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Homologous Series (homologous + series)
Selected AbstractsSynthesis and Microstructural Characterisation of Two New One-Dimensional Members of the (A3NiMnO6),(A3Mn3O9), Homologous Series (A = Ba, Sr)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2003María Hernando Abstract Two new members of the one-dimensional (A3NiMnO6),(A3Mn3O9), homologous series, with the compositions (Sr0.75Ba0.25)5NiMn3O12 and Sr9Ni2Mn5O21, have been synthesised. Their structures can each be described as a hexagonal array of infinite one-dimensional chains of face-sharing polyhedra, running parallel to the c axis and separated by the Sr/Ba cations. The structure of (Sr0.75Ba0.25)5NiMn3O12, which constitutes the (, = 3, , = 2) member of the series, is made up of three face-sharing octahedra linked by one trigonal prism. For Sr9Ni2Mn5O21 (, = 2, , = 1) the sequence of polyhedra along the chains corresponds to a motif consisting of two octahedra,one trigonal prism,three octahedra,one trigonal prism. The manganese atoms occupy the octahedral sites in both phases, while the Ni2+ cations are distributed in the trigonal-prismatic sites in a disordered way. Only a small fraction of these (close to 20%) is located at the centres of the trigonal prisms, 80% being displaced towards the rectangular faces of the polyhedra and giving rise to a square-planar-like coordination. Both oxides present twinned microstructures, as evidenced by SAED and HREM. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] ChemInform Abstract: First-Principles Investigation of R2O3(ZnO)3 (R: Al, Ga, and In) in Homologous Series of Compounds.CHEMINFORM, Issue 14 2008Satoru Yoshioka Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Structural Chemistry of an n = 1 Member of the Ruddlesden,Popper Srn+1 (Co0.5Ta0.5)nO3n+1 Homologous Series: Sr4CoTaO8.CHEMINFORM, Issue 30 2007Khalid Boulahya Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Synthesis and Microstructural Characterization of Two New One-Dimensional Members of the (A3NiMnO6), (A3Mn3O9), Homologous Series (A: Ba, Sr).CHEMINFORM, Issue 39 2003Maria Hernando Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Magnetic Properties of a Homologous Series of Vanadium Jarosite Compounds.CHEMINFORM, Issue 26 2002Dimitris Papoutsakis Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Current,Voltage Characteristics of a Homologous Series of Polycyclic Aromatic HydrocarbonsCHEMISTRY - A EUROPEAN JOURNAL, Issue 26 2007Thilo Böhme Dr. Abstract A novel alkyl-substituted polycyclic aromatic hydrocarbon (PAH) with D2h symmetry and 78 carbon atoms in the aromatic core (C78) was synthesized, thereby completing a homologous series of soluble PAH compounds with increasing size of the aromatic , system (42, 60, and 78 carbon atoms). The optical band gaps were determined by UV/Vis and fluorescence spectroscopy in solution. Scanning tunneling microscopy (STM) and spectroscopy (STS) revealed diode-like current versus voltage (I,V) characteristics through individual aromatic cores in monolayers at the interface between the solution and the basal plane of graphite. The asymmetry of the current,voltage (I,V) characteristics increases with the increasing size of the aromatic core, and the concomitantly decreasing HOMO,LUMO gap. This is attributed to resonant tunneling through the HOMO of the adsorbed molecule, and an asymmetric position of the molecular species in the tunnel junction. Consistently, submolecularly resolved STM images at negative substrate bias are in good agreement with the calculated pattern for the electron densities of the HOMOs. The analysis provides the basis for tailoring rectification with a single molecule in an STM junction. [source] Homologous series of alkylsilylphenyl-substituted poly (p -phenylenevinylene)s for light-emitting diodesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2004Sung-Ho Jin Abstract Substituent-induced electroluminescence polymers,poly[2-(2-dimethyldodecylsilylphenyl)-1,4-phenylenevinylene] [(o -R3Si)PhPPV], poly[2-(3-dimethyldodecylsilylphenyl)-1,4-phenylenevinylene] [(m -R3Si)PhPPV], and poly[2-(4-dimethyldodecylsilylphenyl)-1,4-phenylenevinylene] [(p -R3Si)PhPPV],were synthesized according to the Gilch polymerization method. The band gap and spectroscopic data were tuned by the dimethyldodecylsilyl substituent being changed from the ortho position to the para position in the phenyl side group along the polymer backbone. The weight-average molecular weights and polydispersities were 8.0,96 × 104 and 3.0,3.4, respectively. The maximum photoluminescence wavelengths for (o -R3Si)PhPPV, (m -R3Si)PhPPV, and (p -R3Si)PhPPV appeared around 500,530 nm in the green emission region. Double-layer light-emitting diodes with an indium tin oxide/poly(3,4-ethylenedioxythiophene)/polymer/Al configuration were fabricated with these polymers. The turn-on voltages and the maximum brightness of (o -R3Si)PhPPV, (m -R3Si)PhPPV, and (p -R3Si)PhPPV were 6.5,8.7 V and 1986,5895 cd/m2, respectively. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2347,2355, 2004 [source] Dietary accumulation of perfluorinated acids in juvenile rainbow trout (Oncorhynchus mykiss)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2003Jonathan W. Martin Abstract Perfluorinated acids (PFAs) recently have emerged as persistent global contaminants after their detection in wildlife and humans from various geographic locations. The highest concentrations of perfluorooctane sulfonate are characteristically observed in high trophic level organisms, indicating that PFAs may have a significant bioaccumulation potential. To examine this phenomenon quantitatively, we exposed juvenile rainbow trout (Oncorhynchus mykiss) simultaneously to a homologous series of perfluoroalkyl carboxylates and sulfonates for 34 d in the diet, followed by a 41-d depuration period. Carcass and liver concentrations were determined by using liquid chromatography-tandem mass spectrometry, and kinetic rates were calculated to determine compound-specific bioaccumulation parameters. Depuration rate constants ranged from 0.02 to 0.23/d, and decreased as the length of the fluorinated chain increased. Assimilation efficiency was greater than 50% for all test compounds, indicating efficient absorption from food. Bioaccumulation factors (BAFs) ranged from 0.038 to 1.0 and increased with length of the perfluorinated chain; however, BAFs were not statistically greater than 1 for any PFA. Sulfonates bioaccumulated to a greater extent than carboxylates of equivalent perfluoroalkyl chain length, indicating that hydrophobicity is not the sole determinant of PFA accumulation potential and that the acid function must be considered. Dietary exposure will not result in biomagnification of PFAs in juvenile trout, but extrapolation of these bioaccumulation parameters to larger fish and homeothermic organisms should not be performed. [source] Phytotoxicity of chlorinated aliphatics to hybrid poplar (Populus deltoides × nigra DN34)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2001Annette C Dietz Abstract Effects of a series of chlorinated ethenes and ethanes on hybrid poplar (Populus deltoides × nigra DN34) were assessed in laboratory experiments. Poplar cuttings were grown in sealed reactors with hydroponic solutions and were exposed to a chlorinated solvent for a period of two weeks. Exposure concentrations ranged from 0 to 0.4 mM for perchloroethylene to 0 to 8.4 mM for 1,1-dichloroethane. Effects were assessed by gravimetrically monitoring transpiration and measuring change in cutting mass. The zero-growth concentrations of the chemicals tested were 0.3 mM perchloroethylene, 0.9 mM trichloroethylene, 0.9 mM 1,1,2,2-tetrachloroethane, 2.0 mM 1,1,1-trichloroethane, 2.3 mM 1,1,2-trichloroethane, 4.8 mM trans -dichloroethylene, 5.6 mM 1,1-dichlor-oethylene, 6.0 mM cis -dichloroethylene, and 10.7 mM 1,1-dichloroethane. Adverse effects were found to increase with increasing number of chlorine atoms within a homologous series of ethenes or ethanes. Ethenes were more toxic than similarly chlorinated ethanes. [source] Orbital Splitting and Pairing Energy in Open-Shell Organometallics: A Study of Two Families of 16-Electron Complexes [Cp2M] (M = Cr, Mo, W) and [CpM(PH3)] (M = Co, Rh, Ir)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 12 2005Rinaldo Poli Abstract The singlet,triplet gap for two families of 16-electron organometallic complexes has been examined in detail by DFT calculations at the B3LYP level with polarized basis sets on both metal and ligands. For the first family, the group 6 metallocenes (Cp2M with Cp = ,5 -C5H5 and M = Cr, Mo, W), the singlet,triplet gap (ES , ET) is always positive and decreases continuously on going from Cr to Mo to W. For the family of group 9 CpM(PH3), on the other hand, there is a decrease on going from Co to Rh, followed by a slight increase on going further to Ir. These trends have been analyzed in qualitative monoelectronic terms as a function of the competition between the pairing energy and the orbital gap. While the pairing energy decreases as expected in the order 3d >> 4d > 5d, the orbital gap varies in a different way for the two families and, though quantitatively less important, is responsible for the different trends. It is argued that changes in orbital gap are system-dependent for open-shell organometallic systems, thus it is not possible to establish a universal trend of singlet,triplet gaps for a homologous series of complexes with a group of transition metals. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Synthesis and Microstructural Characterisation of Two New One-Dimensional Members of the (A3NiMnO6),(A3Mn3O9), Homologous Series (A = Ba, Sr)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2003María Hernando Abstract Two new members of the one-dimensional (A3NiMnO6),(A3Mn3O9), homologous series, with the compositions (Sr0.75Ba0.25)5NiMn3O12 and Sr9Ni2Mn5O21, have been synthesised. Their structures can each be described as a hexagonal array of infinite one-dimensional chains of face-sharing polyhedra, running parallel to the c axis and separated by the Sr/Ba cations. The structure of (Sr0.75Ba0.25)5NiMn3O12, which constitutes the (, = 3, , = 2) member of the series, is made up of three face-sharing octahedra linked by one trigonal prism. For Sr9Ni2Mn5O21 (, = 2, , = 1) the sequence of polyhedra along the chains corresponds to a motif consisting of two octahedra,one trigonal prism,three octahedra,one trigonal prism. The manganese atoms occupy the octahedral sites in both phases, while the Ni2+ cations are distributed in the trigonal-prismatic sites in a disordered way. Only a small fraction of these (close to 20%) is located at the centres of the trigonal prisms, 80% being displaced towards the rectangular faces of the polyhedra and giving rise to a square-planar-like coordination. Both oxides present twinned microstructures, as evidenced by SAED and HREM. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Molecular-feature domains with posterodorsal,anteroventral polarity in the symmetrical sensory maps of the mouse olfactory bulb: mapping of odourant-induced Zif268 expressionEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2002Koichiro Inaki Abstract Individual glomeruli in the mammalian olfactory bulb presumably represent a single type of odourant receptor. Thus, the glomerular sheet provides odourant receptor maps at the surface of the olfactory bulb. To understand the basic spatial organization of the olfactory sensory maps, we first compared the spatial distribution of odourant-induced responses measured by the optical imaging of intrinsic signals with that detected immunohistochemically by expressions of Zif268, one of the immediate early gene products in juxtaglomerular cells. In the dorsal surface of the bulb, we detected a clear correlation in the spatial pattern between these responses. In addition, the molecular-feature domains and their polarities (spatial shifts of responses with an increase in carbon chain length) that were defined by the optical imaging method could be also detected by the Zif268 mapping method. We then mapped the Zif268 signals over the entire olfactory bulb using a homologous series of fatty acids and aliphatic alcohols as stimulus odourants. We superimposed the Zif268 signals onto the standard unrolled map with the help of cell adhesion molecule compartments. Each odourant typically elicited two pairs of clusters of dense Zif268 signals. The results showed that molecular-feature domains and their polarities were arranged symmetrically at stereotypical positions in a mirror-image fashion between the lateral and the medial sensory maps. The polarity of each domain was roughly in parallel with the posterodorsal,anteroventral axis that was defined by the cell adhesion molecule compartments. These results suggest that the molecular-feature domain with its fixed polarity is one of the basic structural units in the spatial organization of the odourant receptor maps in the olfactory bulb. [source] Use of TLC-FID and GC-MS/FID to examine the effects of migratory state, diet and captivity on preen wax composition in White-throated Sparrows Zonotrichia albicollisIBIS, Issue 4 2010RAYMOND H. THOMAS Preen wax is important for plumage maintenance and other functions. Its chemical composition is complex, and separating and quantifying its components, commonly by gas chromatography (GC), can be challenging. We present a simple analytical system consisting of thin-layer chromatography/flame ionization detection (TLC-FID) using a solvent system of 100% toluene to analyse the complex compound classes present in preen wax. We used GC and TLC-FID to investigate the effects of migratory status, diet and captivity on the preen wax composition of White-throated Sparrows Zonotrichia albicollis, and to measure the quantity of preen wax on the head, primary and tail feathers. White-throated Sparrows produced preen wax containing only monoesters regardless of migratory state. The monoesters contained several isomers consisting of homologous series of fatty alcohols (C10,C20) and fatty acids (C13,C19) esterified together in different combinations to form monoesters with total carbon numbers ranging from C23 to C38. Weighted average monoester carbon number was greater in captive birds than in wild birds and was greater in captives fed a formulated diet enriched with sesame oil than in birds fed the same diet enriched with fish oil. Captivity and migratory state also affected the complexity of the mixture of monoesters. There was significantly more preen wax on head feathers compared with primary and tail feathers. We suggest that among its many functions, preen wax may play a role in drag reduction by affecting the physical properties of feathers, and/or the fluid flow at their surfaces. [source] Influences of alkyl group chain length and polar head group on chemical skin permeation enhancementJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2001Kevin S. Warner Abstract Previous investigations in our laboratory on the influence of the n -alkanols and the 1-alkyl-2-pyrrolidones as skin permeation enhancers for steroid molecules as permeants demonstrated that the enhancer potencies (based on aqueous concentration values) of these two homologous series were the same when compared at the same alkyl chain length; that is, the contribution of the hydroxyl group and that of the pyrrolidone group to enhancer potency were the same. The purpose of the present study was to further investigate what was believed to be a somewhat surprising finding, and two additional homologous series, the 1,2-alkanediols and N,N -dimethylalkanamides, were selected for study as enhancers. Corticosterone (CS) flux enhancement along the lipoidal pathway of hairless mouse skin stratum corneum was determined with 1,2-hexane-, 1,2-octane-, and 1,2-decanediol and with N,N -dimethylhexanamide, N,N - dimethylheptanamide, N,N -dimethyloctanamide, and N,N -dimethylnonanamide as enhancers. The enhancement factor (E) for the lipoidal pathway was calculated from the CS permeability coefficient and the CS solubility data over a 4 to 100 range of E values. Comparisons of the enhancer potencies of all four homologous series revealed that the enhancer potencies of all were very nearly the same when compared at equal alkyl group chain length. Moreover, the contribution of each of the polar head groups toward the enhancer potency was essentially constant, independent of the alkyl group chain length. It was reasoned that this outcome was either the result of the random selection of four polar head groups making the same contribution to enhancer potency or the result of these particular polar head groups not contributing to enhancer potency. To test the hypothesis that the former was more likely than the latter and that a suitable semipolar organic phase may mimic the microenvironment of the polar head group at the site of enhancer action, n -octanol,phosphate buffered saline (PBS) and n -hexane,PBS partition coefficients were determined for all the enhancers. The n -octanol,PBS partition coefficients for the enhancers, but not the n -hexane,PBS partition coefficients, were very nearly the same when compared at equal alkyl group chain lengths; this result supports the hypothesis that each of the four polar head groups likely contributes the same toward the enhancer potency and locates in the semipolar region of the hairless mouse skin stratum corneum lipid bilayers, which is well-approximated by water-saturated n -octanol. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1143,1153, 2001 [source] Analysis of aldehydes via headspace SPME with on-fiber derivatization to their O -(2,3,4,5,6-pentafluorobenzyl)oxime derivatives and comprehensive 2D-GC-MSJOURNAL OF SEPARATION SCIENCE, JSS, Issue 19 2008Hans-Georg Schmarr Abstract A method for the analysis of the homologous series of alkanals, (E)-2-alkenals, and (E,E)-2,4-alkadienals is described utilizing a headspace solid-phase microextraction (HS-SPME) step and on-fiber derivatization with O -(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) hydrochloride. Oxime derivatives formed on the fiber are desorbed in the gas chromatographic injector and analyzed by comprehensive 2-D GC coupled to quadrupole MS (GC×GC-qMS). Selecting specific fragment ions within the electron impact mass spectra of the oxime derivatives provides a suitable method for the target analysis of these aldehyde classes, which furthermore benefits from the increased separation efficiency by GC×GC. The analysis of higher molecular weight aldehydes is described in wine and grape seed oil as examples. Quantification of the aldehydes utilizes a stable isotope dilution analysis (SIDA) assay with octan-d16 -al as isotopomeric internal standard. Besides the selectivity and sensitivity of aldehyde analysis using PFBHA derivatives, critical aspects on background level contamination and repeatability of the sample preparation method are discussed. Optimization of GC×GC-qMS parameters allowed a considerable saving of the cryogenic medium, involving additional (unmodulated) conditioning runs, rendering the method more amenable to routine analysis. [source] Application of comprehensive multidimensional gas chromatography combined with time-of-flight mass spectrometry (GC×GC-TOFMS) for high resolution analysis of hop essential oilJOURNAL OF SEPARATION SCIENCE, JSS, Issue 5-6 2004Mark T. Roberts Abstract The selection and quality of hops is a major determinant in beer flavour. Brewers acknowledge that distinctive characteristics of different hop varieties can be traced to the composition of their essential oils. The difficulty in characterising complex mixtures such as hop oil using 1-D chromatography is that many compounds co-elute. With the introduction of comprehensive multidimensional capillary gas chromatography (GC×GC), there is a tremendous improvement in the separation power or peak capacity. Recent work using GC×GC with flame ionisation detection has suggested that there may be over 1,000 compounds in hop oil. This work describes the use of GC×GC combined with TOFMS detection (Leco Pegasus 4D instrument) to analyse Target hop oil. The TOFMS spectral acquisition rate of 60 Hz provided sufficient spectra per peak (2-D peak base width of 0.1,0.2 s) for identification (119 components were identified with 45 previously unreported compounds). When analysing results, an advantage of GC×GC coupled to TOFMS is that 2-D chromatograms can be viewed for individual masses that are characteristic of particular functional groups. This allows the analyst to view the various homologous series of compounds although in certain cases coelution may still be present as shown by the esters with mass 75. [source] Microwave-Assisted One-Pot Synthesis of Hyperbranched Epoxide-Amine AdductsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 16 2009Julia Theis Abstract Hyperbranched epoxide-amine adducts were synthesized by a one-pot microwave (MW) assisted reaction. 4-(2,3-epoxypropyl-1-oxy)benzonitrile was hydrogenated using Pd/C under microwave conditions, forming the AB2 monomer 1-aminomethyl-4-(2,3-epoxypropyl-1-oxy)benzene. Depending on the reaction temperature this monomer immediately reacts to give hyperbranched epoxide-amine adducts. Mass spectrometric investigations proved the formation of a homologous series of oligomers containing up to six repeating units. Due to the complexing properties of the poly(amino alcohol) moieties in the presence of Cu2+ ions, large aggregates were formed. [source] Complete multinuclear magnetic resonance characterization of a set of polyfluorinated acids and alcoholsMAGNETIC RESONANCE IN CHEMISTRY, Issue 2 2009Alexander A. Marchione Abstract A complete 1H, 19F, and 13C NMR assignment of a homologous series of polyfluorinated acids and alcohols is reported. These assignments were obtained chiefly through single and multiple-bond 1H,13C and 19F,13C correlation experiments (HSQC, HMBC). 19F NOESY experiments were required for assignment of two compounds with diastereotopic 19F nuclei in the CF2chain of the molecule. Copyright © 2008 John Wiley & Sons, Ltd. [source] Designing for topical delivery: Prodrugs can make the differenceMEDICINAL RESEARCH REVIEWS, Issue 6 2003Kenneth B. Sloan Abstract It has been shown for homologous series of prodrugs that those members who were the more water soluble ones gave the greatest enhancement in topical delivery of the parent drug and not the more lipophilic ones. However, until recently models for topical delivery and equations to predict topical delivery focused only on lipid solubility (SLIPID) or partition coefficient (KOCT:AQ) and molecular volume (or molecular weight, MW) as parameters. Now several equations (transformed Potts,Guy or Series/Parallel) have been developed which include aqueous solubility (SAQ) as a parameter for predicting flux through skin. Experimental fluxes, solubilities, and MW from seven series of prodrugs have been fit to the transformed Potts,Guy equation to give coefficients for log solubility in isopropyl myristate (log SIPM) and log solubility in water (log SAQ) (0.53 and 0.47, respectively) which show, for parent drugs delivered by prodrugs from IPM in vitro through hairless mouse skin, that water solubility is almost as important as lipid solubility. When the transformed Potts,Guy equation was fit to data for the delivery of NSAID from mineral oil (MO) in vivo through human skin, the coefficients were 0.72 log SMO and 0.28 log SAQ. When the transformed Potts,Guy equation was fit to data for the delivery of their parent drugs by three series of prodrugs from water in vitro through hairless mouse skin the coefficients were 0.66 log SIPM and 0.34 log SAQ. Numerous recent examples are also given where more water-soluble members of homologous series of prodrugs give higher flux values from water vehicles in vitro through human skin than the more lipid soluble ones. © 2003 Wiley Periodicals, Inc. Med Res Rev, 23 No. 6, 763,793, 2003 [source] Insecticidal 2-hydroxy-3-alkyl-1,4-naphthoquinones: correlation of inhibition of ubiquinol cytochrome c oxidoreductase (complex III) with insecticidal activityPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 3 2002Philip J Jewess Abstract The insecticidal and in vitro activities of four homologous series of 2-hydroxy and acetoxy-3-substituted-1,4-naphthoquinones have been measured and correlated with their (Log) octanol/water partition coefficients (Log Ko/w). In vitro activity against mitochondrial complex III was only exhibited by 2-hydroxy-3-alkyl-1,4-naphthoquinones, indicating that the 2-acetoxy compounds act as pro-insecticides. Good correlation was observed between in vivo activity against the two-spotted spider mite, Tetranychus urticae and inhibition of complex III isolated from blowfly flight muscle. Both hydroxy and acetoxy analogues of individual compounds exhibited similar levels of in vivo activity with optimum activity for analogues with Log Ko/w values of 7,8. In contrast, the acetoxy derivatives showed superior in vivo activity against the tobacco whitefly, Bemisia tabaci. Complex III isolated from whitefly was optimally inhibited by hydroxy analogues with lower Log Ko/w values (6.0,6.5) and was also more sensitive than the blowfly enzyme to all the compounds tested. © 2002 Society of Chemical Industry [source] Isolation and antimicrobial evaluation of isomeric hydroxy ketones in leaf cuticular waxes of Annona squamosa,PHYTOCHEMICAL ANALYSIS, Issue 1 2007K. Shiva Shanker Abstract A novel natural compound, 11-hydroxy-16-hentriacontanone, has been isolated from the leaf cuticular wax of Annona squamosa along with its known isomer 10-hydroxy-16-hentriacontanone in a ratio of 67:33. This isomeric mixture of hydroxy ketones constituted together 16.5% of the total cuticular waxes. The new compound was characterised using spectral and chromatographic techniques. The major component was found to be 16-hentriacontanone (palmitone), which constituted up to 48% of the total cuticular wax, together with a homologous series of hydrocarbons, fatty aldehydes, fatty alcohols, fatty acids and sterols as minor components. The antimicrobial activity of the isomeric hydroxy ketones was tested against selected Gram-positive and Gram-negative bacterial strains, and also some selected fungal strains, and compared with palmitone. The antibacterial activity of palmitone was significantly higher than that of the isomeric hydroxy ketones, but their antifungal activities were comparable. Copyright © 2006 John Wiley & Sons, Ltd. [source] Electrically conductive sensors for liquids based on ternary immiscible polymer blends containing polyanilinePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10 2004H. Cooper Abstract Electrically conductive blends, containing two immiscible polymers (ethylene vinyl acetate, EVA-19, and copolyamide 6/6.9, CoPA) and polyaniline (PANI), were produced by melt processing. These blends showed a preferred localization of PANI in the CoPA phase, thus enhancing the formation of continuous conducting networks. Electrically conductive PANI-containing filaments produced by a capillary rheometer process at various shear rate levels were studied as sensing materials for a homologous series of alcohols (methanol, ethanol and 1-propanol). All filaments showed a decreasing resistance upon exposure to these solvents. Filaments exposed to methanol, liquid or vapor, exhibited the highest resistance decrease. This behavior was related to the highest polarity of methanol, compared with ethanol and 1-propanol. The filaments' rate of production significantly affects the relative resistance change upon exposure to the various alcohols and their reproducibility. Copyright © 2004 John Wiley & Sons, Ltd. [source] Fabric softeners: nearly instantaneous characterization and quality control of cationic surfactants by easy ambient sonic-spray ionization mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 3 2009Sérgio A. Saraiva A tiny droplet of typical samples of fabric softeners from different commercial brands placed on a smooth paper surface was subjected to easy ambient sonic-spray ionization mass spectrometry (EASI-MS). With no need for sample-preparation or pre-separation procedures, EASI-MS and EASI-MS/MS identify nearly instantaneously the main surfactants and the homologous series employed in their formulations. Adulterated and low quality samples containing no or less efficient softeners are also easily recognized. Copyright © 2009 John Wiley & Sons, Ltd. [source] Analysis of triacetone triperoxide (TATP) and TATP synthetic intermediates by electrospray ionization mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 2 2008Michael E. Sigman The explosive triacetone triperoxide (TATP) has been analyzed by electrospray ionization mass spectrometry (ESI-MS) on a linear quadrupole instrument, giving a 62.5,ng limit of detection in full scan positive ion mode. In the ESI interface with no applied fragmentor voltage the m/z 245 [TATP,+,Na]+ ion was observed along with m/z 215 [TATP,+,Na , C2H6]+ and 81 [(CH3)2CO,+,Na]+. When TATP was ionized by ESI with an applied fragmentor voltage of 75,V, ions at m/z 141 [C4H6O4,+,Na]+ and 172 [C5H9O5,+,Na]+ were also observed. When the precipitates formed in the synthesis of TATP were analyzed before the reaction was complete, a new series of ions was observed in which the ions were separated by 74,m/z units, with ions occurring at m/z 205, 279, 353, 427, 501, 575, 649 and 723. The series of evenly spaced ions is accounted for as oligomeric acetone carbonyl oxides terminated as hydroperoxides, [HOOC(CH3)2{OOC(CH3)2}nOOH,+,Na]+ (n,=,1, 2,,,8). The ESI-MS spectra for this homologous series of oligoperoxides have previously been observed from the ozonolysis of tetramethylethylene at low temperatures. Precipitates from the incomplete reaction mixture, under an applied fragmentor voltage of 100,V in ESI, produced an additional ion observed at m/z 99 [C2H4O3,+,Na]+, and a set of ions separated by 74,m/z units occurring at m/z 173, 247, 321, 395, 469 and 543, proposed to correspond to [CH3CO{OOC(CH3)2}nOOH,+,Na]+ (n,=,1,2,,,5). Support for the assigned structures was obtained through the analysis of both protiated and perdeuterated TATP samples. Copyright © 2007 John Wiley & Sons, Ltd. [source] Differential responses to branched and unsaturated aliphatic hydrocarbons in the rat olfactory systemTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 4 2006Sabrina L. Ho Abstract In an effort to understand mammalian olfactory processing, we have been describing the responses to systematically different odorants in the glomerular layer of the main olfactory bulb of rats. Previously, we demonstrated chemotopically organized and distinct olfactory responses to a homologous series of straight-chained alkanes that consisted of purely hydrocarbon structures, indicating that hydrocarbon chains could serve as molecular features in the combinatorial coding of odorant information. To better understand the processing of hydrocarbon odorants, we now have examined responses to other types of chemical changes in these kinds of molecules, namely, branching and carbon,carbon bond saturation. To this end, we used the [14C]2-deoxyglucose method to determine glomerular responses to a group of eight-carbon branched alkane isomers, unsaturated octenes (double-bonded), and octynes (triple-bonded). In contrast to the differential responses we observed previously for straight-chained alkanes of differing carbon number, the rat olfactory system was not particularly sensitive to these variations in branching and bond saturation. This result was unexpected, given the distinct molecular conformations and property profiles of the odorants. The similarity in activity patterns was paralleled by a similarity in spontaneous perceptual responses measured using a habituation assay. These results demonstrate again the functional relationship between bulbar activity patterns and odor perception. The results further suggest that the olfactory system does not respond equally to all aspects of odorant chemistry, functioning as a specific, rather than a general, chemical analysis system. J. Comp. Neurol. 499:519,532, 2006. © 2006 Wiley-Liss, Inc. [source] Structural investigation of GeSb6Te10 and GeBi6Te10 intermetallic compounds in the chalcogenide homologous seriesACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2010Toshiyuki Matsunaga The crystal structures of GeSb6Te10 and GeBi6Te10 were scrutinized using an X-ray powder diffraction method, which revealed that these compounds crystallize in trigonally distorted cubic close-packed structures with a 51-layer period (). Each layer consists of a triangular atomic net; Te atoms occupy their own specific layers, whereas Ge, Sb and Bi atoms are located in the other layers. In these pseudobinary compounds, random atomic occupations of Ge and Sb/Bi are observed and the layers form two kinds of elemental structural blocks by their successive stacking along the c axis. These compounds can be presumed to be isostructural. It is known that the chemical formula of the chalcogenide compounds with the homologous structures found in these pseudobinary systems can be written as (GeTe)n(Sb2Te3)m or (GeTe)n(Bi2Te3)m (n, m: integer); the GeSb6Te10 and GeBi6Te10 investigated in this study, which correspond to the case in which n = 1 and m = 3, naturally have 3,×,l = 51-layer structures according to a formation rule l = 2n + 5m commonly found in the compounds of these chalcogenide systems (l represents the number of layers in the basic structural unit). Calculations based on the density functional theory revealed that these materials are compound semiconductors with very narrow band gaps. [source] Superspace description of the homologous series Ga2O3(ZnO)mACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2010Yuichi Michiue A unified description for the structures of the homologous series Ga2O3(ZnO)m, gallium zinc oxide, is presented using the superspace formalism. The structures were treated as a compositely modulated structure consisting of two subsystems. One is constructed with metal ions and the other with O ions. The ideal model is given, in which the displacive modulations of ions are well described by the zigzag function with large amplitudes. Alternative settings are also proposed which are analogous to the so-called modular structures. The validity of the model has been confirmed by refinements for phases with m = 6 and m = 9 in the homologous series. A few complex phenomena in real structures are taken into account by modifying the ideal model. [source] Vacancy-ordering effects in AlB2 -type ErGe2 ,x (0.4 < x, 0.5)ACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2008Jeppe Christensen In the Er,Ge system, the compostion range ErGe2 to Er2Ge3 has been investigated. Eight samples were produced by arc melting of the elements, and analyzed using X-ray powder diffraction. Nine crystal structures were found to be present in the samples. The structures are described as a homologous series and presented within the superspace formalism using the superspace group X2/m(,0,)0s, X representing the centring vector (½, ½, 0, ½). In this description the modulation vector q = (,a* + ,c*) is shown to be a direct measure of the Ge content as ErGe2,,,, (, falls in the range to ½). The large composition range is achieved by extended vacancy ordering in the planar 63 net of Ge with subsequent relaxation. [source] Superspace description of the crystal structures of Can(Nb,Ti)nO3n,+,2 (n = 5 and 6)ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2007Jonathan Guevarra The crystal structures of two members of the homologous series Can(Nb,Ti)nO3n,+,2, with n = 5 and 6, are presented within the superspace formalism. A common (3,+,1)-dimensional superspace model is used to describe the crystal structures of both compositions within a particular homologous series, where the primary modulation wavevector and the width of the atomic domains vary systematically with composition. The two crystal structures are characterized as commensurately modulated structures consisting of discontinuous atomic domains described by occupational crenel functions. The displacive modulation functions for the two compounds exhibit similarities, but they also show that the idea of a unified superspace model does not extend toward the precise atomic positions. For n = 6, the centrosymmetric (3,+,1)-dimensional superspace symmetry provides a natural explanation for the pseudo-symmetries that are present in the non-centrosymmetric (three-dimensional) superstructure of this compound. The efficiency of the superspace approach is demonstrated by structure refinements in (3,+,1)-dimensional superspace and by comparing these results with the refinements in their three-dimensional superstructures. [source] 4,4,-Bis(2,2,2-trifluoroethoxymethyl)-2,2,-bipyridineACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2010Norman Lu As part of a homologous series of novel polyfluorinated bipyridyl (bpy) ligands, the title compound, C16H14F6N2O2, contains the smallest fluorinated group, viz. CF3. The molecule resides on a crystallographic inversion centre at the mid-point of the pyridine Cipso,Cipso bond. Therefore, the bpy skeleton lies in an anti conformation to avoid repulsion between the two pyridyl N atoms. Weak intramolecular C,H...N and C,H...O interactions are observed, similar to those in related polyfluorinated bpy,metal complexes. A ,,, interaction is observed between the bpy rings of adjacent molecules and this is probably a primary driving force in crystallization. Weak intermolecular C,H...N hydrogen bonding is present between one of the CF3CH2, methylene H atoms and a pyridyl N atom related by translation along the [010] direction, in addition to weak benzyl-type C,H...F interactions to atoms of the terminal CF3 group. It is of note that the O,CH2CF3 bond is almost perpendicular to the bpy plane. [source] | ||||||||||||||||||||||||||||