Chemical constituents of Jordanian propolis

Seventeen compounds, including a new lanostane triterpenoid, 24(Z)-1β-3β-dihydroxyeupha-7,24-dien-26-oic acid, have been isolated from the methanolic extracts of two samples of Jordanian propolis collected from two different places with different dominant flora. The structures of the isolated compounds were elucidated by spectral methods including IR, UV, MS and 1- and 2-D NMR.     

A simple chemical model for clathrate hydrate inhibition by polyvinylcaprolactam

A dimeric model compound gives structural insight into the mode of interaction of low dosage hydrate inhibitors with water.     

Optimization of improved suspension system with inerter device of the quarter-car model in vibration analysis

In this paper, we analyze an improved suspension system with the incorporated inerter device of the quarter-car model to obtain optimal design parameters for maximum comfort level for a driver and passengers. That is achieved by finding the analytical solution for the system of ordinary differential equations, which enables us to generate an optimization problem whose objective function is based on the international standards of admissible acceleration levels (ISO 2631-1, Mechanical Vibration and Shock—Evaluation of Human Exposure to Whole-Body Vibration–Part 1, 1997). The considered approach ensures the highest level of comfort for the driver and passengers due to a favorable reduction in body vibrations. Numerical examples, based on actually measured road profiles, are presented at the end of the paper to prove the validity of the proposed approach and its suitability for the problem at hand.     

Possible High Power Laser Construction Using a New Discharge Type-Heated Cathode Discharge in the Copper Vapours Continuously Evaporated from the Anode

The possibility to build a high power copper laser using a new type of discharge – heated cathode discharge in the copper vapours continuously evaporated from a melted spot on the anode surface is analysed. From the experimental data on this new discharge type, the equivalent pressure of the copper atoms in the discharge space has been obtained. This pressure can be as high as 1 torr. The density of the power in the discharge volume is evaluated to be more than 1 kW/cm³.     

Micro‐Raman spectroscopy and VP‐SEM/EDS applied to the identification of mineral particles and fibres in histological sections

Histological sections of a patient affected by an important respiratory disease were analysed firstly by optical microscope(OM)—crossed polarisers—to identify the presence of incorporated inorganic particles, with particular attention to the fibrous ones. Then, the particles/fibres that were found were studied both with micro‐Raman spectroscopy and variable‐pressure scanning electron microscopy with energy‐dispersive spectroscopy (VP‐SEM/EDS). The two techniques allowed the in situ characterisation of the inorganic phases without disintegration of the organic matter. Micro‐Raman spectroscopy was able to identify the vibrating chemical groups of the mineral phase associated with the inorganic grain while the crystalline structure was preserved by the biological system. The VP‐SEM/EDS characterisation, defining the elemental chemical composition of the analysed particle/fibre, allowed confirmation of the mineral phase deducible from spectroscopic data or its identification with certainty when the spectroscopic data were not exhaustive. Copyright © 2009 John Wiley & Sons, Ltd.     

Theoretical study of the phototoxicity of naproxen and the active form of nabumetone

Density functional theory using the hybrid functional B3LYP has been employed in order to study the mechanisms of photoinduced decomposition of the closely related nonsteroidal anti-inflammatory drugs naproxen (NP) and 6-methoxy-2-naphthylacetic acid (MNAA; the active form of nabumetone). The photochemical properties and computed energies of various species obtained in this study show that both drugs dominate in their deprotonated forms at physiological pH. The deprotonated acids are unable to decarboxylate from their excited singlets; instead, they decarboxylate from their first excited triplet states with high efficiency, overcoming energy barriers less than 3 and 1 kcal/mol for MNAA and NP, respectively. The ultraviolet and visible spectra of the neutral, deprotonated, and decarboxylated moieties of MNAA and NP are more-or-less similar but with higher probabilites (oscillator strength) for the latter. This fact, as well as the higher reactivity of NP, is explained in terms of the electron-donating effect of the additional methyl group present in NP. Singlet oxygen, superoxide radical anion, and corresponding peroxyl radical species are expected to be formed in different steps throughout the proposed photodegradation pathways of both drugs, which give rise to their effects on biomolecules, for example, lipid peroxidation.     

A generalization of a theorem of Arrow,Barankin and Blackwell to a nonconvex case

The paper presents a generalization of a known density theorem of Arrow, Barankin, and Blackwell for properly efficient points defined as support points of sets with respect to monotonically increasing sublinear functions. This result is shown to hold for nonconvex sets of a partially ordered reflexive Banach space.     

A novel antimicrobial flavonoid from the stem bark of Commiphora pedunculata (Kotschy & Peyr.) Engl.

A new flavonoid, 2-(3,5-dihydroxy-4-methoxy-phenyl)-3,5-dihydroxy-8,8-dimethyl-2,3-dihydro-8H-pyrano[3,2]chromen-4-one, together with previously reported epicatechin was isolated from the ethyl acetate soluble fraction of the methanol extract of the stem bark of Commiphora pedunculata. The structures of these compounds were elucidated based on extensive analysis of their spectral data, including 1 and 2D NMR. The compounds were active against 9 out of 12 tested microorganisms including a resistant strain; vancomycin-resistant entrococci (VRE), Escherichia coli, Staphylococcus aureus and Candida albicans. The zones of inhibition ranged between 22 and 34 mm against the microorganisms. The minimum inhibitory concentration was as low as 6.25 μg/mL against Shigella dysentriae, Bacillus cereus and S. aureus while the minimum bactericidal concentration was as low as 50 μg/mL against Pseudomonas aeruginosa, VRE and C. albicans. This is the first report of the isolation of the compound.