H.C. Ørsted Lectures

Ice sheets, earthquakes and hydraulic fractures are on the agenda when Professor James R. Rice from Harvard gives Ørsted's autumn lecture entitled "Mechanics on our planet: Ice sheets, Earthquakes, Hydraulic fractures" at Technical University of Denmark. James R. Rice is Professor at Harvard University's School of Engineering and Applied Science and Department of Earth and Planetary Sciences. In recent years his research has focused on earth mechanics and the considerable environmental challenges posed by melting glaciers, earthquakes and landslides.

Mars Crustal Magnetism: Through the Lens Sharply, by Dr. John E.P. Connerney, NASA Goddard Space Flight Center. Mars has no global magnetic field of internal origin (a "dynamo"), but must have had one in the past when the crust acquired intense magnetization, presumably by cooling in the presence of an Earth-like magnetic field (thermoremanent magnetization or TRM). The Mars Global Surveyor (MGS) spacecraft, in polar orbit at about 400 km altitude, produced maps of the crustal magnetic field with extraordinary signal to noise. These maps yeild valuable insight.

Harvard Universitet

Learning from the concepts used by green plants photosynthesis, we have developed nanostructured systems affording efficient solar light harvesting and conversion to electricity and fuels. Solar cells using dyes or semiconducting nano-particles as light harvesters supported by mesoscopic oxide films have emerged as credible contenders to conventional p-n junction photovoltaic devices. Separating light absorption from charge carrier transport dye sensitized mesoscopic solar cells (DSCs) were the first to use a three-dimensional nanocrystalline junction for solar electricity production. The standard AM 1.5 solar to electric power conversion efficiency (PCE) has reached 12.9% for laboratory cells and 9.9 % for PV modules. PCEs over 25 % are attained under ambient and indoor light conditions. These features along with excellent long-term stability have fostered first commercial applications, the industrial production of DSC’s attaining presently the multi MW/year scale. Striking advances in the direct generation of fuels such as hydrogen from water and sunlight have been achieved by the judicious design of photosystems composed of nanostructured Fe2O3 or Cu2O.

Climate change is the most serious environmental challenge facing society in the 21st century. The International Panel on Climate Change concluded in 2007 that there is more than 90% probability that human activities are causing the observed changes in the Earth’s climate in recent decades. The average temperature of the Earth's surface has increased so far by about 0.8 degrees Celsius since the Industrial Revolution, and the frequency of extreme weather events such as droughts, floods and intense hurricanes is also increasing. The concentration of carbon dioxide, produced mainly by burning fossil fuels, has increased more than 30% since pre-industrial times. Carbon dioxide is one of several greenhouse gases (GHGs) that trap energy emitted by the Earth to outer space; other greenhouse gases also affected by human activities are methane and nitrous oxide. The consensus of informed experts is that the risk of causing dangerous changes to the climate system increases rapidly if the average temperature rises more than two or three degrees Celsius. Society faces an enormous challenge to effectively reduce greenhouse gas emissions to avoid such dangerous interference with the climate system. This goal can only be achieved by taking simultaneously measures such as significantly increasing energy efficiency in the transportation, building, industrial and other sectors, using renewable energy sources such as solar, wind, geothermal and biomass, and possibly developing and using safer nuclear energy power plants. Fossil fuels such as coal and petroleum can continue to be used beyond a transition period of about one or two decades, but only as long as the emitted carbon dioxide is sequestered and stored in underground reservoirs such as saline domes.

Stanford University School of Medicine

There is considerable interest in devising nanofabrication strategies that rely on the molecular self-assembly of complex fluids and materials. Our efforts over the past several years have been focused on devising strategies to drive and direct that self assembly, largely by developing multiscale modeling models and methods capable of predicting the structure and properties of complex fluids and materials under external fields, including confinement, electric fields, or flow fields. These models and methods can vary considerably in nature and level of resolution, depending on the system and issues of interest. In this presentation I will provide an overview of various modeling approaches, along with their usefulness and limitations, in the context of two distinct nanofabrication platforms of current interest. The first is concerned with the formation of ordered, defect-free block copolymer structures on nanopatterned substrates. A new mesoscopic formalism has been developed to describe the structure and dynamics of block copolymer blends and composites, and we use it to explain the effects of surfaces and different types of confining walls on the free energy (and the concomitant stability) of a variety of morphologies of interest for lithographic fabrication. Many of these morphologies represent non-equilibrium states that are accessed by specific processing routes, and simulations can be used to discern the boundaries between such states and stable, equilibrium morphologies. Some of the insights provided by our work have led to a number of applications that are currently being pursued by the semiconductor and data storage industries; a brief overview of some of those applications will be presented. The second application is concerned with the development of liquid-crystal based biosensors. A multiscale model has been used to design liquid-crystal based devices for detection of biological molecules or toxins. In one implementation, nanoscale particles self-assemble into highly regular structures, including chains, upon exposure to specific chemicals. In a different implementation, liquid crystal nanodroplets are shown to adopt distinct configurations upon exposure to specific analytes. As discussed in this presentation, the models can be used to explain the defects and transmission images that arise in laboratory experiments. Theoretical calculations and simulations can then be used to identify metastable states that are particularly responsive to external perturbations, thereby offering a route for preparation of systems that offer an enhanced response to external stimuli. A recent application of such ideas will be discussed in which sensors for detection of extremely low levels of endotoxin have been demonstrated.