An Approximate Analytical Solution for Counter-Current Spontaneous Imbibition

An approximate analytical solution is provided for one-dimensional, counter- current, spontaneous imbibition of a wetting phase (water) into a semi-infinite porous medium. The solution is based on the assumption that a similarity solution exists for the displacement process. This assumption, in turn, rests on the assumption that the set of relative permeability and capillary pressures curves are unique functions of saturation and do not depend on the nature of the displacement. It further rests on the assumption that the saturation at the imbibition face does not vary with time. It is demonstrated that the solution is in agreement with results obtained from experiments and also numerical analyses of these experiments. The experiments utilize cylindrical samples with the radial surface and one end-face sealed, and with counter-current imbibition occurring at the open end-face. The stage of the experiment that is modeled by the present solution is the period before the imbibition front contacts the sealed end-face. An important finding of the present analysis is that the pressure upstream of the advancing invasion front is a constant. A second, improved solution is also presented; this solution is an iterative, series solution of an integral-differential equation. It converges to a stable solution in very few terms.     

Examination of Template Structural Effects on CEC Chiral Separation Performance of Molecule Imprinted Polymers Made by a Generalized Preparation Protocol

Some acidic chiral templates were used to prepare open tubular (OT) molecule imprinted polymer (MIP) capillary columns to explore the effects of molecular structures of templates on chiral recognition capabilities and to verify the feasibility of the general MIP preparation protocol introduced in the previous study. The templates are phenyl carboxylic acids and their derivatives. Optimization was carried out for chiral separation of template enantiomers for each MIP column through varying pH and composition of eluent. It was found that the preparation protocol can be successfully applied for the appropriate templates with functional groups fulfilling the three-points interaction rule. The chiral separation performances were quite satisfactory for MIPs of such templates although they are yet inferior to the separation performances of the MIP columns fabricated with the templates of profen drugs (2-arylpropionic acids with a large substituent on the phenyl ring). Subtle variations of the template molecular structures have been found to be critical to enhance chiral recognition ability of the resultant MIP column.     

An Identification Problem for First-Order Degenerate Differential Equations

We study a first-order identification problem in a Banach space. We discuss the nondegenerate and mainly the degenerate case. As a first step, suitable hypotheses on the involved closed linear operators are made in order to obtain unique solvability after reduction to a nondegenerate case; the general case is then handled with the help of new results on convolutions. Some applications to partial differential equations motivate this abstract approach.Communicated by I. GalliganiWork partially supported by MIUR (Ministero dell’ Istruzione, dell’ Università e dalla Ricerca), Project PRIN 2004011204 “Analisi Matematica nei Problemi Inversi,” and by the University of Bologna Funds for Selected Research Topics.     

Measuring efficiency and productivity in professional football teams: evidence from the English Premier League

Professional football clubs are unusual businesses, their performance judged on and off the field of play. This study is concerned with measuring the efficiency of clubs in the English Premier League. Information from clubs’ financial statements is used as a measure of corporate performance. To measure changes in efficiency and productivity the Malmquist non-parametric technique has been used. This is derived from the Data Envelopment Analysis (DEA) linear programming approach, with Canonical Correlation Analysis (CCA) being used to ensure the cohesion of the input–output variables. The study concludes that while clubs operate close to efficient levels for the assessed models, there is limited technological advance in their performance in terms of the displacement of the technological frontier. The research was supported by the Investigation Program of the Technical University of Cartagena (Spain) and by the Department of Sports Studies at the University of Stirling (Scotland, UK).     

Plastic deformation of poly-4-methylpentene-1 crystals

The plastic deformation of poly-4-methylpentene-1 (P4MP1) crystals on a unidirectionally drawn substrate has been investigated by electron microscopy. In addition to cracks spanned by fibrils and buckling perpendicular to the stretch direction, both features found in deformation studies of other polymers, a unique slip mechanism leading to sectorization of P4MP1 crystals is observed; deformation was also found to occur by means of localized lamellar thinning. The exact type of plastic deformation occurring in P4MP1 crystals is found to depend on the orientation of the lamellae with respect to the tensile axis. Some evidence for a periodicity on the fibrils studied is given.     

Absolute fluorescence quantum efficiency of GSGG : Cr at ambient temperature

The absolute fluorescence quantum efficiencies of three GSGG : Cr³⁺ samples have been determined at specific excitation wavelengths for the ⁴T₁and ⁴T₂ absorption bands using a novel photocalorimetric compensation technique [1]. For laser excitation in the ⁴T₁ and ⁴T₁ bands, the technique yields the same fluorescence quantum efficiency within experimental error for all three samples, viz. 0.840 ± 0.015. The effect of flourescence reabsorption on the measurements is discussed.     

INAA determination of selenium via77mSe in plasma,semen and hair samples from beef and dairy bulls

Interest in the element selenium with respect to its biological significance has been steadily increasing for the last ten years. Neutron activation analysis has long been used for the accurate determination of selenium in biological samples usually via⁷⁵Se. More recently activation analysts having access to high flux reactors with rapid delivery pneumatic tube facilities; have successfully employed^77mSe. This approach, which is much faster, is particularly well suited to the Missouri University Research Reactor (MURR). The specific interest concerning bulls has to do with the involvement of selenium in the reproductive system. Selenium analysis methodology and data on plasma, semen and 22 tissues from both beef and dairy bulls are presented.     

Point-to-point correlation of sound pressures in reverberation chambers

The reverberation chamber is such a fundamental tool in general acoustics and, in particular, architectural acoustics, that most of its properties have been under intensive study for some years. However, the point-to-point correlation of the sound pressures has received little attention except for an elegant paper by Cook et al. published in 1955.