Observation of sharp resistance anomalies near Tc in granular superconductors

Granular films prepared from well-defined In clusters embedded in Kr (? 10-40 at % Kr) show sharp resistance anomalies very close to the superconducting transition temperature. The observed resistance peak(s), which go(es) above the normal state resistance R_N and which can be as high as ? 1.5 R_N, can be explained by a “mesoscopic” effect: Superconducting percolation aggregates of size ξ_ρ, larger than the superconducting coherence length ξ_S, but smaller than the quasiparticle relaxation length λ_Q*, have a superconducting gap, but are not yet able to carry a supercurrent.     

Day-side auroral signatures based on simultaneous, coordinatedobservations at Svalbard and Greenland

The height distribution of the dayside cusp aurora and the relation between optical emissions and net downward electron energy flux are discussed. These two important characteristics of day-side cusp aurora are still unknown. It is instructive to compare particle flux and optical luminosity because these two quantities should be proportional if the cusp aurora is caused by electron impact, as has been found for nighttime aurora in the oval. Furthermore, there should then be a direct relation between auroral altitudes and particle energy. Based on coordinated auroral observations at Svalbard and Greenland, together with simultaneous, overhead F-9 satellite measurements, these quantities have been evaluated     

Comparison of steam pretreatment of eucalyptus,aspen, and spruce wood chips and their enzymatic hydrolysis

Applied Biochemistry and Biotechnology - Enzymatic hydrolysis of SO2-impregnated, steam-explodedEucalyptus viminalis was carried out at increasing substrate concentrations and enzyme loadings. When...     

Frequency-specific maturation of the eighth nerve and brain-stem auditory pathway: evidence from derived auditory brain-stem responses (ABRs).

Previous studies of human auditory development using frequency-specific auditory brain-stem responses (ABRs) have reported that maturation for both peak and interpeak latencies occurs earlier for responses generated by low-frequency stimuli. In two of these studies, low-frequency ABRs presumed to originate from apical locations in the cochlea were likely dominated by activity from higher frequency regions closer to the base. In the present study, the high-pass noise-masking technique was used to generate derived ABRs that represent activity from isolated place specific regions along the basilar membrane. Analysis of auditory brain-stem maturation based on I-V interpeak latency differences with adult means revealed a frequency-specific pattern of development. Developmental changes occurred faster and mature function was attained earlier for ABRs from the mid-center-frequency (CF) derived conditions than from either the highest or lowest CF derived conditions. The differential maturation of mid-CF derived ABRs may reflect the delayed effects of the pattern of development that occurs in the cochlea.     

Identification by high-performance liquid chromatography of tyrosine ammonia-lyase activity in purified fractions of Phaseolus vulgaris phenylalanine ammonia-lyase.

Activities of phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) were assessed at each stage of a three-step purification of PAL. Assays were performed by high-performance liquid chromatographic (HPLC) separation and ultraviolet detection of reaction products. Use of HPLC permitted assay of low activities of PAL and TAL for periods up to approximately four and two days, respectively. HPLC also facilitated the accurate quantitation of the product of the TAL reaction, trans-p-coumaric acid, which was observed to isomerize readily under experimental conditions. PAL and TAL were associated throughout the purification procedure, with TAL activity at 0.6-1.3% of PAL activity. It was concluded that, contrary to previous reports, TAL and PAL activities are mediated by the same enzyme, or else by chromatographically very similar enzymes.     

Lithium insertion into YBa2Cu3O7

Atomistic computer simulation techniques are used to investigate the effects of lithium insertion into YBa₂Cu₃O₇. Attention is focused on various possible lattice sites occupied by the inserted lithium ions and pathways for their migration. The square-planar position in the Cu(2) layer is calculated to be the most energetically favorable. This is supported by the structural modeling of the ordered lithiated phase Li_0.33YBa₂Cu₃O₇. The calculated activation energies derived from migration profiles are in accord with experimental values and suggest fairly mobile lithium ions.     

Multiplicities of interpoint distances in finite planar sets

What is the maximum number of unit distances between the vertices of a convex n-gon in the plane? We review known partial results for this and other open questions on multiple occurrences of the same interpoint distance in finite planar subsets. Some new results are proved for small n. Challenging conjectures, both old and new, are highlighted.     

Future contributions toJournal of Chemical Crystallography

Future contributions toJournal of Chemical Crystallography