Sex-Pairing Pheromones in Three Sympatric Neotropical Termite Species (Termitidae: Syntermitinae)

Termite colonies are almost always founded by a pair of winged dispersers, in spite of the high costs and low success rates inherent in independent colony foundation. The dispersal flights of imagoes from natal colonies are followed by mate search, mediated by sex-pairing pheromones. Here, we studied the chemistry of sex-pairing pheromones and the related aspects of mate search in winged imagoes of two facultatively parthenogenetic species, Embiratermes neotenicus and Silvestritermes minutus, and an additional species from the same subfamily, Silvestritermes heyeri. All three species are widespread in the Neotropics, including the rainforests of French Guiana. After the dispersal flight and spontaneous loss of wings, females expose their hypertrophied tergal glands situated under abdominal tergites VIII – X. The females are attractive to males and, upon direct contact, the two sexes form characteristic tandems. Chemical analyses indicated that the females secrete species-specific combinations of unbranched, unsaturated C₁₂ primary alcohols from the tergal glands, (3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol (approx. 200 pg per female) and (3Z)-dodec-3-enol (185 pg) in E. neotenicus, (3Z,6Z)-dodeca-3,6-dien-1-ol (3500 pg) in S. heyeri, and (3Z,6Z)-dodeca-3,6-dien-1-ol (300 pg) and (3Z)-dodec-3-enol (50 pg) in S. minutus. (3Z,6Z,8E)-Dodeca-3,6,8-trien-1-ol and (3Z,6Z)-dodeca-3,6-dien-1-ol act as major pheromone components in the respective species and mimic the function of female tergal gland extracts in electrophysiological and behavioral experiments. Biologically relevant amounts of the third compound, (3Z)-dodec-3-enol, elicited non-significant reactions in males of E. neotenicus and S. minutus, and slight synergistic effects in males of S. minutus when tested in combination with the major component.     

Dominant factors for device-to-device occurrence probabilities in cellular networks

Wireless Networks - Device-to-device (D2D) communication is expected to be part of future cellular networks. It is commonly assumed that D2D links will exist and need to be managed. However, the...     

Enhanced solubility and dissolution rate of amiodarone by complexation with β-cyclodextrin through different methods

The aim of this work was to investigate the inclusion complexation between amiodarone (AMD), a practically water insoluble anti arrhythmic agent, and β-cyclodextrin (βCD) in order to improve the solubility and the dissolution rate of the drug, in an attempt to enhance its bioavailability. The complexation was done through different methods: physical mixture (PM), coevaporated (CV), freeze-drying (FD) and spray-drying (SD). The data analysis indicated that the complexes produced by freeze-drying and spray-drying techniques resulted in amorphous samples (data obtained by DSC and XRPD), and showed a possible chemical interaction between OH-βCD group and AMD tertiary amine (visualized by FT-IR). Also, they presented higher thermal stability (demonstrated by TG) and the improvement of the drug dissolution rate.     

Evaluation of oral carvedilol microparticles prepared by simple emulsion technique using poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and polycaprolactone as polymers

Polymeric microparticles containing carvedilol (CRV) were obtained successfully using a simple emulsion/organic evaporating method. Three different formulations were developed using poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and polycaprolactone (PCL) as polymers; the resulting samples were submitted to physical–chemical characterization and in vivo evaluation. The physical–chemical analysis indicated that the PHBV promoted a porous aspect in the microparticle's surface, while PCL a smooth aspect. The PCL-CRV microparticles showed a higher loading efficiency and a longer drug release time, being selected for in vivo evaluation. The in vivo assays indicated that PCL-CRV polymeric microparticles has a pharmacological antihypertensive effect for a longer period of time, representing a good alternative to improved the life quality of the patient that uses this drug.     

Project Tocoen. The Fate of Selected Organic Compounds in the Environment. Part XXVIII. Levels of PAHs and Some Halogenated POPs in Ambient Air in Czech Republic

Abstract

Concentrations of polyaromatic hydrocarbons (PAHs), chlorinated pesticides, polychlorinated biphenyls, dibenzo-p-dioxins and dibenzo-p-furans (PCDDs/Fs) in ambient air in Ko?etice, a background locality in the South Bohemia, have been estimated in the period from July to December 1994. The 24-hours samples have been taken by the means of a high-volume sampler. Sample analysis involved Soxhlet extraction of polyurethane foam, extract preconcentration and chromatographic clean-up procedure followed by HPLC determination of PAHs with fluorescence detection, GC/ECD determination of chlorinated pollutants, and GC/MS determination of PCDDs/Fs. The results of this first detailed study undertaken in Czech Republic are compared with the data obtained by similar projects in industrial and/or urban areas in the Czech Republic and in rural or urban areas in other European countries.     

Improvement of tensile shear strength and wood failure percentage of 1C PUR bonded wooden joints at wet stage by means of DMF priming

Tensile shear tests according to EN 302-1 for load-bearing timber structures were performed on European beech wood (Fagus sylvatica L.) and Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] bonded by means of a one-component polyurethane adhesive (1C PUR). Results reveal a substantial loss of tensile shear strength (TSS) and wood failure percentage (WFP) at the wet stage compared to the dry stage. As can be seen from microscopic images, this is accompanied by a loss of adhesion at the boundary layer. Therefore, the aim of this work was to find a priming fluid that improves the load transmission between adhesive and adherend at the wet stage without introducing formaldehyde into the gluing process. A substantial improvement of TSS and WFP was achieved by means of the hygroscopic organic solvent N,N-dimethylformamide (DMF). In addition, contact angle measurements were carried out, revealing that DMF heavily enhances the wettability of the joining surface. Furthermore, it was attempted to integrate the outcomes into the swelling strain model stated by Frihart in 2009. By way of comparison a hydroxymethylated resorcinol coupling agent, a mixture of diphenylmethane-4,4′-diisocyanate isomers and water were also tested as priming fluids. The data confirm that TSS and WFP of 1C PUR bonded wooden joints do not correlate, whilst WFP is mostly not normally (at wet stage often bimodally) distributed.     

Velocity Distributions after Laser-Induced Desorption of NO from NiO(100)—The Role of the Angular Coordinate

The experimental velocity distributions of NO desorbing from a NiO(100)-surface are simulated using a time-dependent wave packet method. Including the polar angle between the surface normal and the adsorbate molecular axis yields bimodal distributions in the correct velocity range and reasonable desorption probabilities if a resonance lifetime on the order of 25 fs is assumed. For two-dimensional simulations, an angular-independent charge-transfer-state was chosen as excited state in order to investigate the influence of the electronic ground-state on the final state distributions. We compare our results with wave packet calculations using a representative ab initio angular-dependent excited-state potential energy surface using a three-dimensional Hamiltonian.     

Mechanical behavior at low strain of microgel containing elastomers

Synthetic routes for the preparation of microgels with defined particle size, crosslinking density and surface chemistry are described. The mechanical effects caused by incorporating such systems in crosslinked rubber (NR and SBR) are described. The mechanical effects are qualitatively related to the state of clustering which is governed by the particle size and the interfacial tension (δ-parameter difference). The reinforcing effects on Young's modulus and the dynamic shear modulus are explained against a comprehensive theoretical background which assumes kinetically controlled cluster-cluster aggregation (CCA) of colloidal filler particles dispersed in entangled polymers. This leads to a control of rubber material properties by chemical means. Received: 19 December 1997/Revised version: 7 January 1998/Accepted: 7 January 1998