Steady-state acceleration of alkali plasma in external crossed electric and magnetic fields

The results of an experimental investigation of the electromagnetic acceleration of an alkali plasma in single- and double-stage E,H-accelerators are discussed. The nature of the discharge in accelerators with ceramic and metallic walls is investigated. The number of elements of the metallic wall necessary for preventing breakdown is determined. The thrust and efficiency of different constructions are determined, and their efficiencies and effectiveness are compared.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 6, pp. 20–30, November–December, 1974.The authors thank Yu. A. Tetyukhin, M. G. Shevtsov, V. G. Mikhalev, and B. S. Dimanov for participation in the experiments.     

Shear of fibrous suspensions between coaxial cylinders

The shear of fiber suspensions between coaxial cylinders is examined. The model of a suspension constructed in [1, 2] is used in the solution. The solution is sought by the method of series expansion in a small parameter. The first approximation found is compared with experiments [3, 4] and with the solution of the problem of core flows in a pipe [2].     

On the possibility of reducing the penetration capability of shaped-charge jets in a magnetic field

The possibility of reducing the penetration capability of shaped charges by producing a magnetic field ahead of the target with flux lines parallel to the charge axis is considered. The problem is studied on the basis of results of experiments in which a magnetic field was produced in a shaped-charge liner before firing, resulting in a sharp reduction or elimination of penetration. The variation of the magnetic induction in the shaped-charge liner moving in the magnetic field is calculated using the model of two conducting coaxial cylindrical shells corresponding to the charge case and liner and assuming constant induction-current density over the shell thickness. A longitudinal magnetic field is specified on the surface of the outer shell as a function of the spatial distribution of the field ahead of the target and the charge velocity. The magnetic-field intensity that can provide a considerable reduction in the penetration capability of shaped charges of various diameters is estimated. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 3, pp. 112–120, May–June, 2007.     

Special features of the nucleophilic substitution of halogen in alkyl and benzyl halides with anions generated from 4-hydroxy-2-mercapto-6-methylpyrimidine

The nucleophilic substitution of halogen (chlorine, bromine, and iodine) in alkyl and benzyl halides has been effected in aqueous dioxane media with S-and O-anions generated from 4-hydroxy-2-mercapto-6-methylpyrimidine. Under these conditions replacement of halogen proceeds by an S_N2 mechanism and the reactivity of S-anions is 10 times greater than that of O-anions, which is in agreement with the results of ab initio quantum-chemical calculations of the electronic structure and total energy of transition states, carried out within the framework of the restricted Hartree-Fock method, basis 6-31G**. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 874–883, June, 2008.     

Regularities of the stretching and plastic failure of metal shaped-charge jets

The results of physicomathematical modeling obtained within the framework of continuum mechanics by numerical solution of the two-dimensional axisymmetric nonstationary problem of the dynamic deformation of a compressed elastoplastic bar of variable section are presented. Dependences of the quantitative characteristics of stretching and breakup of a shaped-charge jet (the coefficients of ultimate and inertial elongation and the number of individual elements formed in breakup) on the jet parameters and the jet material properties are revealed by calculations. The calculated dependences are compared with experimental data for plastically failing jets of copper and niobium, and the character of the dependences is explained from the physical viewpoint. Bauman Moscow State Technical University, Moscow 107005. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 4, pp. 25–35, July–August, 1999.     

Synthesis of a magnetoactive compound based on iron(II) sulfate

The effect of synthesis parameters on properties of a magnetoactive compound (MAC) prepared via condensation of iron(II) sulfate in the presence of sodium nitrite is investigated. It is found that nitrite ions almost completely coprecipitate with the solid phase during the formation of a magnetoactive compound and subsequently participate in the redox conversions to yield magnetite. In order to obtain a magnetoactive compound with high relative magnetic susceptibility, condensation from the initial solutions is to be carried out at least 15 min after it is prepared; sodium nitrite consumption is to be at least 0.12 mol/mol FeSO₄.     

Mechanochemical preparation and pharmacological activities of water-soluble intermolecular complexes of arabinogalactan with medicinal agents

A possibility of mechanochemical preparation of water-soluble complexes of a plant polysaccharide arabinogalactan and poorly soluble medicinal agents (Sibazon(=Diazepam), Mezapam(=Medazepam), Indometacin, and Azaleptin(=Clozapine)) has been investigated. Their molecular dynamics (NMR relaxation method in solution) and some pharmacological properties have been studied in comparison with the original pharmaceutical drugs.