Periodic Golay pairs and pairwise balanced designs

Journal of Algebraic Combinatorics - In this paper we exploit a relationship between certain pairwise balanced designs with v points and periodic Golay pairs of length v, to classify periodic Golay...     

Quinoline synthesis: scope and regiochemistry of photocyclisation of substituted benzylidenecyclopentanone O-alkyl and O-acetyloximes

Irradiation of substituted 2-benzylidenecyclopentanone O-alkyl and O-acetyloximes in methanol provides a convenient synthesis of alkyl, alkoxy, hydroxy, acetoxy, amino, dimethylamino and benzo substituted annulated quinolines. para-Substituents yield 6-substituted-2,3-dihydro-1H-cyclopenta[b]quinolines with 8-substituted products being obtained from ortho-substituted starting materials. Reactions of meta-substituted precursors are highly regioselective, with alkyl substituents leading to 5-substituted 2,3-dihydro-1H-cyclopenta[b]quinolines and more strongly electron-donating substituents generally resulting in 7-substituted products. 2-Furylmethylene and 2-thienylmethylene analogues yield annulated furo- and thieno-[2,3e]pyridines respectively. Sequential E- to Z-benzylidene group isomerisation and six pi-electron cyclisation steps result in formation of a short-lived dihydroquinoline intermediate which spontaneously aromatises by elimination of an alcohol or acetic acid. For 2-benzylidenecyclopentanone O-allyloxime, singlet excited states are involved in both steps.     

Effective gel for gold nanoparticle formation, support and metal oxide templating

Gold nanoparticles were synthesized using agarose as a reducing agent, which gelled to support the gold nanoparticles, then readily functioned as a template to produce a porous, evenly-distributed Au/TiO(2) nano-hybrid.     

Pressure-induced sequential magnetic pole inversion and antiferromagnetic-ferromagnetic crossover in a trimetallic prussian blue analogue

The flexibility of the structure of Prussian blue analogues and its ability to incorporate a variety of competing magnetic interactions have allowed the design of mixed ferro-ferrimagnets, which span the whole spectrum of magnetic behavior, including the rare phenomenon of magnetization reversal in response to a change in temperature. Hydrostatic pressure is used here to induce multiple reversals of the direction of the spontaneous magnetization in the trimetallic Prussian blue analogue, Rb0.64Ni0.31Mn0.87[Fe(CN)6].2.8H2O. Remarkably, the magnetic response is extremely sensitive to pressure, and the magnetization flips from positive to negative and back to positive in a very narrow pressure range (0 < P < 0.6 kbar). A further increase in pressure to 4.0 kbar induces an internal redox reaction, and the magnetic order switches from ferrimagnetic to bulk ferromagnetism.     

Discovering antimalarials: a new strategy

Recent discoveries have uncovered some key processes that occur in the food vacuole of the malarial parasite. Consequently, new families of potential antimalarials that inhibit HRP-2, a hitherto unexplored drug target, were identified using a novel screening method.     

Latin Squares with Restricted Transversals

The original article to which this erratum refers was correctly published online on 1 December 2011. Due to an error at the publisher, it was then published in Journal of Combinatorial Designs 20: 124–141, 2012 without the required shading in several examples. To correct this, the article is here reprinted in full. The publisher regrets this error. We prove that for all odd there exists a latin square of order 3m that contains an latin subrectangle consisting of entries not in any transversal. We prove that for all even there exists a latin square of order n in which there is at least one transversal, but all transversals coincide on a single entry. A corollary is a new proof of the existence of a latin square without an orthogonal mate, for all odd orders . Finally, we report on an extensive computational study of transversal‐free entries and sets of disjoint transversals in the latin squares of order . In particular, we count the number of species of each order that possess an orthogonal mate. © 2012 Wiley Periodicals, Inc. J. Combin. Designs 20: 344–361, 2012     

Pressure drop in two phase slug/bubble flows in mini scale capillaries

A segmented two phase slug/bubble flow occurs where a liquid and a gas are pumped into the same tube over a range of Reynolds numbers. This segmented two phase flow regime is accompanied by an increase in pressure drop relative to the single phase flow where only one fluid is flowing in a capillary. This work experimentally and theoretically examines the pressure drop encountered by the slug/bubble flow with varying slug lengths in mini channels. In the experimental work the dimensionless parameters of Reynolds number and Capillary number span over three orders of magnitude, and dimensionless slug length ranges over two orders of magnitude to represent flows typical of mini- and micro-scale systems. It is found, in agreement with previous work, that these dimensionless groups provide the correct scaling to represent the pressure drop in two phase slug/bubble flow, although the additional pressure drop caused by the interface regions was found to be ∼40% less than previously reported.     

A statistical-based approach to assessing the fidelity of combinatorial libraries encoded with electrophoric molecular tags. Development and application of tag decode-assisted single bead LC/MS analysis

A statistical sampling protocol is described to assess the fidelity of libraries encoded with molecular tags. The methodology, termed library QA, is based on the combined application of tag decode analysis and single bead LC/MS. The physical existence of library compounds eluted from beads is established by comparing the molecular weight predicted by tag decode with empirical measurement. The goal of sampling is to provide information on overall library fidelity and an indication of the performance of individual library synthons. The minimal sampling size n for library QA is l0 x the largest synthon set. Data are reported as proportion (p) +/- lower and upper boundary (lb-ub) computed at the 95% confidence level (alpha = 0.05). As a practical demonstration, library QA was performed on a 25,200-member library of statine amides (size = 40 x 63 x 10). Sampling was conducted three times at n approximately 630 beads per run for a total of 1902 beads. The overall proportions found for the three runs were consistent with one another: p = 84.4%, lb-ub = 81.5-87.2%; p = 83.1%, lb-ub = 80.2-85.95; and p = 84.5%, lb-ub = 81.8-87.3%, suggesting the true value of p is close to 84% compound confirmation. The performance pi of individual synthons was also computed. Corroboration of QA data with biological screening results obtained from assaying the library against cathepsin D and plasmepsin II is discussed.     

Chemical analysis and water quality

Summary The development of analytical standards for water quality is considered on an historical basis and the present day position reviewed in relation to other bases for quality assessment. The analytical aspects have developed strongly, and continuously, during the past hundred years for fresh water; and there are now many well established compendia of analytical methods, based on collaborative and other cooperative studies. By contrast the standards and analytical methods for sea water have only developed much more recently. Some of the particular analytical problems which arise in the examination of fresh water, rivers and oceans will be considered, together with questions of the automation of methods.Analytical standards still play a very important role in the assessment of water quality. However, there is now a need for quicker methods, automatic methods and in some cases approximate methods which may not have the accuracy and precision of the more detailed procedures but which give results of sufficient accuracy for specific purposes.

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Chemische Analyse und Wasserqualität

Zusammenfassung Die Entwicklung analytischer Standards zur Beurteilung der Wasserqualit ät wird auf historischer Grundlage betrachtet und die gegenwärtigen Verhältnisse werden in Beziehung zu anderen Kriterien der Qualitätsbeurteilung diskutiert. Für Süßwasser haben sich die Methoden während der letzten hundert Jahre kontinuierlich weiter entwickelt und es existieren zahlreiche gut eingeführte Handbücher und Sammelwerke. Auf dem Gebiet der Meereswasseranalyse hat die Entwicklung jedoch erst viel später eingesetzt. Einige spezielle analytische Probleme, die bei der Wasseruntersuchung auftreten, werden zusammen mit Fragen der Automation erörtert.Bei der Beurteilung der Wasserqualität spielen analytische Standards immer noch eine sehr wichtige Rolle. Es werden allerdings gegenwärtig schnellere und automatisierte Methoden benötigt, sowie auch angenäherte Verfahren, die vielleicht nicht die Reproduzierbarkeit und Genauigkeit der eingehenderen Methode aufweisen, jedoch für spezielle Zwecke ausreichende Ergebnisse liefern.

Presented at the 6th Annual Symposium on Recent Advances in the Analytical Chemistry of Pollutants, April 21–23, 1976; Vienna, Austria.