Continuous spinal anaesthesia

CD59 is a cell membrane-bound complement regulatory protein on glomerular cells that inhibits C5b-9 assembly and insertion. This report describes a recently developed model of immune thrombotic microangiopathy (TMA) induced by the renal artery perfusion of anti-glomerular endothelial cell (anti-GEN) antibody. To examine the role of CD59 in protecting the GEN from immune-mediated injury, rats underwent selective renal artery perfusion with F(ab')2 fragments of anti-CD59 monoclonal antibody to block CD59 activity or control mouse IgG followed by anti-GEN antibody or control goat IgG. Neutralization of CD59 in normal rats did not result in any significant functional or histologic changes. Perfusion with anti-CD59 did not change deposition of the pathogenic anti-GEN IgG used to induce the TMA model. However, neutralization of CD59 in the TMA model resulted in more C5b-9 formation in glomeruli, accompanied by increased platelet and fibrin deposition, more severe endothelial injury, and reduced renal function compared with the animals perfused with control F(ab')2 fragments. These results demonstrate directly that CD59 serves a protective role for GEN in this TMA model of rats, and confirm that C5b-9 formation has a critical pathogenic role in the mediation of the disease. CD59 may play an important role in protecting glomerular endothelium from other complement-mediated types of injury.     

CFD modelling for a TiO2-coated glass-bead photoreactor irradiated by optical fibres: Photocatalytic degradation of oxalic acid

Computational fluid dynamics coupled with the radiant transport equation was used to simulate oxalic acid photodegradation in a TiO₂-coated glass-bead photoreactor irradiated by end-emitting optical fibre (EEOF) or side-emitting optical fibre (SEOF) bundles. Light irradiance distributions in the photoreactor were modelled for specular, partially specular and diffusive reactor wall reflectivities with specularly reflective reactor walls best representing the experimental data. The light irradiance distribution for the SEOF bundle was found to be more uniform along the fibre length than for the EEOF bundle. Under the experimental radiant power input (108 mW) the EEOF and SEOF bundles exhibited similar oxalic acid photodegradation rates. However, the developed model demonstrated that at incident radiant power more than ten times greater than the experimental power used, a uniform light distribution gave faster oxalic acid photodegradation with the relative improvement of the SEOF bundle over the EEOF bundle increasing with increasing radiant power. This was attributed to increased electron-hole recombination in photocatalytic surfaces close to the EEOF tip, induced by the increased light irradiance in this region. The model also demonstrated a constant light irradiance profile along the length of a SEOF bundle giving an improved photocatalytic performance when compared to linear or exponentially decaying light profiles.     

The impact of increased interconnection on electricity systems with large penetrations of wind generation: A case study of Ireland and Great Britain

Increased interconnection has been highlighted as potentially facilitating the integration of wind generation in power systems by increasing the flexibility to balance the variable wind output. This paper utilizes a stochastic unit commitment model to simulate the impacts of increased interconnection for the island of Ireland with large penetrations of wind generation. The results suggest that increased interconnection should reduce average prices in Ireland, and the variability of those prices. The simulations also suggest that while increased interconnection may reduce carbon dioxide emissions in Ireland, Great Britain would experience an increase in emissions, resulting in total emissions remaining almost unchanged. The studies suggest that increased interconnection would not reduce excess wind generation. This is because under unit commitment techniques which incorporate wind power forecasts in the scheduling decisions, wind curtailment is minimal even with low levels of interconnection. As would be expected an increase in interconnection should improve system adequacy considerably with a significant reduction in the number of hours when the load and reserve constraints are not met.     

Progress in development of acceptance criteria for local thinned areas in pipe and piping components

Over the last 30 years there has been a considerable amount of research conducted on the effect of corrosion on the burst strength of buried gas and oil transmission pipelines. The results of numerous burst tests on artificial flaws and corroded pipe removed from service were used to validate an empirical analysis that was essentially the limit–load solution for an axial crack in a pipe under pressure loading. This basic concept led to acceptance standards in ANSI B31G, and a more recent modified B31G criterion using the RSTRENG computer program developed at Battelle. This program takes into account variable flaw depths rather than the parabolic flaw shape assumed in the original B31G criterion. Since that time, more fundamental research has been conducted to develop a more accurate and theoretically based failure criterion. The Battelle/Pipeline Research Committee International PCORR computer program is an example of a special purpose shell-element based, finite element, PC criterion for the evaluation of local thinned area (LTA) flaws. This program has evolved with time from linear-elastic to elastic-plastic stress with provisions for axial as well as hoop stresses. The development and new insights into blunt flaw behavior resulting from this program will be one aspect covered in this paper. In the nuclear industry erosion-corrosion, or flow-accelerated corrosion, in single-phase liquid lines has become a major problem. Computer programs, such as the EPRI Checworks program, have been developed to assist the plant operators with deciding where to focus their inspections. However, to date no generally validated acceptance criteria have been developed for the plant piping. Plant piping, whether in nuclear power plants, fossil power plants, or petrochemical plants, have several differences from buried pipelines which need to be considered. The buried pipelines typically have low longitudinal stresses that frequently are compressive, and have no pipe fittings such as tees, elbows, and reducers except at compressor stations. Plant piping needs to consider hoop stresses and axial tension loads from the pressure, as well as, bending stresses from dead-weight loads, thermal expansion stresses, and seismic loads. In an effort to develop flaw acceptance criteria for Section XI of the ASME Boiler and Pressure Vessel Code, the criteria in Code Case N-480 have been revised and implemented into a new code case (the number has not yet been assigned). These criteria essentially use either the ANSI B31G approach for axial flaws, or the ANSI B31.1 or ASME Section III stress analysis rules to show that the residual strength of the thinned region meets the initial design stress limits. This paper presents some of the validation efforts recently undertaken to determine the inherent margins in the design stress equation approach compared with the applied safety factors in the axial and circumferential flaw limit–load solutions in: (i) the gas and oil pipeline industries; (ii) the proposed criteria in Belgium for the nuclear industry and other criteria, and (iii) the preliminary criteria from a recently proposed ASME Code Case on erosion/corrosion acceptance criteria and the ASME Appendix H criteria for flawed ferritic nuclear pipe.     

Channelled optical fibre photoreactor for improved air quality control

An optical fibre reactor with 30 hexagonal-shaped channels distributed within the optical fibre structure was investigated as a gas-phase photocatalytic reactor. TiO₂ photocatalyst, with SiO₂ sol acting as a binder, was coated on the channel walls at a thickness of 1.5 μm. Effective light propagation lengths of 3.4 and 4.9 cm were observed for incidental angles of 81.5° and 87.1°, respectively. The TiO₂-coated channelled optical fibre reactor (COFR) was assessed for the photocatalytic degradation of gas-phase ethylene. The photocatalytic reaction rate of ethylene degradation was linear with respect to the incident photons. The reaction rate order for the incident photons was determined to be 0.93. Despite a longer effective light propagation length for an incidental angle of 87.1°, the quantum yield was independent of the incidental angle. The independence of the quantum yield on the incident photons and the angle of light incidence was attributed to the COFR design, where the propagating light was wholly confined within the reactor and, in turn, more effectively utilised by the TiO₂.     

Photocatalytic mineralisation of organic compounds: a comparison of flame-made TiO2 catalysts

A comparative photocatalytic analysis was carried out on TiO₂ made in a Flame Spray Pyrolysis (FSP) process and flame-made Degussa P25. Both have similar crystallinity, phase composition, phase segregation and a non-porous surface. Hence comparison was made based on their difference in specific surface area, organic adsorption and the amount of OH• generated upon illumination. The photocatalytic activity tests were carried out using the following series of organic compounds: sucrose, glucose, fructose, maleic acid, glyoxylic acid, oxalic acid, isobutyric acid, phenol and methanol. FSP-made TiO₂ outperformed P25 for saccharides mineralisation, while for phenol and methanol mineralisation P25 was better than FSP-made TiO₂. Similar mineralisation rates were observed for both FSP-made and P25 TiO₂ for the mineralisation of carboxylic acids. This shows that the relative performance of the photocatalysts depends on the type of organic compounds to be degraded. The high surface area and possibly a more efficient interfacial charge transfer of FSP-made TiO₂ provided an efficient pathway for saccharides mineralisation. As for phenol and methanol, the mineralisation rates were higher when using P25 due to the greater amount of OH• radicals generated by this photocatalyst. The fast mineralisation rates of carboxylic acids made degradation of these organic compounds to be less affected by the TiO₂ photocatalyst properties and conditions tested in this work.     

Quantification of denitrification potential in carbonaceous trickling filters

Biofilm samples from a carbonaceous trickling filter (TF) were evaluated in bench scale reactors to determine their maximum potential denitrification rates. Intact, undisturbed biofilms were placed into 0.6 L bench-scale reactors filled with sterilized, primary clarifier effluent spiked with nitrate to a final concentration of 16-18 mg/L as N. Dissolved oxygen concentrations were maintained between 2 and 4 mg/L in the bulk aqueous phase. Nitrate loss from the reactors was monitored over a 5h period. Denitrification rates of 3.09-5.55 g-N/m(2)day were observed with no initial lag period. This suggests that the capacity for denitrification is inherent in the biofilm and that denitrification can take place even when oxygen is present in the bulk aqueous phase. There were no significant differences in denitrification rates per unit area of media (g-N/m(2)day) either between (a). experimental runs or (b). sampling locations over the trickling filter. This suggests that denitrification potentials are uniform over the entire volume of the full-scale TF. For wastewater treatment plants with TFs that currently nitrify downstream, this approach may be used to meet less stringent permitted discharge concentrations and may allow some facilities to postpone or eliminate construction of additional unit processes for denitrification.     

Irrelevant speech, serial rehearsal, and temporal distinctiveness: A new approach to the irrelevant speech effect.

D. C. LeCompte (see record 1995-04375-001) showed that the irrelevant speech effect—that is, the impairment of performance by the presentation of irrelevant background speech—extends to free recall, recognition, and cued recall. The present experiments extended the irrelevant speech effect to the missing-item task (Experiments 1 and 2), thereby contradicting a key prediction of the changing state hypothesis, which states that tasks that do not involve serial rehearsal should not be affected by the presence of irrelevant speech. Temporal distinctiveness theory provides an alternative explanation of the irrelevant speech effect. Experiment 3 tested and confirmed a unique prediction of this theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retrospective analysis of operative ankle fractures

A seroprevalence survey to recently proposed adenovirus (AV) serotypes AV 48 and AV 49, isolated primarily from AIDS patients, was conducted among the San Francisco Men's Health Study cohort. This cohort of homosexual, heterosexual, or bisexual HIV-seronegative and -seropositive men from selected San Francisco census tracts has been studied since 1984. The presence or absence of type-specific antibody in 628 serum specimens from 1989 was determined by microneutralization. Thirty of these subjects (26 positive and four negative) were studied longitudinally. Serum specimens taken at 6-month intervals from 1984 to 1993 were tested to characterize antibody response and to document the advent of these new serotypes. Eight subjects were tested against five other AV serotypes for comparison. AV 48 and AV 49 seroprevalence rates were significantly higher in HIV-seropositives, but infection was not limited to the immunocompromised. Sexual preference was not a significant determinant for AV seroprevalence in HIV-seronegatives. However, the extent and duration of the neutralizing antibody response was strikingly different between homosexuals and heterosexuals: an endemic pattern of continuous reexposure over the 9-year period was seen in 90% of 19 homosexuals, while five of six heterosexuals (83%) had an episodic pattern of exposure with antibody decline to undetectable levels. These data suggest that these viruses may be endemic in some part of the homosexual population and that sexual transmission may be the primary source of continuous reexposure.     

Exploiting tumor hypoxia through bioreductive release of diffusible cytotoxins: the cobalt(III)-nitrogen mustard complex SN 24771

PURPOSE: To assess the oxygen dependence of a novel cobalt-nitrogen mustard complex, SN 24771, designed to release a diffusible cytotoxic metabolite in hypoxic tumor microenvironments. METHODS AND MATERIALS: Oxygen dependence of cell killing was assessing in well-stirred single cell suspensions obtained by enzymatic dissociation of EMT6 spheroids, using a sensitive oxygen electrode to measure oxygen concentrations in solution. Cell killing in intact EMT6 spheroids was also compared with that in single cell suspensions. RESULTS: Cytotoxicity of SN 24771 in single cell suspensions was inhibited by very low concentrations of oxygen. The C50 value (O2 required for 50% inhibition of log cell kill) was ca. 0.02% O2 at 1 h, and the K value (O2 required to give a cytotoxic potency equal to the average of that at zero and infinite O2) was of a similar order. However, intact spheroids were much more sensitive to SN 24771 than could be accounted for by the K curve for single cell suspensions, this estimate being based on published data for the oxygen concentration profile in these spheroids. CONCLUSION: The cytotoxicity of SN 24771 is inhibited appreciably at oxygen concentrations which are too low to provide radiosensitization. In this respect, SN 24771 resembles organic bioreductive drugs such as quinones and nitroaromatic compounds. However, the extensive killing observed in multicellular spheroids is consistent with release of a diffusible nitrogen mustard on reduction. Bioreductive drugs with a low K value for activation, but which release a diffusible cytotoxin, may have desirable properties as tumor radiosensitizers.