**5. Conclusions**

In conclusion can say, that even endogenous inoculation with small amount of (Ti + B) strongly increase on refinement in pure aluminum structure. It results from reactions, which proceed between inoculating elements and inoculated metal or charge impurities. These reactions lead to formation of active bases to heterogeneous nucleation of aluminum as high melting small particles of type TiB, TiB2, AlB2, Al3Ti and TiC or TiN, which have analogy in crystal lattice with Al.

However on the basis of conducted analysis of the literature and results of authors researches it was affirmed, that the rotating electromagnetic field generated by induction

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pp. 115-118, ISSN 0543-5846

125-137, ISSN 0924-0136

coil supplied by current with frequency larger than power network, influences liquid metal in time of its solidification in mould, guarantees refinement of structure of pure Al without necessity of application of inoculants sort Ti and B.

This method of exogenous inoculation is important, because Ti and B decrease the degree of purity and electrical conductivity of pure aluminum. Moreover Ti and B are reason of point cracks formation during rolling of ingots.

Presented method of inoculation by use of electromagnetic field is possible to apply in conditions of continuous casting because it allows producing of ingots from aluminum of approx. 99,5% purity with structure without columnar crystals, which are unfavourable from point of view of usable properties.

#### **6. Acknowledgment**

Project financed from means of National Science Centre.

#### **7. References**


coil supplied by current with frequency larger than power network, influences liquid metal in time of its solidification in mould, guarantees refinement of structure of pure Al without

This method of exogenous inoculation is important, because Ti and B decrease the degree of purity and electrical conductivity of pure aluminum. Moreover Ti and B are reason of point

Presented method of inoculation by use of electromagnetic field is possible to apply in conditions of continuous casting because it allows producing of ingots from aluminum of approx. 99,5% purity with structure without columnar crystals, which are unfavourable

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necessity of application of inoculants sort Ti and B.

Project financed from means of National Science Centre.

Hill Book Co. Inc., New York, USA.

No.6, pp. 255-263, ISSN 0004-9352

Congress, Washington, USA

Technology, ISBN 83-7335-223-6, Gliwice, Poland

cracks formation during rolling of ingots.

from point of view of usable properties.

200, ISSN 1468-6996

5623

**6. Acknowledgment** 

**7. References** 

Fraś, E. (2003). *Crystallization of metals*, WNT, ISBN 83-204-2787-8, Warsaw, Poland


**22** 

*1,2Iran 3Serbia* 

**Phosphoramidates: Molecular Packing and** 

**Having a P(O)(N)n(O)3-n (n = 1, 2, 3) Skeleton** 

Compounds containing the P(O)(N)n(O)3-n (n = 1, 2, 3), P(O)(N)m(O)2-mX (m = 1, 2, X = C, Cl, F, S etc.) and P(O)(O)3 moieties are among the well-studied inorganic compounds [an interested reader may find many examples of compounds with the mentioned skeletons through a CSD search, [1]]. *N*,*N*,*N*',*N*',*N*",*N*"-hexamethyl phosphoric triamide (HMPA, Scheme 1) is an important polar aprotic solvent with a high-dielectric constant [2] and an

O

P

(H3C)2N N(CH3)2

Tabun, NCP(O)[N(CH3)2][OCH2CH3] (Scheme 2), Sarin, FP(O)(CH3)[OCH(CH3)2] and Soman, CH3P(O)(F)[OCH(CH3)(C(CH3)3)] are among the well-known "nerve agents" that act as acetylcholinesterase enzyme (AChE) inhibitors in human body and mammals [4].

O

P

N

O

CH3

H2

<sup>C</sup> CH3

C

H3C

N

Scheme 2. Tabun, a nerve agent

excellent ligand for interaction with hard metal-cations [3].

Scheme 1. *N*,*N*,*N*',*N*',*N*",*N*"-hexamethyl phosphoric triamide

**1. Introduction** 

**Hydrogen Bond Strength in Compounds** 

*1Department of Chemistry, Ferdowsi University of Mashhad, Mashhad, 2Department of Chemistry, Zanjan Branch, Islamic Azad University, Zanjan, 3Department of Physics, Faculty of Sciences, University of Novi Sad, Novi Sad,* 

N(CH3)2

Mehrdad Pourayoubi1, Fahimeh Sabbaghi2, Vladimir Divjakovic3 and Atekeh Tarahhomi1

