California NanoSystems Institute
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December 04, 2007

Phaedon Avouris

Streaming Video

Carbon Based Electronics and Optoelectronics
As the scaling of silicon-based devices is approaching its limits, intense efforts are made to find new device platforms. One of the most promising systems is carbon nanotubes (CNTs). Although a variety of different electronic devices based on CNTs have been demonstrated, most of the emphasis has been placed on CNT field-effect transistors (CNTFETs). In these devices a semiconducting CNT molecule replaces silicon as the transistor channel. The resulting devices have superior characteristics, but also pose a set of new physics and technology challenges. In my talk I will discuss these issues and demonstrate solutions that allow the fabrication of not only individual devices with excellent characteristics, but also more complex integrated circuits, such as ring oscillators, based on a single CNT molecule.

In our effort on CNT optoelectronics we are mostly interested in the electrical production of excitations in CNTs. This we accomplish in two different ways. In one mode, excitations are generated by independently injecting electrons and holes in the channel of an ambipolar CNT field-effect transistor (FET). Radiative e-h recombination in such a system produces single nanotube molecule light sources. In a different approach we take advantage of the strong e-h interactions and weak electron-phonon interaction in CNTs that allows for efficient intra-CNT impact excitation by hot carriers under unipolar transport conditions. Our theoretical analysis shows that impact excitation rates are much higher in CNTs compared to 3D solids. Examples of naturally occurring and fabricated structures that emit unipolar electroluminescence will be discussed. Finally, we will discuss the inverse process of light absorption generated currents (photoconductivity) and photovoltage in CNTs and their potential uses.

November 27, 2007

Jonathan Dordick

Streaming Video

Directed Assembly of Functional Biomolecular and Nanoscale Architectures
Nature is unparalleled in its structural and functional diversity. Living organisms make fantastic materials under myriad conditions with properties we cannot emulate today using conventional approaches. In many cases, nature has provided us with a blueprint to design and assemble both natural and synthetic building blocks to create a new generation of functional, organized, and responsive materials. We have taken cues from nature to design materials with unique structural and functional properties, along with new process technologies with the ability to produce a wide range of biomimetic structures. Specifically, we have focused on the generation of nanostructures that are functionalized with and in some cases constructed from biological molecules, complete with tailored selectivities and biocatalytic activities. In one example, we have incorporated enzymes attached to carbon nanotubes and further embedded into polymeric films, coatings, and paints to form biocatalytically active surfaces. In another case, we have used biocatalysis to generate small molecules that self-assemble with high precision to give novel architectures with functional properties. In this talk I will highlight our recent efforts to exploit the interface of biology with materials science.

November 13, 2007

Alex Zettl
Berkeley, University of California

Streaming Video

Nanomaterials for NEMS: Exploiting the unusual electronic, thermal, and mechanical properties of carbon and boron nitride nanotubes
Nanomaterials such as nanotubes and nanocrystals have unusual thermal, electronic, magnetic, and mechanical properties suitable for nanoelectromechanical systems (NEMS) and nanothermo-electromechanical systems (NTEMS) applications. This presentation will explore some of these properties and possible device implementations. Examples include high-frequency, high-Q oscillators, nanorheostats, tunable thermal links, and low-friction linear and rotational bearings.

Experimental results and theoretical models will be presented. A path toward integrating some of these functions together into a single useful device, such as for wireless communications, will be demonstrated.

November 06, 2007

Max G. Lagally
University of Wisconsin-Madison

Streaming Video

Semiconductor Nanomembranes: Science and Technology in Inexact Dimensions
Nanotechnology is almost completely defined by the structures that materials scientists, chemists, and physicists can create. The objects of desire of these researchers have led from buckyballs and quantum dots grown on surfaces to nanotubes, nanorods, and nanowires, and, most recently, to semiconductor nanomembranes, a class of nanostructures with exciting properties. Despite some early history in other materials, what has created the recent enthusiasm are silicon nanomembranes (SiNMs), because SiNMs promise to be the driver that can surmount roadblocks to launch Si device technology into a broader arena. SiNMs are extremely flexible, strain-engineered, thin single-crystal sheets, with thicknesses from several 100 nm to less than 10 nm, with aspect ratios (thickness to lateral dimensions) like a bed sheet. Their novelty is several-fold: they are flexible, they are transferable to other hosts and bond easily, and they can take on a large range of shapes and inexact dimensions (tubes, spirals, ribbons, wires, and combinations) by engineering the strain and the geometry, but they still retain the outstanding features of single-crystal Si. I will describe several unique phenomena associated with SiNMs that we have discovered, with a discussion of a potential novel application in each case, including sensors, Si photonics, nanothermoelectrics, biological monitoring, and flexible electronics.

November 05, 2007

Massimiliano Zecca
Waseda University, Japan
Understanding Human and Humanoid Motions and Emotions
The average age of the Japanese population is rising fast because of an increased life expectancy and a reduced birth rate. In this aging society, it is expected that there will be a growing need for home, medical and nursing care services, including those provided by robots, to assist the elderly both on the physical and the psychological levels. These new devices should be capable of smooth and natural adaptation and interaction with their partners and the environment, should be able to communicate naturally, and should never have a negative effect on humans, neither physical nor emotional. The concept behind all these devices is "partner". In particular, Partner Robots will act as human peers in everyday life and perform mental and communicational supports for humans as well as physical supports.

In this regard, human-robot communication and interaction (particularly in regard to the role of emotions) are extremely important, especially in the case of home and personal assistance for elderly and/or handicapped people. If a robot had a "mind" (intelligence, emotion, and will) similar to the human one, it would be much easier for the robot to adapt and interact with its human partners and the environment. Unfortunately, at present, we do not yet have sufficient knowledge and understanding of humans, and we do not know how to clearly define the criteria to evaluate these interactions.

To solve this problem, we should observe and analyze the human being, an extreme and exquisite example of robotic system. This could lead to the clarification of the basic mechanisms of the human neuromusculoskeletal system, and how its performance is related to emotional perception and expression. This, in turn, will be the core part of a huge range of extremely important applications involving the interactions between people and robots. The possible outcomes of this research for an aging society are tremendous.

The ultimate goal of these research activities is to provide the society with the tools necessary to improve and enhance the quality of life of elderly and disabled people: better health-care systems, human-support devices, teleoperation methods, and so on.

This video of emotion expressions will be the main topic of the talk: Video

To see all the videos and a further description of the robot, please visit this website: WE-4RII

October 30, 2007

Paul Goldbart
University of Illinois at Urbana-Champaign

Streaming Video

Superconductivity and Quantum Interference at the Nanoscale
Superconducting circuitry can now be fabricated at the nanoscale by depositing suitable materials on to individual molecules, such as DNA or carbon nanotubes. In this seminar I shall discuss a fascinating class of nanoscale superconducting circuits -- the nanoscale superconducting quantum interference devices (n-SQUIDs) -- describing how they are made and how they operate. I shall pay particular attention to the electrical resistance of these devices and, especially, its sensitivity to magnetic fields and patterns of supercurrent. These features hint at possible uses of n-SQUIDs, such as mapping the quantum phase of superconducting order and testing for superconducting correlations in novel materials and settings.

October 23, 2007

Darrin Pochan
University of Delaware

Streaming Video

Construction of Nanostructures and Materials through Peptide or Charged Block Copolymer Self-assembly
Bionanotechnology, the emerging field of using biomolecular and biotechnological tools for nanostructure or nanotechnology development, provides exceptional opportunity in the design of new materials. Self-assembly of molecules is an attractive materials construction strategy due to its simplicity in application. By considering peptidic or charged synthetic polymer molecules in the bottom-up materials self-assembly design process, one can take advantage of inherently biomolecular attributes; intramolecular folding events, secondary structure, and electrostatic interactions; in addition to more traditional self-assembling molecular attributes such as amphiphilicty, to define hierarchical material structure and consequent properties. First, design strategies for materials self-assembly based on small (less than 24 amino acids) beta-hairpin peptides will be discussed. Self-assembly of the peptides is predicated on an intramolecular folding event caused by desired solution properties. Importantly, kinetics of self-assembly can be tuned in order to control gelation time allowing for cell encapsulation. The final gel behaves as a shear thinning, but immediately rehealing, solid that is potentially useful for cell injection therapies. Second, synthetic block copolymers with charged corona blocks can be assembled in dilute solution containing multivalent organic counterions to produce novel micelle structures such as toroids. Micelle structure can be tuned between toroids, cylinders, and disks simply by using different concentrations or molecular volumes of organic counterion the kinetic pathway of assembly. The kinetics of block copolymer assembly can be specifically controlled to form hierarchically structured morphologies not possible through traditional block copolymer self-assembly.

October 16, 2007

Mildred Dresselhaus
Massachusetts Institute of Technology

Streaming Video

Why are we so excited about carbon and other nanostructures?
An overview of recent advances in carbon nanostructures research will be presented with special attention given to new directions and trends in the more mature area of carbon nanotubes as well as an overview of the rapidly growing areas of few layer graphene and graphene ribbons. Discussion will also focus on the complementary and contrasting properties of one dimensional nanostructures in general. As an example of such complementary and contrasting properties, the thermal and thermoelectric properties of low dimensional systems will be discussed.

October 09, 2007

Nicola Spaldin

Streaming Video

Exploiting nanoscale interactions to design new multiferroics and magnetoelectrics
The search for a general means to control the coupling between electricity and magnetism has intrigued scientists since Oersted's discovery of electromagnetism in the early 19th century. While tremendous success has been achieved in creating both single phase and composite magnetoelectric materials, the quintessential electric-field switching of magnetism remains a challenge. In this talk we will review the basic phenomenology of multiferroic materials - which combine magnetism and ferroelectricity in a single phase - and magnetoelectric materials, which exhibit coupling between the electric and magnetic orders. We will describe recent progress in both fields, and show how nanoscale phenomena, particularly the symmetry properties of interfaces in nanoscale heterostructures, can lead to enhanced effects. Finally we will discuss the many exciting opportunities for future work in multiferroics and magnetoelectrics.
October 02, 2007

Michael Jung

Streaming Video

BSCCF, Diels-Alders, and Drugs

The first topic to be discussed is the Bioscience Synthetic Chemistry Core Facility. This is a campus-wide resource established to help UCLA bioscientists with issues of medicinal

chemistry and drug discovery. It will be housed in the CNSI but at the moment is located in Dr. Jung's labs in the department of Chemistry and Biochemistry. Several collaborative

projects are already underway under the aegis of the BSCCF. Check out the BSCCF website.

The second part of the seminar will describe the discovery of a new mixed Lewis acid system (5:1 AlBr3:AlMe3) which allows one to prepare extremely hindered functionalized cyclohexenes, e.g., 3, via a normal or a reverse electron demand Diels-Alder reaction (including a stepwise Diels-Alder process). This process prepares compounds that would be extremely difficult to make by any other route. Its application to the synthesis of various natural products will also be presented.
 The third topic is the development of a super antagonist of the androgen receptor, RD-162 and its close analogues, which is now undergoing clinical trials for the treatment of

hormone refractory prostate cancer. The process by which the molecule was designed and tested for anticancer activity will be presented.