Further dynamical and experimental LEED results for a clean W<“001”-(1 × 1) surface structure determination

Full dynamical layer-doubling calculations have been made for comparison with precision LEED spectra for the clean W “001”-(l × 1) surface at approximately 470 K. Using 45 beams and 10 phase shifts, multi-layer spacing calculated spectra are critically compared with 12 experimental curves involving 5 different beams and 5 incidence angles. Both visual judgements and a semi-quantitative peak deviation/penalty evaluation yield the same result. A surface-bulk layer spacing of 1.51 ± 0.05 Å is concluded, a 4.4% contraction, in contrast to the most recent other determination of 1.40 ± 0.03 Å. This analysis re-emphasizes the need for a reliable and objective criterion for comparing observed and calculated LEED spectra, and corrects a potentially important input to the analysis of more complex systems. For example, at low temperatures (<370 K) the W “001” clean surface rearranges to a c(2 × 2) structure.     

On a boundary value problem in the theory of urine formation

A model of the renal medulla introduced by Shohet and Pinter takes the form of a linear two point boundary value problem. It is shown that this boundary value problem can be reduced to an initial value problem, which is of analytical interest and of computational utility.     

Double diffraction dissociation and test of pomeron factorization at the CERN ISR

We report the observation of double diffraction dissociation in the process p + p → (pπ⁺π^?) + X at √s of 45 GeV and momentum transfer in the ?t range 0.15?0.53 GeV² at the CERN ISR. The relative rates for elastic, single and double dissociation reactions measured here are found to agree with the prediction of Pomeron factorization.     

Fluid mechanics of turbomachines: a review

Future development of more efficient turbomachinery depends on improving understanding of the fluid mechanics. This paper reviews advances made in the last five years in calculation methods for steady flow, unsteady flows and stability, and instrumentation and its applications. Fundamental problems which need further study are also indicated     

Determination of submicromolar amounts of uranium(VI) by compleximetric titration with pyridine-2,6-dicarboxylic acid

Uranium(VI) is selectively determined by a compleximetric titration with pyridine-2,6-dicarboxylic acid, using arsenazo-I indicator and hexamethylenetetramine buffer at pH 4.9. Cyclohexanediaminetetraacetic acid and diethylenetriaminepentaacetic acid provide masking of interfering metal ions. A probe colorimeter apparatus is recommended for end-point detection. The relative standard deviation is 0.6% for 0.17–0.76 μmol of uranium.