Only small effects on indicated fuel consumption were found.