Local structural studies of Ba1−x_{1-x}Kx_xFe2_2As2_2 using atomic pair distribution function analysis

Systematic local structural studies of Ba$_{1-x}$K$_x$Fe$_2$As$_2$ system are undertaken at room temperature using atomic pair distribution function (PDF) analysis. The local structure of the Ba$_{1-x}$K$_x$Fe$_2$As$_2$ is found to be well described by the long-range structure extracted from the diffraction experiments, but with anisotropic atomic vibrations of the constituent atoms ($U_{11}$ = $U_{22} \ne U_{33}$). The crystal unit cell parameters, the FeAs$_4$ tetrahedral angle and the pnictogen height above the Fe-plane are seen to show systematic evolution with K doping, underlining the importance of the structural changes, in addition to the charge doping, in determining the properties of Ba$_{1-x}$K$_x$Fe$_2$As$_2$

Quantification of asbestos and other mineral phase burden in necroscopic human lung tissues with a new method

Background: A large amount of studies on asbestos exposure reconstruction have been so far conducted digesting the lung tissues with appropriate reagents, separating the powder from the digestion liquid by filtration and analysing the residue by optical or electron microscopy. This analytical approach has good sensitivity but is not yet well standardized, the investigated portion is not representative of the bulk sample, the results are often characterized by lack of reproducibility and repeatability. Moreover, the numeric quantification of asbestos requires a time-consuming particle by particle analysis. Aim: to develop a new method for the complete quantitative characterization of asbestos and other mineral phases in human lung tissue. Methods: The new method is based on sodium hypochlorite digestion, separation and XRPD analysis. The XRPD approach needs moderate lung tissue amounts (at least 20 g of wet tissue), but allows to conduct a complete quantitative characterization of each crystalline phase in the sample giving bulk-representative results with good reproducibility, accuracy and precision. The detection limit of conventional XRPD was considerably improved by a novel instrumental setting and weight concentrations can be obtained, giving additional information to numeric ones, preferable in clinical and pathogenetic studies but probably not for the exposure reconstruction. Results: Among the analysed autoptic lung tissues, ten samples belonged to subjects occupationally exposed to asbestos and six were collected from urban area controls. Asbestos phases were detected in none of controls and in 5 of 10 occupationally exposed subjects (those with highest exposure history) indicating that this method is suitable for the reconstruction of medium and high asbestos exposures. It has been furthermore confirmed the mineral association found in previous studies: mainly composed by quartz, talc, clay minerals, micas, Fe-Al-Ti oxides and bio-minerals such Ca-phosphates, carbonates and oxalates

Lead-rich phases in partially processed Ag/Bi-2223 composite conductors

The occurrence, composition, and melting behavior of lead-rich phases detected during the thermal processing of Ag/Bi-2223 composite conductors have been investigated by a combination of transmission electron microscopy (TEM), energy dispersive analysis (EDS), x-ray diffraction, differential thermal analysis, and Raman spectroscopy. A (Bi,Pb)-Sr-Ca-Cu-O composition with {open_quotes}4112{close_quotes} metal atom stoichiometry and Pb{approx_equal}Bi was detected during TEM/EDS examinations of partially processed/quenched Ag/Bi-2223 composites. An as-synthesized oxide mix with this stoichiometry was found to melt at a temperature <700{degrees}C. The lead-rich {open_quotes}3221{close_quotes} phase was found to have a wide range of compositional stability in terms of Pb/Bi ratio and Bi + Pb stoichiometry. Evidence was seen for the co-existence of this phase with (Ca,Sr){sub 2}PbO{sub 4} in partially processed Ag/Bi-2223 composites that were cooled slowly through the 800 to 600{degrees}C range

Matrix interpretation of multiple orthogonality

In this work we give an interpretation of a (s(d + 1) + 1)-term recurrence relation in terms of type II multiple orthogonal polynomials.We rewrite this recurrence relation in matrix form and we obtain a three-term recurrence relation for vector polynomials with matrix coefficients. We present a matrix interpretation of the type II multi-orthogonality conditions.We state a Favard type theorem and the expression for the resolvent function associated to the vector of linear functionals. Finally a reinterpretation of the type II Hermite- Padé approximation in matrix form is given

The investigation of phase evolution in composite ceramic superconductors using Raman microscopy techniques

Raman microspectroscopy and imaging techniques have been used to investigate key mechanistic features that influence the formation of layered Bi- and Tl-based superconducting phases during the thermal treatment employed to produce BSCCO and TBCCO composite conductors. Seminal information gained from these studies includes the location of lead-rich nonsuperconducting second phases (NSPS) and the identification of the constituent phases in certain NSP agglomerations that tend to resist dissipation as high-Tc phase formation proceeds to completion

On Fourier integral transforms for qq-Fibonacci and qq-Lucas polynomials

We study in detail two families of $q$-Fibonacci polynomials and $q$-Lucas polynomials, which are defined by non-conventional three-term recurrences. They were recently introduced by Cigler and have been then employed by Cigler and Zeng to construct novel $q$-extensions of classical Hermite polynomials. We show that both of these $q$-polynomial families exhibit simple transformation properties with respect to the classical Fourier integral transform

Thermodynamic and nonstoichiometric behavior of the lead-doped and lead-free Bi-2212 systems

EMF measurements of oxygen fugacities as a function of stoichiometry were made on pb-doped and Pb-free superconducting ceramics at 700-815 C using oxygen titration. Equations of oxygen partial pressure vs composition and temperature were derived from the EMF measurements. Thermodynamic assessments of the partial molar quantities {Delta}{bar H}(O{sub 2}) and {Delta}{bar S}(O{sub 2}) for Pb-doped Bi- 2212 and Pb-free Bi-2212 indicate that the solid-state decomposition of these Bi cuprates at low oxygen partial pressure can be represented by the diphasic CuO-Cu{sub 2}O system. Comparison of these results with Pb-doped Bi-2223 in powder and silver sheath form is presented

Corrosion of structural materials by lead-based reactor coolants.

Advanced nuclear reactor design has, in recent years, focused increasingly on the use of heavy-liquid-metal coolants, such as lead and lead-bismuth eutectic. Similarly, programs on accelerator-based transmutation systems have also considered the use of such coolants. Russian experience with heavy-metal coolants for nuclear reactors has lent credence to the validity of this approach. Of significant concern is the compatibility of structural materials with these coolants. We have used a thermal convection-based test method to allow exposure of candidate materials to molten lead and lead-bismuth flowing under a temperature gradient. The gradient was deemed essential in evaluating the behavior of the test materials in that should preferential dissolution of components of the test material occur we would expect dissolution in the hotter regions and deposition in the colder regions, thus promoting material transport. Results from the interactions of a Si-rich mild steel alloy, AISI S5, and a ferritic-martensitic stainless steel, HT-9, with the molten lead-bismuth are presented

Normothermic and hypothermic oxygenated perfusion for donation after circulatory death in kidney transplantation: Do we pay higher risk of severe infection after transplantation?: A case report

Background: Normothermic and hypothermic oxygenated perfusion for donation after circulatory death in kidney transplantation are becoming popular in Italy, with the purpose of reducing the risk of primary non function and delayed graft function due to the prolonged warm ischemia time. Potential complications related to these procedures are currently under investigation and are continuously emerging with the increasing experience. Post-operative infections - in particular graft arteritis - are a rare complication but determine high risk of mortality and of graft loss. The acute onset of the arterial complications makes it very difficult to find an effective treatment, and early diagnosis is crucial for saving both patient and graft. Prevention of such infections in this particular setting are advisable. Case presentation: We present a patient with an acute arterial rupture after transplantation of a DCD graft treated in-vivo hypothermic oxygenated perfusion. The cause was a severe arteritis of the renal artery caused by Candida krusei and Pseudomonas aeruginosa. We discussed our treatment and we compared it to the other reported series. Conclusion: Fungal infections in DCD transplant may be treacherous and strategies to prevent them should be advocated