1. Asbestos fibers were exploited commercially beginning in the early 20th century, with 50 million metric tons used between 1920-1970. Inhalation of asbestos fibers is associated with pulmonary fibrosis (asbestosis), lung and laryngeal cancers, and malignant mesothelioma, with a long latent period of 20-40 years. The 15-year cumulative mortality from malignant mesothelioma from 1994-2008 is 175,000 deaths.

    The physical and chemical properties of asbestos fibers related to carcinogenicity include fiber dimensions, surface reactivity, and biopersistence following inhalation into the lungs. Long, rigid fibrous materials trigger incomplete or frustrated phagocytosis by target cells in the lungs, resulting in impaired clearance and persistent release of reactive oxygen species and proinflammatory mediators. Direct intraperitoneal injection of carbon nanotubes has also been shown to induce malignant mesothelioma in mice. Carbon nanotubes have shapes and dimensions similar to asbestos fibers; however, their graphenic surface is hydrophobic, while crystalline mineral fibers are hydrophilic. Asbestos fibers and carbon nanotubes are biopersistent; however, carbon nanotubes can be chemically modified to accelerate their degradation by oxidants.

    Carbon nanotubes are a rapidly growing worldwide market, and production is projected to exceed 12,000 metric tons in 2016. At this early stage in commercialization, it should be possible to engineer less toxic, biocompatible, and biodegradable carbon nanotubes to minimize potential adverse health impacts.

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  2. In response to general interest in the events associated with the recent Fukushima disaster in Japan, the Division has scheduled Dr. Robert Budnitz as our speaker. Bob brings considerable expertise to the topic, having spent most of his scientific career involved with nuclear-reactor safety and radioactive-waste safety. Bob’s talk will describe (technically, but in laymen's terms) what happened at the Fukushima reactors during and after the disastrous March 11 earthquake and tsunami, what the radioactive releases have been and what they mean, and what the path forward seems to be at the site. The potential implications that these events might have upon the future of nuclear power in general will also be discussed.

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  3. Historical failure to recognise the connection between surface water and groundwater and to manage river and groundwater systems conjunctively has led to over allocation of water resources. Examples of river systems that have been depleted by groundwater pumping, for example, are well documented.

    Although conjunctive management of surface water and groundwater is preferred, it requires information on the magnitude of the interaction between the two reservoirs. While numerous different methods have been used to measure the exchange flux, the usefulness of many of these methods is limited by the very high spatial and temporal variability of the fluxes involved.

    Methods that have been used successfully to estimate spatial variations in groundwater discharge to streams, over scales of interest to water managers, include water and solute mass balances. Groundwater discharge to streams can be determined from differences between river flow gaugings made at different points along the river, and from measurements of conservative ion concentrations. Sensitivity is greatest, however, when tracers are used whose concentration in the groundwater greatly exceeds that in surface water. This condition is often best met for the naturally occurring radioactive element radon (222Rn). Since radon in surface water is lost by exchange with the atmosphere (which is low in radon), a large contrast in concentration with the groundwater is maintained.

    Measuring changes in groundwater discharge with time is more difficult, because the required frequency of measurements means that only parameters that can be measured remotely are suitable.

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  4. In this presentation, the earliest stages in the formation of a crystal will be discussed. For the example of stable prenucleation CaCO3 clusters, which can already be found prior to nucleation and even in undersaturated solution, it will be shown that an alternative crystallization pathway exists. Basic characterization of the clusters will be presented, and the driving forces for their formation will be discussed.

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  5. In arid and semiarid ecosystems, water availability is a primary driver of ecosystem processes. Water impacts on belowground processes result in large part from the interactions of indigenous microorganisms with soil water. Understanding and predicting how changing patterns of precipitation in California can be expected to impact carbon and nitrogen cycling processes requires integrating the understanding of the biophysics of water in soil, the physiological response mechanisms of soil microbes, and the dynamics of soil water, including the roles of plant evapotranspiration in soil-water dynamics. As soil dries, water film thickness begins to limit the diffusional supply of substrates, and microbes utilize a range of mechanisms to respond to and survive desiccation. Very dry soils experiencing rainfall events produce trace-gas pulses, and the response patterns of indigenous microbes delineate the trace gas dynamics as well as the nutrient cycling responses to wet up.

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Distinguished Scientist Seminar Series

LBNL Earth Sciences Division

The ESD Distinguished Scientist Series is a monthly seminar featuring eminent individuals from various disciplines in the scientific community whose research is outstanding, interdisciplinary, and of broad interest to strategic interest initiatives in…

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The ESD Distinguished Scientist Series is a monthly seminar featuring eminent individuals from various disciplines in the scientific community whose research is outstanding, interdisciplinary, and of broad interest to strategic interest initiatives in the earth sciences. Speakers normally spend a full day with researchers at Earth Sciences Division, LBNL, and the University of California, Berkeley.

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