Self-interaction-corrected electronegativities and hardness for atoms

Electronegativity χ and hardness η for 54 atoms and their positive and negative ions are calculated by means of self-interaction-corrected DFT including correlation terms. The exchange potential energy is treated by local spin density approximation corrected to account for self-interaction effects as suggested by Rae. The highest occupied orbital eigenvalues for ions are identified to the chemical potential μ^± for positive and negative charged atoms depending upon the developing charge process. Values of χ^±δ and η^± for the different ionic species are given for several values of δ. Average values for 〈χ〉 and 〈η〉 in the sense of Mulliken finite formula for neutral atoms are also tabulated and compared with Mulliken values from experimental data. The agreement among them is almost quantitative.     

Effects of NAPL Contaminants on the Permeability of a Soil‐Bentonite Slurry Wall Material

Soilbentonite slurry walls are designed to inhibit the subsurface movement of contaminants from hazardous waste sites. Although it is generally accepted that high concentrations of organic compounds will adversely affect soilbentonite slurry walls and clay liners, previous research investigating the effects of NAPLs on the conductivity of clay wall materials has been inconclusive. In this study the effects of various organics (benzene, aniline, trichloroethylene, ethylene dichloride, methylene chloride) on the effective conductivity of a typical soilbentonite slurry wall material were studied under two effective stress conditions, 200 and 52kPa. The hydraulic conductivity for the soilbentonite material permeated with water averaged 1.52×10^-8cms^-1. Compared to water, there was little change in conductivity when the sample was permeated with a solution containing a NAPL compound at its solubility limit, except for aniline. However, there was a one to two order of magnitude decrease in conductivity when the sample was permeated with a pure NAPL for all NAPLs tested. When the soilbentonite material was permeated with a water/NAPL/water/NAPL sequence, the conductivity decreased one to two orders of magnitude when a NAPL was introduced following water; however, when water was reintroduced after the NAPL, the conductivity increased to the initial hydraulic conductivity. The conductivity again decreased one to two orders of magnitude when the NAPL was reintroduced. This trend occurred for all NAPLs tested, and the fluid properties of the NAPL compounds alone did not account for the decrease in conductivity compared to water.     

A type of matrix Padé approximant inspired by scalar component models

In this paper we define a type of matrix Padé approximant inspired by the identification stage of multivariate time series models considering scalar component models. Of course, the formalization of certain properties in the matrix Padé approximation framework can be applied to time series models and in other fields. Specifically, we want to study matrix Padé approximants as follows: to find rational representations (or rational approximations) of a matrix formal power series, with both matrix polynomials, numerator and denominator, satisfying three conditions: (a) minimum row degrees for the numerator and denominator, (b) an invertible denominator at the origin, and (c) canonical representation (without free parameters).     

Padé Approximation in Economics

In economics, the systematic treatment of data to obtain specific properties from long (or short) data series is a main objective. The use of rational models and related numerical methods can be useful to help to predict the behaviour of relevant economic variables with a certain degree of certainty. This paper is concerned with illustrating the application of several numerical methods, in particular, the corner method, epsilon-algorithm, rs-algorithm and qd-algorithm, to the problem of model identification in time series analysis. These methods, closely related to theoretical research in Padé Approximation, are proposed to identify some type of rational structure associated with economic data in different contexts (financial, marketing, farming). Moreover, they incorporate the expectations of exogenous economic variables to improve the fit and forecasting of classic time series models.     

CE–MS fingerprinting of Laurencia complex algae (Rhodophyta)

The use of CE–ESI‐MS has been considered as a new chemical strategy for the possible discernment of genera and species of the Laurencia complex. After the selection of the CE–MS and the extraction conditions, a total of 28 specimens of the complex, including different species of four genera (Laurencia, Laurenciella, Palisada, and Osmundea) collected from five intertidal locations on the Island of Tenerife (Canary Islands, Spain) were analyzed. CE–MS fingerprints revealed that CE–MS can be used as a useful tool for these studies in order to assess similarities and differences between them and that it constitutes an important starting point for further studies in the field.     

A note on the initial identification of scalar component models

This paper solves an open theoretical question in the identification stage of Scalar Component Models, posed initially by Tiao and Tsay and noted by several researchers, specifically as it refers to the choice of a certain parameter present in the process and which they denote h. The theoretical concept of sure overall orders, instead of the so-called overall orders, is useful in addressing this issue. Using simple examples, we justify the need for our theoretical results. Moreover, we use a Ranks Table and its properties to complement the SCM identification stage with interesting theoretical information without adding significant calculations to the procedure initially proposed by Tiao and Tsay.     

Antioxidant activity and cytotoxicity on tumour cells of the essential oil from Cedronella canariensis var. canariensis (L.) Webb & Berthel. (Lamiaceae)

Cedronella canariensis is a lemon-scented species of the family Lamiaceae endemic to the Canary Islands where it is used in the traditional medicine to prepare infusions or inhalations for anti-catarrhal, tonic, diuretic, hypoglycaemiant, hypotensive, anti-inflammatory and decongestant of the respiratory tract. In this work we investigated for the first time the antioxidant activity of the essential oil and its inhibitory effects on tumour cells (A375, MDA-MB-231, HCT 116) proliferation by DPPH, ABTS, FRAP and MTT assays, respectively. The oil, analysed by GC-ionisation flame detector and GC–MS, was characterised by pinocarvone (58.0%) and β-pinene (10.8%) as the major constituents, being typical of the chemotype ‘canariensis’. Noteworthy was the cytotoxic activity of the oil against the tumour cells examined, with IC₅₀ values of 4.3, 7.3 and 11.4 μg/mL on A375, MDA-MB-231 and HCT 116 tumour cells, respectively, as well as the scavenging activity against the ABTS radical (IC₅₀ of 10.5 μg/mL).     

Detection of nucleic acids in situ: novel oligonucleotide analogues for target-assembled DNA-mounted exciplexes

This research describes the effects of structural variation and medium effects for the novel split-oligonucleotide (tandem) probe systems for exciplex-based fluorescence detection of DNA. In this approach the detection system is split at a molecular level into signal-silent components, which must be assembled correctly into a specific 3-dimensional structure to ensure close proximity of the exciplex partners and the consequent exciplex fluorescence emission on excitation. The model system consists of two 8-mer oligonucleotides, complementary to adjacent sites of a 16-mer DNA target. Each probe oligonucleotide is equipped with functions able to form an exciplex on correct, contiguous hybridization. This study investigates the influence of a number of structural aspects (i.e. chemical structure and composition of exciplex partners, length and structure of linker groups, locations of exciplex partner attachment, as well as effects of media) on the performance of DNA-mounted exciplex systems. The extremely rigorous structural demands for exciplex formation and emission required careful structural design of linkers and partners for exciplex formation, which are here described. Certain organic solvents (especially trifluoroethanol) specifically favour emission of the DNA-mounted exciplexes, probably the net result of the particular duplex structure and specific solvation of the exciplex partners. The exciplexes formed emitted at approximately 480 nm with large Stokes shifts ( approximately 130-140 nm). Comparative studies with pyrene excimer systems were also carried out.