Cellulosics conservation

Chlorites have been used to pulp wood St other fibrous materials. The yield of pulp is high, because not only is cellulose conserved, but also the hemicelluloses remain in the pulp. Their presence gives unusual props to a pulp which becomes ready for making into paper with less mechanical treatment. An important use of Na chlorite is in the prepn of chlorine dioxide for direct use(See Refs)... 

Cellulose nitrate also has widespread use as an adhesive and coating material. Whereas stabilizers are added to products, eg, sodium carbonate as a neutralizer, many conservators are hesitant to use cellulose nitrate materials because of the inherent instabiUty and the dangers to the object from nitric acid, formed when the nitric oxide combines with moisture. 

This essay was written in an attempt to explain our overview of primary cell walls and to reach consensus on the nomenclature of primary cell wall polysaccharides. We present evidence supporting the hypothesis that cellulose, xyloglucan, arabinoxylan, homogalacturonan, RG-I, and RG-II are the six polysaccharides common to all primary cell walls of higher plants. In many cells, these six polysaccharides account for all or nearly all of the primary wall polysaccharides. Like the physically interacting proteins that constitute the electron transport machinery of mitochondria, the structures of the six patently ubiquitous polysaccharides of primary cell walls have been conserved during evolution. Indeed, we hypothesize that the common set of six structural polysaccharides of primary cell walls have been structurally... 

Aqueous uranyl sulfate system, 25 429 Aqueous varnish removal systems, in fine art examination/conservation, 11 413 Aqueous zinc chloride, as cellulose solvent, 11 272... 

Some clues may be available from studies of the decomposition of lignin. Lignin constitutes the second most abundant carbon polymer on earth after cellulose (46). The understanding of biodegradative pathways of lignin and lignin-cellulosic polymers may elucidate the problems of reduced plant productivity associated with surface residues in conservation production systems. 

The T. reesei enzymes could also be cleaved into separate domains by proteolysis, and this was discussed elsewhere (Claeyssens, M., and Tomme, P., this volume). Suffice it to emphasize here that the genes encoding cellulases in C. fimi and T. reesei appear to have arisen by domain shuffling and that the enzymes they encode appear to interact with cellulose in a comparable manner, i.e., a catalytic domain is held on the substrate by a binding domain. Cellulases from the bacterium Clostridium thermocellum also contained sequences analogous to Pro-Thr boxes as well as highly conserved carboxyl terminal sequences (2,17,18). It remains to be seen if they have functional organizations similar to those of the C. fimi and T. reesei enzymes. 

A characteristic feature of the SuSy isoforms is a conserved phosphorylated serine residue near the N-terminus [8-10]. In-vivo studies have demonstrated that phosphorylation and dephosphorylation direct the distribution of SuSy isoforms in the plant cell [10-12]. The soluble phosphorylated SuSy interacts with the actin cytoskeleton in the cytoplasm [13], and the dephosphorylated SuSy isoforms are targeted to the cell membrane to form complexes with other enzymes, e.g., glucan synthase, catalyzing cellulose biosynthesis from sucrose [4, 10, 14]. In this respect, recent studies on the dephosphorylated enzymes by cloning and expression of SMS genes in E. coli have shown differences in some biochemical features when compared to the enzymes isolated from the corresponding plant material. Recom-... 

Sulfate - pRUG DELIVERY SYSTEMS] (Vol 8) - [FIBERS-ACRYLIC] (Vol 10) - [CELLULOSE] (Vol 5) - [COALCONVERSION PROCESSES - CLEANING AND DESULFURIZATION] (Vol 6) - [COALCONVERSION PROCESSES - CLEANING AND DESULFURIZATION] (Vol 6) - [COALCONVERSION PROCESSES - CLEANING AND DESULFURIZATION] (Vol 6) - [COAL] (Vol 6) - [FILTRATION] (Vol 10) - [FINE ARTEXAMINATION AND CONSERVATION] (Vol 10) -in geothermal resources [GEOTHERMAL ENERGY] (Vol 12) -m phosphoric acids [PHOSPHORIC ACID AND PHOSPHATES] (Vol 18) -in steam [STEAM] (Vol 22)... 

Cellulose degradation in an acetic acid environment. Studies in Conservation, 45, 201-10. 

Feller RL, Lee SB, Bogaard J (1986) The kinetics of cellulose deterioration. In Needles HL, Zeronian SH (eds) Historic Textile and Paper Materials Conservation and Characterization. Advances in Chemistry Series 212. ACS, Washington DC, p 329... 

Fig. 5. CHARM predicted interaction between a 16 glucose cellulose chain and the CBM conserved residues.

The novel, conserved aromatic residue F476, which is characteristic of subfamily IIIc CBMs, was particularly interesting in the sense that it did not form a hydrogen bond with the cellodextrin chain, and as a consequence its interaction with the substrate seems to be weak. Therefore, computational studies were conducted on this residue, and the results indicated that mutation of F476 to Y created a hydrogen bond between the CBM and the cellulose chain. This was likely to improve binding, and thus it was selected for site-directed mutagenesis. 

A fuller understanding of the mechanisms by which cellulose Is degraded upon aging Is, of course, of major Importance to conservators. If the major process Is through add hydrolysis, then appropriate treatments, would take the form of deaddiflcatlon and alkalization. If, on the other hand, carbonyl species cause the most damage, reduction treatments would be more suitable. It may also be appropriate to combine both reduction and alkalization treatments QO). 

Extensive research has been published on the chemistry and physics of paper and textiles. From the volume of available work, physical scientists must extract the information required by conservators to assist them in the preservation of fibrous materials. To this end, the Cellulose, Paper, and Textile Division of the American Chemical Society has sponsored four symposia since the mid-1970s on the preservation of paper and textiles of historic and artistic value. These conferences provided a forum where conservators and physical scientists could meet and discuss matters of mutual interest Papers presented at the first three meetings have been published as chapters in three volumes of the Advances in Chemistry Series ... 

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