Phase relations in the system BiO1.5–SrO–CuO at 1123 K

Phase relations in the system Bi-Sr-Cu-O at 1123 K have been investigated using optical microscopy, electron-probe microanalysis (EPMA) and powder X-ray diffraction (XRD) of equilibrated samples. Differential thermal analysis (DTA) was used to confirm liquid formation for compositions rich in BiO1.5. Compositions along the three pseudo-binary sections and inside the pseudo-ternary triangle have been examined. The attainment of equilibrium was facilitated by the use of freshly prepared SrO as the starting material. The loss of Bi2O3 from the sample was minimized by double encapsulation. A complete phase diagram at 1123 K is presented. It differs significantly from versions of the phase diagram published recently.

A Non Quasi-Static Small Signal Model for Long Channel Symmetric DG MOSFET

We propose a compact model for small signal non quasi static analysis of long channel symmetric double gate MOSFET The model is based on the EKV formalism and is valid in all regions of operation and thus suitable for RF circuit design Proposed model is verified with professional numerical device simulator and excellent agreement is found well beyond the cut-off frequency

A simple and inexpensive two channel boxcar integrator

A two-channel boxcar integrator with an analog to digital converter was constructed using integrated circuits wherever convenient. The digital output can be instantaneously displayed or displayed after accumulating many samplings in the totaliser. The totaliser mode provides averaging at the digitiser level and hence the integrator has an infinite holding time. When used in the double boxcar mode the instrument overcomes the problem of any base line instability.

Valokuvallistettu luonto : I. K. Inhan tuotanto luonnon merkityksellistäjänä

Photographized nature I. K. Inha s work as a signification of nature The dissertation examines, through the work of the Finnish photographer and writer I. K. Inha (formerly Konrad Into Nyström) (1865 1930), the different ways in which the signification of nature is achieved. The principal material consists of Inha s work from 1890 to 1925, from which a number of photographs and texts are considered and upon which the photographization of nature is contemplated. The dissertation addresses the issue of how nature is conceived and how the act of photographizing it can be defined. The methodical context of the study is composed of three thematic baskets that structure the material and which consist of narrations on Finnish national perception, nature conservation and understanding the world. In the first case nature is seen as the natural environment encompassing lakes, seashores, forests, and hills, which at the time were often perceived from a utilitarian viewpoint. By the photographization they generated a pictorial narrative that could be shared. The natural environment was thus turned into landscape by means of photography, following the global pictorial concepts picturesque and sublime, as well as the national canons that had been developed in literature and the visual arts. In the narrations concerning nature conservation, the photographization did not merely occur within the limits of presuppositions, but rather nature was given the opportunity to unfold itself. While the photograph was being established as a basis for supporting nature conservation or to highlight the destruction of nature at the hand of Man, an attempt was made to represent subjects that were difficult to convey in photographs, such as nature s power or the miracle of growth. The thesis suggests, that in the third case the concept of nature broke away from its strict interconnection with the natural environment and led to a contemplation of nature that is perceivable in a person. In this context the photograph and the photographization are interpreted as an attempt to understand a person and his or her very existence in the world, while this same existential wonder is seen as being embodied in Inha s portrait of a rune singer and in his photographs of forest interior and water. Further, the thesis asks whether photographing nature could be interpreted as an action similar to the idea of the phenomenological reduction as a means of bypassing the photographer s prevailing way of being.

On a Ratio of Functions of Exponential Random Variables and Some Applications

Consider L independent and identically distributed exponential random variables (r.vs) X-1, X-2 ,..., X-L and positive scalars b(1), b(2) ,..., b(L). In this letter, we present the probability density function (pdf), cumulative distribution function and the Laplace transform of the pdf of the composite r.v Z = (Sigma(L)(j=1) X-j)(2) / (Sigma(L)(j=1) b(j)X(j)). We show that the r.v Z appears in various communication systems such as i) maximal ratio combining of signals received over multiple channels with mismatched noise variances, ii)M-ary phase-shift keying with spatial diversity and imperfect channel estimation, and iii) coded multi-carrier code-division multiple access reception affected by an unknown narrow-band interference, and the statistics of the r.v Z derived here enable us to carry out the performance analysis of such systems in closed-form.

Local texture and microstructure in cube-oriented nickel single crystal deformed by equal channel angular extrusion

Local texture and microstructure was investigated to study the deformation mechanisms during equal channel angular extrusion of a high purity nickel single crystal of initial cube orientation. A detailed texture and microstructure analysis by various diffraction techniques revealed the complexity of the deformation patterns in different locations of the billet. A modeling approach, taking into account slip system activity, was used to interpret the development of this heterogeneous deformation.

A nanosecond molecular dynamics study of antiparallel d(G)(7) quadruplex structures: Effect of the coordinated cations

Nanosecond scale molecular dynamics simulations have been performed on antiparallel Greek key type d(G(7)) quadruplex structures with different coordinated ions, namely Na+ and K+ ion, water and Na+ counter ions, using the AMBER force field and Particle Mesh Ewald technique for electrostatic interactions. Antiparallel structures are stable during the simulation, with root mean square deviation values of similar to1.5 Angstrom from the initial structures. Hydrogen bonding patterns within the G-tetrads depend on the nature of the coordinated ion, with the G-tetrad undergoing local structural variation to accommodate different cations. However, alternating syn-anti arrangement of bases along a chain as well as in a quartet is maintained through out the MD simulation. Coordinated Na+ ions, within the quadruplex cavity are quite mobile within the central channel and can even enter or exit from the quadruplex core, whereas coordinated K+ ions are quite immobile. MD studies at 400 K indicate that K+ ion cannot come out from the quadruplex core without breaking the terminal G-tetrads. Smaller grooves in antiparallel structures are better binding sites for hydrated counter ions, while a string of hydrogen bonded water molecules are observed within both the small and large grooves. The hydration free energy for the K+ ion coordinated structure is more favourable than that for the Na+ ion coordinated antiparallel quadruplex structure.

Chemical Shift of the X-Ray K-Absorption Edge of Cu in Some of Its Compounds, Complexes and Superconductors

Chemical shifts, ΔE, of the X-ray K-absorption edge in several compounds, complexes of copper including its superconducting oxides possessing formal oxidation states +1 and +2 have been measured. It has been shown that the chemical shift is primarily governed by the effective ionic charge on the absorbing ion and the nature of the atoms in the first coordination shell around the absorbing ion. The relation between the chemical shift, ΔE , and the effective charge q on the absorbing ion is found to be ΔE=Aq+Bq2+Cq3+Dq4 (A, B, C and D are constants). The effects of electronegativity, atomic number, oxidation state, crystal structure, the valence d-orbital electrons, etc. on the X-ray absorption chemical shift have been discussed. ©1990 The Physical Society of Japan

Theory of the effects of destruction of localization by inelastic scattering in the resistivity of pure thin potassium wires

Measurements of the electrical resistivity of thin potassium wires at temperatures near 1 K have revealed a minimum in the resistivity as a function of temperature. By proposing that the electrons in these wires have undergone localization, albeit with large localization length, and that inelastic-scattering events destroy the coherence of that state, we can explain both the magnitude and shape of the temperature-dependent resistivity data. Localization of electrons in these wires is to be expected because, due to the high purity of the potassium, the elastic mean free path is comparable to the diameters of the thinnest samples, making the Thouless length lT (or inelastic diffusion length) much larger than the diameter, so that the wire is effectively one dimensional. The inelastic events effectively break the wire into a series of localized segments, whose resistances can be added to obtain the total resistance of the wire. The ensemble-averaged resistance for all possible segmented wires, weighted with a Poisson distribution of inelastic-scattering lengths along the wire, yields a length dependence for the resistance that is proportional to [L3/lin(T)], provided that lin(T)?L, where L is the sample length and lin(T) is some effective temperature-dependent one-dimensional inelastic-scattering length. A more sophisticated approach using a Poisson distribution in inelastic-scattering times, which takes into account the diffusive motion of the electrons along the wire through the Thouless length, yields a length- and temperature-dependent resistivity proportional to (L/lT)4 under appropriate conditions. Inelastic-scattering lifetimes are inferred from the temperature-dependent bulk resistivities (i.e., those of thicker, effectively three-dimensional samples), assuming that a minimum amount of energy must be exchanged for a collision to be effective in destroying the phase coherence of the localized state. If the dominant inelastic mechanism is electron-electron scattering, then our result, given the appropriate choice of the channel number parameter, is consistent with the data. If electron-phason scattering were of comparable importance, then our results would remain consistent. However, the inelastic-scattering lifetime inferred from bulk resistivity data is too short. This is because the electron-phason mechanism dominates in the inelastic-scattering rate, although the two mechanisms may be of comparable importance for the bulk resistivity. Possible reasons why the electron-phason mechanism might be less effective in thin wires than in bulk are discussed.

Phase Relations in the System CaO-Fe2O3-Y2O3 at 1273 K and Compatibility Between Y1-xCaxFeO3-0.5x and Stabilized Zirconia

Phase relations in the system CaO-Fe2O3-Y2O3 in air (P-O2/P-o = 0.21) were explored by equilibrating samples representing eleven compositions in the ternary at 1273 K, followed by quenching to room temperature and phase identification using XRD. Limited mutual solubility was observed between YFeO3 and Ca2Fe2O5. No quaternary oxide was identified. An isothermal section of the phase diagram at 1273 K was constructed from the results. Five three-phase regions and four extended two-phase regions were observed. The extended two-phase regions arise from the limited solid solutions based on the ternary oxides YFeO3 and Ca2Fe2O5. Activities of CaO, Fe2O3 and Y2O3 in the three-phase fields were computed using recently measured thermodynamic data on the ternary oxides. The experimental phase diagram is consistent with thermodynamic data. The computed activities of CaO indicate that compositions of CaO-doped YFeO3 exhibiting good electrical conductivity are not compatible with zirconia-based electrolytes; CaO will react with ZrO2 to form CaZrO3.

An automated thermal relaxation calorimeter for operation at low temperature (0.5 KK)

We describe an automated calorimeter for measurement of specific heat in the temperature range 10 K>T>0.5 K. It uses sample of moderate size (100–1000 mg), has a moderate precision and accuracy (2%–5%), is easy to operate and the measurements can be done quickly with He4 economy. The accuracy of this calorimeter was checked by measurement of specific heat of copper and that of aluminium near its superconducting transition temperature.

Blade manipulators in turbulent channel flow

We report here the results of a series of careful experiments in turbulent channel flow, using various configurations of blade manipulators suggested as optimal in earlier boundary layer studies. The mass flow in the channel could be held constant to better than 0.1%, and the uncertainties in pressure loss measurements were less than 0.1 mm of water; it was therefore possible to make accurate estimates of the global effects of blade manipulation of a kind that are difficult in boundary layer flows. The flow was fully developed at the station where the blades were mounted, and always relaxed to the same state sufficiently far downstream. It is found that, for a given mass flow, the pressure drop to any station downstream is always higher in the manipulated than in the unmanipulated flow, demonstrating that none of the blade manipulators tried reduces net duct losses. However the net increase in duct losses is less than the drag of the blade even in laminar flow, showing that there is a net reduction in the total skin friction drag experienced by the duct, but this relief is only about 20% of the manipulator drag at most.