Practical system for the direct measurement of magneto-caloric effect by micro-thermocouples

A system for direct measurements of the magneto-caloric effect (MCE) exploits a rapid transport of a sample into or from magnetic field in permanent Halbach-type (1 T) or superconducting (4.7 T) magnets. Time dependence of induced changes of the sample temperature, ΔT(t), is detected directly by the differential Cu-Constantan-Cu micro-thermocouples with time steps of 300 ms. A sample placed inside an evacuated simple LN(2) cryostat is either totally isolated (adiabatic conditions) or partly connected with the copper sample holder (non-adiabatic conditions). The last arrangement (a model of the Brayton cycle) is used to simulate an application of MCE in refrigeration techniques. The relations describing ΔT(t) that allow an analysis of MCE of the studied materials are based on the general cooling law. The effect of the first-order magnetic transition on MCE of selected sample is also demonstrated by non-standard ΔT(t) curves measured in the last mentioned experimental arrangements.     

Optimization of the reforming process scheme

The possibility of obtaining stable reforming catalyzate with a benzene content of less than 1 wt. % was demonstrated by mathematical modeling. Two new versions of separation of benzene-forming components from the reaction mixture between the second and third levels were created. In comparison to the standard process, the first version ensures a benzene content in the reformate at the level of 0.01 wt. % with a 12% decreases in its yield, and the second version produces a benzene content at 0.47 wt. % with a 2.9% increase in the yield of reformate. The proposed versions are useful in production of export automotive gasoline that satisfies the Euro 2000 requirements. __________ Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 3, pp. 18 — 22, May — June, 2006.     

Growth of muscle cells on plasma-treated and gold nanoparticles-grafted polytetrafluoroethylene

Polytetrafluoroethylene (PTFE) was modified by Ar plasma with different exposure times. The plasma-activated surface was immersed in biphenyldithiol and subsequently in colloidal solution of Au nanoparticles. The changes in the surface wettability contact angle were examined by goniometry. Atomic force microscopy was used to determine the surface roughness and morphology. Changes in the chemical structure of the modified PTFE were studied using X-ray photoelectron spectroscopy (XPS) and electrokinetic analysis. The interaction of plasma-treated and grafted samples with vascular smooth muscle cell derived from the rat aorta was also studied. Specifically, the number and morphology of the adhered and proliferated cells on the PTFE were studied under in vitro conditions. The plasma treatment and the subsequent biphenyldithiol and Au nanoparticles grafting led to changes in the polymer surface chemistry, morphology, roughness and wettability. The polymer grafting with biphenyl-4,4′-dithiol (BFD) and subsequently with Au nanoparticles led to a decrease in the surface polarity. XPS measurements proved the presence of S and Au on the PTFE surface. Grafting with BFD and Au nanoparticles led to the decrease in surface roughness. In comparison with the pristine polymer, the plasma treatment and Au nanoparticles grafting increased the adhesion and proliferation of vascular smooth muscle cell.     

Compressor designing, manufacturing, and testing at Iskra NPO

Results of acceptance tests and gas-dynamic characteristics of a series of compressors for gas pumping units are reported. The work at the Iskra NPO on compressor making over the past decade and future plans are described.     

Effect of volcanic pumice powder on the fresh properties of self-compacting concretes with and without silica fume

The current study presents an experimental study conducted on the effectiveness of volcanic pumice powder (VP) on the fresh properties of self-compacting concretes (SCCs) with and without silica fume (SF). In the first group, SCCs without SF were produced with 0, 5, 10, and 20 % replacement levels of VP. However, for the second group, SF incorporation was achieved by a constant SF replacement level of 8 %. All of the replacement levels assigned were substitution of cement with the supplementary cementing materials on the basis of weight of total binder. Therefore, totally eight different SCCs were produced. The investigated fresh characteristics of the concretes were slump flow diameter, T _500mm slump flow time, V-funnel flow time, and L-box height ratio. The compressive strength of concretes was also evaluated to indicate the mechanical performance. Moreover, a statistical study, namely general linear model analysis of variance, was performed in order to examine the significance of the critical parameters such as inclusion of SF and replacement level of VP on the properties of SCCs. The results have revealed that increasing the replacement level of VP generally resulted in the increase of fluidity of SCCs without loss of uniformity and with no segregation. Moreover, incorporation of SF provided significant increase in compressive strength while VP caused a systematic decrease.     

Surface plasmon resonance sensor using an optical fiber with an inverted graded-index profile

A new optical fiber sensor based on surface plasmon resonance is described. It uses an optical fiber with an inverted graded-index profile. A theoretical analysis of the optical propagation when a point light source was used and a computation of the optical power transmitted by the fiber were performed. Experiments were carried out to measure changes of the transmitted power caused by refractive-index variations of the surrounding dielectric medium. Both the simulation and experiments have shown that the sensor exhibits high sensitivity for changes of the surrounding medium in a refractive index range from 1.33 to 1.39.     

Checking the operation of power units at thermal power stations in the mode of selective primary control of frequency during field system tests in the unified energy system

We present the results from unique system tests for ascertaining whether 210–800-MW power units can participate in selective primary and automatic secondary control of frequency and power. Conditions under which the tests were carried out are described in detail, the results of which confirmed that all the selected power units are ready to participate in selective primary and automatic secondary control of frequency and power.