Rupture mechanisms

Screw presses were traditionally used for seeds and fruits that had to be mechanically ruptured to release the liquid in the seeds or cells... 

Protection against osmotic or mechanical rupture. The walls of neighboring cells interact in cementing the cells together to form the plant. Channels for fluid circulation and for cell-cell communication pass through the walls. 

In the pressure-jump method, the solution is pressurized, usually to several thousand atmospheres. At the desired moment a diaphragm is mechanically ruptured. The... 

On repeated freeze-drying of microgels with EUP-components an irreversible formation of an insoluble aggregate was observed [ 135]. It was supposed that this aggregation is due to radical reactions between adjacent microgel particles. The radicals are possibly formed by a mechanical rupture of chains due to stresses within the particles caused by freezing. 

Venting Venting is the process that is used to deal with liquids or liquefied compressed gases where a danger, such as an explosion or mechanical rupture of the container or vessel, is considered likely. The method of venting will depend on the nature of the hazardous material. In general, it involves the controlled release of material to reduce and contain the pressure and diminish the probability of an explosion. 

A number of plants of the Solanum and Nlcotlana genera are particularly adept at producing sticky leaf exudates. In some wild potato species, an exudate is discharged from glandular hairs when aphids mechanically rupture the cell walls (33). The clear, water soluble exudate is stable in the absence of O2,... 

The action of ultrasonic waves seems likely to be the result of mechanical rupture of the long chain molecules of nitrocellulose on being rubbed by the violently oscillating particles of solvent. Thus it is one of rare examples of depolymerization brought about by mechanical forces. Further evidence in favour of the supposition that mechanical forces may cause the substance to depolymerize is provided by the... 

In the first monolayer of conjugated model material, a model molecular solid or a polymer adsorbate, assume that no chemistry (covalent bonding) occurs, since, in the absence of, for example, mechanical rupturing, the bonds at the surface of the molecular film are completely satisfied. This assumption is supported by the fact that, at least for condensed molecular solids, vapor-deposited films may be re-evaporated (removed) from the surface by gentle heating in UHV. 

Preparation of DMS0-Soluble Starch-g-PAN Samples and Water-Soluble Starch-g-Polyacrylamide. Five grams of starch- -PAN (prepared by either ceric- or cobalt-60 initiation) was dispersed in 333 g of DMSO, and the dispersion was heated for 2 hr at 115°C. The cooled dispersion was then treated with ultrasound for 10 min to mechanically rupture gel particles and to render the polymer soluble (Branson Sonifier, Model S 125 ... 

Longobardi et al. [162] used chromatophores (specialized pigment-bearing structures obtained by mechanical rupture of the Rb. Sphaeroides) and liposomes in order to investigate the role played by the cytoplasmic bacterium membrane. They found that the SECM feedback process is mediated by membrane-bound redox species (Fig. 23b) and that the oxidant species inside Rb. Sphaeroides is most probably ubiquinone that resides in the cytoplasmic membrane pool. 

Thus, electron magnetic resonance is an important tool in the detection and structure analysis of radicals in polymeric systems (during formation, oxidation, irradiation, pyrolysis and mechanical rupture). From these patterns the chemical structure of the radicals may be derived. For the study of short-lived radicals flow systems have been developed. Free radicals in glassy polymers, however, may have an extremely long life. 

In this method the solution is pressurized to several thousand atmospheres. At a desired time a diaphragm is mechanically ruptured. The system then relaxes to the equilibrium position at atmospheric pressure. The magnitude of the concentration jump depends on the value of A V. For an equilibrium reaction with A V = 5 cm3 mol-1, the constant K will change by about 2 percent per 100 bars of pressure. 

Hard fats are used to coat water-soluble bioactives. Release occurs by heating above the melting point of the fat or by mechanical rupture. Fat coatings have been used for protecting many water-soluble materials, which may otherwise be volatilized or damaged during thermal processing and to deliver materials such as ferrous sulfate, vitamins and other minerals. The peptides of casein hydrolysates encapsulated in lipospheres were shown to have reduced bitterness (Barbosa et al. 2004). 

Several methods can be performed after the above protocol to obtain a certain size of liposomes for complexation with siRNA probe sonication can be used to reduce the size of liposomes by introducing a mechanical rupture of membranes however, probe sonication can create lipid breakdown or introduce pieces of titanium from the sonicator itself into the sample. 

It was observed for chloride-breakdown of the passive film on metallic iron in neutral borate solution that the amount of chloride ions required for initiating the local passivity breakdown is dependent on the film thickness, film defects, and electric field in the film as well as on the solution pH [41,42]. It was also observed that at the initial stage of the passivity breakdown the passive film locally dissolves and becomes thinner around the breakdown embryo before the underlying metal begins to dissolve in pitting at the passivity breakdown site [42,43]. From these observations, it is likely that the passivity breakdown is not a mechanical rupture of the passive film but a localized mode of dissolution of the passive film accelerated by the adsorption of aggressive anions on the film. 

Cell fractionation by mechanical rupture has already come under investigation. Two separate studies of mechanical rupture of yeast showed different rates of release for enzymes in different cell locations (13,14). Wall-linked and periplasmic enzymes were released relatively faster than total protein, soluble cytoplasmic enzymes at about the same rate, and the mitochondrial enzyme fumarase later than total protein (13). Proteolysis by the yeast s own enzymes was not found to be a problem. Activities of the released enzymes declined slowly or not at all when disruption was continued after the end of protein release, and the effect of shear was not separated from the effect of proteolysis. Shetty and Kinsella (15) also found a low rate of proteolysis after mechanical disruption, though thiol reagents added to weaken the cell walls before disruption caused an important increase in the extent of protein breakdown. 

The experiments conducted so far at the site in range of depths between 3000 and 3800 m show that hydraulic stimulation techniques can considerably increase the permeability in a rock volume that can extend up to several hundred meters around the well, thereby serving to establish connections between the wells. The major impact of the hydraulic stimulation could be explained by hydromechanical mechanisms (ruptures in fracture planes). However in the near well at the scale of some meters, a decrease of the impedancy is outlined via hydraulic vibration tests and is presently not well understood. As at this scale, the hydromechanical effect cannot be dissociated from the thermal effect due to the injection of a cold water in a hot media, the thermo-hydro-mechanical responses of the stimulated fractures must be investigated. 

Pressure Effects — There is no rise above atmospheric pressure, thus there will be no pressure effects unless the material is confined. Then the blast effect will be from mechanical rupturing of the pressure vessel. 

Pressure Effects — High local pressures can be produced (100 -10 psi). However, when confined, much of the blast effect is the result of sudden mechanical rupturing of the pressure vessel, which will generally produce fragments. 

Table 5.5 Various Block Copolymers Prepared by Mechanical Rupture of Polymer Chains in Presence of Monomer... 

Another critical value is that necessary to break all the molecules crossing a plane, in the absence of any other energy-absorbing processes. This minimum energy requirement for mechanical rupture is found to be about 50 J/m it is treated in the following section. Finally, there are the considerably larger values found in normal fracture experiments, ranging from 100 to 100,000 J/m. These are described in Section 10.5. 

---