Swimming devices

Some bacteria boast a marvelous swimming device, the flagellum, which has no counterpart in more complex cells.8 In 1973 it was discovered that some bacteria swim by rotating their flagella. So the bacterial flagellum acts as a rotary propeller—in contrast to the cilium, which acts more like an oar. 

It is clear that there is enormous complexity within each ctenophore plate it would be a herculean task to reproduce the molecular motor of each cilium and to assemble literally millions of these mechanisms into a ctenophore-like swimming device. It is possible, however, to distill and mimic key features of the actuator and control system ... 

The experimental and theoretical results provided here suggest that, depending on the force, displacement and speed requirements of a practical device, the geometric parameters and shape of the actuator can be optimized suitably to satisfy the device requirements. As a case study, a swimming device propelled with the bending type actuators is presented next to demonstrate the influence of the actuator geometry on a functional system. 

As reported before [65,66,67,68,69], when designing a swimming device, there are two paramount factors to consider (i) the shape, mechanical properties and the locations of propulsors/fins on the device and (ii) their movement pattern. Fish is a good example to... 

Figure 10.18 The prototype swimming device with poiymer actuators as the propuision elements - fins (Reproduced with permission from Bioinspir. Biomim., Establishment of a biomimetic device based on tri-layer polymer actuators-propulsion fins by Alici, G., et a., 2, SI8-30. Copyright (2007) lOP).

Fig. 16 (a) Configuration of the prototype swimming device articulated with tri-layer polymer actuator and (b) the input voltage applied to each fin consecutively with a delay (Alici et al. 2007)... 

The swimming devices with bending actuators powered and controlled robotic fish as the caudal fins. The microrobotic atm made of the PPy microactuators could grab and lift a glass bead. Based on the unique characteristics of low activation voltage and biocompatibility, the bending actuators can be used as the steerable catheters, guide... 

Contamination of silicon wafers by heavy metals is a major cause of low yields in the manufacture of electronic devices. Concentrations in the order of 1011 cm-3 [Ha2] are sufficient to affect the device performance, because impurity atoms constitute recombination centers for minority carriers and thereby reduce their lifetime [Scl7]. In addition, precipitates caused by contaminants may affect gate oxide quality. Note that a contamination of 1011 cnT3 corresponds to a pinhead of iron (1 mm3) dissolved in a swimming pool of silicon (850 m3). Such minute contamination levels are far below the detection limit of the standard analytical techniques used in chemistry. The best way to detect such traces of contaminants is to measure the induced change in electronic properties itself, such as the oxide defect density or the minority carrier lifetime, respectively diffusion length. 

Examples of some of the current uses for these adhesives include retention of automotive gaskets, weather stripping, side trim, and wiring harnesses athletic shoes swim masks shotgun recoil pads arrow feathers dolls and doll furniture circuit board component mounting and wire tacking and lipstick tube and compact mirrors. Aledical devices include balloon catheters and tubing sets the adhesives are used by morticians to seal eyes and lips. 

Hebert, M., A. Evenson, L. Lumley and J. Meyerhoff. 1998. Effect of acute social defeat on activity in the forced swim test parametric studies in DBA/2 mice using a novel measurement device. Aggress Behav 24 257-69. 

Microfluidic device can be used to sort cells. Fluorescence-activated cell sorter (FACS) machines have been scaled down to chip size. Single cell manipulation at a high speed is made possible by the fast response time of an integrated piezoelectric (PZT) actuator. Cells are sorted on the detected optically expression [46]. Cells can also be separated in an electric held on the basis of electrically distinguishable phenotypes [47]. Other cell sorters look at the fitness of the cell. For example, semen can be fractionated by their ability to swim through interfaces between adjacent laminar streams into separate streamlines, which enables isolation of motile, morphologically normal spermatozoa from semen samples [48]. This resulted in a microscale sperm sorter in which high-quality sperm can be isolated and used for in vitro fertilization [49]. 

Scientists are examining the natural world to find supersensitive detectors because many organisms are sensitive to tiny amounts of chemicals in their environments—for example, the sensitive noses of bloodhounds. One of these natural measuring devices uses the sensory hairs from Hawaiian red swimming crabs, which are connected to electrical analyzers and used to detect hormones at levels as low as 10 g/L. 

Low-temperature irradiation devices are used with increasing frequency, especially to study radiation-induced defects in solids. A liquid-nitrogen irradiation device, which has operated for over 15,000 hours, has been described previously P]. However, certain defects anneal out or are transformed well below 77 °K and their study requires irradiation at lower temperatures. Two liquid-helium [ " ] and one liquid-hydrogen [ ] reactor irradiation devices have been reported in the literature. This paper describes an irradiation device at the temperature of boiling neon, which was installed in the Melusine swimming-pool reactor of the Nuclear Research Center of Grenoble. 

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