Exceptional trivalent cayley graphs for dihedral groups

If n is divisible by at least three distinct primes, the dihedral group D_n can be generated by three nonredundant, involuntary elements. We study the Cayley graphs resulting from such a presentation of D_n for several families of n and for all admissible n < 120. All these graphs are trivalent, bipartite, Hamiltonian, of girth 6, and are regular representations of their groups. For each n, the isomorphism classes are determined and the graphs are described by a simple code.     

Mechanical and hydrogen characteristics of hermetically coated optical fibre

Corning's hermetically coated fibre has been evaluated for mechanical and hydrogen performance under severe test conditions using large sample sizes. The results indicate that the carbon coating is truly hermetic, and that it provides an effective barrier for preventing hydrogen and water from reaching the glass surface. As a result the hermetically coated fibre possesses superior resistance to fatigue and hydrogen permeation over standard fibre. These attributes make this hermetically coated fibre and excellent candidate for use in terrestrial communication and undersea cables, as well as in other special applications where a harsh environment is present.     

TOPICS IN POLYMER PHYSICS（With CD-Rom）

This important book emphasizes the basic derivation of many key equations used in polymer physics. Phrases such as “it can be easily shown that” and “it readily follows that”, seen in many textbooks, are seldom used here. The models, assumptions and key equations underlying concepts are presented in the text; details used in the derivations are given in the accompanying CD-Rom. The CD-Rom also contains problems （with solutions in many cases） which test the reader＇s grasp of the material, as well as a glossary of symbols.     

The angular intensity correlation functions C(1) and C(10) for the scattering of light from randomly rough dielectric and metal surfaces

We study the statistical properties of the scattering matrix S(q|k) for the problem of the scattering of light of frequency ω from a randomly rough one-dimensional surface, defined by the equation x₃=ζ(x₁), where the surface profile function ζ(x₁) constitutes a zero-mean, stationary, Gaussian random process. This is done by studying the effects of S(q|k) on the angular intensity correlation function C(q,k|q',k')=〈I(q|k)I(q'|k')〉-〈I(q|k)〉〈I(q'|k')〉, where the intensity I(q|k) is defined in terms of S(q|k) by I(q|k)=L^-1₁(ω/c)|S(q|k)|², with L₁ the length of the x₁ axis covered by the random surface. We focus our attention on the C⁽¹⁾ and C⁽¹⁰⁾ correlation functions, which are the contributions to C(q,k|q',k') proportional to δ(q-k-q'+k') and δ(q-k+q'-k'), respectively. The existence of both of these correlation functions is consistent with the amplitude of the scattered field obeying complex Gaussian statistics in the limit of a long surface and in the presence of weak surface roughness. We show that the deviation of the statistics of the scattering matrix from complex circular Gaussian statistics and the C⁽¹⁰⁾ correlation function are determined by exactly the same statistical moment of S(q|k). As the random surface becomes rougher, the amplitude of the scattered field no longer obeys complex Gaussian statistics but obeys complex circular Gaussian statistics instead. In this case the C⁽¹⁰⁾ correlation function should therefore vanish. This result is confirmed by numerical simulation calculations.     

An insight into antimicrobial activity of the freshwater bryozoan Pectinatella magnifica

The antimicrobial activity of five crude extracts of the freshwater bryozoan Pectinatella magnifica (Leidy, 1851) was evaluated in vitro for the first time. P. magnifica acetone extract exhibited the highest antibacterial activity (minimum inhibitory concentrations (MIC) 0.004–0.350 mg/mL and MBC 0.007–0.500 mg/mL), while its methanol extract showed the most promising antifungal activity (MIC 0.03–0.12 mg/mL and MFC 0.06–0.25 mg/mL). Furthermore, at a concentration of 0.25 MIC, the methanol extract reduced biofilm formation of the bacterial strain Pseudomonas aeruginosa PAO1 in a considerable extent (59.14%). FTIR spectra of the most active extracts indicate the presence of carbonyl compounds, long-chain alcohols and/or sterols. According to the experimental data obtained, P. magnifica methanol extract may be considered as a good resource of novel natural products with potent antibiofilm activity against the bacterium well known for its resistance.     

Synthesis of the first unnatural schisantherins and their effects in multidrug-resistant cancer cells

Schisandrol A, a dibenzocyclooctadiene lignan, was obtained by a simplified procedure from Schisandra chinensis fruits. Its reaction with carboxylic acids to give new esters (schisantherins) required special conditions such as microwave irradiation. An X-ray single crystal structure analysis of schisandrol A revealed a sterical shielding of the secondary OH group as the likely reason. The cinnamoate inhibited the P-gp drug transporters of multidrug-resistant human Kb-V1 cervix carcinoma cells better than the natural benzoate and comparable to the clinical sensitizer verapamil.     

Speciation of manganese binding to biomolecules in pine nuts (Pinus pinea) by two-dimensional liquid chromatography coupled to ultraviolet and inductively coupled plasma mass spectrometry detectors followed by identification by electrospray ionization mass spectrometry

Advances in analytical methodology for speciation of manganese in pine nuts are presented in this work. The approach is based on the use of orthogonal chromatographic systems, namely size-exclusion chromatography (SEC) of the extracts and strong anion exchange (IEC) of the fractions collected by the first column. In both columns, manganese elution is first monitored by a quadrupole inductively coupled plasma mass spectrometry (ICP-MS) instrument equipped with an octopole reaction cell and an ultraviolet (UV) detector. SEC is performed by using two columns covering the molecular weight range from <10 to 70 kDa that allows an initial screening of the molecular weight of the Mn species. The higher resolution capability of the low molecular weight range column is the reason to use the latter for further experiments. The fraction from SEC-ICP-MS in which Mn is present at highest concentration is submitted to IEC-ICP-MS allowing Mn-citrate and MnCl(2) identification by retention time matching with standards. The concentration of these species is estimated to be 75 and 125 microg kg(-1) (as Mn), respectively, in the pine nuts samples and the presence of Mn-citrate is confirmed by nanoelectrospray ionization quadrupole time-of-flight mass spectrometry (nESI-QqTOF-MS). In the same fraction, a third Mn-containing peak is detected in the IEC-UV-ICP-MS chromatogram. This peak corresponds to a protein containing Mn that was later submitted to a tryptic digestion and analyzed by nESI-QqTOF. The MS/MS data of a doubly charged peptide are used to obtain the sequence of the protein with the Mascot search engine. The peak turned out to be isocitrate dehydrogenase, a protein commonly associated with Mn. Copyright (c) 2008 John Wiley & Sons, Ltd.     

Synthesis, primary photophysical and antibacterial properties of naphthyl ester cinoxacin and nalidixic acid derivatives

We have synthesized two naphthyl ester quinolone derivates and determined their ability to generate reactive oxygen species (ROS) such as (1)O(2), ()OH, H(2)O(2) upon photolysis with UV-A light. The ability of cinoxacin (1) and nalidixic acid (2), and their naphthyl ester derivatives (3 and 4) to generate a dose-dependent amount of singlet oxygen and ROS (()(-)O(2), ()OH) in cell-free systems was detected by histidine assay and by luminol-enhanced chemiluminescence (LCL), respectively. Their electronic absorption and emission spectra were quantified and their photostability was determined. Their tendency to generate peroxidic derivative species showed the following order: 3>4; in contrast, their ability to generate singlet oxygen was 4>3 and these were better sensitizers than their parent quinolones 1 and 2. The antibacterial activity in darkness and under irradiation of compounds 3 and 4 was tested on Escherichia coli and compared with that of their parent compounds. An enhanced antibacterial activity by irradiation of the naphthyl esters of cinoxacin and nalidixic acid on E. coli was observed.