Periods, long

The preparation can be kept for long periods in a refrigerator, preferably in smooth, brown, alkali-free bottles it should not be kept above 20° for more than a few hours at 30°, it may undergo sudden decomposition and a serious explosion may result. 

CAUTION. Ethers that have been stored for long periods, particularly in partly-filled bottles, frequently contain small quantities of highly explosive peroxides. The presence of peroxides may be detected either by the per-chromic acid test of qualitative inorganic analysis (addition of an acidified solution of potassium dichromate) or by the liberation of iodine from acidified potassium iodide solution (compare Section 11,47,7). The peroxides are nonvolatile and may accumulate in the flask during the distillation of the ether the residue is explosive and may detonate, when distilled, with sufficient violence to shatter the apparatus and cause serious personal injury. If peroxides are found, they must first be removed by treatment with acidified ferrous sulphate solution (Section 11,47,7) or with sodium sulphite solution or with stannous chloride solution (Section VI, 12). The common extraction solvents diethyl ether and di-tso-propyl ether are particularly prone to the formation of peroxides. 

Electro-magnetic emission in the radiowave range is for long period of time used for water basins diagnostics. 

Intennittency, in tire context of chaotic dynamical systems, is characterized by long periods of nearly periodic or Taminar motion interspersed by chaotic bursts of random duration [28]. Witliin tliis broad phenomenological 

This reaction proceeds very slowly in absence of light, and aqueous solutions of potassium manganate(VII) are effectively stable for long periods if kept in dark bottles. 

An even less complicated reaction vessel may be used for reactions in liquid amtnonia which produce only a small amount of "heat" over a relatively long period and which proceed under homogeneous conditions. The conversion can then be performed in a one-necked flask with a stopper + gas outlet or small hole. 

The acid chloride is available commercially, but it is more economical to prepare it from the acid as and when required. Furthermore, 3 5-dini-trobenzoyl chloride tends to undergo hydrolysis if kept for long periods, particularly if the stock bottle is frequently opened. The substance may, however, be stored under light petroleum. 

Drill ships are used in deep water and remote areas, and these vessels are equipped with a drilling unit positioned in the middle of the ship. Positioning is achieved dynamically by computer controlled thrusters. The ample storage space allows operation for long periods of time without re-supply. 

The crude sulphonyl chloride, even if dry, cannot bo kept without considerable decomposition. It may be purified by dissolving it in a mixture of equal volumes of benzene and acetone, separating the water, and allowing the solvent to evaporate until crystallisation occurs the recrystallised substance may be preserved for long periods. 

Combustion in an incinerator is the only practical way to deal with many waste streams.This is particularly true of solid and concentrated wastes and toxic wastes such as those containing halogenated hydrocarbons, pesticides, herbicides, etc. Many of the toxic substances encountered resist biological degradation and persist in the natural environment for a long period of time. Unless they are in dilute aqueous solution, the most effective treatment is usually incineration. 

An ethereal solution of diazomethane is usually prepared immediately before it is required for reaction. Two intermediates may be used for this purpose, viz., nitrosomethylurea and p-tolylsulphonylmethylnitrosamide a number of methods are available for obtaining the former the latter is prepared from methylamine and p-toluenesulphonyl chloride. Nitrosomethylurea is not very stable at room temperatures and must be kept at 0° on the other hand p-tolylsulphonylmethylnitrosamide is a stable solid, which can be kept for long periods at room temperature in a dark bottle. 

It remains to investigate the zeros of Cg t) arising from having divided out by. The position and number of these zeros depend only weakly on G, but depends markedly on the fomi that the time-dependent Hamiltonian H(x, () has. It can be shown that (again due to the smallness of ci,C2,...) these zeros are near the real axis. If the Hamiltonian can be represented by a small number of sinusoidal terms, then the number of fundamental roots will be small. However, in the t plane these will recur with a period characteristic of the periodicity of the Hamiltonian. These are relatively long periods compared to the recurrence period of the roots of the previous kind, which is characteristically shorter by a factor of 

Adsorbates can physisorb onto a surface into a shallow potential well, typically 0.25 eV or less [25]. In physisorption, or physical adsorption, the electronic structure of the system is barely perturbed by the interaction, and the physisorbed species are held onto a surface by weak van der Waals forces. This attractive force is due to charge fiuctuations in the surface and adsorbed molecules, such as mutually induced dipole moments. Because of the weak nature of this interaction, the equilibrium distance at which physisorbed molecules reside above a surface is relatively large, of the order of 3 A or so. Physisorbed species can be induced to remain adsorbed for a long period of time if the sample temperature is held sufficiently low. Thus, most studies of physisorption are carried out with the sample cooled by liquid nitrogen or helium. 

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