Cellulose sheet

In a recent study, this so-called SPOT synthesis was applied for the preparation of pyrimidines [45]. The group of Blackwell described primarily the appropriate support modification of commercially available cellulose sheets (Scheme 7.28). The initial introduction of the amine spacer was achieved within 15 min utilizing micro-wave irradiation, as compared to 6 h by conventional heating. The acid-cleavable Wang-type linker was attached by classical methods at ambient temperature. 

Lesser et al (75) used cellulose sheets with fluorescent indicator, acetic acid/0.01M aqueous disodium edetate (3 97), and observed an Rf value of O.78 for hydralazine. On silica gel with fluorescent indicator, the Rf value was less than 0.05 with (a) chloroform/n-heptane/ acetic acid (6 4 1), and (b) cyclohexane/chloroform/ acetonitrile (1 2 1). 

Figure 11.22 represents a paper electrophoresis apparatus. The soaked cellulose sheet is sandwiched between two horizontal glass plates with the ends dipped into vessels containing more electrolyte solution. The electrodes are also dipped into these vessels, as shown. The sample is spotted in the center of the sheet, and the oppositely charged ions then have room to migrate in opposite directions on the sheet. Qualitative analysis is performed much as with paper chromatography, by comparing the distances the... 

Before 1800 Cotton, flax, wool, and silk fibers bitumens caulking materials glass and hydraulic cements leather and cellulose sheet (paper) natural rubber Hevea brasiliensis), gutta percha, balata, and shellac 1839 Vulcanization of rubber (Charles Goodyear)... 

The electrophoresis is run at 1000 V cvfor 30-45 min. After finishing, the cellulose sheet is dried in a stream of warm air. For visual detection of amino acids the cellulose sheet is sprayed with Soln. B and incubated in a drying oven at 110-120 °C until blue spots appear. Autoradiography or a Phospholmager detects P-labled amino acids. 

Mark the start with a pencil on a PEI Cellulose sheet (dimensions as in Protocol 3.1.2) and apply the samples with a microliter syringe or a pipet. 

The decorative plastic laminates widely used for countertops and cabinets are based on melamine—formaldehyde resin (see Laminates). Several layers of phenolic-saturated kraft paper are placed in a press and a sheet of CC-cellulose paper printed with the desired design and impregnated with melamine—formaldehyde resin is placed over them. Then a clear CC-cellulose sheet, similarly impregnated with the resin, is placed on top to form a clear, protective surface over the decorative sheet. The assembly is cured under heat and pressure up to 138°C and 10 MPa (1450 psi). A similar process is used to make wall paneling, but because the surfaces need not be as resistant to abrasion and wear, laminates for wall panels are cured under lower pressure, about 2 MPa (290 psi). 

Hawlisch, H., Muller, M., Frank, R., Bautsch, W., Klos, A., and Kohl, J. (2001) Sitespecific anti-C3a receptor single-chain antibodies selected by differential panning on cellulose sheets. Anal. Biochem. 293, 142-145. 

The results of irradiating the pora-quinoid structures (compounds 1-4) absorbed onto cellulose sheets are summarized in Figure 2. Examination of the photolysis data indicates that with the notable exception of 2-methoxy-l,4-benzoquinone the remainingpara-quinone model compounds did not cause any further darkening of the handsheets during irradiation. Indeed, several of the quinones exhibit a minor brightening response upon photolysis which could be attributed to a photo-bleaching effect, but the lack of a complete mass balance makes this conclusion tenuous. 

The peptides were synthesized as large spots (diameter about 0.6 cm) at high density, which can reach up to 1.9 fimol/cm2 (32). About 1000 peptides were synthesized per 20 x 29 cm cellulose sheet. After the final side-chain deprotection step, the membrane was washed and the peptides were cleaved from the membrane (33). At this point, the peptides still remain adsorbed onto the membrane but will dissolve once a liquid is added. The peptides were then punched out with a normal single-hole puncher, and the spots were transferred into a 96-well microtiter plate. Distilled water was added in each well to dissolve the peptides. 

Shoaf and Lium [103] used thin layer chromatography to separate algal chlorophylls from their degradation products. Chlorophyll is extracted from the algae with dimethyl sulphide and chromatographed on commercially available thin layer cellulose sheets, using 2% methanol and 98% petroleum ether as solvents, before determination by either spectrophotometry or fluorometry. 

Fig. 12.5. Flow diagram for manufacture of viscose yarn (1) cellulose sheets and caustic soda (2) steeping press (3) shredder (4) xanthating churn (5) dissolver (6) caustic supply (7) ripener (8) filtration (9) deaeration (10) filtration (11) continuous process (12) tire cord (13) pot spinning (14) staple spinning.

The cellulose sheets are loaded vertically, but loosely, into a combination steeping bath and press (Fig. 12.6), which is slowly filled with a solution of 17-19 percent caustic, where they remain for about 1 hr. In the steeping, the alpha cellulose is converted into alkali or soda cellulose at the same time, as already mentioned, the caustic solution removes most of the beta and gamma cellu-... 

These studies were later extended to the ignition of specially prepared cellulose sheets" as a model for the broad class of kindling fuels. These sheets were made from a single batch of wood a-cellu-lose, with various proportions of carbon black added to provide a variation in optical properties from white to black. The thickness of the sheet varied within the range of 0.002 to 0.03". Furthermore, the samples were prepared in two densities, which gave two different sets of heat-conduction properties. Thus, the experimental samples had the same chemical properties but a considerable latitude for variation in physical properties. The samples were exposed to constant thermal radiation at levels of 2—23 cal.cm. sec. , to establish the relationship between the threshold of ignition (with the exposure parameter) and the fuel properties. 

A solution of the adenosine derivative (2 mmol) in 1,0-1.6 M aq chloroacetaldchyde (20 mL) at pH 4.0 4.5 was stirred at 24-37 C for 12-72 h until no starting material was detectable by TLC (on Easterman chromatogram cellulose sheets using i-PrCOjH/NH OH/HjO, 71 1 24, v/v/v) and until the peak ratios 265/275 run became constant in the UV absorption spectra. The etheno product was decolorized with charcoal and evaporated to dryness in vacuo, Recrystallization of the residue by dissolving in a minimum amount of HjO, followed by addition of EtOH and EtjO to the cloud point or reprecipitation from aq EtOH followed by an EtOH wash yielded pure product (yield 90-95%). 

These include membranes made of liquid electroactive substances or with electroactive substances dissolved in a suitable non-volatile, water-immiscible solvent (mediator). In early designs, the organic phase was placed between two aqueous phases in bulk or with the support of a thin, porous cellulose sheet, sintered glass, or the like. As work with these sensors proceeded, more durable polymer supports were developed, most often poly(vinyl chloride) (PVC). An electroactive... 

Paper, or cellulose, electrophoresis was introduced in the early 1950s as a separation technique for proteins. Prior to the start of the electrophoretic run, the cellulose sheet is saturated with the running buffer and placed in a tank, as shown in Figure 9.5. The sample is then applied as a spot or a line, the tank is covered and the electric field is applied. After the separation has proceeded for a sufficient time, the paper is removed and dried. The separated components are then located by color, by fluorescence under UV light, or after staining with a dye. If the components have been radiolabeled, autoradiography of the entire paper will yield a separation pattern. 

Figure 9-2. NaOH and water absorbed by cellulose sheet at 25 C [13, 14]. 1-total alkali absorbed, 2-preferentially absorbed alkali, 3-water absorbed.

A different way to produce chemical microarrays in situ is spot synthesis of combinatorial libraries on cellulose sheets [56]. Spot synthesis is configured as an open system to be operated at room temperature. Despite attempts to replace cellulose with polypropylene as a synthesis support [57], cellulose is still the support of choice for spot synthesis, and reaction conditions have to be compatible with the restricted chemical stability of cellulose. Due to the acid labihty of such membranes, the diversity content of these arrays was initially restricted to the synthesis of peptides. Recently, a method was described that could widen the scope of spot synthesis arrays. Germeroth and coworkers [57] succeeded in the assembly of a library of 8000 cellulose-bound 1,3,5-triazines under mild reaction conditions. They employed a strategy that took advantage of a temperature-dependent, successive displacement of cyanuric chlorides by different nucleophiles in a first report of the synthesis of smaU organic compounds on ceUulose sheets. 

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