Resistance to Micro-organisms

Wood acetylated with thioacetic acid showed resistance to decay and termites at low WPG around 12. The available information on pattern of substitution of hydroxyls during acetylation with acetic anhydride suggests substitution of lignin hydroxyls at low acetylation levels. Resistance to micro-organisms, particularly those consuming cellulose, even at low acetylation... 

Urea-formaldehyde resins (UFR) are the most prominent examples of the class of thermosetting resins usually referred to as amino resins. There are various advantages to the use of UFR, including low cost, ease of use under a wide variety of curing conditions, low cure temperatures, water solubility, resistance to micro organisms and to abrasion, hardness, excellent thermal properties, etc. 

A large part of the litter problem consists of polymeric substances, among which polyolefins are preponderent due to their wide application as packaging materials. As was already shown, PO exhibit a significant resistance to micro-organisms attack... 

Particularly interesting seems to be the conclusion of Schreck and Ludwig [27], who hypothesized that the barometric resistance of micro-organisms is caused by a mechanical factor, but is also dependent upon the protein-structure of microbes, as there is a deep relationship between the effect of pressure and temperature on proteins and micro-organisms. In other words, pressure acts on proteins located in specific sites where they are particularly sensitive to mechanical stress. 

In a departure from the usual study of arsenic metabolites in mammals, Kuehnelt et at. (1997) found mainly arsenate, arsenite and dimethylarsinic acid, and traces of methylarsonic acid and arsenobetaine in ants living close to an arsenic smelter. The low total arsenic levels, about 12.6mg kg-1, in the ants was suggested as indicative of a protective mechanism which prevents the uptake of arsenic from the high ambient levels. The resistance of micro-organisms to arsenic compounds has been reviewed (Cervantes et at., 1994). 

Sterilization specifications should be easy to develop. The pharmacopeias allow sterilization specifications to be developed from a basis of no actual data concerning the numbers and thermal resistances of micro-organisms actually contaminating the items to be sterilized. Although this statement may appear initially to be barren of scientific reason, this is in fact not the case. What the pharmacopeias provide are... 

If the Di2i-value in product of B. stearothermophilus is equal to or less than its D i-value in water, and the sterilization specification is based on overkill, then bio-validation must be done with spores suspended in water. However, if the sterilization specification has been tailored specifically to the resistance of micro-organisms in the product, then bio-validation must be done with the spores suspended in product. Otherwise falsely unfavorable results may occur. 

Plastics vary in their susceptibility to micro-organisms. Plastics based on polyesters are attacked fairly rapidly, whilst the polyether based plastics are much more resistant. However, the situation is a very complex one, as many of the plasticisers and vulcanisers used in the production of plastics are able to support microbial growth. Once these have been removed, the plastic frequently becomes brittle irrespective of type. 

Modem membrane systems are compact and modular, in addition to their high selectivity (that can provide substance concentrations as low as parts per billion) and low energy consumption. Therefore, membrane units can relatively easily be introduced on existing production sites. Furthermore, modem membranes present high resistance to heat, to acid and alkaline conditions, to a number of other aggressive chemicals and to micro-organisms. Membrane processes do not destroy pollutants, they only separate them into a concentrate. It is possible to... 

Almost no engineering material is safe from or immune to microbial corrosion. In Chapter 8 the vulnerability and susceptibility of copper and cupronickels, duplex stainless steels and concrete will be discussed in a brief and informative manner. I had my reasons for picking these materials copper and its alloys have the reputation of being poisonous to micro-organisms, duplex stainless steels are known for their high resistance to corrosion thanks to their duplex microstructures of ferrite and austenite, and concrete is widely used in both the marine and water industries because of its good performance and cost effectiveness. 

Shoren et al. [66] suggest that EAA somehow interferes with starch accessibility to micro-organisms and their hydrolytic enzymes. Amylose in starch forms V-type exclusion complexes with EAA that make it highly resistant to starch-hydrolyzing enzymes [66, 67]. 

Resistance to penetration by micro-organisms is covered by EN 374-2 and protection from low temperatures in EN 511. Careful handling and regular inspection are essential since chemicals and abrasion will eventually cause deterioration of gloves. Rinsing in clean water and drying naturally will prolong their life. 

As other cheaper materials usually give satisfactory performance, nickel and nickel alloys are not normally required for applications involving resistance to corrosion underground. Data on their behaviour in these circumstances are therefore sparse in particular, whether micro-organisms responsible for the accelerated corrosion of ferrous and other metals in certain anaerobic soils have any influence on nickel and its alloys, is uncertain. 

Micro-organisms with resistance to environmental stresses such as solvents, extremes of pH, high salt concentration, and having broad temperature and dissolved oxygen optima are more suited to process applications. Improved process instrumentation and... 

To achieve overproduction of phenylalanine, the micro-organism should be derepressed at the pheA level and free of inhibition at the arcG level. Both genes are located on the chromosomal DNA of the micro-organism and, by means of amino add analogues such as p-fluoro-DL-phenylalanine, it is possible to make (phenylalanine) feedback resistant mutants of E.cdi (pheA and oroF mutants). The following procedure can be used ... 

The ability of micro-organisms to produce pectic enzymes in vitro constitutes no proof of their pathogenicity. Some micro-organisms produce pectic enzymes on synthetic-nutrient media, but do not always possess the ability to produce them in vivo. An important role is here played by the susceptibility or resistance of the plant to the effect of the pathogen. Production of D-galacturonanase and pectines-terase by Fusarium oxysporum f. lycopersici was found to be much higher on susceptible than on resistant tomato-stems.287 Likewise,... 

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