Porous silicon bulk acoustic wave resonator with integrated transducer

ABSTRACT: : We report that porous silicon acoustic Bragg reflectors and AlN-based transducers can be successfully combined and processed in a commercial solidly mounted resonator production line. The resulting device takes advantage of the unique acoustic properties of porous silicon in order to form a monolithically integrated bulk acoustic wave resonator.     

Specific features of the temperature dependence of the conduction electron concentration in the narrow-gap and zero-gap states of Cd<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Hg<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Te

Results of studies of the conductivity σ and the Hall coefficient R in the Cd _x Hg_{1 − x} Te crystals with x = 0.1, 0.12, 0.14, and 0.15 are analyzed in the temperature range T = 4.2–300 K and the magnetic field range B = 0.005–2.22 T. Using data on the R(B) in low and high magnetic fields and the data on σ(T), electron and hole concentrations and mobilities are determined. It is shown that the electron concentration n in the studied samples is almost independent of T in the range 4.2–15 K, while as T increases, it increases according to the law n ∝ T ^r (r > 3/2), where r = f(n, T, x). It is found that r varies from 1.7 at x = 0.1 to 3.1 at compositions with x = 0.14 and 0.15. The results for n(T) are compared with theory, taking into account nonparabolicity of the variance law for ⃛(T), and with the theory of impurity states in narrow-gap and zero-gap semiconductors. It is shown that the constancy of n(T) up to ∼15 K and the strong dependence n(T) (r > 3/2) at higher temperatures are caused by the intense ionization of electrons localized at acceptor states.     

Aquathermolysis of heavy oil in reservoir conditions with the use of oil-soluble catalysts: part I – changes in composition of saturated hydrocarbons

Abstract

This paper is devoted to the study of aquathermolysis processes of heavy oil produced by CSS technology on Boca de Jaruco oil field. Various catalysts based on cobalt, nickel, iron and copper were used for intensification of in-situ upgrading processes of heavy oil. The first paper in series is presented results of transformation of crude oil and its saturate fraction after thermal treatment with and without catalysts by SARA analysis, MALDI mass-spectrometry, FTIR-spectroscopy and gas chromatography. It is revealed, that catalysts provide more deep conversion of asphaltenes and resins into lighter hydrocarbons. Particularly, for the given heavy oil, catalysts based on iron and nickel organic salts are more effective to reduce the content of high molecular weight components (asphaltenes). Saturates fraction after thermal treatment in presence of the catalysts is enriched with lighter alkanes in comparison to the crude oil treated without catalysts. Obtained results show that crude oil recovered by catalytic aquathermolysis processes will be better quality than the original oil in the place.     

Radiation grafting of N,N-dimethylaminoethylmethacrylate onto poly(ethylene terephthalate)

Summary Radiation-induced graft polymerization of N,N-dimethylaminoethylmethacrylate (DMAEMA) from 50% solution in chloroform onto poly(ethylene terephthalate) (PET) was carried out by means of mutual γ-irradiation of polymer in presence of liquid or vapor phase monomer solutions (direct method), or by grafting of monomer from this liquid solution onto polymer preirradiated in air. It has been shown higher effectiveness of grafting by the direct method from vapor phase of monomer or by the preirradiation method as compared with direct grafting from liquid monomer solution. Grafting did not affect crystallinity, transparency and durability of the starting PET. Received: 18 November 1999/Revised version: 7 February 2000/Accepted: 8 February 2000     

A study of the thermal degradation of poly(vinyl chloride)

A thermal degradation of poly(vinyl chloride) (PVC) was studied. This was an essential step in the investigation of the compatibility of PVC-based systems because mixing in industry and in the preparation of materials is carried out in the viscous flow range close to thermal degradation. Original Russian Text ? K.A. Polozkov, A.E. Chalykh, V.K. Gerasimov, V.V. Matveev, A.D. Aliev, 2008, published in Fizikokhimiya Poverkhnosti i Zashchita Materialov, 2008, Vol. 44, No. 5, pp. 537–540.     

A Method of Generating Random Vectors with a Given Probability Density Function

We propose a method for generating random independent vectors that have a given continuous distribution density with compact support. The main advantage of the proposed method are guaranteed estimates of the error in the generation of random vectors. We show an illustrative experimental comparison of the proposed method with the Metropolis-Hastings algorithm.