Optical fibers coated with non-linear Langmuir-Blodgett films

We report second harmonic generation (SHG) in structures composed of optical fiber cores coated with Langmuir-Blodgett non-linear films. Such structures may serve as attractive alternatives to currently available coated slab non-linear waveguides. The fabrication of frequency doublers, couplers and modulators on optical fibers would eliminate the difficult problems of coupling from planar signal conditioners, sensors and detectors onto fiber transmission systems. In addition, the small size of fibers allows for the high energy densities required for non-linear interactions to exist over large distances.

Our results confirm that fibers can be coated and the deposition ratio monitored, provided that a sufficient number are dipped simultaneously. The dependence of SHG on distance as well as the variation with number of layers for a hemicyanine dye deposited on multimode fiber cores are discussed.     

The Use of Synchronous Demodulation for the Measurement of Eye Movements by Means of an Ocular Magnetic Search Coil

This paper describes an eye position monitoring system that can be built using inexpensive components for the demodulator. It uses a two-frequency (f and 2f) technique which provides excellent channel separation with a miinimum of adjustment and wide dynamic signal range. Phasing errors produce no crosstalk effects for a pure sine-wave signal. It should be noted that this system will also work as a single-frequency two-phase system, merely by changing the driver unit.     

The Pneumatic Biped “Lucy” Actuated with Pleated Pneumatic Artificial Muscles

This paper reports on the bipedal robot Lucy which is actuated by pleated pneumatic artificial muscles. This novel actuator is very suitable to be used in machines which move by means of legs. Besides its high power to weight ratio the actuator has an adaptable passive behavior, meaning the stiffness of the actuator can be changed on-line. This allows to change the natural frequency of the system while controlling angular joint positions. The main control concept intended for Lucy is joint trajectory control while selecting appropriate actuator compliance characteristics in order to reduce control efforts and energy consumption which is of great importance towards the autonomy of legged robots. Presently Lucy has made her first steps with the implementation of basic control strategies.The pleated pneumatic artificial muscle and its characteristics will be discussed briefly and the design of Lucy which is made modular on mechanical as well as electronic hardware level will be described in detail. To pressurize the muscles, a lightweight valve system has been developed which will be presented together with the fundamental control aspects of a joint actuated with two antagonistically setup artificial muscles. Additionally the first experimental results will be shown and briefly discussed.Björn Verrelst (1972) Study of Mechanical Engineering at the Vrije Universiteit Brussel, graduated in 1996. Since 1998 researcher and teaching assistant at the Vrije Universiteit Brussel. The focus of his research is the use of pneumatic artificial muscles in the walking biped Lucy for dynamically balanced walking.Ronald Van Ham (1976) Study of Electro-Mechanical Engineering at the Vrije Universiteit Brussel, graduated in 1999. Since 1999 researcher and teaching assistant at the Vrije Universiteit Brussel. The focus of his research is the use of adaptable compliance of pneumatic artificial muscles in the walking biped Lucy.Bram Vanderborght (1980) Study of Mechanical Engineeringat the Vrije Universiteit Brussel, graduated in 2003. Since 2003 researcher at the Vrije Universiteit Brussel, supported by the Fund for Scientific Research Flanders (Belgium). The focus of his research is the use of adaptable compliance of pneumatic artificial muscles in the dynamically balanced biped Lucy.Frank Daerden (1966) Study of Mechanical Engineering at the Vrije Universiteit Brussel. Ph.D. in Applied Sciences, Vrije Universiteit Brussel, 1999. Research and teaching assistant at the Vrije Universiteit Brussel, 1991–1999. Doctor-Assistant at the dept. of Mechanical Engineering, Vrije Universiteit Brussel since 1999, visiting Professor since 2003.Dirk Lefeber (1956) Study of Civil Engineering at the Vrije Universiteit Brussel. Ph.D. in Applied Sciences, Vrije Universiteit Brussel, 1986. Professor at the dept. of Mechanical Engineering, head of the Multibody Mechanics Research Group, Vrije Universiteit Brussel.Jimmy Vermeulen (1973) Study of Mechanical Engineering at the Vrije Universiteit Brussel. Ph.D. in Applied Sciences, Vrije Universiteit Brussel, 2004. Research and teaching assistant at the Vrije Universiteit Brussel, 1996–2004. Post-Doctoral researcher at the dept. of Mechanical Engineering, Vrije Universiteit Brussel since 2004. The focus of his research is trajectory generation and control of dynamically balanced legged robots.     

A general in situ hydrothermal rolling-up formation of one-dimensional, single-crystalline lead telluride nanostructures

In this study we demonstrate that one-dimensional (1D) nanostructured lead telluride (PbTe) can be synthesized in a hydrothermal reaction between lead foil and tellurium powder. The resulting materials were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The formation of the 1D structure can be explained by an in situ hydrothermal rolling-up mechanism whereby PbTe is formed hydrothermally and deposited on the lead substrate. The lead underneath the PbTe layer is then selectively etched by a cetyltrimethylammonium bromide solution, thus allowing the PbTe to roll up into 1D structures. This method can be extended to prepare other 1D tellurides, including CdTe, Cu(2)Te, and Ag(2)Te.     

Spray Drying of Lactobacillus plantarum WCFS1 Guided by Predictive Modeling

Shelf life of probiotic microorganisms can be retained by drying. Spray drying is an economically interesting alternative to freeze drying with that respect. However, the viability can decrease due to the drying process and testing it is laborious and expensive. This research shows that the viability of Lactobacillus plantarum WCFS1 during pilot scale drying can be predicted with kinetics gathered at a single droplet level. Using this approach, it could be demonstrated that the viability of L. plantarum WCFS1 during spray drying is mainly determined by the combination of temperature and moisture content during the first 0.5 seconds after atomization. The combination of a high moisture content and a high temperature appeared most detrimental to the residual viability. Moreover, it was found to be important to take into account the particle size distribution during atomization when predicting viability, since this has a large effect on the moisture content during this first 0.5 seconds. Finally, it was observed that shelf life during storage was mainly determined by the moisture content of the powder. A lower moisture content resulted in a higher viability. Above a moisture content of 6%, shelf life stability rapidly decreased in the applied maltodextrin (DE = 16) matrix.     

Scytodecamide from the Cultured Scytonema sp. UIC 10036 Expands the Chemical and Genetic Diversity of Cyanobactins

Cyanobactins are a large family of cyanobacterial ribosomally synthesized and post-translationally modified peptides (RiPPs) often associated with biological activities, such as cytotoxicity, antiviral, and antimalarial activities. They are traditionally described as cyclic molecules containing heterocyclized amino acids. However, this definition has been recently challenged by the discovery of short, linear cyanobactins containing three to five amino acids as well as cyanobactins containing no heterocyclized residues. Herein we report the discovery of scytodecamide ( 1 ) from the freshwater cyanobacterium Scytonema sp. UIC 10036. Structural elucidation based on mass spectrometry, 1D and 2D NMR spectroscopy, and Marfey's method revealed 1 to be a linear decapeptide with an N-terminal N-methylation and a C-terminal amidation. The genome of Scytonema sp. UIC 10036 was sequenced, and bioinformatic analysis revealed a cyanobactin-like biosynthetic gene cluster consistent with the structure of 1 . The discovery of 1 as a novel linear peptide containing an N-terminal N-methylation and a C-terminal amidation expands the chemical and genetic diversity of the cyanobactin family of compounds.     

Reduced autonomy workspace (RAW)—an interaction design approach for human-automation cooperation

Cognition, Technology & Work - Lack of support for handling a reduction of autonomy in a highly autonomous automation may lead to a stressful situation for a human when forced to take over. We...