Potentiometric flow-injection determination of iodide and iodine

A potentiometric flow-injection system is described, in which iodide in the concentration range 10(-6)-10(-1)M may be determined at rates of up to 360 samples/hr at a flow-rate of 17.8 ml/min. Iodine, after on-line reduction to iodide with 0.1M sodium metabisulphite, can also be determined, with a throughput of 60 samples/hr for 10(-5)-10(-3)M iodine. Analyses of two pharmaceutical preparations for iodide and iodine are reported, and the results are in reasonable agreement with titrimetric values.     

Synthesis and cytotoxicity of 28-carboxymethoxy lupane triterpenoids.Preference of 28-O-acylation over 28-O-alkylation of betulm by ethyl bromoacetate

28-Carboxymethoxy lupane tritepenoids 3 and 4 were synthesized by alkylation of betulin with the THP protected 2- hydroxyethyl iodide followed by oxidation and reduction.Direct reaction of betulin(5) or betulone(10) with ethyl bromoacetate led to 28-O-acylation,instead of 28-O-alkylation.The targeted compounds 3 and 4 were not cytotoxic at the highest concentration tested(75μmol/L),suggesting that elongation of the chain length at the 28-position in both betulinic acid(1) and betulonic acid(2) was detrim...     

Structural entailment

We give a number of characterizations of structural entailment. In particular, we show that an alter ego structurally entails an algebraic relation s on a finite algebra if and only if s can be obtained via a local construct from . We show, via a range of applications, that, whereas entailment is important in the study of dualisability, structural entailment is important in the study of full and strong dualisability. We also give an application to the transfer of strong dualities that connects this paper to our earlier paper [9] on full versus strong duality. Received June 27, 2003; accepted in final form May 12, 2005.     

The morphology of α-Al2O3 and α-Fe2O3: The importance of surface relaxation

Current methods for predicting crystal morphology from structure ignore the fact that real crystal surfaces are not necessarily exact terminations of the bulk structure. Instead, surfaces relax and in so doing minimise the total surface energy. This lowering of the surface energy and its influence on crystal morphology are here calculated and illustrated for α-Al₂O₃ (corundum) and α-Fe₂O₃ (haematite). The results are compared with previous studies based on Hartman-Perdok theory.     

From rectangular bands to k -primal algebras

We begin by giving a new proof that every finite rectangular band is naturally dualisable. Motivated by the dualising structure arising from this proof, we call an algebra k-primal if it is (isomorphic to) a product of k independent primal algebras. For each k \geq 2 we exhibit a strong duality between the quasi-variety generated by a k -primal algebra and the topological quasi-variety \lilcat D _k of Boolean topological k-dimensional diagonal algebras. The category \lilcat D ₂ is the category of compact, totally disconnected rectangular bands. This duality extends Hu’s duality for varieties generated by a primal algebra to the k -dimensional case. We find that Hu’s ``uniqueness principle’’ for such varieties also extends to the k -dimensional case, namely, we show that a quasi-variety is equivalent as a category to the quasi-variety generated by a k -primal algebra if and only if it is itself generated by a k -primal algebra.     

Crystallisation from a Water‐in‐Oil Emulsion as a Route to Enantiomer Separation: The Case of dl‐Threonine

The use of crystalliation as a means of separating enantiomers is well known. The utility of commonly applied seeding approaches is limited by the ultimate crystallisation of the antipode. Here we demonstrate how the combination of colloid science and crystal chemistry can lead to an emulsion based process yielding robust separation of a purified solid and impure liquid phases with ultimate product ee of up to 90 %. Threonine is used as a model to demonstrate the viability of the method but it is clear that extension to include, for example, simultaneous racemisation within the disperse phase is easily possible and would transform this from a separation to a preparation process.     

APS/CNM Users Meeting: Celebrating the International Year of Light

The International Year of Light and Light-Based Technologies (IYL) is a global initiative, adopted by the United Nations, to highlight the importance of light and optics technologies, and synchrotron light sources are recognized as important tools in revealing the atomic and molecular details of the world around us. The 2015 joint Advanced Photon Source (APS)/Center for Nanoscale Materials (CNM) Users Meeting was held on May 11–14. This article reports on the APS portion of the meeting. Apropos to both the IYL and the twentieth anniversary of the first X-ray beam at the APS, research highlights were presented and opportunities for upgrading the performance of the APS were discussed.     

Multisorted dualisability: change of base

We prove that if a quasivariety A{\mathcal{A}} generated by a finite family M{\mathcal{M}} of finite algebras has a multisorted duality based on M{\mathcal{M}}, then A{\mathcal{A}} has a multisorted duality based on any finite family of finite algebras that generates it.