Effect of compaction on bisulfide diffusive transport through MX-80 bentonite.

Canada's deep geological repository (DGR) design includes an engineered barrier system where highly compacted bentonite (HCB) surrounds the copper-coated used fuel containers (UFCs). Microbial-influenced corrosion is a potential threat to long-term integrity of UFC as bisulfide (HS-) may be produced by microbial activities under anaerobic conditions and transported via diffusion through the HCB to reach the UFC surface, resulting in corrosion of copper. Therefore, understanding HS- transport mechanisms through HCB is critical for accurate prediction of copper corrosion allowance. This study investigated HS- transport behaviour through MX-80 bentonite at dry densities 1070-1615 kg m-3 by performing through-diffusion experiments. Following HS- diffusion, bromide (Br-) diffusion and Raman spectroscopy analyses were performed to explore possible physical or mineralogical alterations of bentonite caused by interacting with HS-. In addition, accessible porosity ε was estimated using extended Archie's law. Effective diffusion coefficient of HS- was found 2.5 × 10-12 m2 s-1 and 5.0× 10-12 m2 s-1 for dry densities 1330 and 1070 kg m-3, respectively. No HS- breakthrough was observed for highly compacted bentonite (1535-1615 kg m-3) over the experimental timeframe (170 days). Raman spectroscopy results revealed that HS- reacted with iron in bentonite and precipitated as mackinawite and, therefore, it was immobilized. Finally, results of this study imply that HS- transport towards UFC will be highly controlled by the available iron content and dry density of the buffer material.

A design chart for estimation of horizontal displacement in municipal landfills.

This paper describes the development of a design chart for the estimation of maximum horizontal displacement within a municipal landfill using the height and the side slope of the landfill. The design chart is based on the results of a finite element parametric study in which the behaviour of the municipal solid waste (MSW) was modeled using a non-linear elastic hyperbolic model. The model input parameters, i.e. non-linear stiffness, shear strength and unit weight of MSW, were obtained from laboratory testing data and an extensive stochastic numerical modelling exercise. Non-linear variations of unit weight as well as Young's modulus of MSW with depth were incorporated in the finite element analyses. The validity of the design chart was assessed using field monitoring results from a large landfill located in Ontario, Canada.

Development of the statocyst in Aplysia californica. I. Observations on statoconial development.

The gravity receptor organs of gastropod molluscs, such as Aplysia californica, are bilateral paired statocysts, which contain dense statoconia within a fluid-filled cyst. Gravitational forces on the statoconia are sensed through their interaction with ciliated mechanoreceptor cells in the wall of the cyst. Larval Aplysia contain a single statolith within each statocyst; when the animals grow to a critical size, they begin producing multiple statoconia, a process that continues throughout life. The number of statoconia is highly correlated with animal weight but poorly correlated with age, indicating that stone production is related to total metabolism. The single statolith has an amorphous internal structure whereas the multiple statoconia have calcification deposited on concentric layers of membrane or matrix protein. The statolith appears to be produced within the cyst lumen but the multiple statoconia are produced within supporting cells between the receptor cells. Large adult animals have statoconia larger than those in early post-metamorphic animals which have just started producing multiple stones. The maximum statocyst diameter at which the receptor-cell cilia can suspend the statolith in the center of the cyst lumen is 45 microns; production of multiple stones begins when the cyst reaches this size. The mechanisms by which statoconia production is initiated and controlled are discussed.

Inhibitory activity of papain on facultative pathogens--short communication.

Papain, a proteolytic enzyme obtained from papaya was found inhibitory on few facultative pathogens. While Escherichia coli, Staphylococcus albus, Klebsiella pneumoniae and Enterobacter cloacae were inhibited at concentration from 200 ppm on the cell density of Staphylococcus faecalis decreased only at higher concentration of papain (400-800 ppm).

Traditional concepts of mental disorder among Indian psychiatric patients: preliminary report of work in progress.

In a medically pluralistic setting a range of health care providers offer not only different forms of treatment, but different ways of understanding illness. Even within a single tradition, these concepts evolve over time. Chapters in the classical texts of Ayurveda describe varieties of severe mental disorder (unmada) arising from a particular humoral imbalance (dosa) or arising in association with specific demons and deities (bhuta) that produce distinct character changes and symptom patterns. Patients currently presenting for treatment of mental disorder may describe their illness with reference to these concepts, but they also rely on other indigenous traditional concepts such as astrology, karma, the effects of other humoral relationships, such as semen loss and so forth; or they may rely on ideas derived from cosmopolitan medicine or both. Patients presenting to allopathic psychiatric centers in India were studied to determine whether patterns of help seeking could be predicted from the conceptual model by which they understood their illness. We elicited explanatory models from patients and obtained a history of prior consultations to other types of healer. Preliminary findings were notable for the pervasiveness of prior use of folk healers and the prominence of somatic symptoms among patients presenting to these allopathic physicians. Hypotheses regarding the impact of explanatory models on patterns of medical help seeking require further study from a larger and more diverse data base.

Projection of lactation milk yield from part records in crossbred dairy cows.

First lactation records of a total of 242 Jersey (JH), Brown Swiss (BH) and Holstein-Friesian (FH) halfbreeds from Hariana cows were studied for projecting 300 d milk yield from 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38 and 40 weeks' milk yield. The correlation coefficients between 300 d milk yield and part records ranged from 0.84 to 0.9 in the JH, 0.80 to 0.90 in the BH and 0.72 to 0.86 in the FH groups. Prediction equations and standard errors of estimation for prediction of 300 d milk yield for an individual animal are presented. It is suggested that part records up to 16, 22 and 22 weeks may be used for projecting 300 d yield with sufficient accuracy in the JH, BH and FH groups respectively.