Constructions of optimal orthogonal arrays with repeated rows

We construct orthogonal arrays ${\mathsf{OA}}_{\lambda }(k,n)$ (of strength two) having a row that is repeated $m$ times, where $m$ is as large as possible. In particular, we consider OAs where the ratio $m∕\lambda$ is as large as possible; these OAs are termed optimal. We provide constructions of optimal OAs for any $k\ge n+1$, albeit with large $\lambda$. We also study basic OAs; these are optimal OAs in which $gcd(m,\lambda )=1$. We construct a basic OA with $n=2$ and $k=4t+1$, provided that a Hadamard matrix of order $8t+4$ exists. This completely solves the problem of constructing basic OAs with $n=2$, modulo the Hadamard matrix conjecture.     

The preparation,characterization and thermal analysis studies on complexes of cobalt(II) with 2-, 3-, 4-cyanopyridines

Some complexes of the thiocyanates, chlorides, bromides, iodides, nitrates and sulphates of cobalt(II) with 2-, 3-, 4-cyanopyridines have been prepared. The stereochemical configurations of the complexes were deduced using spectral and magnetic properties. The decomposition of the complexes was studied by thermogravimetry and differential thermal analysis.     

Antifungal activity of sakurasosaponin from the root extract of Jacquinia flammea

The methanolic crude extract from the roots of Jacquinia flammea showed moderate antifungal activity against dermatophytes and very strong antifungal activity against Colletotrichum gloeosporioides. The bioassay-guided purification of the extract, using a combination of vacuum-liquid chromatography and high performance liquid chromatography, allowed the identification of sakurasosaponin as the main metabolite responsible for the antifungal activity.     

Glycosylated constituents of iris fulva and Iris brevicaulis

The major constituents of leaf extracts of Iris fulva KER GAWL. comprised a known flavone C-glycoside, 5,4'-dihydroxy-7-methoxyflavone-6-C-(6?-O-(E)-p-coumaroyl-β-glucopyranosyl)(1?→2″)-β-glucopyranoside (1) and the new monoterpene glycoside, linalyl-6'-O-(3″-hydroxy-3″-methylglutaroyl)-β-D-glucopyranoside (2), both of which were prominent components of Iris brevicaulis RAF. leaf extracts. The structure of a new polyacylated sucrose derivative (3a) obtained from the rhizomes of I. fulva was elucidated as 3-O-(E)-p-coumaroyl-β-D-fructofuranosyl-(2?1')-[2″,4″,6″-tri-O-acetyl-β-D-glucopyranosyl-(1″→3')-(2',6'-di-O-acetyl-4'-O-(E)-p-coumaroyl-α-D-glucopyranoside)]. Selective hydrolysis of the 4″-O-acetyl moiety of the terminal β-glucopyranosyl residue of 3a occurred after several hours in solution giving 3-O-(E)-p-coumaroyl-β-D-fructofuranosyl-(2?1')-[2″,6″-di-O-acetyl-β-D-glucopyranosyl-(1″→3')-(2',6'-di-O-acetyl-4'-O-(E)-p-coumaroyl-α-D-glucopyranoside)] (3b), which subsequently underwent further deacetylation.     

An off-axis Hartmann sensor for the measurement of absorption-induced wavefront distortion in advanced gravitational wave interferometers

We describe a novel off-axis Hartmann wavefront sensor, developed for the measurement of wavefront distortions induced in the mirrors (test masses) of advanced gravitational wave interferometers by residual absorption of the circulating laser power.     

Corrigendum to “The distribution of the number of arrivals in a subinterval of a busy period of a single server queue”

The purpose of this corrigendum is two-fold. First, we acknowledge that two results in our paper (Novak et al. in Queueing Syst. 53:105–114, 2006) can be obtained from earlier results of Prabhu and Bhat. Second, we make corrections to Theorem 2.2, Corollary 2.1 and Theorem 4.2 of Novak et al. (Queueing Syst. 53:105–114, 2006).      

Suppression of self-pulsing in Tm:YAlO3 lasers via current feedback

Self-pulsing of continuous-wave Tm:YAlO₃ lasers limits their use for a variety of important applications. We demonstrate for the first time that the pulsing can be suppressed via feedback to the pump diode laser, a technique that is suitable for both external resonator and monolithic lasers. We also show that the optical transfer function of the laser is that of an unstable relaxation oscillator.     

Data-directed scan sequence for the general assignment of C-glycosylflavone O-glycosides in plant extracts by liquid chromatography-ion trap mass spectrometry

An ion trap LC-MS/MS method is described for the analysis of C-glycosylflavone O-glycosides in crude methanolic extracts of plants. The method employs survey scans with and without the application of up-front collision induced dissociation (CID) to generate diagnostic ions for data-directed MS/MS. The spectra acquired allow assignment of the C-linked sugar to either the C-6 or C-8 position of the aglycone and provide data on the molecular mass of the compound, the number and type of O-linked sugars and the molecular mass of the flavone aglycone. These data for the majority of C-glycosylflavone O-glycosides in an extract are obtained automatically in one LC-MS/MS analysis without manual pre-programming. Key to the assignment of the C-6 or C-8 site of C-glycosylation is the generation, by up-front CID, of the (0,1)X+ product ion formed by internal cleavage of the C-linked sugar. MS/MS of this ion is found to have diagnostic value in addition to the (0,2)X+ product ion described by other authors. Ion trap MS/MS spectra of [M+H]+ of the 6,8-di-C-glycosylflavones schaftoside and isoschaftoside show an additional and previously unreported diagnostic product ion that is useful in determining the type of sugar at the C-6 position. The product ion spectra of protonated kaempferol 3-O-glucosylrhamnosides show similarities to the spectra of C-glycosylflavone O-glycosides; this is a potential source of confusion if the analysis of such glycosides is limited solely to MS/MS of [M+H]+.