Sonification time

Fig. 6.4. Ultrasonic degradation of poly(acrylamide) (PAAm), c=0.0045 g mM, =1.8 to 0.1 x10 g moM, of poly(acrylamide-co-acrylate) (PAAm/AAcNa), c=0.0045 g m My,=S.S to 0.06x10 g mo - of xanthan gum, c=0.0005 g m - My,= 43 to 2.1 xIO g moM and schizophyllan,c=0.001 g mM,/Ww=8.9 to 0.35x10 g mol Ultrasonic power output for PAAm and PAAm/AAcNa approx. 25 W cm", for xanthan gum and schizophyllan approx. 30 W cm". The molar mass reaches a constant value after longer sonification times. Data from [53]...

The molar mass of the degraded sample depends on the sonification time. This is shown for a hydroxyethylsulfoethyl cellulose (HESEC) in aqueous solution in... 

Fig. 6.6. Differential distribution of the molar mass M for a homologous series of ultrasonically degraded hydroxyethylsulfoethyl cellulose. The sonification time is given for each data set. Data from [55]...

Fig. 6.6. Accordingly, the molar mass shows an exponential decay with the sonification time. After 4 h a minimum molar mass of 40,000 g mol" is reached. Longer ultrasonification times do not lead to a further decrease of the molar mass.

The intrinsic viscosity as a function of the sonification time in Table 6.3 shows a similar progression as the molar mass. The intrinsic viscosity decreases exponentially with time and reaches the minimum value of 140 ml/g for this polymer and the chosen energy input. The polydispersity MJM also decreases sUghtly with the sonification time. 

Table 11.1 Cloisite Na, H2O (distilled) and glycerol d.001 spacing (A) for varying ratios at different sonification times...

Sonification time (minutes) 1 4 (clay water) 1 5 (clay water) 1 10 (clay water) 1 10 (clay glycerol) 1 10 10 (clay glycerol water)... 

A similar RP-HPLC method has been developed for the determination of isoflavones in soybean powder. Ground soybean powder (100 g) was extracted four times with 300 ml of hexane, then the defatted powder was extracted with six solvents or solvent mixtures such as acetone, methanol-water (4 1, v/v), methanol-ethyl acetate-acetone (1 1 1, v/v), acetone-0.1 M HC1 (5 1, v/v), methanol-water (4 1, v/v) plus 0.1 M HC1 (5 1, v/v), and methanol-ethyl acetate-acetone (1 1 1, v/v) plus 0.1 M HC1 (5 1, v/v). An aliquot of 0.5 g defatted or non-defatted soybean powder was shaken for 2h or sonificated for lh with 5 ml... 

Components of a photosystem can be inserted selectively into the lipid wall or the inner cavity of the vesicle. For this purpose the lipid and components insoluble in water are dispersed together in aqueous solution by sonification. This leads to an occlusion of water insoluble components within the lipid bilayer. The vesicle membrane is sufficiently stable and impermeable for a number of ions. This allows one to prepare, by gel-filtering, the media of different ionic composition inside and outside the vesicle as shown in Fig. 2b. Such asymmetry of chemical content can be preserved for a rather long time (from several hours to several days). Recently the surfactant molecules with double bonds, which can be polymerized after vesicle preparation, were used for further enhancement of vesicle stability [37-39]. Such polymerized vesicles are stable for several months. 

The use of sonification in reactions 120-123 involving short-lived carbon-11 increased markedly the yield and reduced the reaction times . 

The photoresist-patterned Si substrates were placed in a sample holder inside an appropriate reaction vessel (approx. 500 mL, home-built) and 2 g HMDS was added to the bottom of the glass vessel. The reaction took 30 min at room temperature. After silanization the substrates were immersed in a remover solution (5 min, Microposit 1165), washed with methylene chloride/acetone (1 1 v/v), then wiped with ethanol-soaked tissue (KimWipe), rinsed with water, and sonified in cyclohexane (sonification repeated three times, replacing the cyclohexane). Water contact angle 84775765° (advancing/static/receding). 

Precursors prepared with high intensity US show large particles (precursors II, 12). With increasing time of sonification the particles become smaller (13). The influence of temperature seems to enhance this effect (15). 

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