Eliashberg theory for disordered superconductors. II. Tunneling into disordered two-dimensional Pb films

A series ofc-axis oriented YBa₂Cu₃O _x -films with different oxygen content were prepared by laser deposition. The oxygen contentx was determined by X-ray diffraction and by resonant Rutherford-back-scattering (RRBS) measurements. Thec-axis length in these films of YBa₂Cu₃O _x is about 0.5% larger compared to bulk values. We describe transport measurements in magnetic fields up to 7 Tesla between room temperature andT _c in samples with an oxygen content between the orthorhombic-to-tetragonal transition (x6.4) and full oxygenation (x7). The ratio /R _H was investigated with respect to the two-dimensional Luttinger liquid theory and the model of the two-dimensional ionic metal. We report on deviations from the expected quadratic temperature behaviour of /R _H , especially in films with high oxygen content.     

Combination of three analytical techniques for speciation of Al in environmental samples

An analytical scheme is proposed which combines three speciation techniques for determination of particular Al species in soil extracts and percolating waters. A cation-exchange fast protein liquid chromatography — inductively coupled plasma atomic emission spectrometry (FPLC-ICP-AES) procedure, a microcolumn chelating ion-exchange chromatography- atomic absorption spectrometry (MCC-ETAAS) technique and the 8-hydroxyquinoline spectrophotometric method (8HQ-spectrophotometry) were employed. The FPLC-ICP-AES procedure offers determination of Al³⁺ (retention time 4.5 min) and Al(OH)²⁺ species (retention time 4.0 min) which are separated from Al(OH)⁺ ₂ (retention time 1.5min). AlF²⁺ coelutes with Al(OH)²⁺ species, while Al(SO₄)⁺, AlF⁺ ₂ and negatively charged Al organic complexes coelute with Al(OH)⁺ ₂ species. The MCC-ETAAS technique enables determination of the sum of positively charged monomeric aqua- and hydroxy-Al species plus sulphate- and fluoro-Al complexes. Employing the 8HQ-spectrophotometry the sum of positively charged monomeric aqua- and hydroxy-Al species plus sulphato- and most of the labile organic Al species are determined. The sensitivities of these selected techniques were adequate for speciation of Al in the samples analyzed. On the basis of the specific selectivity of a particular technique various groups of Al species may be determined. Thus, the comparison of analytical data from complementary procedures provides more comprehensive information on Al species present in soil extracts and percolating waters.     

Estimation and setting starting values in ARMA algorithms

For the given observations set of the ARMA (autoregressive moving average) process, the likelihood function depends, not only on model parameters, but on the starting values of the input and output. Therefore, it is called theconditional likelihood function. Theunconditional likelihood function can be obtained in two ways. The first is to set the starting values to zero, as is often done, and the second is to set them to the properly estimated values. The difference between these two types of likelihood functions is significant when the given data sequence is short, and any of the zeros of the moving average part is close to the boundary of the unit circle.In this paper the direct method of starting value estimation and its application to two off-line ARMA estimation algorithms, the maximum likelihood (ML) algorithm and the iterative inverse filtering (ITIF) algorithm, is proposed. Experimental results prove both increased efficiency and stability of these algorithms.The importance of setting the starting values properly is also significant when the recursive algorithm, with previously estimated parameters, has to be restarted. The advantage of the proposed reinitialization method is shown on the recursive lattice algorithm working in the block mode.     

Nonordered quantum logic and its YES-NO representation

It is shown that an orthomodular lattice is an ortholattice in which aunique operation of bi-implication corresponds to the equality relation and that the ordering relation in the binary formulation of quantum logic as well as the operation of implication (conditional) in quantum logic are completely irrelevant for their axiomatization. The soundness and completeness theorems for the corresponding algebraic unified quantum logic are proved. A proper semantics, i.e., a representation of quantum logic, is given by means of a new YES-NO relation which might enable a proof of the finite model property and the decidability of quantum logic. A statistical YES-NO physical interpretation of the quantum logical propositions is provided.     

Radon and gamma-radiation measurements in schools on the territory of the abandoned uranium mine “Žirovski vrhl”

On the territory of the abandoned uranium mine irovski vrh, Slovenia, indoor radon and gamma dose rate measurements were carried out in nineteen schools from February 10 to May 10, 1995, using scintillation cells and etched track detectors for radon and thermoluminescence dosimeters for gamma-ray detection. In five schools indoor radon levels exceeded 400 Bq·m^-3, which is the proposed Slovene action level. The maximum average radon value of 1600 Bq·m^-3 and the maximum gamma-dose rate of 172 Sv·month^-1 were found in the same school. According to the ICRP 65 methodology, annual effective doses from radon decay products ranged from 0.05 to 6.10 mSv for pupils and from 0.04 to 4.90 mSv for teachers. Gamma dose rates ranged from 0.05 to 0.19 mSv·y^-1 for pupils and from 0.07 to 0.27 mSv·y^-1 for teachers.     

Structural characterization of chondroitin/dermatan sulfate oligosaccharides from bovine aorta by capillary electrophoresis and electrospray ionization quadrupole time-of-flight tandem mass spectrometry

An analytical approach based on high-performance capillary electrophoresis (CE) in conjunction with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS) has been developed for providing the basis to obtain new insights into the domain structure of the glycosaminoglycan (GAG) moiety of proteoglycans. The feasibility and performance of the off-line CE/ESI-QTOF-MS approach in GAG oligosaccharide analysis were assessed by screening a chondroitin/dermatan sulfate (DS) oligosaccharide mixture obtained from bovine aorta by enzymatic depolymerization by chondroitin B lyase. The CS/DS mixture was analyzed by CE using 50 mM ammonium acetate, pH 12.0, dissolved in aqueous methanol (2:3; v/v), as a CE carrier. Structural identification of the GAG components was achieved using off-line CE/nanoESI-QTOF-MS and-MS/MS experiments. ESI-QTOF instrumental parameters were found to play an important role in the MS screening of the CE-separated GAG species. By optimizing the ESI conditions, oligosaccharides differing in chain length and degree of sulfation could be detected. The building block composition, the size of the carbohydrate chain, as well as structural features of the repeating HexA-GalNAc, HexA-GalNAc(S) units, have been determined using MS/MS by applying collision-induced dissociation at low energies. Cleavage of GAG chains by chondroitin B lyase occurs with formation of structural markers useful for identification of IdoA-containing domains.     

Kinetic determination of codeine in pharmaceutical preparations

A kinetic method for the determination of codeine, based on its inhibitor action on the catalytic decomposition of hydrogen peroxide by cobalt(II), is presented. It has been found that the effect of codeine is most pronounced in the presence of 5% v/v ethylene glycol. The reaction is followed photometrically. Codeine can be determined in concentrations ranging from 0.80×10^–5 M to 2.4×10^–5 M. The method has been applied to the determination of codeine in pharmaceutical preparations.