In serial mode

In order to collect data via the serial port or A/D in background mode, the computer must initiate a multi-tasked routine. The limitation of this approach is the software overhead it introduces and the risk of data loss should the computer crash. When the data logger is used in background mode, the computer could be turned off and back on while a run is in progress with no loss of data. 

MS/MS Duty Cycle Typical MS/MS analysis is a serial process, relying on the selection of precursors (peptides) in MS mode, followed by high-energy fragmentation in MS/MS. This process is termed data dependent acquisition (DDA). The duty cycle for the completion of MS and MS/MS cycles (the time necessary for MS/MS spectrum acquisition) is of primary importance. When the separation performance is viewed from the mass spectrometry perspective, the peak capacity can be characterized by the number of MS/MS scans, yielding successful... 

In a serial mode (Fig. 36.1), one experimental step (in catalysis research this is usually the preparation of the ligand or the catalyst) is repeated n times before moving on to the next step. The only difference with traditional research is that the complete experiment (synfhesis/testing/analysis) is carried out for a set of catalysts rather than for an individual species. For example, a library of ligands from the same class can be assembled via traditional organic synthesis prior to its testing in catalysis. (A library of compounds is a rather large collection of different compounds with some common features and usually the same function, for example triarylphosphines or imidazolidinones.) Ideally, the compounds in the library can be structurally varied in at least two positions to ere-... 

The DSP-16 can either be a master (called active in DSP-16 terminology) or a slave ( passive ). All the DSP-16s except the final mix DSP are in passive mode. They are fed clocks from the final mix DSP. This guarantees that all DSPs are on the same output clock. The final mix DSP also provides the left/right clock so that the channels are synchronized as well. The serial data output of the DSP-16 is fed to the serial data input of the next DSP-16 in line. All of the serial I/O is done via flat ribbon cables on the end of the cards. 

Phase 3 Digital To Host. A/D conversion moves into the laboratory device and BCD or ASCII digits are sent in serial or parallel to the host. The laboratory device now looks like a terminal. The controller operates in character interrupt mode. Logical extensions of this technology have followed the manner in which we interface terminals. The first interface is a single card interfaces and then multiple interfaces per card. However, both are interrupt driven and considerably load the CPU. The next logical step is a DMA or silo controller. There are "standards the RS-232-C (in many variations) and the IEEE-488. 

Many commercial photochemical reactor systems make use of the batch recirculation mode for the treatment of highly contaminated wastewaters of limited volume. On the other hand, cascades of photoreactor modules (in serial or parallel mode) allow the gradual treatment of contaminated water streams with a very high photon flow Op in total. Hence, there exist powerful photochemical waste-... 

In the serial mode, the digital word (number) is sent to the computer one bit at a time. Now a binary counter provides a parallel output since each of the output bits has its own data output channel and the value of each output bit is simultaneously available. To use a serial transmission scheme, this parallel output must be put into serial form. One way to accomplish this is to use a Universal Asynchronous Receiver Transmitter (UART). The detailed operation of the UART will not be given here as it is not germane to the subject of this book. It is sufficient to say that the heart of the UART is a shift register and the shift register is strobed by a signal from the computer that displaces the binary number, bit by bit, sequentially from the register to the computer. 

The parallel data transfer mode is simple to use and allows for greater flexibility than the serial mode. However, it requires numerous connections between the PIA and the A/D Converter, and is, therefore limited to those cases where the converter and computer are very close. This type of transmission is very popular in chromatographs which have a built-in dedicated computer. 

Safe Mode Starts Windows 2000 using only basic files and drivers (mouse, except serial mice monitor keyboard mass storage base video default system services and no network connections). Once in Safe Mode, you can restore files that are missing or fix a configuration error. 

Automated sample preparation can be accomplished by using a batch or a serial approach. In the batch mode, multiple samples are prepared and then transferred to the analytical instrument for measurement. In the serial mode, samples are prepared one at a time and the SP device is connected (integrated) with the analytical instrument only. 

The direct measurement of the nonbound fraction is attractive because of its simplicity and since it, in principle, allows the derivation of binding energies. The measurements can here take place in a parallel or serial mode (Fig. 7.7). The... 

The Hewlett-Packard (HP) 7686 PrepStation System workstation allows you to write a program that will condition, load, rinse, and elute your SPE columns (Fig. 10.4, Table 10.4). A dedicated DOS-based ChemStation computer system by HP is required to run the instrument. The software uses a Menu Selectable Approach. The instrument operates in a serial mode and works with HP s disposable SPE cartridges. Individual flow rates for condition, load, rinse, and elute are selected. The workstation may be used to perform volumetric dilutions, sample mixing, bar-code reading, evaporation, and derivatization. When used with an HP 1050 HPLC or HP 5890 GC direct injections are possible. The instrument is also available in a stand-alone... 

There are a few ways of linking the techniques of LC-MS and LC-NMR. The most common method is in a parallel mode by splitting the flow, e.g. 50 1, so as to direct the majority of it to the NMR due to its relative insensitivity. This means that the analytes are detected simultaneously by both detectors and possibly also by UV, which may actually be used as the trigger to begin detection by the NMR and MS modules. Alternatively, the rapidly acquired MS data can be used to direct the NMR experiments or vice versa. A second method of interfacing the two techniques is to use the serial mode or stopped flow mode, which enables more sensitive NMR experiments to be carried out. A recent development in stopped flow NMR is the inclusion of in-line solid phase extraction (SPE) after the LC. The SPE acts as a fraction collector for individual compounds. This trapping/ washing step can improve sensitivity several fold. A third method is fraction collection, where samples from the LC are collected in a loop for analysis later, perhaps after certain data have been reviewed. 

It is the intention of this chapter to illustrate the progress made to date through fast to ultrafast HPLC in a serial mode and then the development and application of parallel HPLC analysis to both of these separation modalities. 

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