The epicuticle of various Drosophila species consists of long-chain cuticular hydrocarbons (CHCs) and their derivatives that play a role in waterproofing and a dynamic means of chemical communication. Here, via gas chromatography and mass spectrometry, we identified and quantified the epicuticular composition of D. recens and D. subquinaria, two closely related species that show a pattern of reproductive character displacement in nature. Twenty-four compounds were identified with the most abundant, 11-cis-Vaccenyl acetate, present only in males of each species. Also exclusive to males were five tri-acylglycerides. The 18 remaining compounds were CHCs, all shared between the sexes and species. These CHCs were composed of odd carbon numbers (C29, C31, C33, and C35), with an increase in structural isomers in the C33 and C35 groups. Saturated hydrocarbons comprise only methyl-branched alkanes and were found only in the C29 and C31 groups. Alkenes were the least prevalent, with alkadienes dominating the chromatographic landscape in the longer chain lengths. Sexual dimorphism was extensive with 6/8 of the logcontrast CHCs differing significantly in relative concentration between males and females in D. recens and D. subquinaria, respectively. Males of the two species also differed significantly in relative concentration of six CHCs, while females differed in none. Female-choice mating trials revealed directional sexual selection on male CHCs in a population of each species, consistent with female mate preferences for these traits. The sexual selection vectors differed significantly in multivariate trait space, suggesting that different pheromone blends determine male attractiveness in each species.

An experimental gas-phase study of the intensities and fragmentation patterns of [Mn.(H(2)O)(n)](2+) and [Mn.(ROH)(n)](2+) complexes shows the combinations [Mn.(H(2)O)(4)](2+) and [Mn.(ROH)(4)](2+) to be stable. Evidence in complexes involving the alcohols methanol, ethanol, 1-propanol, and 2-propanol favors preferential fragmentation to [Mn.(ROH)(4)](2+), whereas the fragmentation data for water is less clear. Supporting density functional calculations show that both [Mn.(H(2)O)(4)](2+) and [Mn.(MeOH)(4)](2+) adopt stable tetrahedral configurations, similar to those proposed for biochemical systems where solvent availability and coordination is restricted. Calculated incremental binding energies show a gradual decline on going from one to six solvent molecules, with a step occurring between four and five molecules. The addition of further solvent molecules to the stable [Mn.(MeOH)(4)](2+) unit shows a preference for [Mn.(MeOH)(4)(MeOH)(1,2)](2+) structures, where the extra molecules occupy hydrogen-bonded sites in the form of a secondary solvation shell. Very similar behavior is seen on the part of water. As part of an analysis of the experimental data, the calculations have explored the influence different spins states of Mn(2+) have on solvent geometry. It is concluded that the experimental observations are best reproduced when the central Mn(2+) ion is in the high-spin (6)S ground state. The results are also considered in terms of the biochemical activity of Mn(2+) where the ion is capable of isomorphous substitution with Zn(2+), which itself exhibits a preference for tetrahedral coordination.

The burden of disease from bacterial meningitis is highest in low-income countries (1). Early initiation of antibiotic therapy is important in reducing the risk for mortality. Current treatment guidelines recommend the use of an expanded-spectrum cephalosporin (cefotaxime or ceftriaxone) (2), but these therapies increasingly are limited by drug resistance, and are threatened by the proliferation of substandard and falsified medicines (3,4). In February 2013, a case of bacterial meningitis following a middle ear infection was diagnosed in an adolescent at the Mulago National Referral Hospital in Kampala, Uganda. Once-daily treatment with 2 g of intravenous ceftriaxone administered according to guidelines failed, and the patient died. To determine whether the patient's treatment failure and subsequent death might be related to the ceftriaxone product administered, a sealed vial similar to the one administered to the patient was analyzed at the University of Ottawa, Canada, and was found to contain only 0.455 g of the drug, not 1 g as stated by the manufacturer. This would have resulted in subtherapeutic dosing. Substandard medicines are a global problem that disproportionately affects low-income countries, leading to fatal consequences and promoting the emergence of drug resistance (4).

A brief search in Sci Finder for oxalic acid and oxalates will reward the researcher with a staggering 129,280 hits. However, the generation of alkali metal and silver anions via collision-induced dissociation of the metal oxalate anion has not been previously been reported, though Tian and coworkers recently investigated the dissociation of lithium oxalate [18]. The exothermic decomposition of alkali metal oxalate anion to carbon dioxide in the collision cell of a triple quadrupole mass spectrometer leaves no place for the electron to reside, resulting in a double electron-transfer reaction to produce an alkali metal anion. This reaction is facilitated by the negative electron affinity of carbon dioxide and, as such, the authors believe that metal oxalates are potentially unique in this respect. The observed dissociation reactions for collision with argon gas (1.7-1.8 ϫ 10 Ϫ3 mbar) for oxalic acid and various alkali metal oxalates are discussed and summarized. Silver oxalate is also included to demonstrate the propensity of this system to generate transition-metal anions, as well. (J Am Soc Mass Spectrom 2010, 21, 1944 -1946) © 2010 American Society for Mass Spectrometry T he chemical concept of metals producing positive ions (cations) and non-metals negative ions (anions) is a fundamental precept taught as early as in high school and reinforced throughout a person's university career. However, under certain conditions, metal anions can be created and, as such, their electron affinities are well characterized and calculated both experimentally and theoretically [1]. In solution, alkali metal anions (except lithium) in 'supra molecule complexes' have been prepared in THF and crown ethers. These characteristically blue solutions are now fabricated to control the amount of metal ions, including metal anions. Such solutions have been extensively studied for use in organic synthesis and elucidation of charge-transfer to solvent dynamics (CTTS) [2][3][4][5][6][7][8][9]. In the gas phase, a beam of positively charged alkali cations created from metal vapor can undergo double electron capture to generate a low density negative ion beam [10]. Other means of negative ion generation include discharge and sputter ion sources, namely Cs ϩ ions with a suitable metal cathode [11]. Studies in ion traps utilize dissociative electron attachment to create metal anions [12]. Thus, metal anions are created only via complex experimental procedures or specific experimental apparatus. This paper outlines a method for the production of metal anions requiring a simple oxalate salt solution and a commercially available triple quadrupole mass spectrometer.Oxalic acid is one of the oldest known acids, first isolated from wood sorrel (Oxalis acetosella). It is often found as salt oxalates in many biological systems; particular well known is calcium oxalate found in rhubarb root, known for both its medicinal properties and as a potential poison. Ammonium oxalate is found in guano and there is evidence for the sodium and potassium salts pres...

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