Bundled fibres

Also, for parallel multichannel devices, the source image can be divided, and injected simultaneously into a number (for example up to eight) of output fibres. Alternatively for more demanding diffuse reflectance or diffuse transmission applications with much lower optical throughput the whole source image dimension can be used, but injected into micro- or macro-bundle fibre optics. 

Optical fibres can be used as single fibres or in the form of fibre bundles. Fibre bundles often are used as carriers for chemical receptor layers in optodes. Single fibres become increasingly meaningful for miniature chemical sensors. 

Fluoramphiboles were crystallized mainly in the form of fibres and needles, rarely as dissociated aggregates, which were formed by non-splited bundled fibres (Fig. 10, 11). By their size the fibres and needles in the basic mass were inferior to the crystals in the brush. Thinner crystals were obtained from the blend with serp>entinite, while the thicker ones -from pyroxenite. 

Neckaf, B., Das, D., (2006) Mechanics of parallel fibre bundles, Fibres Textiies in Eastern Europe, 14 (3), pp. 23-28... 

Figure 9.10 Interlocking of fibrils at the edge of a bundled fibre with adjacent hydration products (after Akers and Garrett [4]).

Tow A large bundle of fibres generally 10,000 or more, not twisted. 

In conclusion, wc have shown the interesting information which one can get from electrical resistivity measurements on SWCNT and MWCNT and the exciting applications which can be derived. MWCNTs behave as an ultimate carbon fibre revealing specific 2D quantum transport features at low temperatures weak localisation and universal conductance fluctuations. SWCNTs behave as pure quantum wires which, if limited in length, reduce to quantum dots. Thus, each type of CNT has its own features which are strongly dependent on the dimensionality of the electronic gas. We have also briefly discussed the very recent experimental results obtained on the thermopower of SWCNT bundles and the effect of intercalation on the electrical resistivity of these systems. 

In this case study, an enzymatic hydrolysis reaction, the racemic ibuprofen ester, i.e. (R)-and (S)-ibuprofen esters in equimolar mixture, undergoes a kinetic resolution in a biphasic enzymatic membrane reactor (EMR). In kinetic resolution, the two enantiomers react at different rates lipase originated from Candida rugosa shows a greater stereopreference towards the (S)-enantiomer. The membrane module consisted of multiple bundles of polymeric hydrophilic hollow fibre. The membrane separated the two immiscible phases, i.e. organic in the shell side and aqueous in the lumen. Racemic substrate in the organic phase reacted with immobilised enzyme on the membrane where the hydrolysis reaction took place, and the product (S)-ibuprofen acid was extracted into the aqueous phase. 

Many other opportunities exist due to the enormous flexibility of the preparative method, and the ability to incorporate many different species. Very recently, a great deal of work has been published concerning methods of producing these materials with specific physical forms, such as spheres, discs and fibres. Such possibilities will pave the way to new application areas such as molecular wires, where the silica fibre acts as an insulator, and the inside of the pore is filled with a metal or indeed a conducting polymer, such that nanoscale wires and electronic devices can be fabricated. Initial work on the production of highly porous electrodes has already been successfully carried out, and the extension to uni-directional bundles of wires will no doubt soon follow. 

More direct support for a role of free-radical species in the mechanisms underlying diaphragm fatigue was provided by Reid et al. (1992a, 1992b). They studied fibre bundles from rat diaphragm in vitro and demonstrated an apparent increase in intracellular (Reid et al.. 

An extra-bulbar olfactory pathway (EBOP) is present in teleosts and in some non-teleost genera. Olfactory fibres run within the medial forebrain bundle, and can be traced (by SBA lectin binding) beyond the olfactory bulb into areas such as the ventral telencephalon, and/or the preoptic nucleus (Hofmann and Meyer, 1995). The projection of the EBOP fibres is similar in the sturgeon, but in other non-teleosts the primary olfactory fibres reach diencephalic target nuclei. 

The two main olfactory tracts [Fig. 2.19(a)] comprise an ipsilateral bundle — in the lateral olfactory tract (LOT) — and some contralateral fibres in the anterior olfactory habenular tract (AOHT). The input from the MOS and AOS shows no inter-familial differences in the final brain locations, apart from minor anatomical variants (Schmidt, 1990). 

Using co-extrusion it is possible to make fibres with a nylon 6,6 inner core (Tm 264°C) and a nylon 6 outer shell (Tm 215°C). By applying pressure and heat between these two temperatures to bundles of these two fibres, a non-woven mat can be made. 

There is a number of alternative Raman imaging techniques these include using the Hadamard transform technique [25-27], and such as fibre-bundle image compression, which however is not yet commercially available [26-31]. However in the latter approach, the laser power on the sample could be high, since the beam is not defocused, and the possibility of sample damage increases. 

When the fibres are assembled into a bundle, another type of losses occurs. Each fibre consists of the core and the cladding and the latter should be kept as thin as possible so as much light as possible can be transmitted by the light-carrying cores. The fraction of the core surface per unit area is called packing factor and it depends on diameter of core, cladding and gaps between the fibres. 

The construction of the optoelectronic interface can be based on a silicon photodiode since analytical and reference wavelengths are from the visible and the IR regions, respectively. The signals can be filtered out by optical filters (then two photodiodes are required) or one photodiode can be synchronised with modulation waves of the LEDs used. Finally, silica optical fibres can be used as light waveguides. The choice between single fibre or bundle is determined by the application of the sensor. 

A single optical fibre cannot be a suitable tool for the last mentioned application as well as for many others arranged in the reflection layout. For these applications individual optical fibres are collected to sets - bundles. Such optical elements are particularly convenient for image transmission. In chemical sensing, fibre bundles can be employed for remote Raman, fluorescence or absorption spectroscopy4,40, for visualisation etc. The... 

Figure 5. Single-point IR sensor head layouts a transmission probe with fibre coupling b transflectance probe with variable pathlength and single fibre coupling c (diffuse) reflection probe with single illumination fibre and collection fibre bundle d two-reflection ATR probe with fibre-optic coupling e multi-reflection ATR probe (DiComp -type) f ATR fibre...

Figure 7. Exemplary Raman sensor layouts a reflection-type probe with single excitation fibre and collection fibre bundle b angular probe with internal laser diode c sensing fibre probe.

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