Classification of some large sets and designs

In this paper, we briefly introduce an algorithm, based on the standard basis of trades, which has proven successful in the complete classification of certain combinatorial objects.     

Calibration-free laser-induced plasma analysis of a metallic alloy with self-absorption correction

Identification and concentration measurement of constituent elements of a metallic alloy is demonstrated by calibration-free laser-induced breakdown spectroscopy (CF-LIBS) according to a special peak intensity-based model and considering the self-absorption effect. In this procedure, which is based on the line pair ratio method, the effect of line widths, though needs to be theoretically considered, may be approximately ignored. This is mainly true for the multiplet lines, but this property, in the case of some generic spectral lines in a measured spectrum, can be sometimes regarded. Initially, the optical penetration depth and therefrom self-absorption coefficient of each selected spectral line is calculated using the experimental (self-absorbed) intensity of the line. Then, the true (non-self-absorbed) intensity, which is basis of the conventional CF-LIBS calculation, is obtained through a recursive algorithm implemented by the MATLAB programming. In the experimental examination, the recorded spectrum reflects that the metallic alloy is consisted of gold, copper and silver. The concentration of elements is calculated with and without regarding self-absorption correction using 27 trios of spectral lines related to the elements. The average concentrations signify that the measurement error relative to the certified value for the concentration of the gold is modified from 3.56 % in the normal way to 0.34 % after applying self-absorption correction.     

Classification of designs with nontrivial automorphism groups

In this article, we introduce a new orderly backtrack algorithm with efficient isomorph rejection for classification of t‐designs. As an application, we classify all simple 2‐(13,3,2) designs with nontrivial automorphism groups. The total number of such designs amounts to 1,897,386. The decomposability of the designs is also considered. © 2005 Wiley Periodicals, Inc. J Combin Designs 14: 479–489, 2006     

Nuclear Quadrupole Resonance and Stereochemistry II. Vicinal cis- and trans-dichloro derivatives of carbocyclic systems

The ³⁵Cl quadrupole resonance frequencies of sets of isomeric vicinal dichloro derivatives of carbocyclic molecules are presented. In all cases except one – cis- and trans-1, 2-dichloro-acenaphthene – the configuration has only a small effect on the resonance frequency. This implies that the frequency-differences in cyclic α-chloroethers reported in Part I of this series [1] are indeed due to a specific interaction with the oxygen atom. The difference between the acenaphthenes may be due to hyperconjugation between the C? Cl bond and the aromatic system.     

A simple and rapid high-performance liquid chromatography method for determining furosemide, hydrochlorothiazide, and phenol red: applicability to intestinal permeability studies

A simple reversed-phase high-performance liquid chromatography (HPLC) method with ultraviolet detection at 280 nm was developed for simultaneous quantitation of furosemide and hydrochlorothiazide along with phenol red as a nonabsorbable marker for in situ permeability studies in anaesthetized rats. A jejunal segment of approximately 10 cm was isolated and cannulated in both ends for inlet and outlet solution. The perfusate was collected every 10 min, and samples were analyzed using the developed method. The mobile phase was acetonitrile-water-triethylamine-glacial acetic acid (41.5 + 57.4 + 0.1 + 0.9, adjusted to pH 5.6) at a flow rate of 1 mL/min; the run time was 9 min. The calibration graphs were linear for all 3 compounds (r > 0.999) across the concentration range of 7.93-125 microg/mL for phenol red and 6.25-100 microg/mL for hydrochlorothiazide and furosemide. The limits of quantitation were 7.2, 8.9, and 6.8 microg/mL for furosemide, hydrochlorothiazide, and phenol red, respectively. The coefficients of variation for intraassay and interassay precision were less than or equal to 7.6%, and the accuracy was between 93.2-103.4%. Using the single pass intestinal perfusion technique and the suggested HPLC method for sample analysis, mean values of 0.25 x 10(-4) (+/-0.16) cm/s and 0.22 x 10(-4) (+/-0.13) cm/s were obtained for furosemide and hydrochlorothiazide, respectively.     

Determination of ergosterol as an indicator of fungal biomass in various samples using non-discriminating flash pyrolysis

Ergosterol is the major sterol constituent of most fungi. Since it is present in negligible amounts in higher plants, it can be used as a chemical marker for the presence of fungal contamination. A number of different ergosterol assays have been developed for the quantification of fungi in various samples. The paper presents the development of a new method for ergosterol detection based on the combination of non-discriminating flash pyrolysis with gas chromatography/mass spectrometry (Py-GC/MS). The design of the non-discriminating Py-GC/MS systems assures efficient transfer of high-molecular-weight pyrolysis products to the GC column for separation, followed by analyte detection by MS. The method was tested on different types of samples, including baker's yeast (Saccharomyces cerevisiae), moldy bread, indoor dust, and a leaf infected with powdery mildew. Ergosterol was detected in all these samples at levels ranging from approximately 4mg/g for the baker's yeast to approximately 6mug/g for household dust. The main benefits of non-discriminating pyrolysis over other techniques include elimination of the need for sample preparation, small sample size required and short analysis time.     

LS[7](3,5,11( exists

In this article, we employ trades to construct an instance of an LS[7](3,5,11) which is the smallest unresolved LS[7](3,k,v) [ 9 ]. © 2003 Wiley Periodicals, Inc. J Combin Designs 11: 312–316, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.10021     

One‐pot and Environmentally Friendly Synthesis of New Spiroindolones Using Functionalized Multiwall Carbon Nanotubes as Powerful Catalyst

Multiwall carbon nanotubes were functionalized and then used as powerful nanocatalyst for the one‐pot, three‐component synthesis of new spiroindolones. Functionalized multiwall carbon nanotubes (FMWCNTs) showed a good catalytic ability and recyclability in the current reaction. The present strategy offers some interesting advantages such as simplicity, high yields of products, and non‐toxic nature.     

Synthesis of carboxymethyl β-cyclodextrin bonded Fe3O4@SiO2–NH2 core-shell magnetic nanocomposite adsorbent for effective removal of Pb(II) from wastewater

Journal of Sol-Gel Science and Technology - In this work, a novel functionalized magnetic Fe3O4@SiO2 core-shell nanoparticles grafted with carboxymethyl β-cyclodextrin (CM-β-CD) is...