Pretreatment alkaline

Utilization of resonance effects can facilitate unenhanced Raman measurement of surfaces and make the technique more versatile. For instance, a fluorescein derivative and another dye were used as resonantly Raman scattering labels for hydroxyl and carbonyl groups on glassy carbon surfaces. The labels were covalently bonded to the surface, their fluorescence was quenched by the carbon surface, and their resonance Raman spectra could be observed at surface coverages of approximately 1%. These labels enabled assess to changes in surface coverage by C-OH and C=0 with acidic or alkaline pretreatment [4.293]. 

The possible benefits of prescouring to remove such contaminants should also be considered. Alkaline pretreatments, including boiling off of cotton, have a profound effect on AOX values after chlorite bleaching (Tables 10.21 and 10.22). It can be beneficial, from the viewpoint of both AOX and whiteness, to follow a chlorite bleach with a peroxide treatment. Linen yarns after an alkaline scour and chlorite bleach gave a whiteness value of 63.9 with an unacceptably high AOX value of 8.0 ppm. These results were improved to 78.5 and 1.2 ppm respectively after peroxide treatment [224]-... 

Cai, M., Liu, J., and Wei, Y. 2004. Enhanced biological production from sewage sludge with alkaline pretreatment. Environ. Sci. Technol.,38,3195-3202. 

Among these numerous factors some are detrimental to hydrogen spillover, especially 02 and CO, or limited contact between the source and the acceptor (cases B and C in Fig. 1). When carbon is the acceptor, an acidic or alkaline pretreatment does not affect subsequent spillover experiments. Added water is either an accelerating promoter or without influence, though it may be formed from 02 in the system and in this case it lowers the rate of spillover (46). 

High-power ultrasound has the potential to increase the pore volume and to reduce the crystallinity of cellulosic biomass. The effect of ultrasound pretreatment on the microstructure of alkaline-pretreated corn stover is shown in Figures 14.5a and b. The pretreated stover sample showed significant disruption of the cell wall (Figure 14.5b). Thermal and chemical pretreatments (acid) make the cellulose more accessible to enzyme by opening up cleavage sites. Such pretreatments however, also... 

FIGURE 14.5 Scanning electron micrographs of alkaline-pretreated corn stover (a) control (nonsonicated) (b) sonicated for 40 s. 

Undesirable deactivation may be caused by high temperature and time, for example, caused by transport and storage and also by enzyme poisons such as certain surfactants (especially cationic ones), formaldehyde-containing products or heavy metal ions. An activation effect on cellulases was reported by Nicolai and co-workers. Alkaline pretreatment, low concentrations of selected non-ionic surfactants, polycarboxylic acids and polyvinyl pyrrolidone can enhance the bio-fmishing of cellulosics. 

Acid or alkaline treatments of particulate feeds have been shown to improve digester gas yields (17.22-25). Acid hydrolysis was not used in our work because severe reaction conditions are required, and there is considerable decomposition of the hydrolytic products under these conditions ( ). Dilute alkaline pretreatment was evaluated because alkali was shown to be more effective in promoting hydrolysis of cellulosic biomass than acid (17,26). It is postulated, for example, that sodium hydroxide breaks down the cross-linked lignin macro-molecules surrounding the cellulose fibers into alkali-soluble lower-molecular-weight units. In this way, the cellulose fibers are exposed for... 

Basic manufacturing procedures for animal glues generally involve alkaline pretreatment (for hide glues) or acidic pretreatment (for bone glues). The raw materials for hide glues... 

Mirahmadi K, Kabir MM, Jeihanipour A, Karimi K, Tahetzadeh M. (2010). Alkaline pretreatment of spruce and birch to improve bioethanol and biogas production. Bioresources, 5, 928-938. 

In a different approach, Csanyi et al. [15] attempted to show the importance of the bound penicillin to the continuing production of penicillinase, by removing the bound penicillin from cells by treatment at pH 9.5 in tris buffer. A correlation was found between loss of bound penicillin and decline in subsequent penicillinase production. The alkaline treatment also slowed the rate of penicillinase synthesis for about 20 minutes before a return to a steady rate occurred. The same alkaline treatment, applied for varying times to the cells before induction, affected the lag before penieillinase synthesis reached a steady state after the induction. In the extreme case quoted, 30 minutes of alkaline pretreatment delayed penicillinase synthesis for 60 minutes. The temperature of treatment was also critieal little effect was produced at 30°C or under. Reinduction by penicillin after an induced culture had been treated with alkaline tris was rapid, the rate of synthesis rising immediately to the new induced level. In view of the general disturbance to the cells caused by the alkaline treatment and the many factors that can affect penicillinase synthesis in B. cereus (see later sections), it cannot be concluded that the effect of the alkaline treatment demonstrates solely a link between the bound penicillin and penicillinase synthesis. 

Table 3A.6 Chemical composition of soluble organic dry matter during alkaline pretreatment of silver birch (Betulapendula) (% of initial dry matter) Component e 8 ...

Prior to chromatographic analysis of foods, acid or alkaline pretreatment is used to liberate nicotinic acid (Hengen and deVries, 1985). Katsui (1972) described a method for determining nicotinic acid in coffee. After extraction with HCl and decoloration with lead carbonate, the solution was spotted on chromatographic paper and developed in a mobile phase of -butanol-ammonia-water (100 2 16). Spots were visualized using cyanogen bromide and benzidine. This procedure is probably applicable to TLC on cellulose. 

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