η,η′→ππγ with coupled channels

The decays η,η′→π⁺π⁻γ are investigated within an approach that combines one-loop chiral perturbation theory with a coupled channel Bethe–Salpeter equation which satisfies unitarity constraints and generates vector mesons dynamically from composite states of two pseudoscalar mesons. It is furthermore shown that the inclusion of the η′ as a dynamical degree of freedom does not renormalize the Wess–Zumino–Witten term.     

Supersymmetric contributions to direct CP violation in K→ππγ decays

We analyze the supersymmetric contributions to direct–CP–violating observables in K→ππγ decays induced by gluino–mediated magnetic–penguin operators. We find that ε′_+−γ and the differential width asymmetry of K^±→π^±π⁰γ decays could be substantially enhanced with respect to their Standard Model values, especially in the scenario where ε′/ε is dominated by supersymmetric contributions. These observables could therefore provide a useful tool to search for New Physics effects in |ΔS|=1 transitions, complementary to ε′/ε and rare decays.     

High-temperature strength of Ni3Al - Ni3Nb alloys

Conclusions The concentration dependences have been found for the bending and compression strength of Ni₃Al–Ni₃Nb alloys in the temperature range 20–1200 °, and the corresponding dependence for the tensile strength has been found at room temperature. It has been shown that the alloys with 45 and 90 wt.% Ni₃Nb are the strongest. The concentration dependences of the strength of these alloys have been compared with their physical properties.Translated from Izvestiya Vysshlkh Uchebnykh Zavedenii, Fizika, Vol. 12, No. 7, pp. 55–59, July, 1969.     

Experimental study and calculations of nitric oxide absorption in the γ(0,0) and γ(1,0) bands for strong temperature conditions

Absorption spectra of nitric oxide in the γ(0,0) and γ(1,0) bands have been measured for hard temperature conditions up to 1700 K in order to validate a model for the simulation of these two bands. The good agreement between experiments and calculations (relative errors of 2–5% for the γ(0,0) band and 10–15% for the γ(1,0) band) consolidates the two important assumptions concerning the intermediate Hund's case between (a) and (b) for the X²Π state of the γ(0,0) and γ(1,0) absorption bands and the use of collisional broadening parameters of γ(0,0) to simulate the γ(1,0) band. Using this simulation, a study of the Beer–Lambert law behavior at high temperature has been carried out. With the instrument resolution used for these experiments, it was shown that a correction of the Beer–Lambert law is necessary. To apply this technique for the measurements of NO concentrations inside the combustion chamber of an optical SI engine, a new formulation of the Beer–Lambert law has been introduced, since the modified form proposed in the literature is no longer applicable in the total column range of interest.     

Yb3+sensitized Er3+-doped waveguide amplifiers: a theoretical approach

Silicate and phosphate glass waveguide amplifiers doped with Er³⁺, and co-doped with Er³⁺/Yb³⁺ are theoretically studied. Configurations for core and core–cladding doped waveguide amplifiers are considered. It is shown that gain in the core–cladding doped amplifiers is considerably higher than core doped amplifiers. It is also shown that with input signal power up to 1 and 200mW pump power, a 12.5dB gain can be achieved in a 3cm long waveguide amplifier, with a noise figure of 3dB.     

Investigation of Glasses and Glaze Coats of Composition R2O–RO–Fe2O3(FeO)–Al2O3–B2O3–SiO2 by the EPR Method

The valence state and the coordination environment of the paramagnetic centers of iron ions in glasses and vitreous coats of composition R₂O–RO–Fe₂O₃(FeO)–Al₂O₃–B₂O₃–SiO₂ have been investigated by the EPR method. The tetrahedral and octahedral coordinations of Fe³⁺ ions have been revealed. The character of change in the EPR spectra of the materials studied in the vitreous and vitrocrystalline state has been determined. It is shown that the coordination number of iron ions is dependent on the crystallization processes.     

High-Resolution Laser Spectroscopy of YbCl: The AΠ–XΣ Transition

The A²Π–X²Σ⁺ transition of ¹⁷⁴Yb³⁵Cl and ¹⁷²Yb³⁵Cl has been rotationally analyzed for the first time. Doppler-limited laser excitation spectroscopy with selective detection of fluorescence was used to obtain spectra of the 0–0 and 1–0 bands with a measurement accuracy of approximately 0.0035 cm⁻¹. Resolved fluorescence was used to record the 0–1, 0–2, and 0–3 bands and to unequivocally assign the rotational numbering, N, to the laser excitation spectra. In total, over 1300 line positions have been measured and assigned for each of the two isotopomers and employed in least-squares fits of molecular parameters. The principal results for the A²Π state are A_e = 1491.494(2) cm⁻¹ and R_e = 2.4433(1) Å, and for the X²Σ⁺ state, R_e = 2.4883(2) Å and γ_e = 4.59(2) × 10⁻³ cm⁻¹. The interaction between the X²Σ⁺ and A²Π states has been investigated and is shown to be the main contributor to the spin–rotation splitting in the ground state.     

Fabrication of combined 0–3 and 1–3 connectivities PZT/epoxy resin composites

PZT/epoxy resin composites of combined 0–3 and 1–3 connectivities were fabricated, for the first time, using suction, dice and fill techniques. Two types of composites (PZT(m)/epoxy resin and PZT(sp)/epoxy resin) were produced using PZT powders prepared by mixed oxide and spray-drying methods. Physical, mechanical, dielectric and piezoelectric properties of the composites were examined. Generally, overall results between the two composites were found to be very similar (volumetric changes ∼34–37%, d₃₃∼20.2–25.3 pC/N, K_p∼0.54–0.61). Higher density was found in PZT(sp)/epoxy resin, however, due to better packing of particles. Moreover, both PZT/epoxy resin composites exhibited very low acoustic impedance (Z∼4.12–4.84 Mrayls), which is very close to that of human tissue and water. Therefore, these new composites may be suitable for use in medical applications. PACS 81.05.Qk; 81.05.Zx; 77.87.-s     

Time-resolved emission spectroscopy of gadolinium vanadate ceramics (GdVO4:Bi3+)

The preparation of GdVO₄:Bi³⁺ ceramics is indicated. Bismuth shows a strong tendency to evaporate during the sintering process. Time-resolved emission spectroscopy shows for sufficiently low Bi³⁺ concentrations subsequently: blue VO ₄ ^3– emission with a decay time corresponding to the transfer rate (10⁶ s^–1), yellow VO ₄ ^3– –Bi³⁺ emission, rare-earth impurity emission and VO ₄ ^3– –Bi³⁺ afterglow.     

The influence of different fabrication processes on characteristics of excess Bi2O3-doped 0.95 (Na0.5Bi0.5)TiO3–0.05 BaTiO3 ceramics

In this study, we will develop the influences of the excess x wt% (x=0, 1, 2, and 3) Bi₂O₃-doped and the different fabricating process on the sintering and dielectric characteristics of 0.95 (Na_0.5Bi_0.5)TiO₃–0.05 BaTiO₃ ferroelectric ceramics with the aid of SEM and X-ray diffraction patterns, and dielectric–temperature curves. The 0.95 (Na_0.5Bi_0.5)TiO₃–0.05 BaTiO₃+x wt% Bi₂O₃ ceramics are fabricated by two different processes. The first process is that (Na_0.5Bi_0.5)TiO₃ composition is calcined at 850 °C and BaTiO₃ composition is calcined at 1100 °C, then the calcined (Na_0.5Bi_0.5)TiO₃ and BaTiO₃ powders are mixed in according to 0.95 (Na_0.5Bi_0.5)TiO₃–0.05 BaTiO₃+x wt% Bi₂O₃ compositions. The second process is that the raw materials are mixed in accordance to the 0.95 (Na_0.5Bi_0.5)TiO₃–0.05 BaTiO₃+x wt% Bi₂O₃ compositions and then calcining at 900 °C. The sintering process is carried out in air for 2 h from 1120 to 1240 °C. After sintering, the effects of process parameters on the dielectric characteristics will be developed by the dielectric–temperature curves. Dielectric–temperature properties are also investigated at the temperatures of 30–350 °C and at the frequencies of 10 kHz–1 MHz.     

Argon ion laser-induced BaS BΣ-AΣ, A′Π, aΠ, and XΣ fluorescence spectra: Analysis of A A′, A a, and A′ a perturbations

The 333.6-, 351.1-, and 363.8-nm lines of a cw argon ion laser are found to coincide with the BaS B¹Σ⁺-X¹Σ⁺ (12, 0) R(17), (6, 0) P(35), and (3, 0) R(125) transitions, respectively. Fluorescence transitions from the laser-prepared upper levels terminating in X¹Σ⁺ V = 0–28, A¹Σ⁺ V = 1–3, A′¹Π V = 1–13, and a³Π₁ V = 3–12 are assigned. These results are combined with a previous analysis of the extensively perturbed BaS A¹Σ⁺-X¹Σ⁺ system [R. F. Barrow, W. G. Burton, and P. A. Jones, Trans. Farad. Soc.67, 902–906 (1971)]. Every observed perturbation of the BaS A¹Σ⁺ state is electronically and vibrationally assigned. The levels a³Π₀ V = 10–13, a³Π₁ V = 12–14, a³Π₂ V = 15, and A′¹Π V = 10–13 are sampled via their perturbations of A¹Σ⁺ V = 0–2. Although the mutual interactions of the a³Π, A′¹Π, and A¹Σ⁺ states approach Hund's case (c) limit, a complete deperturbation is performed from a case (a) starting point. Of the five lowest energy electronic states of BaS, only b³Σ⁺ remains uncharacterized. Principal deperturbed molecular constants are (in cm⁻¹, 1σ uncertainties in parentheses):

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Ab initio study of structural and electronic properties of BiAlO3 and BiGaO3

The first principles within the full potential linearized augmented plane wave (FP-LAPW) method was applied to study the structural and electronic properties of cubic perovskite-type compounds BiAlO₃ and BiGaO₃. The lattice constant, bulk modulus, its pressure derivative, band structure and density of states were obtained. The results show that BiGaO₃ should exhibit higher hardness and stiffness than BiAlO₃. The Al–O or Ga–O bonds are typically covalent with a strong hybridizations as well as Bi–O ones that have a significant ionic character. Both materials are weakly ionic and exhibit wide and indirect band gaps, which are typical of insulators.     

Characterization of the ξ-carbide in ex-service 1Cr-0.5 Mo steels

The ξ-carbide, also described as Fe₂MoC and M_aC_b, has been identified at ferrite grain boundaries in 1Cr-0.5Mo steels exposed to elevated temperatures (500–530°C) for prolonged periods (65,000–170,000 hr). The structure and composition of the phase have been characterized using electron microdiffraction and energy-dispersive X-ray spectroscopy (EDXS) respectively. Analysis of microdiffraction patterns supports the proposal that the ξ-carbide has a monoclinic unit cell, rather than the orthorhombic unit cell first proposed. The ranges of metallic element concentrations in the ξ-carbide (i.e. 48–59 at.% Fe, 22–29 at.% Mo, 7–16 at.% Cr, 4–7 at.% Mn and 3–6 at.% Si) are unique compared to those of other carbide precipitates identified in the 1Cr-0.5Mo steels, which means that the ξ-carbide may be identified rapidly on extraction replicas using qualitative EDXS.     

Evolution of chirality from γ soft Ru to triaxial Ru

Rotational bands in ^108,110,112Ru have been investigated by means of γ–γ–γ and γ–γ(θ) coincidences of prompt γ rays emitted in the spontaneous fission of ²⁵²Cf. The positive parity bands are described by different versions of IBA, where ¹⁰⁸Ru is best described as a γ-soft nucleus whereas ^110,112Ru are more like rigid triaxial rotors. New ΔI=1 negative parity doublet bands are found. In case of ^110,112Ru, these are interpreted as soft chiral vibrations. Many of the experimental findings can be explained by microscopic calculations that combine the TAC mean-field with random phase approximation but a simple geometrical explanation is not apparent.     

Polyacrylonitrile–sulfolane–CuX2 (X=Cl, Br, CF3SO3) solid polymer electrolyte

A series of polyacrylonitrile–sulfolane–CuX₂ (PAN–TMS–CuX₂, where X=Cl, Br, CF₃SO₃) polymer electrolytes, of thickness between 0.03 and 0.07 cm, were prepared by means of the solution cast technique. The solvent content was as high as 60–70 wt.%. Conductivities of the foils obtained from impedance measurements were of the order of 10⁻³ Ω⁻¹ cm⁻¹. Temperature variation of the conductivity for all the systems studied was of the Arrhenius type. Exchange current density at the Cuelectrolyte interface, determined from the Tafel plot, was of the order of milliampere (mA). Cyclic voltammetry showed the irreversible character of the copper plating–stripping process.     

Effect of Fe2O3 and Cr2O3 on the Processes of Pyroxene Formation in Silicate Glasses

We have investigated the processes of pyroxene formation in crystallization of glasses of the system SiO₂–Al₂O₃–CaO–MgO–Na₂O stimulated with chromium and iron oxides introduced together. It is found that sharp activation of the processes of pyroxene formation occurs in the temperature interval of thermal treatment 850–900°C. Interpretation of the absorption bands is carried out and conclusions are drawn on the structural role of the iron and aluminum ions in the process of formation of a pyroxene solid solution.     

Studies of vibrational relaxation in CDF3 following intense laser excitation

The V-T/R relaxation time of CDF₃ was measured studying the laser-induced infrared fluorescence emitted by vibrationally excited CDF₃. Following excitation by the 10R(12) line of a TEA CO₂ laser infrared fluorescence has been detected without spectral resolution in the 1100–700 cm^–1 range. A decay rate of 28.8 ms^–1 Torr^–1 was obtained for pure CDF₃ when it is excited with a fluence of 390 mJ/cm². Measurements have also been made in the presence of different bath gases (He, Ne, Ar, Xe, and CHF₃).     

Solubility of Na2Co3 in NaCl:CaCl2 crystals

Measurements of electrical conductivity of NaCl 10^–5 molar fr. CaCl2 (1–80)×10^–5 molar fr. Na₂CO₃ crystals have been used to determine the temperature dependence of the solubility of CO₃-ions over the temperature range from 75 to 530 °C. The total solubility of CO₃-ions and that of [CO ₃ ^2– -vacancy] complexes may be expressed by simple relationships andc _ka=3·19× 10^–2 exp (–0·25 eV/kT), resp. The heat of solution of complexes is equal to 0·25 eV and that of free CO ₃ ^2– ions is higher than 1·2 eV. Under conditions of the thermal equilibrium between the solid solution and precipitate, the ratio of Na₂CO₃ and CaCO₃ components in the precipitate has been calculated at various temperatures and CO₃ concentrations.     

Pulsed laser deposition of aluminate YAlO3 and LaAlO3 thin films for alternative gate dielectric applications

Amorphous aluminate YAlO₃ (YAO) thin films on n-type silicon wafers as gate dielectric layers of metal–oxide–semiconductor devices are prepared by pulsed laser deposition. As a comparison, amorphous aluminate LaAlO₃ (LAO) thin films are also prepared. The structural and electrical characterization shows that the as-prepared YAO films remain amorphous until 900 °C and the dielectric constant is ∼14. The measured leakage current of less than 10^-3 A/cm² at a bias of V_G=1.0 V for ∼40-nm-thick YAO and LAO films obeys the Fowler–Nordheim tunneling mechanism. It is revealed that the electrical property can be significantly affected by the oxygen pressure during deposition and post rapid thermal annealing, which may change the fixed negative charge density at the gate interface. PACS 77.55.+f; 81.15.Fg; 81.40.Ef     

Oxidation states of Cu,Ba and Y in superconducting YBa2Cu3O7−x

A high temperature (91.2 K) Y–Ba–Cu–O superconductor has been studied by monochromatized XPS core level measurements. The position, shape and satellite emission of Cu 2p indicate a mixture of Cu valencies 2+ and 1+ with some indication for the existence of a third oxidation state of 3+. The two component structure of the Ba 3d line suggests two principal Ba–O configurations due to oxygen vacancies. The shape and position of the Y 3d doublet imply only weak Y–O interactions.