Moving-wire

The melt flows from the extmder iato the die where it flows around the bend and around the core tube. On the far side of the core tube, it forms a weld. Melt sticks to and is pulled by the moving wire. Details of the sizes and shapes of the die parts ia contact with the melt are important ia obtaining a smooth coating at high rates. The die exit usually is the same diameter as that of the coated wire and there is Httle drawdown. Die openings are small and pressures iaside the die are high at ca 35 MPa (5000 psi). Wire takeup systems operate as high as 2000 m /min. 

Paper Production and Properties. During the paper production process, the wood pulp is mixed into an aqueous slurry, which is poured onto a continuously moving wire mesh and drained by gravity. Additional water is then squee2ed out of the paper by a felt web pressed from above. This pressed side, referred to as the felt side, has smaller, finer fibers and is therefore smoother. It is also the preferred printing side. 

The process itself often sets requirements on the ventilation parameters, and it also affects the ventilation—for example, by secondary flows coming from moving wires or trucks. A very special case is clean rooms, where the high purity requirements set strict target conditions for ventilation. 

Castro and Canselier [114] similarly used reverse phase HPLC with methanol-water containing a low concentration of nitric acid as eluent. Quantification was made possible by using a moving-wire flame ionization detector. 

In some respects, the detector comparable to the RI is the moving wire system. Here, the solution eluting from the column drips on to a wire, with roughly 3% remaining on the wire. 

Adsorption chromatography using small particle silica or alumina has also been employed in the separation of biologically meaningful substances. Phospholipids, for example, have been separated on silica (38). One of the big problems for such substances is detection, since many of the compounds are not U.V. active. Generally, the refractive index detector is employed for isocratic operation, and the moving wire detector for gradient operation. Formation of U.V.-active derivatives is also possible (39). 

Moving wire/belt Direct liquid introduction Thermospray Particle beam... 

Moving inject(LC) 565 Moving wire di ctor (LC) 593 Multidiaensional chroaatography 790... 

A low consistency suspension of fibres, pigments and chemical additives (thin stock) flows on to the moving wire mesh filtration medium of the paper machine where the wet web is formed. The water which drains away in this process (white water) is then recycled as far as it is practical to do so and is used to dilute the incoming high consistency suspension (thick stock). Retention can be considered either in overall terms or in terms of a single pass of the thin stock across the machine wire (first pass retention). For efficient operation, paper makers aim to achieve as high a first pass retention as possible, which they do by the use of retention aids. This reduces material losses and also assists in minimising the level of suspended solids in the effluent. 

Because little has been said concerning difficulties arising from derivati-zation of samples to render them suitable for GC analysis, replacement of GC by HPLC for non-volatile or thermally labile compounds is a possibility. However, the demands of reproducible solvent removal for a reliable LC-C-IRMS approach are formidable. Caimi and Brenna [685,686] have developed an instrument based on a moving wire transport system. The analytes are deposited on the wire as they elute from the HPLC column and, after solvent drying at 200 °C, are transported into an 800 °C combustion furnace loaded with CuO, where the resulting C02 is picked up by an He carrier stream and swept via a drying trap into the IRMS. 

The moving wire interface was developed by Scott et al., and the moving belt interface by McFadden et al. ° This was the first commercial interface for LC/MS, introduced in 1977. In both of the techniques, the eluent is deposited onto a stainless-steel wire, or a plate usually made of polyimide (known as Kapton), followed by the removal of the solvent in vacuum. The residual solid analyte is vaporized into an ionization... 

The moving wire device has a number of major shortcomings. Due to the small surface area of the stainless-steel wire, such as available from a 0.1 mm diameter wire, the device can only accommodate about 10 pL/min eluent which results in poor sensitivity. The system is difficult to operate in a continuous mode. Modification of the moving wire approach has led to the invention of a continuous moving belt, which offers improved transfer efficiency and therefore higher sensitivity. The moving belt interface is capable of handling up to 1 mL/min of mobile phase. 

An alternative to direct liquid introduction is the moving belt, or moving-wire, transport interface. Because all l.c. solvents are evaporated before the sample is transported into the ion source, fewer restrictions are placed on solvent type, flow rates, or buffer composition. This system has been used for analysis of mixtures of pentoses, hexoses, and disaccha-rides. ... 

Place the block of ice on the board and drape the wire across the top as shown in the drawing.The ice just beneath the wire will melt because of the pressure exerted by the wire. The melted ice above the wire then refreezes, trapping the downward-moving wire inside the ice. 

Maggs [36] developed an electron-capture detector (ECD) which was based 6n the moving wire transport system. This type of detector is now available commercially (Table 3.5). Nota and Palombardi [37] described a system in which the column eluent was continuously nebulized and part of which was directed into the interior of an ECD. 

Silica gel G (30), and Uni si 1 (31,32). All of these LC procedures are hampered by the absence of an adequate detection system. Although the lack of on-line detection has impeded the adaptation of the LC procedures to HPLC, preparative HPLC of glycolipids has been performed on silica SI 60 with post-column, off-line TLC detection (30) and with a moving wire detector (31). The procedure described below for per-O-benzoylation of glycolipids with benzoic anhydride in pyridine and DMAP as catalyst avoids N-benzoylation problem and provides a convenient method for the detection and preparative isolation of glycolipids. The application of this procedure for the isolation of 15 mg of glycolipids in a single HPLC run is described. 

Conversion of fiberboard furnish to board begins with the felting operation. Fibers suspended in a liquid or gaseous fluid are deposited on a moving wire and concentrated into an interfelted mat by the removal of the suspending fluid. Application of pressure between rolls or platens in the cold-press operation further reduces interfiber void space and expresses the forming fluid. 

A third type of paper machine is also utilized to a lesser extent the twin wire machine. Instead of depositing a fiber slurry onto a moving wire, the fiber dispersions are delivered into the gap of two moving wires. Machines of this type remove water from both top and bottom surfaces by pressure. Twin wire machines are capable of very high speeds. 

The following chromatograms were obtained with the Fractosil 200 silica gel and the Pye moving wire detector as shown in Figure 2. They were plotted by the computer. The axes are the response in millivolts versus time in seconds. When the computer reconstructed the chromatogram, the Y-axis could be magnified from 0 to 520 millivolts. 

Paper is made by slurrying cellulose fibers at a very low concentration and filtering off most of the water on the moving wire screen of a Fourdrinier machine. 

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