Interfacing multiple devices

Small compnter systems interface (SCSI) A cabhng and software protocol used to interface multiple devices to a computer system. These devices maybe internal and/or external to the computer itself. Several variations of SCSI exist. 

One current trend in modern analytical instrumentation is to use devices lhat connect to the computer via a USB port (see Table 4-4). The USB standard allows connection of up to 127 different devices in a simple, straightforward manner. C urrently. printers, cameras, disk drives, scanners, webcams, networking components, some data-acquisition systems, and some analytical instruments are available with USB interfaces. Some devices now include a FireWire connection. With these, several devices can be connected in series (daisy-chained) so that only one FireWire port is required for multiple units. Devices that require very high-speed connections, such as the data-acquisition board shown in Figure 4-12b. still require interface lioards that connect directly to the internal computer bus. 

Note that this is a very simplified case. A liquid junction, dual-layer insulator, trapped charges in the insulator, surface states at the insulator/semiconductor interface, channel doping profile, and multiple connecting metals have been omitted, for the sake of simplicity. They would be present in all real devices and situations, but would not affect the thought analysis in any significant way. 

Capillary Zone Electrophoresis. The primary advantage of capillary electrophoresis can be found in the simplicity of the instrument. Basic experimental components include a high-voltage power supply, two buffer reservoirs, a fused silica capillary, and a detector. The basic setup is usually completed with enhanced features such as multiple injection devices, autosamplers, sample and capillary temperature controls, programmable power supplies, multiple detectors, fraction collection, and computer interfacing. 

The second law of thermodynamics denies the possibility of processes in which the only change is transfer of heat from a higher to a lower temperature. The zeroth law deals with thermal equilibrium and thus, by implication, the direction of heat transfer. However, the zeroth law applies only to heat transfer at a single interface, whereas the second law can deal with processes in which devices accomplish the heat transfer. These devices can have multiple interfaces with the heat reservoirs and can change during the process, as long as their change is cyclic. 

In some cases, substrates and enzymes are not soluble in the same solvent. To achieve efficient substrate conversion, a large interface between the immiscible fluids has to be established, by the formation of microemulsions or multiple-phase flow that can be conveniently obtained in microfluidic devices. Until now only a couple of examples are published in which a two-phase flow is used for biocatalysis. Goto and coworkers [431] were first to study an enzymatic reaction in a two-phase flow in a microfluidic device, in which the oxidation ofp-chlorophenol by the enzyme laccase (lignin peroxidase) was analyzed (Scheme 4.106). The surface-active enzyme was solubilized in a succinic acid aqueous buffer and the substrate (p-chlorophenol) was dissolved in isooctane. The transformation ofp-chlorophenol occurred mainly at... 

---