Far downstream analysis for the Blasius boundary-layer stability problem

In this paper, we examine the large Reynolds number (Re) asymptoticstructure of the wave number in the Orr–Sommerfeld regionfor the Blasius boundary layer on a semi-infinite flat plategiven by Goldstein (1983, J. Fluid Mech., 127, 59–81).We show that the inclusion of the term which contains the leading-ordernon-parallel effects, at O(Re^{– 1/2}), leads to a non-uniformexpansion. By considering the far downstream form of each termin the asymptotic expansion, we derive a length scale at whichthe non-uniformity appears, and compare this position with theposition seen in plots of the wave number.     

Wrap-around partitioning for block bidiagonal linear systems

A stable vector algorithm for the solution of block diagonallinear systems is obtained by a permutation of the unknownscalled wrap-around partitioning combined with standard QR factorization.Wrap-around partitioning uses blocking and selects the unknownsin the blocks in turns. After a suitable orthogonal eliminationstep one ends up with a reduced system which is again blockbidiagonal and so wrap-around partitioning can be applied again.Using a simple model for vectorization overhead it is shownthat small block sizes give best performance. The minimal blocksize 2, which corresponds to cyclic reduction, is suboptimaldue to memory bank conflicts.     

Absolute Intensities of the 10-µm Bands of (16)O(3)

Two hundred ninety experimental absolute intensities of nu(1) and nu(3) transitions of ozone have been measured, with good accuracy (<2%). They are used to derive the transition-moment parameters for these bands. The agreement between our observed and calculated line intensities is satisfactory. This work shows that the intensities of these two bands are on average 4% smaller than those used in the literature. In addition, 20 intensities of the nu(2) + nu(3) - nu(2) band confirm this value. Also, 42 line intensities of the 2nu(1)-nu(3) band are reported. Copyright 2001 Academic Press.     

Comparative chemical, cytotoxicity and antileishmanial properties of essential oils from Chenopodium ambrosioides

In countries where leishmaniasis is endemic, there are not very many treatment alternatives and most options have problems associated with their use. Plants and their natural products constitute good sources of interesting lead compounds that could be potentially active against Leishmania. Chenopodium ambrosioides is a plant that is widely used in popular medicine and its antiparasitic effects have been documented, including the antileishmanial potentialities of Chenopodium oil. The objective of this study was to determine the chemical composition, in-vitro cytotoxicity and antileishmanial activity of essential oils extracted from C. ambrosioides, which received different treatments prior to extraction. The chemical characterization by GC-MS of the three essential oil samples showed similar composition and the major components were alpha-terpinene (17.0-20.7%), p-cymene (20.2-21.1%) and ascaridole (30.5-47.1%). The essential oils exhibited similar antileishmanial activities against intracellular amastigote form, with IC50 values between 4.7 and 12.4 microg/mL. However, a lower cytotoxicity was displayed by the essential oil extracted from fresh green vegetable material, which was statistically different (P < 0.05) from the other samples. This study demonstrated that the prior treatment of plant material did not interfere with the antiparasitic activity of essential oils from C. ambrosioides but did change their cytotoxicity, which should be taken into account in further studies.     

Gel growth of α and γ glycine and their characterization

The microbial free single crystals of α and γ glycine were grown from gel at room temperature in a new chemical route. These crystals showed a superior quality than the solution grown crystals. The metastable α-form and the stable γ-form of glycine were crystallized in silica gel by solubility reduction method. The form of crystallization is confirmed by single crystal and powder X-ray diffraction analyses. The crystals of α and γ glycine were found to crystallize in monoclinic and hexagonal crystal systems, respectively. For analyzing the functional group and thermal stability of α and γ glycine crystals, spectroscopic and thermal analyses have been carried out. The dielectric studies were performed to find the dielectric constant of the grown crystals and the results are discussed. Second harmonic generation efficiency of the crystal was measured by Kurtz’s powder method using Nd:YAG laser and it was found to be 2.68 times that of potassium dihydrogen phosphate crystals.