Natural mechanism

Cell membranes are lipophilic and designed to be barriers against large anionic molecules, although there is a natural mechanism for intercellular transport of anionic oligonucleotides. In order to enhance membrane transport, antisense oligonucleotides are frequentiy modified by covalent attachment of carrier molecules or lipophilic groups. 

A problem arises in using platelet reinforcements if their naturally mechanically weak crystallographic direction is aligned perpendicular to the crack front. The platelets easily fracture in this orientation. Further research is needed to grow platelets with favorable crystallographic orientations. 

A natural mechanism for the local reduction of cell spacings (or creation of a new cell) is either a nucleation in one of the grooves (the liquid is supercooled) or, even more likely, the formation of a new cell out of a side branch in such a groove. Alternatively, tip-splitting of a cell may give the same result [121]. 

Accidental vapor cloud explosions do not occur under controlled conditions. Various experimental programs have been carried out simulating real accidents. Quantities of fuel were spilled, dispersed by natural mechanisms, and ignited. Full-scale experiments on flame propagation in fuel-air clouds are extremely laborious and expensive, so only a few such experiments have been conducted. 

Experimental programs partly devoted to the study of deflagration speeds in unconfined environments free of obstacles, after dispersion of a vapor cloud by natural mechanisms included... 

Because there is no natural mechanism for producing isotopically pure Th, any measurable Th in a sample for °Th/U dating implies the presence of at least some °Th when the sample (mineral or mineral assemblage) was formed. This initial °Th must then be subtracted from the total measured °Th before a valid °Th/U age can be calculated. In addition, a correction for initial U isotopes is required when the material being dated is a mechanical mixture of an isotopically homogeneous detrital material with an initially thorium-free mineral such as chemically precipitated carbonate. In these cases we are usually interested only in the time of formation of the Th-free material, and so must also subtract the detrital and before calculating the °ThAJ age. 

Ultraviolet wavelengths of 290-310 nm from the UV-B band of radiation constitute the principal tissue-damaging rays of the sun, which are not fully atmospherically filtered. An hour s exposure to the summer sun and its damaging rays can produce a painful burn with a characteristic erythema. The skin has natural mechanisms to prevent or minimize such sun-induced trauma, but it takes time to set these into place. Upon... 

Vaughan, Thomas and Rebecca Vaughan. Aqua Vitae Non Vitis or, the radical humiditie of Nature mechanically, and magically dissected by the conduct of fire, and ferment (British Library MS, Sloane 1741 edited and translated with an introduction by Donald R. Dickson. Edited by Donald R. Dickson. Tempe (AZ) Arizona Center for Medieval and Renaissance Studies, 2001. liii, 270 p. 

Yoshimitsu Hirao and C. C. Patterson. Lead Aerosol Pollution in the High Sierra Overrides Natural Mechanisms Which Exclude Lead from a Food Chain. Science. 184 (May 31, 1974) 989-992. 

These natural mechanisms may be replaced or augmented with artificial genetic strategies which are themselves controlled by transgenesis. Such strategies include... 

Stapleton JJ, DeVay JE (1995) Soil solarization a natural mechanism of integrated pest management. In Reuveni R (ed) Novel approaches to integrated pest management. Lewis, Boca Raton, FL, USA, pp 309-322... 

Brookman, G. T., Flanagan, M., and Kebe, J. O., 1985a, Literature Survey Unassisted Natural Mechanisms to Reduce Concentrations of Soluble Gasoline Components American Petroleum Institute of Health and Environmental Sciences Department, No. 4415, August, 1985, 73 pp. 

Rossi, F. (1986). The 02 -forming NADPH oxidase of the phagocytes Nature, mechanisms of activation and function. Biochim. Biophys. Acta 853, 65-89. 

Arsenic occurs primarily in sulphide minerals associated with copper ores, and to a lesser extent with zinc, lead and gold ores. Arsenic is produced as a by-product of the smelting of these metals. Primary arsenic production has now ceased in the USA and Europe, and most arsenic is now imported from China and Mexico. The volatility of arsenic represents a significant concern, and there is at present no known natural mechanism by which arsenic is immobilized in the environment. Anthropogenic activities account for an input of some 19000 tonnes into the atmosphere, compared with 12000 tonnes from natural processes, such as volcanism and forest fires (Ayres and Ayres, 1996). 

Huntington JA, Baglin TP. Targeting thrombin -rational drug design from natural mechanisms. Trends Pharmacol Sci 2003 24 589-95. 

The metals released from the glassfills and the glassroads during corrosion would be dispersed in the environment without further control by the authorities. In this way, released concentrations and loads of metals can be directly compared with fluxes resulting from natural mechanisms and anthropogenic activities. 

Naida I, Zapadnyuk V, Povstyanoy N et al (1993) Age-related pecuharities of natural mechanisms of detoxication and curative action of Enterosgel in bum disease. Klinichna Khirurgiya 9-10 53-56, In Russian... 

Russelljones, G. (1996). Utilization of the natural mechanism for vitamin B-12 uptake for the oral delivery of therapeutics. Eur. J. Pharmaceut. Biopharmaceut., 42, 241-249. 

The concept of stochastic pulsations offers also a natural mechanism to explain episodical mass loss as due to occasionally occurring exceptionally large or rapidly moving pulsation elements. In forwarding this suggestion we realize that its proof should still be given. 

Helix induction can be augmented by mimicking natural mechanisms using a variety of synthetic expedients. In general, these approaches seek to either stabilize or mimic helix nucleation sites or to naturally or artificially secure side-chain linkages. In most cases, these transformations make use of additional synthetic procedures beyond standard peptide synthesis methodologies to juxtapose amino acids or essential elements thereof in a manner that mimics a protein helix. 

The transfer of heat from layer to layer is a natural mechanism of flame propagation. The cooling of the combustion products which follows combustion does not by itself inhibit combustion. 

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