The mineralogical characterization of dry-powder barriers in Al reduction cells

Dry-powder barrier layers have been investigated in recent years to prevent fluorine penetration and degradation of insulating refractories and cell walls. The deterioration of insulating materials and cell walls is undesirable as it results in increased thermal conductivity and, therefore, higher operating costs. The mineralogy of two dry-powder barriers was characterized by several methods. Results show that after 893 days in an aluminum reduction cell, corundum and wollastonite-based powder formed an incomplete calcium-fluoride barrier. This dry powder contained a vermiculite base. An anorthite-based powder was tested in a laboratory trial and formed a nepheline barrier with complete conversion of fluorine to stable mineralogical phases after 100 hours. Testing of this anorthite-based powder in aluminum-plant reduction cells is currently in progress. Ann M. Hagni earned her Ph.D. in geology at the University of Missouri-Rolla in 1995. She is currently manager of applied mineralogy and analytical chemistry at A.P. Green Industries. Dr. Hagni is also a member of TMS.     

The importance of surface roughness for implant incorporation

318 threaded implants with a diameter of 3.7 mm, length 6 to 7 mm and a pitch-height of 0.6 mm were inserted in 56 New Zealand white rabbits. Implants of varying surface roughness were produced by a blasting procedure using 25m 75m and 250 μm sized particles. As- machined, (i.e turned) implants served as controls. The implant surface roughness was measured with the confocal laser scanner (TopScan 3D), and appropriate software was used for visual and numerical characterization. After implantation time of 4 weeks, 12 weeks or 1 year, the animals were euthanized. The implants were evaluated with respect to the peak removal torque, the percentage of bone-to-implant contact.The results from the animal experiments demonstrated, generally, higher removal torques and higher percentages of bone-to-implant contact for implants blasted with 25 and 75 μm sized blasting particles than with as-turned or 250 μm blasted implants. The corresponding average height deviation for the 4 surfaces was 1 μm 1.5 μm 0.7 μm and 2.0 μm When comparing the 25 and the 75 μm blasted implants it was found that 75 μm blasted screws showed the strongest bone fixation.     

健康影响评估之规划师版:哪些工具有用?

健康影响评估(HIA:Health Impact Assessment)为那些希望将健康方面的考量引入规划过程的人提供了一种吸引人的方法。目前,HIA主要应用于美国以外的国家,并由公共健康领域的专家带头,但其有望解决规划所涉及的人类健康问题。本文阐述了HIA的历史及与其他类似工具的关系,回顾了HIA的现有理论和实践,并讨论了其在目前规划措施中所扮演的角色。笔者认为,通过完善既有的HIA工具,可使规划师认识到HIA对于当下规划过程是有用的补充而非累赘的附加要求。笔者在文末探讨了HIA具有的独特优势,其更加明确地关注人类健康这一重要问题,从而能够与公共健康和相关领域的潜在盟友进行进一步紧密合作。     

Autism-friendly architecture from the outside in and the inside out: an explorative study based on autobiographies of autistic people

Researchers and designers each developed a particular vision on autism-friendly architecture. Because the basis of this vision is not always clear, questions arise about its meaning and value and about how it can be put to use. People with a diagnosis on the autism spectrum are central to these questions, yet risk to disappear from the picture. Refocusing the discourse about autism-friendly architecture on them was the aim of the explorative study reported here. Six autobiographies written by autistic (young) adults were analysed from two different viewpoints. First, concepts from design guidelines concerning autism-friendly architecture were confronted with fragments from these autobiographies. The second part of the analysis started from the autobiographies themselves. This analysis shows that concepts can be interpreted in multiple ways. They can reinforce but also counteract each other, thus asking for critical judgment. An open space is preferred by some autistic people because it affords having an overview, which increases predictability, and distancing oneself from others without being isolated. Others might like this space to be subdivided into several separate spaces, which affords a sense of structure or reduces sensory inputs present in one room. The six autobiographies provide a glimpse of autistic people’s world of experience. Analysing these is a first step in revealing what architecture can actually mean from their point of view. For them, the material environment has a prominent meaning that is, however, not always reducible to design guidelines. It offers them something to hold on to, relate to or structure their reality.     

Foraging for identity: the relationships between landscape activities and landscape identity after catastrophic landscape change

ABSTRACT

In this article, we deal with landscape activities in relation to changing landscape identity after a major wildfire in Sweden in 2014. The aim was to investigate the relationships between 22 landscape activities (before the fire) and 2 components (emotion and cognition) of landscape identity (before and after the fire). A total of 656 respondents living nearby the fire area participated in this study. Before the fire, a positive association was found between the activities of enjoying nature and foraging, and both components of landscape identity. This suggests that the more participants enjoyed nature and picked berries and mushrooms, the stronger their attachment to the landscape (emotion), and the more they remembered and reasoned about the landscape (cognition). Post fire, these relationships were found only between the two components of landscape identity and foraging. This implies a significant role of this type of activity for keeping ‘alive’ landscape identity.     

Effect of nonionic surfactants on the oxidation of carbaryl by anodic Fenton treatment

As a potentially promising technology, anodic Fenton treatment (AFT) has been shown to be very successful in pesticide removal. However, the influence of other constituents in the pesticide formulation, such as nonionic surfactants, has not been addressed. In this study, the effect of Triton X (TX) on the degradation kinetics and pathways of carbaryl undergoing AFT was investigated in an effort to facilitate its practical application. The presence of Triton X-100 was found to slow down the carbaryl degradation rate. This result can be attributed to the consumption of hydroxyl radicals ((*)OH) by surfactants and the formation of a carbaryl...TX...Fe(3+) complex, resulting in the unavailability of carbaryl to (*)OH attack. The modified AFT kinetic model previously developed in this laboratory shows an excellent fit to the carbaryl degradation profile (R(2)>0.998), supporting the formation of a carbaryl...TX...Fe(3+) complex. The carbaryl degradation rate decreased as Triton X-100 concentration increased from 20 to 1000 mg L(-1). Both (*)OH consumption by surfactants and complex formation are responsible for the degradation rate reduction below the critical micelle concentration (CMC), whereas the complex and micelle formation becomes a more dominant factor above the CMC. The effect of ethylene oxide (EO) numbers of a given nonionic surfactant mainly lies in the consumption of hydroxyl radicals, which increases with the length of the EO chain, but does not significantly affect the formation of the carbaryl...TX...Fe(3+) complex. Based on the GC-MS and LC-ESI-MS results, no evidence was found that the carbaryl degradation pathway was affected. Carbaryl was typically oxidized to 1-naphthol and 1,4-naphthoquinone similar to what is observed in the absence of surfactants. Triton X-100 was degraded via the breakdown of EO chains and omega-oxidation of the terminal methyl group, which resulted in the production of a series of ethoxylate oligomers.     

Analyses of the grouting results for a section of the APSE tunnel at Äspö Hard Rock Laboratory

The grouting results for a tunnel at a depth of 450 m in crystalline rock at Äspö HRL were studied. The aims were to investigate whether the methodology used resulted in a successful grouting design and producing a sufficiently dry tunnel, and whether grout penetration and inflow into the finished tunnel corresponded to the predictions. An analysis was made of data from an original cored borehole, drilled before the tunnel was constructed and mapped thoroughly with regard to fractures and transmissivities. The predicted inflow into the tunnel was calculated and found to be four times higher than the measured inflow. The latter was 5 l/min along the 70 m tunnel, considered to be a good result at the current depth. New cored control boreholes were drilled along a section of the tunnel. The inflow positions and quantities in these holes, and the positions of grout found in the corresponding cores, were compared with the data from the original borehole. It was found that at the predicted positions of larger fractures, grout was observed and there was no inflow, showing that these had been successfully sealed. At the predicted positions of small fractures, no grout was visible in the cores, and small inflows showed that the grout had not sealed these fractures. The results indicated that cement-based grout successfully sealed fractures down to a hydraulic aperture of about 50 μm but not below 30 μm. This concurs with the initial design aimed at sealing fractures larger than 50 μm.     

Bacterial pathogen incidences in sludge from Swedish sewage treatment plants

This study surveyed the presence of bacterial pathogens in eight Swedish sewage treatment plants (STPs), with four different treatment methods, focusing on detection of zoonotic bacteria in raw and treated sludge. Salmonella spp., Listeria monocytogenes, Campylobacter coli and jejuni, Escherichia coli O157 and indicator bacteria were investigated. Samplings were performed from July 2000 to June 2002, resulting in 64 raw sludge samples and 69 treated sludge samples. The samples from raw sludge (67%) and treated sludge (55%) were positive for Salmonella; 49 different serotypes were detected. Restriction enzyme analysis and pulsed field gel electrophoresis of Salmonella serotypes indicated that Salmonella persists in STPs and that there is a continuous supply of new strains. There are differences in treatment methods concerning the reduction of pathogens and indicator bacteria. If spread on arable land, sludge increases the environmental load of pathogens; this increases the risk for spreading diseases to people and animals.     

Statistical analysis of baseline load models for non-residential buildings

Policymakers are encouraging the development of standardized and consistent methods to quantify the electric load impacts of demand response programs. For load impacts, an essential part of the analysis is the estimation of the baseline load profile. In this paper, we present a statistical evaluation of the performance of several different models used to calculate baselines for commercial buildings participating in a demand response program in California. In our approach, we use the model to estimate baseline loads for a large set of proxy event days for which the actual load data are also available. Measures of the accuracy and bias of different models, the importance of weather effects, and the effect of applying morning adjustment factors (which use data from the day of the event to adjust the estimated baseline) are presented. Our results suggest that (1) the accuracy of baseline load models can be improved substantially by applying a morning adjustment, (2) the characterization of building loads by variability and weather sensitivity is a useful indicator of which types of baseline models will perform well, and (3) models that incorporate temperature either improve the accuracy of the model fit or do not change it.