Kinetic Testing and Sorption Studies by Modified Weathering Cells to Characterize the Potential to Generate Contaminated Neutral Drainage

Techniques developed for acid mine drainage (AMD) prediction might not be suitable for contaminated neutral drainage (CND) generating sites. The Tio mine waste is known to generate Ni contaminated neutral drainage in some of the piles, but humidity cell tests fail to generate the Ni concentrations observed in the field. Weathering cell tests (small-scale humidity cell tests) were performed on fresh and weathered (produced 25 years ago) waste rock samples from the Tio mine containing various levels of hemo-ilmenite ore, and results were compared to humidity cell results on similar samples. The main constituents of the waste rock are the hemo-ilmenite ore and the plagioclase gangue; these minerals were purified from the waste rocks and the purified fractions were also submitted to weathering cell tests. The fresh waste rock samples were also submitted to sorption cells (modified weathering cells), which showed that the waste rocks have an important Ni sorption potential and that the sorbed phases are stable under weathering cell conditions. Even though the Ni concentrations obtained from the laboratory tests remain significantly lower than those obtained in field conditions (from field test pads and from waste rock piles), the results from the present study give important insight into the geochemical processes implicated in CND generation.     

Fast photochemical oxidation of proteins for comparing structures of protein-ligand complexes: the calmodulin-peptide model system

Fast photochemical oxidation of proteins (FPOP) is a mass spectrometry-based protein footprinting method that modifies proteins on the microsecond time scale. Highly reactive (?)OH, produced by laser photolysis of hydrogen peroxide, oxidatively modifies the side chains of approximately one-half the common amino acids on this time scale. Because of the short labeling exposure, only solvent-accessible residues are sampled. Quantification of the modification extent for the apo and holo states of a protein-ligand complex provides structurally sensitive information at the amino-acid level to compare the structures of unknown protein complexes with known ones. We report here the use of FPOP to monitor the structural changes of calmodulin in its established binding to M13 of the skeletal muscle myosin light chain kinase. We use the outcome to establish the unknown structures resulting from binding with melittin and mastoparan. The structural comparison follows a comprehensive examination of the extent of FPOP modifications as measured by proteolysis and LC-MS/MS for each protein-ligand equilibrium. The results not only show that the three calmodulin-peptide complexes have similar structures but also reveal those regions of the protein that became more or less solvent-accessible upon binding. This approach has the potential for relatively high throughput, information-dense characterization of a series of protein-ligand complexes in biochemistry and drug discovery when the structure of one reference complex is known, as is the case for calmodulin and M13 of the skeletal muscle myosin light chain kinase, and the structures of related complexes are not.     

Housing and the Material Imagination – Earth,Fire, Air and Water

This paper focuses on the possibilities of the material imagination as a theoretical and practical lens for contemporary housing research. The emphasis is on housing/home as complex material cultural assemblages interwoven across the four key ancient elements: earth, air, fire and water. The principle behind the material imagination is that “matter” – which we are immersed in and indeed ourselves composed of – is important, indeed underpins everything, and yet is typically rendered invisible within housing theory and research. As a critical response to social scientific engagement – “a needed radical corrective” – the potential of the material imagination for housing theory and practice is considered in ways that purposively attend to the elemental dimensions of housing as dynamic, fluid environments comprised of living matter. Suggestions for taking this approach forward through empirical housing studies are outlined.     

Browning Inhibition and Textural Changes of Pre-Peeled Potatoes Caused by Anaerobic Conditions

Sulphite treatment is often used for inhibition of enzymatic browning of pre-peeled potatoes. Introduction of CO₂ or N₂ gases in the immersion water was investigated as an alternative to sulphite. The samples were stored at 4 °C. Daily introduction of the gases reduced the O₂ content from approx. 8.8 mg/L (measured at 20 °C) to 0.2-1.9 mg/L during the immersion period. The CO₂ treatment inhibited the browning completely and N₂ treatment did not. It is assumed that this is due to the lower pH in the CO₂ water. When CO₂ was added only one time at the start of the experiment, it also inhibited discoloration, but the immersion water developed a weak brown colour. Both the CO₂ and the N₂ treatment induced hardening in the outer potato tuber tissue after cooking after 4-7 d of storage, as did Na₂SO₃ solutions.     

Statistical analysis of the quantal basis of secretory granule formation

ABSTRACT The size distribution of vesicles exocytosed from secretory cells displays quantal nature, vesicle volume is periodic multi‐modal, suggesting that these heterogeneous vesicles are aggregate sums of a variable number of homogeneous basic granules. Whether heterogeneity is a lumping‐together artifact of the measurement or an inherent intra‐cell feature of the vesicles is an unresolved question. Recent empirical evidence will be provided for the quantal nature of intra‐cell vesicle volume, supporting the controversial paradigm of homotypic fusion: basic cytoplasmic granules fuse with each other to create heterogeneously sized vesicles. An EM‐algorithm‐based method is presented for the conversion of multi‐modal to quantal data that provides as by‐product estimates of means and variances of basic granule packaging. Microsc. Res. Tech. 77:1–10, 2014. © 2013 Wiley Periodicals, Inc.     

Reproductive health and work: different experiences

Mesenchymal hamartoma is a rare liver lesion. This lesion was found in a 7-month-old girl with high serum alphafaetoprotein serum levels and was composed of loose connective tissue containing a certain number of epithelial cells of biliary or hepatic origin. Immunohistochemical studies showed that cytokeratins 7 and 19 were localized in bile duct epithelium. The ultrastructural study showed that the hamartoma was composed of well differentiated ductal structures surrounded by a myxoid mesenchyma with cysts formed either from degenerative mesenchymal areas or from dilated ducts. Flow cytometric analysis of nuclei from frozen tissue revealed that the lesion was DNA aneuploid, with a DNA index of 1.28.     

On the Parameters of Human Visual Performance: An Investigation of the Benefits of Antialiasing

A two-part experiment was conducted to investigate the effects of aliasing artifacts and screen resolution on a simple visual recognition task. The results indicate that in many cases far less realism may be necessary in synthetic computer-generated imagery than is often assumed. The first part of the experiment was a subjective rating of image quality. The second part measured the relationship between image quality and task effectiveness: Subjects were asked to discriminate between images of two types of objects similar to objects used in experiments involving mental rotation. At higher resolutions, the elimination of aliasing artifacts did not significantly improve subjects' performances. At intermediate and low resolutions, comparable to what might be used for iconic menus, the reduction in aliasing artifacts improved performance. The subjective ratings indicate that for both high and low resolution the elimination of aliasing artifacts does not improve quality, whereas images rendered at intermediate resolutions are significantly degraded by aliasing artifacts to the extent that antialiasing improves the subjective rating. These results are interpreted in the context of an ongoing research program aimed at identifying the parameters of real-time human performance for graphics workstations.     

Does Virtual Reality Enhance the Management of Stress When Paired With Exercise? An Exploratory Study.

The purpose of the present study was to assess the psychological benefits of virtual reality paired with aerobic exercise in a laboratory setting. In this study, 154 introductory psychology students were randomly assigned to 1 of 4 20-min conditions (a) walking outside around campus, (b) walking on a laboratory treadmill combined with virtual reality to experience both virtual and actual exercise, (c) walking on the laboratory treadmill without virtual reality, and (d) experiencing a virtual walk with virtual reality without actual exercise. Our results suggest that virtual reality may enhance some of the psychological benefits of exercise when paired with actual exercise under certain conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rapid fabrication of large aspheric optics

By combining efficient fabrication processes and advanced testing methods, a real production capability exists for the manufacture of large, aspheric optics. Currently, a five-axis computer-controlled optical surfacing unit is used for rapid grinding and polishing of elements up to four metres in size. This paper decribed the processes and equipment in use today and concludes with a scenario for meeting projected future fabrication needs.