Sonic treatment

When the microencapsulated liposomes are left untreated the lipid bilayer provides a barrier to diffusion through which the entrapped protein does not pass until the liposomes gradually become leaky, primarily due to oxidation of the phospholipid side chains. This mechanism results in a delayed release. Triton or sonic treatment of the microencapsulated liposomes provide pulsed re ease. Since both detergent and sonication disrupt lipid bi ayers, the mechanism by which pulsed release is achieved may be that these stimuli initially disrupt the liposomes and then the lipid reforms around some of the protein solution inside the capsule, possibly in an altered lamellar form alternatively, the treatment could disrupt only the more susceptible liposomes, leading to two phases of release, first from the freed protein and later from protein that remained liposome-entrapped. 

This is a novel type of polymer effect due to a polymer chain shape where chemical bond stability is impaired by superimposed random shearing forces at some definite site of the molecule. A similar effect has been reported by Oster upon sonic treatment of tabacco mosaic virus where the polymer aggregates are dissociated75). 

The composite displayed a strong mechanical resistance, neither formation of fine powder nor nanofiber loss being observed after sonication treatments (weight loss lower than lwt.%). This indicates the strong anchorage of the carbon nano fibers on the macroscopic graphite felt, which is required to resist the industrial conditions of use. 

The use of elicitors can significantly enhance the production of metabolites. The elicitors are divided mainly in two groups. The biotic elicitors which are compounds of biological origin (e.g. fungal spores, fungal cell wall fractions, cellulase, chitosane) and the abiotic elicitors which include metal ions, high salt concentrations, UV radiations, sonication. Treatment of Hyoscyamus muticus hairy roots with 50-500 jig/ml of chitosane resulted in a 5-fold increase in the accumulation of hyoscyamine [84]. Similar results were obtained by Halperin and Flores [85] who obtained, with hairy roots of the same species, hyoscyamine up to 6-fold when elicited with mannitol. 

In regard to the cell-bound cellulase, however, no exact locality and function in the cell has been fully studied in general. The cells of Ps. fluorescens grown on 0.5% cellobiose were, therefore, fractionated principally according to the method of Burrous and Wood (5). At the same time, part of the same sample of cells was subjected to direct disintegration by sonic treatment and the sonicate was centrifuged to use as a standard for enzyme assays. The results are summarized in Table I. 

The mechanical stability was evaluated on the basis of the change of the PSD of each sample, determined either before and after 3-min sonication treatment by ultra-sound. Sonication was performed by a Hielscher Ultraschallprozessor UP 200s apparatus. 

In our study, no macroaggregates were found after experimental models were suspended in water. However, the various clayAf/- or Fe-/polyphenol interactions produced aggregates characterized by widely different texture and mechanical stability, as evaluated by the Particle-Size Distribution (PSD) of the solid phases determined before and after sonication treatments. 

All the compared models were sparingly soluble in water, with particular reference to the /-containing materials, albeit the sonication treatment significantly increased the amounts of both Al- and Fe- released in solution. Considerably higher amounts of Al- and Fe- were extracted by the other tested reactants. 

Fig. 3. Particle-size distribution of C-Al-pp and C-Fe-pp aggregates determined before (b.s.) and after (a.s.) sonication treatment.

Hua and Hoffinann (13) observed that the extent of CCI4 degradation was greater than 99% after 90 minutes of sonication treatment. The initial concentration was held constant in their etqreriments at 0.20 O.OS mM ( 300 mg/L). Loss of CG4 due to volatilization was found to be less tiian 2% in separately run control experiments conducted in the absence of sonication (52). The pH after sonolytic degradation of CCI4 was near 3.5 the principal products observed were OG, Cl, C2CI4, and C2CI6 (52). The distribution of products and chemical intermediates after 90 minutes of ultrasonic treatment is summarized in Table II below. 

Among purple bacteria, energy transformation rates are rather low in Rhodopseudomonas palustris (ATCC 11168) due to a weakly membrane-bound RpFi-ATPase. Cell breakage by high pressure or sonication treatment resulted in a crude chromatophore preparation with a lag phase of about 6 h where no energy induced uptake or phosphorylation rate could be observed (Fig.1), caused by RpFi-solubilization and passive H+ flow through the RpFi-leaks (1). The light-induced H+ uptake could be restored by N,N dicyclohexylcarbodiimide (DCCD) which seals the RpFi-leaks. 

Levy and Toury (1970) have determined the activities of several enzymes, in purified membrane and matrix fractions, isolated hrom liver mitochondria after successive digitonin and sonication treatments (Levy et al, 1967). The conditions of the experiments are not strictly comparable to those described previously, but the results are similar in indicating a lack of parallelism in the developmental behavior of mitochondrial enzymes—even enzymes from the same compartment. 

The hyperbranched PILs represent effective stabilizers in heterogeneous polymerization reactions. When employing water-soluble PEHO-ClImOTs as the emulsifier in the 2,2 -azobis(2-methylpropionitrile) (AIBN) initiated mini-emulsion polymerization of styrene, stable polystyrene (PS) latexes were obtained. Characterization by means of transmission electron microscopy (TEM) indicated the presence of spherical PS nanoparticles (see Figure 7.5). Further studies revealed that, by modifying parameters such as the PIL/monomer ratio and the duration of the ultra-sonication treatment prior to the polymerization, the mean diameter of the obtained PS particles can be varied from 40 nm to 110 nm. In contrast to PEHOClImOTs, the use of the low-molecular-weight ILs 1,3-dimethylimidazolium tosylate or 1-butyl-3-methylimidazolium tosylate did not result in the formation of stable latexes. 

Figure 7.10 Response of a PIL-stabilized ferrofluid prepared by phase transfer of magnetite nanoparticles from water into toluene by PEHO-ClSImOTs to a permanent magnet (left) and graphene nanosheets in toluene in the absence (a) and presence (b) of PEHO-C18ImOTs, 1 hour after mixing and ultra-sonication treatment (right).

Table 1 Differences in sonication treatments for the different dispersed 1.5 wt% PC/CNF nanocomposite samples analysis (reproduced with permission of John Wiley Sons, Inc., B. Lively et al., Polymer Composites [31]) ...

The role of the ribonucleoprotein particles which (presumably) are attached to the cytoplasmic membranes, and vdiich, according to the elegant experiments of McQuillen and co-workers (67) are the seat of nascent protein in vivo, has not been determined in the in vitro system. When, however the membrane preparations are subjected to sonic treatment and then centrifuged, it is uniformly found that the supernatant is devoid of activity, and the sediment (which would contain any existing nucleoprotein particles) retains some, albeit much reduced, activity. 

Physical characteristics Sensitive to sonic treatment and osmotic shock Sensitive to sonic treatment Stable when dry ... 

The mechanism of MWCNT de-entanglement is expected to be very similar to the one described for SWCNTs, although the initial state is different. Note that if the sonication treatment is too aggressive and/ or lasts too long, it can lead to local damage of the CNT walls, if not to CNT shortening. Local damage deteriorates both electrical and mechanical properties. At the end of the sonication process, a dispersion of mainly individual CNTs with adsorbed surfactant molecules on their surface is obtained. 

---