The Electroreduction of Gadolinium and Dysprosium Ions in Equimolar NaCl-KCl Melt

The mechanism of rare earth metals (Gd and Dy) chloride complexes electroreduction on the tungsten electrode in equimolar NaCl-KCl melt at 973 K has been studied by linear and cyclic voltammetry. Some kinetic parameters of processes were calculated. It was shown that the tungsten electrode was indifferent to gadolinium and dysprosium which were reduced on the surface. We found that the discharge mechanism of gadolinium and dysprosium chloride complexes was described by three-electron step when the steady-state conditions of polarization were limited by the mass transfer stage. The conditions of nonstationary polarization made the slowness of the charge transfer stage. The diffusion coefficient of gadolinium and dysprosium ions was calculated, the diffusion coefficient of GdCl3-6 ions was (0.9 ± 0.2) × 10-5 cm2.s-1, and for DYCI3-6 ions, it was (1.60 ± 0.2) × 10-5 сm2.s-1.

气相色谱法探究聚醚醚酮的热降解及热氧化降解（英文）

Poly(ether ether ketone)(PEEK)was synthesized via polycondensation of hydroquinone with 4,4′-difluorobenzophenone at 320℃for 5 h.Thermal and thermo-oxidative degradation of PEEK was studied over a wide range of temperatures.In an inert medium,decomposition of the polymer occurred in one stage,with the formation of a coke residue accounting for approximately 50%of the original polymer mass.In air,the mass loss curve exhibited two distinct stages.The first stage involved breakdown of the main polymer chain,the speed of which indicated a radical chain failure mechanism.In the second stage,the rate of mass loss clearly decreased,indicating a transition from the radical chain failure mechanism to simple combustion reactions(wherein the polymer combusted completely).To further investigate the nature of the processes occurring during the pyrolysis of PEEK,the investigations were carried out using gas chromatograph under isothermal conditions.It was concluded that during thermal degradation,the decomposition of the polymer starts with the rupture of ketone and ether bonds and proceeds to destruction of the benzene ring at higher temperatures,which is accompanied by the formation of H2O and CH4.Above 500℃,the polymer degradation further involved thermohydrolysis.The thermo-oxidation of PEEK,which was accompanied mainly by the formation ofH2,was noticeable beginning at 325℃.The total yield of the latter indicated oxidation of fragments of the benzene ring.

The Study of Different Structuring Techniques for Creation of Non-Evaporable Getters

The results of observation of different structuring techniques of thin metal layers applied in micro system technologies are presented. The Ti V getter films formed by magnetron sputtering have been explored using scanning electron and atomic-force microscopy, Brunauer-Emmett-Teller method, thermogravimetric analysis and fractal geometry. The film sorption capacity for hydrogen given by thermogravimetry was of 7.7 m3·Pa·g-1. To estimate the effective surface area, the fractal geometry tools were used and the calculated value of the specific surface area was about 155 m2/m3. The second object under investigation was a structure composed of micro- and mesoporous silicon and copper layer deposited electrochemically on the pore walls. Porous silicon when coupled with a reactive metal or alloy is expected to be an effective getter for micro system techniques. The use of porous silicon and specific conditions of depositions allows to form the structure of complex fractal type with a specific surface area of 167 m2/cm3.

The new approaches in a process engineering high power microwaves diodes millimeter wave band

The reachings in the field of deriving modern materials of a microelectronics engineering are especially effective, when the process engineering of manufacture of the concrete device allows maximum to realize the resources, included in active structure.In the report the outcomes of results on a considerable diminution of thermal restrictions generating impatt diodes millimeter （mm） wave band are submitted with the purpose of improving exit pupils and reliability. The complex of original design technological receptions has allowed to solve a problem of making multimesa wave band structures, in which the thermal resistance is possible to reduce in inverse proportionn,where n-number of mesa structures. The sectional process engineering has general purpose character and is applicable to the most composite materials in particular to heterostrucructures and all types of made on their bases microwaves diodes containing a mesa structure. The results are illustrated on silicon double drift six mesa structure 5 mm wave band for which the level of an output continuous power 1.04 watts on frequency 65.9 GH2 is obtained. Thus p-n junction temperature did not exceed 220℃ usual copper heatsink also was utillized. The electronic snapshots and outcomes of investigation of thermal fields silicon mesa diodes of a various configuration are reduced: to six mesa, eight mesa, ring.Singularity of a sectional process engineering are higher specific mechanical loadings at assembly of devices, therefore with the purpose of a raise of reliability and percent of an exit of suitable devices designed and the procedure permitting to inspect on starting plates amplitude and a strain gradient in active region is tested X-ray diffraction method that is especially important for heterostructure mesa diodes.

Polyimides with improved operational by properties

One of directions of basic researches in the field of chemical process engineerings is making new polymeric materials for electronics and aviation teсhnique distinguished by boosted production characteristics. The value of aromatic polyimides (PI) as industrial thermally sound polymers is well-known. However alongside with a complex of valuable properties they have also series of shortages: high temperatures and difficulty of reaching of 100% conversion at ring formation polyamic acids (PAA) and their instability in time, low stability to hydrolysis, poor adhesion to line of substratums etc. all this in some cases restricts or makes to impossible application PI in practice. The complex examinations, spent by us, the solid-phase of thermal cyclyzation PAA and its model junctions have reduced in an establishment of correlation associations between a degree and velocity of ring-formation, thermal stability and reagent resistance, stregth that has allowed to govern process of deriving PI with a necessary level of production characteristics. Use of some components, for example, heterocyclic basic amines-azoles, promotes acceleration and lowering of a temperature band of ring-formation PAA, and also magnification of a degree of ring-formation, that reduces in a considerable raise thermal and chemical resistance, mechanical and dielectric parameters and insulant properties which are not varying at long-lived operation.The modes of deriving of various materials designed on the basis of industrial PAA of a lacquer consisting in introduction of azoles, plasticizing and adhesion components. It is shown, that the coats obtained from modified polymers, have boosted adhesion, high thermal, mechanical, insulant and other properties maintained in requirements of climatic trials.

Synthesis of New Polymer Ionomers via Ring-Opening Metathesis Polymerization

The N-pentafluorophenyl-exo-endo-norbornene-5,6-dicarboximide (2a) and N-phenyl-exo-endo-nor-bornene-5,6-dicarboximide (2b) monomers were synthesized and polymerized via ring-opening metathesis polymerization (ROMP) using bis(tricyclohexylphosphine) benzylidene ruthenium(IV) dichloride (I) and tricyclohexylphosphine [1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene][benzylidene] ruthenium dichloride (II). Both catalysts were used to synthesize random and block high molecular weight copolymers which were further hydrogenated using a Wilkinson’s catalyst. Then, the saturated copolymers were modified by reacting with sodium 4-hydroxybenzene-sulfonate dihydrate to generate new ionomers with fluoro-sulfonic acid pendant groups.

Infinite Frobenius Groups Generated by Elements of Order 3

A semidirect product G=F⋋H of groups F and H is called a Frobenius group if the following two conditions are satisfied:(F1)H acts freely on F,that is,fh=f for f in F and h in H only if^(h)=1 or f=1.(F2)Every non-identity element h∈H of finite order n induces in F by conjugation in G a splitting automorphism,that is,ff^(h)⋯fh^(n−1)=1 for every f∈F;in other words,the order of f^(h−1)is equal to n.We describe the normal structure of a Frobenius group with periodic subgroup H generated by elements of order 3.