OBJECTIVES:To evaluate complications after distal radius fracture surgery.
DESIGN:Prospective registry study.
SETTING:Nationwide registry study.
PATIENTS:A total of 36,618 patients who underwent ...surgery because of a distal radius fracture during the period from January 1, 2001 to December 31, 2009 were followed from the date of operation until the occurrence of either reoperation, a new distal radius fracture, death, or December 31, 2010, whichever occurred first.
MAIN OUTCOME MEASUREMENT:The occurrence of reoperations after different surgical methods is presented as proportions, incidence rates, and in a Kaplan–Meier survival analysis curve. Types and distributions of complications are presented for pinning, external fixation (EF), and plating, respectively.
RESULTS:The incidence of reoperation after fracture surgery using EF, pins, and plating was 100 95% confidence interval (CI)93–107, 140 (95% CI127–153), and 222 (95% CI207–237) per 10,000 person years, respectively. After stratified analysis adjusting for age and gender, the differences remained significant when comparing plating with EF (P = 0.001) and pinning (P = 0.01). Pinning and EF patients displayed an earlier onset of the complications when compared with plated patients.
CONCLUSIONS:The incidence of reoperation was higher for patients treated with a plate than for patients treated with pins or EF. The timing of the reoperations differed in that pinning and EF patients displayed an earlier onset when compared with plated patients.
LEVEL OF EVIDENCE:Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.
Deficiencies in drinking water distribution networks, such as cross-connections, may lead to contamination of the drinking water and pose a serious health risk to consumers. Cross-connections and ...backflows are considered among the most severe public health risks in distribution networks. The aim of this paper was to provide a framework for estimating the risk of infection from cross-connection and backflow events. Campylobacter, norovirus, and Cryptosporidium were chosen as reference pathogens for this study. The theoretical framework was constructed based on the fault tree analysis methodology. National aggregated cross-connection incident data was used to calculate the probability of a contamination event occurring in Swedish networks. Three risk cases were evaluated: endemic, elevated, and extreme. Quantitative microbial risk assessment (QMRA) was used to assess daily risk of infection for average national estimates. The framework was also evaluated using local data from the Gothenburg network. The daily risk of infection from cross-connection and backflow events in Swedish networks was generally above an acceptable target level of 10−6 for all reference pathogens and modelled cases; the exception was for the Gothenburg system where the risk was lower than 10−7. An outbreak case study was used to validate the framework results. For the outbreak case study, contaminant transport in the network was simulated using hydraulic modelling (EPANET), and risk estimates were calculated using QMRA. The outbreak simulation predicted between 97 and 148 symptomatic infections, while the epidemiological survey conducted during the outbreak reported 179 cases of illness. The fault tree analysis framework was successfully validated using an outbreak case study, though it was shown on the example of Gothenburg that local data is still needed for well-performing systems. The framework can help inform microbial risk assessments for drinking water suppliers, especially ones with limited resources and expertise in this area.
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•Study of cross-connections and backflows in drinking water distribution networks•Assessment using national-aggregated data showed high infection risks.•Assessment using local data showed acceptable infection risks.•National data can be used for risk assessment, especially if local data are lacking.
The environmental and economic consequences of four recycling and disposal options for municipal sewage sludge have been assessed. The four options were: agricultural application, co-incineration ...with waste, incineration combined with phosphorus recovery (Bio-Con) and fractionation including phosphorus recovery (Cambi-KREPRO). Life cycle assessment (LCA) was used to assess the environmental consequences, while effects in the district heating system were analysed using the energy system model MARTES. Co-incineration had the best energy balance, but without recovery of phosphorus. In the Bio-Con and Cambi-KREPRO processes both phosphorus and energy could be recovered. Compared to Cambi-KREPRO, Bio-Con was more effective in most respects, but suffered from higher emissions to air. Spreading sludge on agricultural land was the least preferable option from an environmental point of view. Energy was required for transportation, spreading and pasteurisation of the sludge, whereas the other three options enabled energy recovery. Spreading also caused release of nutrients and acidifying substances and transferred the content of heavy metals in the sludge to agricultural soil. The economic assessment showed that agricultural application had the lowest cost of the options, whereas co-incineration had the highest cost. The difference in cost between Bio-Con and Cambi-KREPRO was small, but since the technologies are new and untried in a commercial context, these results are uncertain. This study has shown that two sludge handling options, incineration and direct application to agricultural soil, have respectively economic and environmental restrictions. The development of relatively low cost phosphorus recovery technologies has the potential to reconcile the environmental and economic aspects of sustainability.
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•Low sulfur-exposure temperature leads to more severe deactivation.•SO2 exposure decreases N2O selectivity.•Different deactivation mechanisms are seen for lab- and engine-aged ...catalysts.
Selective catalytic reduction of nitrogen oxides is an efficient technique for emission abatement in heavy-duty vehicles. Cu-SSZ-13 SCR catalysts are more active than vanadium-based catalysts at low temperatures, but are more sensitive to deactivation by sulfur. Consequently, there is a need to study poisoning by sulfur for this catalyst material. This experimental investigation focuses on the effect of sulfur on the low-temperature performance of Cu-SSZ-13 SCR catalysts. The effect of sulfur exposure temperature, and the influence of the NO2/NOx ratio, are considered and two different regeneration temperatures are compared. In addition, catalyst samples from an engine-aged catalyst are evaluated. The SO2 exposure temperature is shown to have an important impact on the deactivation of the Cu-SSZ-13 catalyst. The lowest sulfur exposure temperature (220 °C) results in the most severe deactivation, while the highest temperature during sulfur exposure (400 °C) results in the lowest degree of deactivation. This was found to be related to the amount of sulfur on the catalyst. Additionally, SO2 exposure was shown to decrease the N2O selectivity. The engine-aged catalyst has a decreased performance in terms of both decreased activity and increased N2O selectivity. For this catalyst, impurities from fuel and engine-oil can play a role in the deactivation. Different deactivation mechanisms are seen for the lab- and engine-aged catalysts.
Identifying the most suitable risk-reduction measures in drinking water systems requires a thorough analysis of possible alternatives. In addition to the effects on the risk level, also the economic ...aspects of the risk-reduction alternatives are commonly considered important. Drinking water supplies are complex systems and to avoid sub-optimisation of risk-reduction measures, the entire system from source to tap needs to be considered. There is a lack of methods for quantification of water supply risk reduction in an economic context for entire drinking water systems. The aim of this paper is to present a novel approach for risk assessment in combination with economic analysis to evaluate risk-reduction measures based on a source-to-tap approach. The approach combines a probabilistic and dynamic fault tree method with cost-effectiveness analysis (CEA). The developed approach comprises the following main parts: (1) quantification of risk reduction of alternatives using a probabilistic fault tree model of the entire system; (2) combination of the modelling results with CEA; and (3) evaluation of the alternatives with respect to the risk reduction, the probability of not reaching water safety targets and the cost-effectiveness. The fault tree method and CEA enable comparison of risk-reduction measures in the same quantitative unit and consider costs and uncertainties. The approach provides a structured and thorough analysis of risk-reduction measures that facilitates transparency and long-term planning of drinking water systems in order to avoid sub-optimisation of available resources for risk reduction.
Capture of suspended particles by cylindrical collectors is an important mechanism in many aquatic processes, such as larval settlement, suspension feeding, and vegetative filtration. In these ...processes, the collector Reynolds number $(Re_{\text{c}})$, based on the collector diameter, ranges from well below 1 to 1,000. No analytical solutions exist to describe capture over most of this range. Capture is typically described by the efficiency, η, defined as the ratio of the upstream span of particles that are captured on the collector to the collector diameter. Here, laboratory experiments are used to measure capture efficiency of a single cylinder as a function of $Re_{\text{c}}$ and particle ratio, R, which is the ratio of particle diameter to collector diameter $Re_{\text{c}}$ is varied from 50 to 500 and three values of R are used: 0.03, 0.015, and 0.008. The selected particles have a specific gravity of 1.03. For smooth cylinders, capture increases with both $Re_{\text{c}}$ and R but is more strongly dependent on R. This result indicates that, in aquatic systems, where flow velocity and suspended particle type and size are fixed, higher capture efficiency will occur on the smallest collectors (those with largest R). Furthermore, we examine a similar experiment in which particles are collected by branched structures. We show that capture to individual cylindrical branches within a compound structure can be predicted by single-cylinder efficiencies. Finally, capture was increased when roughness elements were added to the collectors.
Seasonal variability in the removal of dissolved organic matter (DOM) by drinking water biological activated carbon (BAC) filters is often attributed to temperature changes. However, it can be rather ...difficult to directly relate temperature to treatment efficiency at full scale due to seasonal variations in other influential parameters like DOM concentration and character, and microbial activity. Furthermore, processes in BAC filters include adsorption, desorption and biodegradation within biofilms while each respond differently to temperature. This study aimed to decouple these processes by studying the removal of various DOM fractions from coagulated and settled drinking water when in contact with aged (>3 years) BAC filter material at different water temperatures. DOM removal was measured as changes in dissolved organic carbon (DOC), ultraviolet absorbance at 254 nm (UV
254
) and fluorescence. Under the particular experimental conditions there was little evidence of biological removal; instead, removal of DOM fractions emitting at longer wavelengths ("humic-like", >430 nm) was consistent with chemisorption, removal of DOM emitting at intermediate wavelengths ("humic-like", 390-420 nm) was consistent with physisorption, and multiple mechanisms were indicated for "protein-like" (<380 nm) DOM. Non-biological mechanisms of DOM removal by aged BAC filters are often assumed to be unimportant; however, these results suggest they are important for some DOM fractions, especially during periods of reduced microbial activity.
Physical and chemical adsorption by aged biological active carbon (BAC) filters were observed for some organic matter fractions, and may represent important removal mechanisms during periods of low microbial activity.
The influence of catalyst properties on the activity and selectivity of hydrogen generation by methanol reforming over copper-based catalysts impregnated on γ-alumina pellets has been investigated. ...In the experiments, three sets of copper-based catalysts with various compositions were tested: Cu/Zn/Al
2O
3, Cu/Cr/Al
2O
3 and Cu/Zr/Al
2O
3. The catalysts were characterized using temperature programmed reduction (TPR), temperature programmed oxidation (TPO), SEM–EDS, Brunauer–Emmett–Teller (BET) surface area measurement and X-ray diffraction (XRD). The copper surface area was determined by pulse chemisorption using N
2O. We found a correlation between the copper surface area and catalytic activity. The activity tests were performed in a fixed bed reactor with 15
g of spherical catalyst pellets using a gas hourly space velocity (GHSV) of 25,000. The results of the activity tests indicate that the choice of promoter and the catalyst composition greatly influence the activity as well as the selectivity for CO
2 formation. The highest conversions were achieved for the zinc-containing catalysts (Cu/Zn/Al
2O
3) for both steam reforming and the combined reforming process. Complete conversion of methanol was only obtained for the zinc-containing catalysts when running the steam reforming process. The combined reforming process generally yielded a product stream containing lower carbon monoxide concentrations compared to steam reforming at the equivalent reactor temperature for all of the catalysts tested.
A combination of first-principles thermodynamics and density functional theory (DFT) was applied for the prediction of sulfur-poisoned monomeric Cu/Fe species formed in the SSZ-13 catalyst framework ...under selective catalytic reduction (SCR)-relevant conditions in the presence of sulfur dioxide, ammonia, oxygen, and water. Differences in fresh and sulfur-poisoned species were found for Cu- and Fe-SSZ-13 catalysts containing one Al (1Al sites) or two Al (2Al sites) in 6-membered rings (6MRs) or 8-membered rings (8MRs). The impact of ammonia concentration during low- and high-temperature sulfur-poisoning on Cu- and Fe-speciation was also investigated. SCR-relevant concentrations of ammonia in the gas mixture led to the formation of ammonium sulfates over copper in 2Al and 1Al sites of Cu-SSZ-13, while bisulfate and sulfuric acid species were predicted at these copper sites either in the absence of ammonia or at negligible concentrations of ammonia during low- and high-temperature poisoning. The absence of ammonia in the gas mixture led to the formation of iron-bisulfates at 2Al sites of Fe-SSZ-13 during low-temperature poisoning, while the formation of ammonium sulfates was favorable under SCR-relevant conditions. In contrast to the facile formation of ammonium sulfates at copper sites of Cu-SSZ-13, only ammonium-free iron-sulfates formed at 1Al sites in Fe-SSZ-13 under realistic operational conditions. The regeneration of 2Al sites of Cu-SSZ-13 was predicted to occur at higher temperatures compared to 2Al sites in Fe-SSZ-13, whereas the opposite was predicted for 1Al sites. The analysis of fresh and regenerated Cu/Fe species was carried out as well. These theoretical results on model catalysts provide a first step in the understanding of sulfur-poisoning in Fe-SSZ-13 catalysts, supporting further experimental investigations to improve NH3-SCR catalysts for meeting future emission standards.
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