The Oxidation of Tetraborane

Ludlum, Kenneth H.; Wiberley, Stephen E.; Bauer, Walter

doi:10.21236/ad0259093

Cited by 3 publications

(2 citation statements)

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“…Ludlum noticed a change in the molecular weight of poly(A) when 5O/, adenine residues were methylated [23,24]. For 15O/, methyladenine we observed, as others [18,19], a cooperative melting.…”

Section: Discussionsupporting

confidence: 83%

A Study of Methylated Polyadenylic Acid

Thrierr¹,

Leng²

1971

European Journal of Biochemistry

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Copolymers with different contents of adenine and N,-methyl adenine residues have been studied, polyadenylic acid being methylated by dimethylsulfate. Thermal stability, circular dichroism and light scattering measurements are in favor of a two-strand structure a t neutral pH. Thermal stability of these products is much less sensitive to ionic strength than that of most polynucleotides, and in some cases independent of ionic strength. These copolymers interact or not with poly(U), depending on the percentage of N,-methyl adenine residues. Copolymers with high contents of methyladenine interact with poly(A) at neutral pH. These copolymers do not bind DNA-dependent RNA polymerase. Some results a t acid pH are also reported.A large number of studies have been devoted to solutions of synthetic polynucleotides in order to understand their physical properties and also because they may be considered as model molecules for deoxyribonucleic acid (DNA). We are interested, in the laboratory, by the properties of chemically methylated DNA [1,2]. Alkylating reagents react with DNA and give rise to physical and biological changes (see reviews [3-51. On the other hand, methylated bases are largely found in natural nucleic acids and their functions are still obscure. For these reasons and in order to explain some results that we found on methylated DNA [2], studies have been carried out with samples of polyadenylic acid, poly(A), which had reacted with dimethyl sulfate. Despite the fact that sites of the reaction are different in native DNA and poly(A), some interesting comparisons are possible [ 21. MATERIAL AND METHODSPolyadenylic Acid Polyadenylic acid was purchased from Miles Chemical Company. After several treatments with phenol, the product was fractionnated in 3 fractions according to the method of Eisenberg and Felsenfeld [6]. Each fraction was dialysed against 0.01 M EDTA, then exhaustively against distilled water and lyophilized. The first fraction was used in this work. MethylationWe used the method of Michelson and GrunbergManago Enzyme. DNA-dependent RNA polymerase (EC 2.7.7.6).(4 mg/ml) were added 0.16 ml tri-n-butylamine and 0.05 ml dimethyl sulfate; the solution was shaken a t 4" for different times (from 5min to 48 h, the amount of methylated adenine residues depends upon the time of reaction). At the termination of the reaction 0.05 ml M cacodylate buffer pH 7 was added; the solution was treated with ether (3 times), dialysed against 0.1 M NaC1, 0.05 M sodium cacodylate, then against distilled water and lyophilized.Methylation occurs in the Nl position of adenine, as shown by identification in the acid hydrolysate (1 N HC1, 100" for 1 h). The hydrolysate was chromatographed in the solvent system n-butanol-NH,OH 6 N (180 : 30, v/v) and only two spots were observed (adenine and Nl-methyl adenine) [8]; in the solvent system isopropanol -concentrated HC1-H,O (170 :41: 39, v/v/v) adenine and Nl-methyl adenine have the same mobility [9], and no other spot was found. The relative percentage of adenine and Nl-methyl a...

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Section: Discussionsupporting

confidence: 83%

A Study of Methylated Polyadenylic Acid

Thrierr¹,

Leng²

1971

European Journal of Biochemistry

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“…This increased oxidation could indicate that incorporated hydrogen increases reactivity toward oxygen, but also could reflect increased surface area (Figure ). When hydrogenated boron oxidizes in air, it could form B 2 O 3 (as in unhydrogenated boron), but one might expect that the surface would consist of hydrated forms of the oxide, such as H 3 BO 3 , HBO 2 , or H 2 B 4 O 7 , which form in oxidation of boranes. , The presence of some degree of hydration is confirmed by the strong OH stretching signal observed in the IR spectrum of oxidized, H 2 -milled boron (Figure ).…”

Section: Resultsmentioning

confidence: 95%

Boron Nanoparticles with High Hydrogen Loading: Mechanism for B–H Binding and Potential for Improved Combustibility and Specific Impulse

Perez

McMahon

et al. 2014

ACS Appl. Mater. Interfaces

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Ball milling of boron in an H2 atmosphere was found to result in hydrogen uptake of up to 5% by weight (36 mol %). The nature of the hydrogen binding to boron was probed by a combination of ab initio theory, IR spectroscopy, thermogravimetric analysis, and mass spectral measurements of gases evolved during sample heating. The dominant binding mode is found to be H atoms bound to B atoms in the surface layer of the particles, and the high hydrogen loading results from production of very high surface area, indicating that gaseous H2 is an effective agent promoting size reduction in milling. Hydrogen incorporated in the samples was found to be stable for at least a month under ambient conditions. Desorption is observed beginning at ∼60 °C and continuing as the temperature is increased, with broad desorption features peaking at ∼250 and ∼450 °C, and ending at ∼800 °C. Unprotected hydrogenated boron nanoparticles were found to be reactive with O2 producing a hydrated boron oxide surface layer that decomposed readily at 100 °C leading to desorption of H2O. Hydrogenated boron nanoparticles were found to promote a higher flame height in the hypergolic ignition of ionic liquids upon contact with nitric acid.

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