Water radio-active

Reinhoudt et al. also reported water-soluble pseudorotaxane-terminated dendrimers possessing a radio-active metal core for radiotherapeutical applications... 

The most dangerous in their long-term effects are the tailing dumps containing radio-active waste, which are also located in the vicinity of the Dnepr bed or near smaller rivers in the Dnepr catchment basin. Many tailing dump levees and toxic radio-active waste hoarder dams are in extremely poor condition. They can be easily destroyed by natural factors (minor earthquakes, floods, rise of subterranean waters) or by man-made acts (like a terrorist act with the use of explosives), with all ensuing consequences. 

At the time of the discovery of radio-activity, about seventy-five substances were called elements in other words, about seventy-five different substances were known to chemists, none of which had been separated into unlike parts, none of which had been made by the coalescence of unlike substances. Compounds of only two of these substances, uranium and thorium, are radio-active. Radio-activity is a very remarkable phenomenon. So far as we know at present, radio-activity is not a property of the substances which form almost the whole of the rocks, the waters, and the atmosphere of the earth it is not a property of the materials which constitute living organisms. It is a property of some thirty substances—of course, the number may be increased—a few of which are found widely distributed in rocks and waters, but none of which is found anywhere except in extraordinarily minute quantity. Radium is the most abundant of these substances but only a very few grains of radium chloride can be obtained from a couple of tons of pitchblende. 

Exchange resins are also employed for the concentration of ions present in very dilute solutions instances are the recovery of silver from photographic residues, chromate from the waste liquor of chromium plating and magnesium from sea water. They have also been used for the separation of rare earths (p. 426), and of uranium, plutonium and radio-active fission products (p. 437), and for plutonium and uranium-233 purification. A striking application was the historic separation of single atoms of mendelevium on a sulphonated polystyrene resin and their elution therefrom, at 87 , with a-hydroxyisobutyrate (Seaborg, 1955). 

Adsorption onto activated charcoal (Norit A) has been used for small oligonucleotides, up to tetranucleotides (Crane and Lipman 1953 Mandeles and Kammen 1966). The method is quicker and more convenient than DEAE-cellulose chromatography. Mandeles and Kammen (1966) used Norit A suspended in 1 mM phosphate 1 mM pyrophosphate buffer at pH 6.0 at a concentration of 100 mg/ml. The nucleotide solution is adjusted to pH 3 and 5 mg Norit for every optical density unit ( 40 pg) of nucleotides is added. The charcoal is collected on a filter paper and washed with water. (A good quantitative measure of or radio-activity may be obtained by counting the dry filter paper in a Geiger-Muller thin window counter.) The nucleotide material is eluted with a small volume of a mixture of ethanol, water and ammonia (600 400 6.5 v/v/v) which is then removed by drying under reduced pressure at 40°C. 

Lind and Bardwell have summarized the effects of radio-active materials on methane oxidation. Under the influence of the alpha radiation from radon the oxidation of methane proceeded completely to carbon dioxide and water. The oxidation took place in one step, and from the numerical relation between the number of gaseous ions produced and the methane molecules oxidized, the formation of triplet ion clusters was postulated as shown ... 

Radio labeled studies also showed that higher temperatures cause C-acylation of aromatics to occur. When the saponified residue, after distillation of 1- C acetic acid followed by washing with water and freeze-drying with benzene, was measured for radio activity, it had almost 0.5 meq of acetate per gram of sample. 

We also found that water, methanol and ethanol adsorbed on coal. When high-volatile bituminous coal was treated with 3h20, methanol- C, and ethanol-l-l C at room temperature for a period of 24h, the residue retained some radioactivity. The soxlet extraction with non-radio active solvent of these treated samples caused some decrease in the radio-activity. 

The purpose of the reactor gas atmosphere is to provide an inert, non-radio active environment in the reactor, to remove moisture and foreign gases from the reactor in order to prevent graphite burnout, to serve as the heat transfer media between the graphite and process tubes and to detect water leaks within the reactor. To perform these functions to control graphite temperatures and to meet reactivity requirements mixtures of helium and carbon dioxide or nitrogen are used. 

The exhaust air from a radio-chemical laboratory should be filtered to extract dust. In general, however, no additional exhaust air treatment is necessary in a water laboratory measuring radioactivity in water samples. The exhaust air is monitored for radio-active aerosols by filtration of a specific quantity of air via membrane filters, and by measuring the deposit on the membrane filter. 

C, 100 D, 1000 pmol/litre. Perchloric acid extracts of the cells (a) and medium (b) were prepared, and subjected to anion exchange HPLC on a Lichrosorb AN 10 anion exchange column under the following conditions water/-ammonium phosphate 0.8 molar pH 4.5, gradient from 3 to 100% with a delay of 1 minute, sweep time of 10 minutes and a flow rate of 2 ml/minute. Elution positions of orotate and uridine species were determined by UV absorption of simultaneously injected markers fractions were collected and radio-activity plotted against eluate number for the neutralized cell (a) and medium (b) extracts. In the latter case only the labelled uridine is depicted. The identity of the markers is as follows 1, uridine 2, UMP 3, UDP-glucose 4, orotate 5, UDP 6, UTP. 

It is reported that mild carbon steels may be effectively protected by as little as 55 ppm of KTc04 in aerated distilled water at temperatures up to 250oC. This corrosion protection is limited to closed systems, since technetium is radioative and must be confined. 9sTc has a specific activity of 6.2 X lOs Bq/g. Activity of this level must not be allowed to spread. 99Tc is a contamination hazard and should be handled in a glove box. 

As an example consider the exchange reaction between benzyl iodide and free iodide ions, Eq. (3-43).6 Mixing ethanolic solutions of benzyl iodide and radio-labeled potassium iodide started the isotopic exchange. At different times, samples were withdrawn and added to a benzene-water mixture, causing separation into two layers. The aqueous layer contained the iodide ions, and the organic layer contained the benzyl iodide. The activity of 1311 was determined in each layer. 

P18. Popov, I. N., and Lewin, G., Photochemiluminescent detection of antiradical activity II. Testing of nonenzymic water-soluble antioxidants. Free Radio. Biol. Med. 17, 267—271 (1994). 

To determine the effects of the deprivation of specific micronutrients on the water hyacinth (Eichhornia crassipes), Colley et al. (1979) studied the rate of uptake of iron and manganese in comparison with phosphorus. Results indicated that all three elements were actively absorbed by the root systems, but the rates of absorption differed markedly. The rate of absorption of manganese by roots was 13 and 21 times that for radio-iron and -phosphorus, and iron was taken up by the roots at nearly twice the rate of phosphorus. Manganese translocation appeared to be faster than phosphorus translocation by an order of magnitude and 65 times faster than iron translocation. 

In order to determine the number of histidine residues involved in zinc coordination, the L chains of TeTx and BoNT/A, B and E were modified with diethyl pyrocarbonate (DEPC), a reagent that specifically modifies histidine residues. In each case, two additional histidines were modified in the apo-toxin that were not affected in the holo-neurotoxin (Schiavo etal., 1992 b, c). These results indicate that the zinc atom of CNTs is coordinated via two histidines and a Glu-bound water molecule, as in thermolysin. Mutations at the two histidines of the motif inactivate TeTx and suppress its ability to bind radio-labeled Zn " (Yamasaki etal., 1994 b). In addition, mutations of the conserved Glu-271 and Glu-272 of TeTx, predicted to be in an a-helical segment (Lebeda and Olson, 1994), result in decreased zinc binding and loss of activity. Based on these experimental results, it has... 

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