Published online May 7. Received Sep 10; Accepted Mar 6. Copyright Chan et al.
In one embodiment the method involves adding hydrazine to a solution containing submicron sized domains of a soluble second phase which domains bear a plurality of pendant acid groups to form a salt between the hydrazine and pendant acid groups.
Addition of selenous acid to the solution results in reduction of the selenium contained therein to zero valent selenium which selenium is produced in the form of a stable colloidal dispersion.
The art of electrostatographic copying, originally disclosed by C. This is followed by exposing the plate to activating radiation in imagewise configuration which results in dissipation of the electrostatic charge in a pattern known as the latent image.
The latent image is developed by contacting it with an electroscopic marking material commonly referred to as toner. This material is electrostatically attracted to the latent image which is, by definition, in the configuration of those portions of the photoreceptor which were not exposed to the activating radiation.
The toner image Locus of control and reaction formation be subsequently transferred to paper and fused to it to form a permanent copy. Following this, the latent image is erased by discharging the plate and excess toner is cleaned from it to prepare the plate for the next cycle.
A photoconductive material which has achieved considerable commercial success is amorphous selenium. This material is applied to the conductive substrate by vapor deposition techniques which provide the desired photosensitive plate. Trigonal selenium in a binder matrix may also be used in some cases.
A less expensive way to apply a layer of selenium would be to cast the layer from a colloidal dispersion of selenium. Such a process is problematical, however, because of the difficulties encountered in forming stable colloidal dispersions of selenium at reasonable selenium concentrations.
Colloidal dispersions of selenium have been prepared by reacting hydrazine with selenous acid in an aqueous solution containing gelatin. The preparation of monodisperse selenium sols formed on gold nucleation sites is reported in the Journal of Colloidal and Interface Science, Symposium Issue, pp.
Those dispersions are, however, of very low concentration which renders their use in practical applications problematical. It is known that hydrazine will react with selenous acid to form zero valent selenium by the reaction: It would be desirable and it is an object of the present invention to provide a novel process for the formation of stable, colloidal dispersions of selenium.
Another object is to provide such a process in which colloidal concentrations containing up to 25 weight percent selenium and greater can be formed. A further object is to provide such a process in which the selenium is formed by the reduction of selenous acid or an alkyl selenite by hydrazine or a substituted hydrazine.
The method comprises the steps of: STR1 wherein R2 and R3 are independently H or alkyl of 1 to 20 carbon atoms and R4 is alkylene of 1 to 20 carbon atoms to the solution to reduce the selenium in the selenous acid or alkyl selenite to zero valent selenium and thereby form a stable colloidal dispersion of selenium.
In general, the locus control process involves a chemical reaction occurring in a discrete domain, e.
By-products of the reaction are preferably those species which can be removed from the reaction medium without undue processing. In one embodiment, the present invention extends the known ability of hydrazine and certain hydrazine derivatives to reduce the selenium in selenous acid and certain alkyl selenites to zero valent selenium.
By forming the free selenium in the proximity of micellar or macromolecular species, it is bound to these discrete domains, and, because of the solubility of these domains in the bulk medium, stable, colloidal dispersions of selenium result.
The first step of the process is to provide a solution containing a soluble second phase. The second phase comprises soluble domains bearing functional groups necessary for the desired reaction to proceed so that the reaction products are created only at the sites at which they are stabilized.
The second phase normally comprises polymer molecules in solution or surfactant molecules in concentrations above their critical micelle concentration. The domain size range is submicron and preferably from 50 A to A. These domains act as mini reaction vessels and if they have the right functionality, a specific reaction can be caused to occur at a specific site.
The functional groups of the domain are in the form of pendant species of the desired reactivity. The pendant groups can be anionic or cationic so as to form salts with materials capable of reducing selenous acid to selenium.
Thus, when the pendant groups are acidic, hydrazine can be added to the solution to form a salt which acts as the reducing agent. Alternatively the pendant groups can be cationic and a reducing salt formed by adding an anionic species such as HSO3 - HSe.
Alternatively the pendant groups can be species which are themselves oxidizable by selenous acid as would be the case with a polymer having pendant ascorbic acid, oxime, aldehydric, acyl hydrazine, acyl hydrazone or hydrazine residues.
One type of second phase domains useful in the instant invention contain a plurality of acidic groups. The acidic groups are selected from those acids which have a pK less than 6, i. STR2 It has been found that hydrazine in the form of its protonated salt will reduce selenous acid just as will free hydrazine.
This is probably the case because selenous acid is not easily reduced in a neutral or basic solution, and slight acidity, most easily provided by leaving a portion of unsubstituted acidic groups in the domain, is necessary. As the process is carried out, the hydrazine is decomposed to nitrogen gas and the acid group is regenerated thereby allowing one to add additional hydrazine and a new charge of selenous acid thereby incorporating more and more selenous acid into the polymer.
As hydrazine and selenous acid are added, aqueous dispersions of amorphous selenium are formed which are bound to the domains.Feb 04, · One promising approach involves the incorporation of a locus control region (LCR) into a transgene construct.
was used as template for a positive control reaction. SalI digestion of the bp product resulted in the formation of the expected fragments of and Locus of Control: Individual's with an internal locus of control believe that they have control over their work environment.
The constable's complaints show that they believe they are in . Sign In. Whoops! There was a problem previewing tranceformingnlp.com Retrying. Start studying PSY Ch Learn vocabulary, terms, and more with flashcards, games, and other study tools.
Research on locus of control indicates that internals are _____ than externals. A)more dependent B)more intelligent an internal locus of control. B) a reaction formation. C) learned helplessness. D) neurotic anxiety. E. In general, the locus control process involves a chemical reaction occurring in a discrete domain, e.g.
macromolecules or surfactant micelles, different from the bulk reaction medium with at least one of the participating reagents being bound in the domain. Locus of Control and Reaction to Illness To examine the relationship between locus of control and reaction to illness, Pearsons correlation coefficients between measure of locus of control and each of the above 11 factor scores were computed.
Results of this analysis are shown in Table 1.