NanoWalker: a fully autonomous highly integrated miniature robot for nanoscale measurements

The aim of this project is to develop the smallest and most sophisticated wireless fully autonomous instrumented robot capable of subatomic movements. The robot named 'NanoWalker' should bring a new paradigm in the way instruments are built while providing a sophisticated platform for a new range of applications. The project involves primarily the investigation of a new legged locomotion based on piezo-actuators with advanced micro-assembly techniques applied to complex embedded electronic systems; the development of new miniature instruments, micro-manipulators, integrated behavior for controlling, searching and scanning at the atomic scale; and the development of a subatomic navigation system. Besides all the new technologies and techniques that we intend to develop and which will be applicable to many areas and systems, the NanoWalker should provide a suitable yet more flexible and powerful platform compared to traditional macro-scaled instruments. It is anticipated that this new form of highly integrated autonomous microsystem will be used as the main building block for a new generation of measurement and inspection systems. In this paper, the main components of the NanoWalker are briefly described.Seaver Institut

Glucose Starvation Boosts Entamoeba histolytica Virulence

The unicellular parasite, Entamoeba histolytica, is exposed to numerous adverse conditions, such as nutrient deprivation, during its life cycle stages in the human host. In the present study, we examined whether the parasite virulence could be influenced by glucose starvation (GS). The migratory behaviour of the parasite and its capability to kill mammalian cells and to lyse erythrocytes is strongly enhanced following GS. In order to gain insights into the mechanism underlying the GS boosting effects on virulence, we analyzed differences in protein expression levels in control and glucose-starved trophozoites, by quantitative proteomic analysis. We observed that upstream regulatory element 3-binding protein (URE3-BP), a transcription factor that modulates E.histolytica virulence, and the lysine-rich protein 1 (KRiP1) which is induced during liver abscess development, are upregulated by GS. We also analyzed E. histolytica membrane fractions and noticed that the Gal/GalNAc lectin light subunit LgL1 is up-regulated by GS. Surprisingly, amoebapore A (Ap-A) and cysteine proteinase A5 (CP-A5), two important E. histolytica virulence factors, were strongly down-regulated by GS. While the boosting effect of GS on E. histolytica virulence was conserved in strains silenced for Ap-A and CP-A5, it was lost in LgL1 and in KRiP1 down-regulated strains. These data emphasize the unexpected role of GS in the modulation of E.histolytica virulence and the involvement of KRiP1 and Lgl1 in this phenomenon

Fast shape memory alloy actuators

In this thesis techniques for fabricating fast contracting and relaxing shape memory alloy (SMA) fibers are presented. Shape memory alloy fibers have demonstrated the largest stress and highest power to mass ratio of any known actuator technology. However their practical application has been plagued by three major drawbacks, namely: (1) relatively slow expansion of the material despite rapid contraction; (2) problems of mechanically and electrically connecting to the material due to the violent nature of their contractions; and (3) low efficiency in the conversion of electrical energy or heat into mechanical energy. The work associated with this thesis has led to solutions to the first two problems allowing even sub-millisecond contraction-expansion cycle times, and fibers to be attached via light weight but high strength and high conductivity joints. The properties of these fibers are extensively studied. Both linear and rotary actuators are built using these fibers.A new technique is presented to mount nickel-titanium (NiTi) SMA fibers. NiTi alloys are not readily bonded, soldered, brazed or welded to other materials. The new method employs metal deposited on the fiber or between two fibers or between fibers and other parts, creating metallic attachments that are mechanically sound and electrically conductive. Furthermore a new process for the three-dimensional microfabrication by localized electrodeposition and etching has also been developed. This latter process, combined with the first process, can be used to integrate NiTi alloys in micro-mechanisms. The good electrical contacts as well as mechanical contact provided by the new attachment mechanisms are important, since they allow the rapid methods to be employed.Several apparatus were built to study the response of NiTi fibers, in particular to very fast current pulses. Experimental results were obtained to describe the response of the fibers, such as their speed, hysteresis, stiffness and resistivity, and show how these variables change dynamically as a function of time, temperature and stress. Other measurements important for the design of new actuators were done, such as those of efficiency when fast actuation with large current pulses is used.In the third part of the thesis a novel application for fast fiber actuators is presented in the form of a fast rotary motor for in-the-wheel car rotary motors

Micro-Scale III-V/Ge Multijunction Solar Cell with Through Cell Via Contacts

International audienc

Micro-Scale III-V/Ge Multijunction Solar Cell with Through Cell Via Contacts

International audienc

Genome evolution in yeasts.

Identifying the mechanisms of eukaryotic genome evolution by comparative genomics is often complicated by the multiplicity of events that have taken place throughout the history of individual lineages, leaving only distorted and superimposed traces in the genome of each living organism. The hemiascomycete yeasts, with their compact genomes, similar lifestyle and distinct sexual and physiological properties, provide a unique opportunity to explore such mechanisms. We present here the complete, assembled genome sequences of four yeast species, selected to represent a broad evolutionary range within a single eukaryotic phylum, that after analysis proved to be molecularly as diverse as the entire phylum of chordates. A total of approximately 24,200 novel genes were identified, the translation products of which were classified together with Saccharomyces cerevisiae proteins into about 4,700 families, forming the basis for interspecific comparisons. Analysis of chromosome maps and genome redundancies reveal that the different yeast lineages have evolved through a marked interplay between several distinct molecular mechanisms, including tandem gene repeat formation, segmental duplication, a massive genome duplication and extensive gene loss