HPLC determination of clenbuterol in pharmaceutical gel formulations

A quick, accurate, reproducible high performance liquid chromatographic (HPLC) method for the determination of clenbuterol in the presence of some common pharmaceutical preservatives (i.e., methyl and propyl paraben) is described. The method is specific enough to separate and determine clenbuterol in the presence of degradation products of the formulation components. Extraction of interfering formulation components provides the necessary clean-up to determine clenbuterol via HPLC.     

On translation planes of orderq 2 that admit a group of orderq 2 (q−1); bartolone's theorem

This article is concerned with translation planesP of orderq ² and kernelK isomorphic toG F(q). IfP admits a collineation groupG in the linear translation. complement and the order ofG K/K isq ²(q?1) then it is shown thatP is either a semifield plane or is a Lüneburg-Tits, Walker or Betten plane. This generalizes earlier work of Bartolone.     

List multicolorings of graphs with measurable sets

In an ordinary list multicoloring of a graph, the vertices are “colored” with subsets of pre‐assigned finite sets (called “lists”) in such a way that adjacent vertices are colored with disjoint sets. Here we consider the analog of such colorings in which the lists are measurable sets from an arbitrary atomless, semifinite measure space, and the color sets are to have prescribed measures rather than prescribed cardinalities. We adapt a proof technique of Bollobás and Varopoulos to prove an analog of one of the major theorems about ordinary list multicolorings, a generalization and extension of Hall's marriage theorem, due to Cropper, Gyárfás, and Lehel. © 2006 Wiley Periodicals, Inc. J Graph Theory 54: 179–193, 2007     

Synthesis and cation distribution of copper-substituted spinel-related lithium ferrite

Single-phased Cu²⁺-substituted spinel-related Li_0.5Fe_2.5O₄ was synthesized by sintering a mixture of Cu²⁺-substituted corundum-related α-Fe₂O₃ and Li₂CO₃ at 700 °C which is ∼325-400 °C lower than the temperature at which the material is prepared by the conventional ceramic methods. X-ray powder diffraction, X-ray photoelectron spectroscopy, Mössbauer spectroscopy and magnetic measurements were used to characterize the material. In contrast to high-temperature synthetic routes, the present one leads to a Cu⁺-and Fe²⁺-cation free material, thereby optimizing its technological value. Rietveld refinement of the XRD data favors a structural model in which Cu²⁺ substitutes for both Fe³⁺ and Li⁺ at the octahedral sites. Mössbauer and magnetic data are consistent with this model if spin thermal reversal and/or spin canting are taken into account for the later.     

On the category of weak Cayley table morphisms between groups

Weak Cayley table functions between groups are generalized conjugacy-preserving homomorphisms, under which products of images are conjugate to images of products. There is a weak Cayley table bijection between two groups iff they have the same 2-characters. In this paper, weak Cayley table functions are augmented to include the specific conjugating elements, leading to the concept of a weak (Cayley table) morphism. If the conjugating elements are chosen subject to a crossed-product condition, then the weak morphisms between groups form a category. The forgetful functor to this category from the category of group homomorphisms is shown to possess a left adjoint. Two weak morphisms are said to be homotopic if they project to the same weak Cayley table function. As a first step in the analysis of the category of weak morphisms, the group of units of the monoid of weak morphisms homotopic to the identity automorphism of a group is described.     

A 7160 theorem for bin packing

The FIRST FIT DECREASING algorithm for bin packing has long been famous for its guarantee that no packing it generates will use more than $\text{11}\text{9}\text{= 1.222…}$ times the optimal number of bins. We present a simple modified version that has essentially the same running time, should perform at least as well on average, and yet provides a guarantee of $\text{71}\text{60}\text{= 1.18333…}$.     

Determination of thermally labile oxygen in high-temperature superconducting ceramics by metastable transfer emission spectrometry

A microwave-induced discharge spectrometric method is described for determining temperature profiles of oxygen and carbon evolution from solids. Profiles of oxygen and carbon evolved from Ba₂YCu₃O₇ over the temperature range 50–1000° C are obtained by chemiluminescent formation of NO and CN resulting from reactions with active nitrogen. Intensity profiles measured at 304.3 and 388.3 nm respectively show coincident maxima at 750 and 930° C for O₂ and CO_x evolution. In the case of oxygen, evolution is observed also over the broad range 175 to 975° C with an additional maximum at approximately 490° C. Integration of NO intensity over time compared to results from calibration graphs using known gases provided a means of determining the mass of oxygen evolved from samples. Comparisons showed these results to be within ± 10% of the gravimetric result with a correlation coefficient greater than 0.95.     

A submersible flow analysis system

A submersible chemical analyzer (SCANNER) has been developed which can perform analyses in situ in the ocean. The SCANNER is based on a modified flow-injection system and can be used to automate virtually any spectrophotometric determination that can be done by flow injection analysis. The SCANNER consists of a multichannel peristaltic pump, solid-state colorimeters, manifold tubing, valves, and an electronic module. All of the components are pressure-tolerant, except the electronics module, which is placed in a pressure housing. Typical detection limits are of the order of 0.1 μM. Sample introduction is continuous. The SCANNER has been tested successfully to pressures of 3300 dbar in the laboratory and to depths of 2500 m in the ocean. Examples of silicate and sulfide determinations around animal communities in a deep-sea hydrothermal vent field are presented.