Mechanical cell disintegration

Mechanical cell disintegration by crushing or milling leads to a particle size reduction which in turn results in an increasing degree of cell disintegration as the particle size becomes close to or is less than the cell size. 

Enzymatic maceration, which is a softening of plant tissue by the use of enzymes, has some potential quality advantages over mechanical-thermal disintegration as maceration is obtained with less damage to the cell walls. The major part of the plant cells remains intact by enzymatic maceration [25], as the enzymes attack only the space between the cells, and with only rare injury to the cell membrane [26]. The intact cells protect nutritional components within the cells which minimise flavour changes and deterioration on storage [27,28]. 

Doulah MS (1977) Mechanism of disintegration of biological cells in ultrasonic cavitation. Biotech Bioeng 19 649-660... 

Vanadate stimulates protein kinases in the cytosol, as demonstrated in adipose cells and extracts. The activation of a membrane and cytosolic protein tyrosine kinase have been demonstrated in adipocytes, and the membranous enzyme has been postulated to be a way to involve PI-3K actions without activation of insulin receptor substrate-1 (IRS-1) in the insulin signal transduction pathway [140], It is always difficult to determine if protein kinase activation is direct or the result of stimulation of a protein phosphatase. The fact that kinase stimulation was seen in isolated extracts after cell disintegration in this adipocyte cell system supports the idea that vanadium addition to cells could directly stimulate kinases via an as-yet-undetermined mechanism. In other experiments with 3T3-L1 adipocytes bis(acetylacetonato)oxovana-dium (IV) BMOV and bis(l-N-oxide-pyridine-2thiolato)oxovanadium (TV) caused increased tyrosine phosphorylation of both the insulin receptor and IRS-1 in a synergistic way with insulin, as measured by antibodies to phosphotyrosine residues [141]. 

Mechanical homogenizer cell disintegration while in suspension in a liquid. Wet milling. 

An example of mechanical aids to cavitation can be found in the field of ultrasonic cell disintegration. These activators are often glass beads or ceramic disks, but sand or plastic chunks can also be employed. Other examples of solids added to improve cavitation effects are silicon carbide, any hard ceramic material or AI2O3 for micronizing species or for surface abrasion, Si02 which favors mechanochemical events, talc for the activation and probably alteration of the chemical properties of surfaces. 

The application of an external pulsed electric field (PEF), the induced local structural changes of the cell membrane, and also the increase in permeability due to the appearance of permanent membrane pores were found to positively affect any subsequent drying processes of porous plant materials. PEF provides an alternative to the mechanical, thermal or enzymatic cell disintegration of plant tissue, providing a short-term (milliseconds), low-energy pretreatment (<10kJkg-Y... 

Cell disintegration may also be achieved using techniques other than PEF or ultrasound, with different mechanisms of action ... 

TAT liposomes remain intact within one hour of translocation and slowly migrate through the cell, bypassing the endocytic pathway, to the perinuclear zone where they disintegrate (95). The mechanism utilized by TAT to migrate across the membrane was thought to be energy independent because it operates at similar rates at both 4°C and 37°C (95,96). Cell entry by TAT is also unhindered by metabolic inhibitors such as sodium azide or iodoacetamide (97). Peptides constructed of both the d and l amino acids of Antp can be detected intracellularly, the inference of which is that no specific receptor was required because both isomers had equal potential (98,99). 

Solid polymer and gel polymer electrolytes could be viewed as the special variation of the solution-type electrolyte. In the former, the solvents are polar macromolecules that dissolve salts, while, in the latter, only a small portion of high polymer is employed as the mechanical matrix, which is either soaked with or swollen by essentially the same liquid electrolytes. One exception exists molten salt (ionic liquid) electrolytes where no solvent is present and the dissociation of opposite ions is solely achieved by the thermal disintegration of the salt lattice (melting). Polymer electrolyte will be reviewed in section 8 ( Novel Electrolyte Systems ), although lithium ion technology based on gel polymer electrolytes has in fact entered the market and accounted for 4% of lithium ion cells manufactured in 2000. On the other hand, ionic liquid electrolytes will be omitted, due to both the limited literature concerning this topic and the fact that the application of ionic liquid electrolytes in lithium ion devices remains dubious. Since most of the ionic liquid systems are still in a supercooled state at ambient temperature, it is unlikely that the metastable liquid state could be maintained in an actual electrochemical device, wherein electrode materials would serve as effective nucleation sites for crystallization. 

X-ray radiography was used to study the failure mechanism and capacity loss due to disintegration of the Al-Li alloy during cycling of the cell Li-Al/KCl-LiCl/Te (79). 

It should also be mentioned that the application of wood nanocellulose prepared by the described techniques - where the cell wall is further disintegrated by mechanical treatment - leads to lower-strength cellulose fiber-reinforced composites than in the corresponding BC materials [34]. 

Cell lysis Mechanical methods pressure shearing, ultrasonic disintegration, bead-mill homogenizers Nonmechanical methods enzymatic lysis, osmotic lysis, freezing and thawing, detergent-based lysis and electroporation... 

The stationary phase is followed by a decline period in which cell death is not compensated by cells in proliferation. Cell death can occur by two distinct mechanisms, named necrosis and apoptosis. Necrosis occurs as a result of an irreversible injury and normal homeostasis is lost. In vivo, this form of death generally affects the neighboring cells and may result in inflammation. Autodestruction occurs by activation of hydrolases when there is a lack of nutrients and oxygen, followed by progressive disorganization and complete disintegration of the cell. 

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