COMPARISON OF THE NITROLYSIS OF 1, 3-DICYCLOHEXYLIMIDAZOLIDINE WITH THAT OF HEXAMETHYLENETETRAMINE

1950 ◽  
Vol 28b (5) ◽  
pp. 213-224 ◽  
Author(s):  
J. L. Boivin ◽  
George F Wright
Keyword(s):  
Nitric Acid ◽  
Ammonium Nitrate ◽  
The Other ◽  
Nitrate Salt ◽  
Other Hand ◽  
Dinitro Derivative ◽  
Basic Amine

The nitrolysis of N,N′-dicyclohexylimidazolidine has been effected with formation of the nitrate salt, the nitroso derivative, and the aceto derivative of N,N′-dicyclohexyl-N-nitro-1,2-diaminoethane. The absence of the dinitro derivative suggests that demethylolation is not related to nitramine formation. When formaldehyde splits off to leave a weakly basic amine, as in hexamethylenetetramine nitrolysis, then subsequent nitration will occur; but it will not take place if the resulting amine is strongly basic. Nitrolysis will depend also on reactivity of nitric acid, which can be decreased by addition of ammonium nitrate. This decrease will prevent esterification of intermediate N-methylolamines but not nitrolysis of hexamethylenetetramine types. However both nitrolysis and esterification are thus prevented with dicyclohexylimidazolidine. On the other hand the two nitrolyses are related by the fact that both are accelerated by electropositive chlorine.

Studies of phase transformations in nitrates and nitrites I. Changes in ultra-violet absorption spectra on melting

1963 ◽  
Vol 276 (1367) ◽  
pp. 437-452 ◽  
Keyword(s):  
Nitric Acid ◽  
Phase Transformations ◽  
Ammonium Nitrate ◽  
Absorption Spectra ◽  
Ultra Violet ◽  
The Other ◽  
Sodium Potassium ◽  
Nearest Neighbours ◽  
Isopropyl Nitrate ◽  
Sodium And Potassium

Ultra-violet absorption spectra of ions in crystals are sensitive to their environment of neighbouring ions. This fact is utilized to study melting processes in nitrates and nitrites, with particular reference to changes in the average shell of nearest neighbours around any ion, on passing from crystal to melt. For the nitrates of sodium, potassium, rubidium, caesium, thallium and silver, for ammonium nitrate and for the nitrites of sodium and potassium this shell appears to contract on melting, which is attributed to the formation of association complexes in the melt. For the two crystal hydrates HNO 3 . H 2 O and HNO 3 . 3H 2 O, corresponding changes are observed, suggesting that the structure and absorption spectra correspond with the ions (OH 3 )+ and NO - 3 in the crystals, likewise giving rise to tighter association complexes on melting. Pure nitric acid on the other hand behaves in a manner more closely similar to isopropyl nitrate.

On the cause of the reduction of metals from solutions of their salts by the voltaic circuit

1843 ◽  
Vol 4 ◽  
pp. 447-448
Keyword(s):  
Nitric Acid ◽  
Acid Solution ◽  
Large Scale ◽  
Saline Solution ◽  
The Other ◽  
Negative Pole ◽  
Other Hand ◽  
Metallic Salt ◽  
Electric Polarity

The reduction of a metal from its saline solution by the agency of voltaic electricity, has, the author states, been explained in three different ways. By Hisinger, by Berzelius, and by Faraday it has been ascribed to the liberation of hydrogen in this process: Davy and others considered it as resulting directly from the attraction o the metal to the negative pole: and Daniell conceives that the metal is directly electrolysed by the action of the voltaic circuit. The author found that the ends of copper wires, placed in a solution of sulphate of copper between two platina poles in the circuit, mani­fest electric polarity; so that while one end is dissolving, the other is receiving deposits of copper: he also found that platina was, in like manner, susceptible of polarity, although in a much less degree than copper, when placed in similar circumstances. With a view to determine the influence of nascent hydrogen in the voltaic reduc­tion of metals, he impregnated pieces of coke and of porous char­coal with hydrogen, by placing them, while in contact with a metal, in an acid solution, when they thus constituted the negative pole of the circuit; and he found that the pieces thus charged readily re­duced the metals of solutions into which they were immersed; and thence infers that the hydrogen is the agent in these reductions. From another set of experiments he concludes, that during these decompositions, water is really formed at the negative pole; a circumstance which he conceives is the chief source of the difficulties ex­perienced in electro-metallurgic operations when they are conducted on a large scale, but which may be avoided by a particular mode of arranging the elements of the circuit so as to ensure the uniform diffusion of the salt. The author obtained the immediate reduction of gold, platina, palladium, copper, silver and tin from their solutions by the agency of hydrogen contained in a tube, with a piece of platinized platina in contact with the metallic salt: nitric acid and persalts of iron, on the other hand, yielded their oxygen by the influence of the same agent.

A Tritium–Hydrogen Exchange Procedure for Determining the Concentration of Exchangeable Sites on PAN Based Carbon Fibres

1997 ◽  
Vol 9 (3) ◽  
pp. 281-290 ◽  
Author(s):  
Ian Hamerton ◽  
John N Hay ◽  
Brendan J Howlin ◽  
John R Jones ◽  
Shui-Yu Lu ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Active Sites ◽  
Hydrogen Exchange ◽  
The Other ◽  
Carbon Fibres ◽  
Other Hand ◽  
Non Destructive

A non-destructive tritium–hydrogen exchange procedure has been developed in order to determine the concentration of exchangeable hydrogens on surfaces, and in this particular instance it has been used on carbon fibres. The results show that the concentrations of ‘active sites’ on the surfaces of Courtaulds Grafil XAS and XAU carbon fibres are 2.61 and 0.08 μmol g−1 respectively. When the XAS fibres are subjected to a standard methylation procedure the concentration of exchangeable hydrogens is reduced to 0.79 μmol g−1.On the other hand, when XAU fibres are subjected to oxidation in concentrated nitric acid, the concentration of exchangeable hydrogens is increased to 10.27 μmol g−1.

scholarly journals II. Note on the decomposition of sulphuric acid by pentachloride of phosphorus

1856 ◽  
Vol 7 ◽  
pp. 11-15 ◽  
Keyword(s):  
Nitric Acid ◽  
Sulphuric Acid ◽  
Mechanical Mixture ◽  
The Other ◽  
Acid Sulphate ◽  
Other Hand ◽  
Equivalent Quantity

Chemists have long been aware of the fact that some acids unite with bases in one proportion only, others in two or more proportions. Thus a given quantity of nitric acid forms with what is termed its equivalent of potash, a definite nitrate of potash; if less than this equivalent quantity of potash were added to the nitric acid, the product would be a mechanical mixture of the same nitrate of potash with uncombined nitric acid; if more than the equivalent of potash were added, the excess of alkali would remain uncombined. Sulphuric acid, on the other hand, is capable of forming two compounds with potash, and it depends upon the proportions in which the two substances are brought together whether the neutral or acid sulphate is formed.

scholarly journals XX. On the separation of iron from other metals

1821 ◽  
Vol 111 ◽  
pp. 293-299
Keyword(s):  
Nitric Acid ◽  
Large Scale ◽  
The Other ◽  
Exact Method ◽  
General Application ◽  
Other Hand ◽  
Analytical Research

An easy and exact method of separating iron from the other metals with which it may happen to be mixed, has always been a desideratum in chemistry. Every one con­versant with the analysis of minerals is aware of the difficulty of the problem, which indeed is such that, in experiments conducted on any thing like a large scale, it might hitherto be regarded as insuperable. In consequence of this, and of the importance of the enquiry, there is hardly a chemist of eminence who has not proposed some process for the pur­pose, but (with the exception of that which depends on the insolubility of the persuccinate of the obnoxious metal, which I have not tried, and which is too expensive to be resorted to for any but the nicer purposes of analytical research) they are all of them either inadequate to the end proposed, intole­rably tedious, or limited in their application. That which I have now to propose, on the other hand, is liable to none of these objections, being mathematically rigorous, of general application, and possessing in the highest degree the advan­tages of facility, celerity, and cheapness. It is briefly this : The solution containing iron, is to be brought to the maxi­mum of oxidation, which can be communicated to it by boiling with nitric acid. It is then to be just neutralized while in a state of ebullition , by carbonate of ammonia. The whole of the iron to the last atom, is precipitated, and the whole of the other metals present (which I suppose to be manganese, cerium, nickel, and cobalt), remains in solution.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

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