Nanoscale spatial limitations of large-area substrate conformal imprint lithography.

We demonstrate a soft-imprint nanofabrication technique offering nanometer resolution over an area as large as a 150 mm diameter wafer. It makes use of a composite imprint stamp composed of a quaternary siloxane-modified poly-di-methyl-siloxane patterned rubber layer with a relatively high Young's modulus that is laminated on a thin glass support. The in-plane stiffness of the stamp avoids pattern deformation over large areas, while out-of-plane flexibility allows conformal contact to be made over the entire substrate area. The stamp is used in conjunction with a novel tetra-methyl-ortho-siloxane/methyl-tri-methoxy-siloxane sol-gel imprint resist material developed to replicate nanoscale features in rigid silica at room temperature. We demonstrate better than 10 nm resolution in imprinted line gratings and individual pillars with aspect ratio as high as 5:1. Gaps as small as 6 nm can be reproduced. The patterns can be used as an etch mask to pattern 150 mm diameter silicon and quartz substrates while maintaining sub-10 nm resolution.

Ethylene glycol exposures managed by the ASPCA National Animal Poison Control Center from July 1995 to December 1997.

Five-hundred and ten cases of ethylene glycol (EG) exposures in animals were compiled by the ASPCA National Animal Poison Control Center from July 1995 through December 1997. Case distribution was analyzed by species, sex, age, weight, seasonality, treatment intervention and final outcome. Dogs and cats were most commonly involved (98.0%). The sex distribution was approximately equal. Adult animals accounted for the majority of cases. Exposures were commonly (57.0%) from container spill, engine flush, or engine leak and were in or around the home (66.0%). Cases were reported throughout the year with slight increase during March-May. Among cases with a known final outcome, 59.0% did not show clinical signs and death/euthanasia, major and minor illness was reported in 28.0%, 5.0% and 8.0%. In view of the widespread use and potential toxicity of EG, the low number of EG exposures reported (510) among the total number of hazardous exposures (97,383) to all substances for the same period was remarkable. The EG exposures resulting in animal death/euthanasia were lower than previously published.

Chinaberry poisoning in two dogs.

Two young dogs became acutely ill following ingestion of fallen fruit from a chinaberry tree (Melia azedarach). Clinical signs of poisoning developed within hours and were characteristic of gastrointestinal and CNS disturbances. Despite prompt and aggressive emergency treatment, neither dog survived longer than 36 hours after the onset of clinical signs of poisoning. Necropsy of 1 dog revealed severe renal congestion, moderate hepatic congestion, and a moderate amount of serosanguineous fluid in the abdominal cavity. To the best of our knowledge, previous reports of chinaberry poisoning of dogs are lacking. However, chinaberry poisoning is well documented in human beings and other animals. Therefore, we strongly recommend that dogs, in addition to other animals, have restricted access to chinaberry trees and their fruit to prevent potential poisoning.

Legionellosis--the 1980 San Francisco outbreak.

During the first half of March 1980, an unseasonal outbreak of legionellosis, which involved at least 14 of approximately 1,000 workers, occurred in a 6-month-old office building in San Francisco. An epidemiologic investigation revealed that persons 50 yr of age and older were at increased risk of disease. The outbreak was temporally associated with operation of the building's air conditioning system. In addition, Legionella pneumophila Serogroups 1, 4, and 6 were identified in water samples taken from a rooftop air conditioning cooling tower located directly across the street from an area of recent excavation.

The identification and elimination of a potential lead hazard in an urban park.

During development of a park in Oakland, California, a potential public helath hazard due to lead in the soil (approximately 1,000 to 100,000 ppm) was identified through cooperative sampling and analysis efforts of the staffs at the county and state health departments. Analysis of samples collected at various locations and depths in the park, coupled with a three-dimensional model of the lead values obtained, indicated steps necessary to eliminate the hazard. The county undertook the abatement program, and with the elimination of the health hazard, the park development has been completed. Concomitant blood lead screening of neighborhood children failed to establish the park as a source of elevated lead in any of the children tested.