Cellulose spectrum

Dlmethyloldlhydroxyethylene urea (DMIMEU) Is used to Impart durable press properties to cellulose. Spectra of the treated cellulose, untreated cellulose and the difference between the two are shown In Figure 4. In this case the area under the curve between 1740 and... 

At the heart of the interpretation of the spectra is the postulate that sharper multiplet features associated with chemically equilvalent carbon atoms in the cellulose spectra are expressions of magnetically inequivalent sites within the unit cells. If this "fine structure" were due to some other cause, then the conclusion of multiple crystalline forms would be called into serious question. The fact that the ratios of multiplet intensities for given resonances, such as that of C4 or Cl, vary from sample to sample and rarely have ratios of small whole numbers, reinforces the crystalline composite hypothesis. 

The more dramatic spectral changes in Figure 6 are caused by strong acid hydrolysis, rather than beating. Spectra 6D and 6E appear to be "sharper-featured" (more crystalline) versions of the higher plant cellulose spectra (see Figures 2, 3 and 5). There is a dominant upfield shoulder at C4 compared to the downfield shoulder the central component of Cl is also greatly reduced. 

A survey of several native celluloses reinforced the similarity of the higher plant celluloses to one another, although limits of resolution and questions of chemical purity in the cellulose chains make comparison difficult and less meaningful. A parallel survey of NMR spectra from the more chemically pure algal celluloses and the bacterial cellulose, Acetobacter xylinum, indicated a general uniformity, albeit these spectra were distinct from the spectra of the higher plant celluloses. These algal cellulose spectra, however, showed small variations, outside of experimental error, which were taken as evidence for crystalline polymorphy. 

The structural differences between Ig and Ig are not understood yet. Atalla (18) compared the Raman spectra of various native celluloses with different Ig to Ig ratios. He also compared the native cellulose spectra with the spectrum of cellulose II. The spectra of... 

Two classes of experiments were conducted. In both sets of experiments, fibers in which the cellulose chains are oriented parallel to the fiber axis were used. In the first class of experiments, the plane of polarization of the incident light was changed relative to the axis of the fibers by rotating the fibers around the optical axis of the microscope (see Figure 2a). The dependence of the band intensities on the polarization of the incident light was studied to determine the directional character of the vibrational motions. This information was used to advance the assignment of the Raman spectrum of cellulose. Spectra from Valonia, ramie, and mercerized ramie fibers, which have different allomorphic compositions, were compared to study the structural differences between the allo-morphs. 

The cellulose I spectra were also compared with spectra of ceTTulose II recorded from a mercerized ramie fiber. Figures 7 and 8 show the Raman spectra of these three celluloses. Spectra were recorded with the electric vector of the incident light parallel and perpendicular to the chain axis. These spectra can be divided into two regions. The region below 1600 cm (Figure 7) is most sensitive to the conformation of the cellulose backbone (especially below 700 cm" ). 

The most significant difference between the two native cellulose spectra in the low frequency region is that the intensity of the peak at 913 cm is greater in the ramie spectra. This peak is also more intense in the spectrum of bacterial cellulose than in the... 

A series of eight THPOH-NH3 treated fabrics was examined. The spectra of the untreated cotton, the treated cotton, and the difference spectrum obtained subtracting the untreated cellulose spectrum from that of the treated fabric as obtained on the FTIR are shown In Figure 2. It Is very difficult to distinguish the 1655... 

Figure 6 shows spectra of five preparations of algal celluloses obtained from Cladophora spectrum A is from the original purified cellulose, spectrum B is that of the same cellulose beaten in a Waring Blender for 5 h while dispersed in water at 1 solids consistency, spectrum C is like B except that the beating was carried out at 3 solids consistency, spectrum D is that of the beaten cellulose in spectrum B following acid hydrolysis in 4N HCl for 44 h at 100 C (22 mass recovery), and... 

Figure 11 illustrates the application of this technique to a sample of Rhlzoclonlum cellulose. Spectrum llA and IIB are different only in that the low-level comb of c Dante pulses is absent (llA) or present (IIB). Proton decoupling was applied for 20ms during the Dante sequence this decoupling was also present in the experiment without the Dante pulses in order to make comparison between these two experiments most meaningful. 

Figure 29 Stackplot spectra of medieval parchment vellum from cantoral No. 3 in the Biblioteca at Valladolid the spectrum of the repaired vellum indicates no proteinaceous features and a clear match with the cellulose spectrum from a natural cotton boll. Wave-number region 2700-...

The pattern of variation of the multiplets differ among the samples. The relative intensities are not constant and they are not in the ratios of small numbers as would be expected if they arose from different points within a single unit cell. The spectral intensities are also not consistent within a single unit cell. The spectral intensities are also not consistent with the possibility of three independent crystal forms. According to Atalla therefore a model based on two independent crystalline forms seems most possible. In Fig. 5, the spectrum of pure cellulose II is given. 

The Fourier Trairsform Infrared (FTIR) spectrum obtained from non-adapted tomato cell walls is very similar to that from the onion parenchyma cell wall (both contain cellulose, xyloglucan and pectin) although there is more protein in the tomato walls (amide stretches at 1550 and 1650 cm-i) (Fig 4). In DCB-adapted tomato cell walls, the spectrum more closely resembles that of either purified pectins or of a commercial polygalacturonic acid sample from Sigma with peaks in common at 1140, 1095, 1070, 1015 and 950 cm-t in the carbohydrate region of the spectrum as well as the free acid stretches at 1600 and 1414 cm-i and an ester peak at 1725 cm-k An ester band at 1740 cm-i is evident in both onion parenchyma and non-adapted tomato cell wall samples. It is possible that this shift in the ester peak simply reflects the different local molecular environment of this bond, but it is also possible that a different ester is made in the DCB-adapted cell walls, as phenolic esters absorb around 1720 cm-i whilst carboxylic esters absorb at 1740 cm-k The... 

We used modifications of the standard solid-state CP-MAS (cross-polarisation, magic-angle spinning) experiment to allow the proton relaxation characteristics to be measured for each peak in the C spectrum. It is known that highly mobile, hydrated polymers can not be seen using either usual CP-MAS C spectrum or solution NMR (6). We found, however, that by a combination of a long-contact experiment and a delayed-contact experiment we could reconstruct a C spectrum of the cell-wall components that are normally too mobile to be visible. With these techniques we were able to determine the mobility of pectins and their approximate spatial location in comparison to cellulose. 

Both the 2, helix and the 3, helix are represented in the low mobility spectrum of polymers close to cellulose (figure 4), although there was some interference from xyloglucan signals. 

If cellulose exists in the cell wall as a network within a pectic matrix, the pectin that is within about 2nm of the cellulose network maybe on or near exposed surfaces of cellulose microfibrils. Both the gel and the eggbox pectins are represented in this low mobility spectrum. 

Vertical surface collectors can readily provide information on relative drift (e.g., the amount of drift from one field trial compared to another). However, it is difficult to obtain absolute data unless the precise collection characteristics are known for the droplet size spectrum at the point of spray collection, wind speed and air turbulence intensity. " The SDTF conducted studies in wind tunnels to compare the collection efficiency of different types of drift collector used in its field studies. These studies showed that collection efficiency on strings was several orders of magnitude higher for 0.8-mm diameter cotton string than for 2-mm diameter polyethylene line and vertical o -cellulose strips or squares. The higher collection efficiency for the cotton... 

Herzog and Janke (46) found that the intensity of the X-ray spectrum of the wood and of the cellulose in the wood was the same. Thus, they suggested that cellulose is not chemically combined with the lignin of the wood. 

All polymers utilized in this investigation have been listed in Table 2, along with their supplier and the concentration range over which they were tested. Polymers were either used as received or purified by filtration through a 0.22 or 0.45-pm MiUipore cellulose acetate membrane. For aseptic applications autoclaving was carried out for 20 min at a temperature of 121 °C. Qualitative properties of each polymer are listed in Table 3. For polymers supplied as solutions, dialysis was carried out in membranes (Spectrum Medical Industries, Houston, TX) with a MWCO of 10,000 daltons. 

The 13C-n.m.r. spectrum of 0-(2-hydroxyethyl)cellulose partly degraded enzymically (d.s. 0.8) in D20 at 30° (see Fig. 39,B) was similar, except for the region arising from the substituent, which is [-0-(CH2-CH2-0) -CH2-CH20] with n = 2 or 3. Because the spectral shifts occurring on 0-(2-hydroxyethyl)ation are close to those caused by O-(carboxymethyl)ation, a pattern of O-substitution similar to those already discussed was present. 

The elution profile of cytochrome P-448 (absorption at 418 nm) and epoxide hydratase activity from a sodium cholate-solubi-lized hepatic microsomal preparation (from DBA-treated male skates) applied to a DEAE-cellulose column and eluted with Buffer II is shown in Fig. 3. The void volume of the column contained significant amounts of epoxide hydratase activity. Fractions 40-70 (Fig. 3) were combined, and concentrated. The carbon monoxide difference spectrum, which had an absorption maximum at 448 nm in the induced state, is shown in Fig. 4. This form of the cytochrome (i.e.,... 

Fig. 7.15. Ammonia-Py-DCI mass spectrum of cellulose and total ion current. Adapted from Ref. [91] by permission. Research Council of Canada, 1994.

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