bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluorene‐Based Conjugated Poly(azomethine)s: Synthesis, Photophysical Properties, and Theoretical Electronic Structures
Authors: Liu Cheng‐Liang , Chen Wen‐Chang 
Published: October 2005

AbstractSummary: Soluble conjugated poly(azomethine)s, PFI and PFCI, were synthesized from 2,7‐diformyl‐9,9′‐dioctylfluorene (DFOF) with diamines. The replacement of the fluorene (PFI) by carbazole (PFCI) reduces the ionization potential but enhances the band gap (Eg) due to the kink disorder introduced by the 3,6‐carbazole. The optical absorption or photoluminescence of the synthesized PFI or PFCI is sensitive to good/poor solvent ratio, acid environment, or metal ions. The variation of the planarity on the polymer backbone and intermolecular charge transfer explain the above spectral tuning by chemical species. The theoretical results based on the density functional theory (DFT) suggest that the PFI and PFCI show a non‐coplanar conformation due to steric repulsion force between the adjacent hydrogen atoms. It could be resolved by replacing the fluorene or carbazole ring by thiophene (PFTI) or 3,4‐ethylenedioxythiophene (PFEI). The coplanar geometry and possible intramolecular charge transfer lead to the Eg of 2.17 and 2.03 eV for the PFTI and PFEI, respectively. The smaller effective mass of the PFTI or PFEI also indicates that both polymers could be p‐type semiconductors for organic electronics.Chemical structures of fluorene‐based conjugated poly(azomethine)s.magnified imageChemical structures of fluorene‐based conjugated poly(azomethine)s.
Polystyrene End‐Labeled with 2,7‐Dibromofluorene Synthesized Using an Adaptation of Reverse Atom Transfer Radical Polymerization
Authors: Ludwig Bellamarie , Tillman Eric S. 
Published: October 2005

AbstractSummary: Polystyrene with high amounts of end‐labeling was synthesized using initiating systems comprised of conventional radical initiators and 2,7‐dibromofluorene or other fluorene derivatives in an adaptation of reverse atom transfer radical polymerization (RATRP). Benzoyl peroxide (BPO) or 2,2′‐azoisobutyronitrile (AIBN) were decomposed and allowed to react with 2,7‐dibromofluorene, 2‐bromofluorene, or fluorene in the presence of ligand‐bound CuX2 allowing for abstraction of the 9‐H from the fluorenyl species and the establishment of an equilibrium between the subsequent active radical and the dormant alkyl halide. Gel permeation chromatography (GPC) traces indicated CuCl2‐catalyzed reactions produced polymers possessing narrow polydispersity index (PDI) values <1.3 with AIBN and 2,7‐dibromofluorene systems, while analogous reactions catalyzed using CuBr2 were less controlled (PDI > 1.7). Analysis of the polymers using UV‐vis spectroscopy and UV‐GPC demonstrated competition between initiation from both the conventional radical initiator and fluorenyl species generating polymers end‐labeled with both the 2,7‐dibromofluorene and isobutyronitrile groups. Fluorene or 2‐bromofluorene as co‐initiators led to lowered amounts of end‐labeling, but the polymers generally possessed lower PDI values compared to 2,7‐dibromofluorene systems.
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Effect of a mixture of iprobenfos and malathion on the development of malathion resistance in the mosquito Culex pipiens pallens Coq
Authors: Tao Li‐Ming , Yang Jian‐Zhong , Zhuang Pei‐Jun , Tang Zhen‐Hua 
Published: October 2005

AbstractA malathion‐resistant (RM) strain of Culex pipiens pallens Coq was obtained by successively selecting a field population with malathion in the laboratory. The synergistic effect of iprobenfos on malathion toxicity and α‐naphthyl acetate (α‐NA) esterase assay revealed that malathion resistance in the RM strain was associated with increased α‐NA esterase activity and the synergism was mainly due to the inhibition by iprobenfos of this activity. There was no difference in α‐NA esterase activity between the larvae and female adults in the susceptible (S) strain, but the activity in the adults was 13‐fold higher than in the larvae of the RM strain. To understand the effect of the application of a mixture of iprobenfos and malathion on the evolution of malathion resistance, an artificial strain (Syn) was generated by mixing the RM and S strains with 0.1 frequency of the malathion‐resistant individuals. The offspring of the Syn strain were divided into two sub‐strains, Rm and Rm+ibp, which were successively treated with, respectively, malathion alone and malathion + iprobenfos (1:2) at LC70. In the mixture, the fungicide iprobenfos acted as a synergist of malathion. After treatment for 10 generations, the resistance level to malathion was 317.4‐fold for the Rm sub‐strain, whereas for the Rm+ibp sub‐strain it was only 38.9‐fold, compared with the Syn strain. Similar results were obtained by measurement of α‐NA esterase activity from both larvae and female adults. The α‐NA esterase activities in larvae and female adults at F10 generation were 2.6‐ and 10.9‐fold from the Rm+ibp sub‐strain and 5.7‐ and 98.5‐fold from the Rm sub‐strain, respectively, compared with the Syn strain. The above results suggested that iprobenfos, although it cannot completely stop or prevent the onset of malathion resistance, could dramatically delay its evolution. Copyright © 2005 Society of Chemical Industry
Effect of pretreatment with piperonyl butoxide on pyrethroid efficacy against insecticide‐resistant Helicoverpa armigera (Lepidoptera: Noctuidae) and Bemisia tabaci (Sternorrhyncha: Aleyrodidae)
Authors: Young Susan J , Gunning Robin V , Moores Graham D 
Published: October 2005

AbstractPyrethroid resistance in B‐type Bemisia tabaci Gennadius and Australian Helicoverpa armigera Hübner field populations is primarily conferred by esterase isoenzymes which metabolise and sequester pyrethroid insecticides. It has been shown previously that pyrethroid resistance‐associated esterases in H. armigera are inhibited by the insecticide synergist piperonyl butoxide (PBO) over a 22‐h period. It is demonstrated here that similar inhibition can be obtained against B‐type B. tabaci. Small‐scale field trials showed excellent levels of pyrethroid control when insects were pretreated with PBO and then dosed with pyrethroid during the time of maximum esterase inhibition. These results demonstrate that PBO can restore pyrethroid efficacy in the field against both B‐type B. tabaci and resistant H. armigera. Copyright © 2005 Society of Chemical Industry
Comparative biological activities of a plaque‐purified variant and a Turkish native isolate of SpliNPV‐B against Spodoptera littoralis (Lepidoptera: Noctuidae)
Authors: Toprak Umut , Bayram Şerife , Gürkan Oktay M 
Published: October 2005

AbstractThe noctuid moth Spodoptera littoralis (Boisduval) is an important pest of many cultivated plants worldwide and five different geographical Nucleopolyhedrovirus (NPV) strains of this pest have been isolated to date. Two of these, a plaque‐purified variant of the S. littoralis NPV from Morocco (SpliNPV‐M2) and a SpliNPV isolated from field‐infected S. littoralis larvae found in Turkey (SpliNPV‐TR1), were compared biologically in terms of infectiveness (median lethal dose, LD50) for third instars and in terms of virulence (median lethal time, LT50) for neonates and third‐instar S. littoralis larvae. The LD50 values of SpliNPV‐TR1 and SpliNPV‐M2 were 20.73 and 185.21 occlusion bodies (OBs)/larva, respectively, with non‐overlapping confidence limits indicating they were significantly different. Thus, SpliNPV‐M2 was found to be significantly less infective (about nine times higher LD50) than SpliNPV‐TR1. The LT50 values of neonates for SpliNPV‐M2 and SpliNPV‐TR1 were 37 and 43.9 h at a concentration of 106 OBs ml−1, respectively. For these same isolates, the LT50 values at a concentration of 3 × 106 OBs ml−1 were calculated as 35.6 and 41.7 h, respectively. The LT50 values of third instars for SpliNPV‐M2 and SpliNPV‐TR1 were 147.4 and 160.5 h, respectively, at a dose of 3000 OBs/larva and 145.4 and 152.4 h, respectively, for the same isolates at a dose of 20 000 OBs/larva. On the other hand, Helicoverpa armigera (Hübner) and Agrotis ipsilon (Hufnagel) revealed a lack of lethality of the SpliNPV‐TR1 isolate. Copyright © 2005 Society of Chemical Industry
Comparative study of dielectric functions of complex organic heterostructures
Authors: Gordan O. D. , Hermann S. , Friedrich M. , Zahn D. R. T. 
Published: October 2005

AbstractOrganic/organic heterostructures and mixed layers were prepared by organic molecular beam deposition (OMBD) in high vacuum (HV) on hydrogen passivated (111) oriented silicon. The substrates were kept at room temperature during the deposition. The organic superstructures consisting in alternative layers of tris‐(8‐hydroxyquinoline)‐aluminum(III) (Alq3)/N,N′‐Di‐[(1‐naphthyl)‐N,N′‐diphenyl]‐(1,1′‐biphenyl)‐4,4′‐diamine (α‐NPD) and 3,4,9,10‐perylenetetracarboxylic dianhydride (PTCDA)/copper phthalocyanine (CuPc) were investigated by means of spectroscopic ellipsometry in the 0.73–5 eV spectral range. Additionally reflection infra‐red (IR) measurements were performed using p‐ and s‐polarisation.Taking into account the dielectric function of the single layers the optical response of the Alq3/α‐NPD superstructure can be modeled assuming sharp interfaces. However, for the PTCDA/CuPc superstructure the optical response requires a more sophisticated approach than simply superimposing the responses of the individual layers. The deviation between simulated and experimental data is assigned to the molecular interaction at the interfaces between PTCDA and CuPc. This can affect the molecular orientation and the optical properties. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectroscopic ellipsometry and reflectance anisotropy spectroscopy of biomolecular layers on silicon surfaces
Authors: Zahn Dietrich R. T. , Silaghi Simona D. , Cobet Christoph , Friedrich Marion , Esser Norbert 
Published: October 2005

AbstractThe optical properties of the DNA bases deposited on flat and vicinal, hydrogen passivated Si(111) substrates are studied using spectroscopic ellipsometry (SE) up to 9.5 eV photon energy employing synchrotron radiation and reflectance anisotropy spectroscopy (RAS). The results for the dielectric function reveal strong optical anisotropy for adenine and guanine while the other two molecules form layers with isotropic properties. The experimentally derived dielectric functions are compared to density functional theory calculations of the optical response. Particularly interesting is the RAS response of the DNA bases as a function of thickness when deposited on vicinal Si surfaces. Ordering in the layers is induced by the step and terrace structure of the vicinal Si substrates. Even though the molecular structure is not dramatically different the RAS response is very distinct and allows an unambiguous identification of the bases. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman analysis of embedded monolayers and quantum dots
Authors: Geurts J. , Wagner V. 
Published: October 2005

AbstractWe demonstrate the potential of resonant Raman spectroscopy from vibration modes for the analysis of embedded monolayers and quantum dots. As representative systems, we present results for CdSe, embedded either in BeTe or in ZnSe. The vibration spectra reflect a distinctly different behaviour. For CdSe in BeTe, they reveal atomically sharp interfaces, especially when the interface bonds are chosen to be Cd–Te. In addition, the vibration modes reflect the onset of quantum dot formation. They are described by ab initio calculations. In contrast, in case of CdSe quantum dots in ZnSe, the vibration spectra are explained in terms of ternary (Cd,Zn)Se modes with increasing Cd content for increasing nominal CdSe coverage. Thus, they reveal a noticeable interfacial intermixing on the scale of a few monolayers. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
VUV‐ellipsometry on GaN: Probing conduction band properties by core level excitations
Authors: Esser N. , Rakel M. , Cobet C. , Schmidt W. G. , Braun W. , Cardona M. 
Published: October 2005

AbstractSpectral ellipsometry is a widely used method for analysing optical properties of materials. In particular electronic interband transitions of many semiconductor materials have been intensively studied employing ellipsometry from the near‐infrared to the ultra‐violet (UV) spectral range. Electronic excitations involving core‐levels, on the other hand, have been a domain of synchrotron based X‐ray absorption spectroscopy or electron loss spectroscopy. We apply spectral ellipsometry in the vacuum‐UV spectral range to study core level excitations in GaN. The results proof that VUV‐ellipsometry is a very versatile tool to obtain information on the p‐like component of the density of states (DOS) related to the conduction bands of GaN. Excitations of the 3d core level of Ga are shown to be linked to the partial DOS at the Ga site within the lattice (complementary to the information obtained on nitrogen sites by X‐ray absorption at the N1s edge). (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
β‐Fragmentation of alkoxyl radicals: Natural bond orbital analysis
Authors: Leblanc Marie , Siri Didier , Marque Sylvain R. A. , Grimaldi Sandra , Bertin Denis , Tordo Paul 
Published: October 2005

AbstractAlkoxyl radicals are often generated in order to perform regioselective hydrogen atom abstraction. However, their β‐fragmentation generates alkyl radicals that are less efficient to abstract hydrogen atoms. We have performed density functional theory (DFT) calculations [UB3LYP/6‐31+G(d,p)] followed by a natural bond orbital (NBO) analysis on a series of alkoxyl radicals. The β‐fragmentation of these radicals is discussed in terms of bond population and hyperconjugative interactions. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
What can we do with an effective group potential?
Authors: Carissan Yannick , Bessac Fabienne , Alary Fabienne , Heully Jean‐Louis , Poteau Romuald 
Published: October 2005

AbstractThe method, called effective group potential, (EGP), which includes the effect of a group of atoms in a single potential, has been used successfully in a large variety of applications. Using the EGP method, optimal geometries, harmonic vibrational frequencies, activation energies, and transition energies can be safely calculated with various correlation methods even for rather large molecules. The usefulness of this method for the theoretical study of a selection of some rather difficult cases is presented. It is shown that, even if many atoms are removed from a fragment and, furthermore, if most of the electrons on the remaining atoms are removed as well, very good accuracy can be conserved. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
When stress is mental illness: A study of anxiety and depression in employees who use occupational stress counselling schemes
Authors: Arthur Andrew R. 
Published: October 2005

AbstractA previous study found that 86 per cent of employees (n = 111) who experience stress in the workplace and sought help from their workplace counselling schemes (Employee Assistance Programmes) had serious mental health problems, but the low participation rate (24 per cent) restricted generalizability and the measure used [General Health Questionnaire (GHQ‐12)] did not allow diagnosis. The present study (n = 58) improved the participation rate to 35 per cent and used a different version of the original measure (GHQ‐28) that allowed diagnostic differentiation as well as validation of the original findings. This new study found almost exactly the same high levels of mental health problems existed (86 per cent) in employees who remained at their work and that participants had higher rates of anxiety than depression. This finding is at variance with the usual co‐morbid presentation of anxiety and depression found in community based mental health services and suggests that depression may be an important differentiating factor between those who can remain at work and use counselling and those who cannot. There are implications for those who provide mental health services. The results of this study further reinforce the suggestion that workplace stress may be yet another name for common mental health problems that require professional help and treatment. Copyright © 2005 John Wiley & Sons, Ltd.
Numerical study of turbulent flow around a wind turbine nacelle
Authors: Masson Christian , Smaïli Arezki 
Published: October 2005

AbstractThis article presents a numerical method for the simulation of turbulent flow around the nacelle of a horizontal axis wind turbine. The flow field around the turbine and nacelle is described by the Reynolds‐averaged Navier–Stokes equations. The k–ϵ model has been chosen for closure of the time‐averaged turbulent flow equations. The rotor disc is modelled using the actuator disc concept. The main purpose of this article is to assess the impacts of the variation of some operational parameters (e.g. blade pitch angle changes) and atmospheric turbulence upon the relationship between wind speed measured near the nacelle and freestream wind speed established for an isolated turbine. Simulation results were compared with experimental data (from a typical stall‐controlled, commercially available wind turbine rated higher than 600 kW). In general, good qualitative agreements have been found that validate the proposed method. It has been shown that a level of accuracy sufficient for use in power performance testing can be obtained only when a proper aerodynamic analysis of the inboard non‐lifting cylindrical sections of the blade is included. Furthermore, the numerical method has proven to be a useful tool for locating nacelle anemometers. Copyright © 2005 John Wiley & Sons, Ltd.
Molecular genetic study of introgression between Saccharomyces bayanus and S. cerevisiae
Authors: Naumova Elena S. , Naumov Gennadi I. , Masneuf‐Pomarède Isabelle , Aigle Michel , Dubourdieu Denis 
Published: October 2005

AbstractThe genomic constitution of different S. bayanus strains and natural interspecific Saccharomyces hybrids has been studied by genetic and molecular methods. Unlike S. bayanus var. uvarum, some S. bayanus var. bayanus strains (the type culture CBS 380, CBS 378, CBS 425, CBS 1548) harbour a number of S. cerevisiae subtelomeric sequences: Y′, pEL50, SUC, RTM and MAL. The two varieties, having 86–100% nDNA–nDNA reassociation, are partly genetically isolated from one another but completely isolated from S. cerevisiae. Genetic and molecular data support the maintaining of var. bayanus and var. uvarum strains in the species S. bayanus. Using Southern hybridization with species‐specific molecular markers, RFLP of the MET2 gene and flow cytometry analysis, we showed that the non‐S. cerevisiae parents are different in lager brewing yeasts and in wine hybrid strains. Our results suggest that S. pastorianus is a hybrid between S. cerevisiae and S. bayanus var. bayanus, while S. bayanus var. uvarum contributed to the formation of the wine hybrids S6U and CID1. According to the partial sequence of ACT1 gene and flow cytometry analysis, strain CID1 is a triple hybrid between S. cerevisiae, S. kudriavzevii and S. bayanus var. uvarum. Copyright © 2005 John Wiley & Sons, Ltd.
Enantioselective Catalysis. 157 [1] Carbohydrate‐Based, Water‐Soluble Ligands for the Stereoselective Hydrogenation of Folic Acid
Authors: Brunner Henri , Keck Christian 
Published: October 2005

AbstractThe new chiral ligands 11–30 were synthesized by combining aldehydes and ketones, able for coordination, with mono‐ and disaccharides via oxime ether bridges stable towards hydrolysis. Due to their OH groups they were water‐soluble (except 11 and 19), whereas their acetylated analogs dissolved in organic solvents. The new ligands were used in homogeneous and heterogenized catalysts for the stereoselective hydrogenation of folic acid 31, the formylated hydrogenation product 33 of which is the anticancer drug Leucovorine.
Reaktionen eines (N,N,O)Zn‐OH‐Komplexes mit Heterocumulen‐Derivaten
Authors: Tekeste Teame , Vahrenkamp Heinrich 
Published: October 2005

AbstractReactions of a (N,N,O)Zn‐OH Complex with Heterocumulene DerivativesThe zinc‐aqua complex of the (N,N,O) ligand bis(2‐picolyl)(2‐hydroxylato‐3,5‐di‐tert‐butyl‐benzyl)amine can be deprotonated in situ to the (N,N,O)Zn‐OH complex. The latter reacts in alcoholic solution with CS2 and RNCS (R = p‐nitrophenyl) under insertion to from the (N,N,O)Zn‐S‐CS‐OR and (N,N,O)Zn‐S‐C(NR)OR complexes. RNCO undergoes hydrolytic decomposition, leading to a carbonate‐bridged trinuclear complex. Thiocyanate replaces the hydroxide ligand. Urea and thiourea (L) are incorporated as the cationic (N,N,O)Zn‐L complexes. The relation of these reactions to the functioning of hydrolytic zinc enzymes is discussed.
Reactivity of Copper(I) Complexes with Tripodal Ligands towards O2: Structures of a Precursor [L3CuI(NCCH3)](BF4), L3 = Tris(3‐isopropyl‐4,5‐trimethylenepyrazolyl)methane and of its Oxidation Product [L3CuII(μ‐OH)2CuIIL3](BF4)2 with Strong Antiferromagnetic Spin‐Spin Coupling
Authors: Kaim Wolfgang , Titze Christoph , Schurr Thilo , Sieger Monika , Lawson Max , Jordanov Jeanne , Rojas Darío , García Ana M. , Manzur Jorge 
Published: October 2005

AbstractThe molecular structure of the highly oxygen‐sensitive complex [L3CuI(NCCH3)](BF4) (1) reveals approximately symmetrical coordination by the fac‐tridentate (tripodal) ligand L3 = tris(3‐isopropyl‐4,5‐trimethylenepyrazolyl)methane and a rather short CuI‐N(acetonitrile) distance of 1.865(5) Å. In CH2Cl2 at −78 °C the colourless compound reacts with O2 to yield a labile purple intermediate (λmax 517 nm) – presumably a peroxodicopper(II) complex – which decomposes at −30 °C. No such intermediate was observed on reaction of the CuI complex of bis(2‐pyridylmethyl)benzylamine with O2 at −80 °C. However, an EPR spectrum with g‖ = 2.17 and g⊥ = 2.03 without 63,65Cu hyperfine splitting was observed at low temperatures. Exposure of the precursor 1 to air under ambient conditions yields dinuclear [L3CuII(μ‐OH)2CuIIL3](BF4)2 (2) which exhibits an EPR detectable dissociation into monomers in CH2Cl2 solution. The structure of the hexakis(dichloromethane) solvate of 2 with Cu–Cu and Cu‐O distances of 3.055 and 1.94Å, respectively, is typical for dihydroxo‐bridged dicopper compounds with square‐pyramidal CuII configuration (τ = 0.03), adopting an anti arrangement. In agreement with the relatively wide Cu‐O‐Cu angles of 103.5° an analysis of the temperature dependence of the magnetic susceptibility revealed a rather strong (J = −633 cm−1) antiparallel spin‐spin coupling. The effect is ascribed to the steric bulk of the ligand L3.
Studien zur Synthese, Struktur und Reaktivität heterozyklischer Metallonitridophosphinate
Authors: Bauer Tillmann , Chatterjee Saurav , Schulz Stephan , Nieger Martin , Krossing Ingo 
Published: October 2005

AbstractStudies on the Synthesis, Structure and Reactivity of Heterocyclic Metallonitridophosphinatest‐BuP(NH2)2 reacts with base‐stabilized group 13 trihydrides with adduct formation (THF‐BH3), with reduction to give t‐BuPH2 (Me3N‐AlH3) and with elimination of H2 and formation of a metallonitridophosphinate (Me3N‐GaH3). In contrast, the reaction with Cp*TiMe3 proceeds with formation of the four‐membered heterocycle [t‐Bu(H)P(NH)2Ti(Cp*)Me2]. The aluminonitridophosphinate [t‐Bu(H)P(NH)2AlMe2]2 reacts with C‐H acidic reagents such as ROH, H2O with protonation of the N atom and subsequent formation of t‐BuP(NH2)2. This general reaction sequence was used for the synthesis of the first alumino(oxo)nitridophosphinate [t‐Bu(H)P(NH)OAlMe2]2. The compounds were characterized by spectroscopic methods (1H, 13C, IR, mass spectrometry) and single crystal X‐ray diffraction ([t‐Bu(H)P(NH)2Ti(Cp*)Me2], [t‐Bu(H)P(NH)OAlMe2]2).