bluuebunny/crossref_metadata_2025 huggingface dataset:
The times they are a‐changin' (Bob Dylan, 1964)
Authors: Bradley Deborah A. , Redman Bruce G.
Published: October 2007

New targeted therapies are available for the treatment of advanced kidney cancer. The knowledge gained with these agents has resulted in a change in the approach and design of clinical research for this disease.
Neoadjuvant therapy followed by prostatectomy for clinically localized prostate cancer
Authors: Sonpavde Guru , Chi Kim N. , Powles Thomas , Sweeney Christopher J. , Hahn Noah , Hutson Thomas E. , Galsky Matthew D. , Berry William R. , Kadmon Dov
Published: October 2007

The results of this assessment of the literature indicated that neoadjuvant therapy followed by prostatectomy may improve long‐term outcomes for patients with high‐risk localized disease. In addition, this approach provides a paradigm for evaluating the activity and mechanism of action of new agents as correlative studies are facilitated by the availability of tumor tissue before and after therapy. The authors determined that a multidisciplinary approach involving oncologists, urologists, and pathologists is critical to the success of this model. Recent and ongoing studies of neoadjuvant therapy followed by prostatectomy were reviewed. Cancer 2007. © 2007 American Cancer Society.
Molecular Dynamic Simulations of Ionic Liquids: A Reliable Description of Structure, Thermodynamics and Dynamics
Authors: Köddermann Thorsten , Paschek Dietmar , Ludwig Ralf
Published: October 2007

The parameterization of a new force‐field and its validation for the liquid description of five imidazolium‐based ionic liquids [Cnmim][NTf2] (n=1,2,4,6,8) are described. The proposed force‐field is derived to reproduce densities, self‐diffusion coefficients for cations and ions as well as NMR rotational correlation times for cations and water molecules in [C2mim][NTf2]. The temperature dependence and the cation chain‐length dependence of these properties is described well. Very good agreement between simulated and experimental values for the heats of vaporization, shear viscosities and NMR rotational correlation times is also achieved. All properties are crucial for understanding the nature and interaction of ionic liquids. The good performance of the new force‐field suggests that the Lennard–Jones interactions previously were strongly overestimated. The given force‐field now allows us to investigate other important properties of this class of ionic liquids such as the micro segregation of ionic liquids, ion pair formation, lifetimes of ion pairs and the solvent dependency of these properties.
Context‐specific calls signal infants' needs in a strepsirrhine primate, the gray mouse lemur (Microcebus murinus)
Authors: Scheumann Marina , Zimmermann Elke , Deichsel Guntram
Published: October 2007

The presence of context‐specific communication sounds, structurally different call types related to particular situations and potentially expressing distinct emotions of the caller, were not systematically studied in infants of strepsirrhine primates. We exposed suckling's of gray mouse lemurs (Microcebus murinus) in an infant separation paradigm to three distinct contexts (isolation, threat‐induced, grooming). An audio–videographic analysis of sound‐correlated infant behaviors and a simultaneous multiparametric sound analysis revealed context‐specific calls. Peak frequency predicted their acoustic classification best. Findings provided first evidence for a strepsirrhine primate that infant communication sounds may express distinct contexts and thereby infant's need reliably. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 708–718, 2007.
Preobesity in the infant OLETF rat: The role of suckling
Authors: Schroeder Mariana , Lavi‐Avnon Yael , Zagoory‐Sharon Orna , Weller Aron , Moran Timothy H.
Published: October 2007

The Otsuka Long Evans Tokushima Fatty (OLETF) rat model of obesity, which lacks CCK1 receptors, has been extensively investigated over the last decade. We have recently focused on the early developmental stages of this strain, finding that OLETF pups are heavier than controls from birth and hyperphagic already from postnatal (PN) Day 2. OLETF mothers present differential maternal behavior patterns and increased nursing time and frequency, which might contribute to the preobese characteristics of the pups. The present investigation examined the pups' ability to gain weight from the nursing episodes. First, we measured the pups' weight gain from one nursing bout from their own dam. Next we examined the pups' weight gain after a feeding competition test with control pups from foster dams of both strains. OLETF pups gained more weight than controls from their own dams on PN Week 1 due to a higher suckling rate (and/or efficacy) and on PN Week 3 due to increased nursing time. When competing with control pups, OLETF pups gained significantly more weight after the same nursing bout, regardless of the strain of the mother. Body mass index (BMI) was significantly higher in OLETF pups compared to controls. The maternal parameters assessed from the experiment were latencies to pup retrieval and to nursing, and nursing duration; differences were only observed in nursing time. OLETF dams increased their average nursing time over the PN weeks, while control dams decreased their nursing time toward weaning. The results suggest an important contribution of OLETF pups toward their own preobese development. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 685–691, 2007.
Advantages of mixed effects models over traditional ANOVA models in developmental studies: A worked example in a mouse model of fetal alcohol syndrome
Authors: Wainwright Patricia E. , Leatherdale Scott T. , Dubin Joel A.
Published: October 2007

Developmental studies in animals often violate the assumption of statistical independence of observations due to the hierarchical nature of the data (i.e., pups cluster by litter, correlation of individual observations over time). Mixed effect modeling (MEM) provides a robust analytical approach for addressing problems associated with hierarchical data. This article compares the application of MEM to traditional ANOVA models within the context of a developmental study of prenatal ethanol exposure in mice. The results of the MEM analyses supported the ANOVA results in showing that a large proportion of the variability in both behavioral score and brain weight could be explained by ethanol. The MEM also identified that there were significant interactions between ethanol and litter size in relation to behavioral scores and brain weight. In addition, the longitudinal modeling approach using linear MEM allowed us to model for flexible weight gain over time, as well as to provide precise estimates of these effects, which would be difficult in repeated measures ANOVA. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 664–674, 2007.
Individual differences in salivary cortisol and alpha‐amylase in mothers and their infants: Relation to tobacco smoke exposure
Authors: Granger Douglas A. , Blair Clancy , Willoughby Michael , Kivlighan Katie T. , Hibel Leah C. , Fortunato Christine K. , Wiegand Lauren E.
Published: October 2007

Tobacco smoke exposure affects the activity of both the hypothalamic–pituitary–adrenal (HPA) axis and the sympathetic nervous system (SNS). Statistics reveal 41 million children in the U.S. are regularly exposed to tobacco smoke, but we know little about the effects of environmental tobacco smoke exposure on HPA and SNS activity in early childhood. This study assayed cotinine (a metabolite of nicotine), cortisol, and alpha‐amylase (sAA) in the saliva of mother–infant dyads from 197 low income and ethnically diverse families. The dyads were identified as tobacco smoke exposed (N = 82) or nonexposed (N = 115) based on maternal self‐reports of smoking and salivary cotinine levels greater or less than 10 ng/ml. As expected, higher rates of maternal smoking behavior were associated with higher levels of cotinine in mothers' and their infants' saliva. On average, smoking mothers' salivary cotinine levels were 281 times higher compared to their nonsmoking counterparts, and 23 times higher compared to their own infant's salivary cotinine levels. Infants of smoking mothers had salivary cotinine levels that were four times higher than infants with nonsmoking mothers. Mothers who smoked had higher salivary cortisol levels and lower sAA activity compared to nonsmoking mothers. There were no associations between maternal smoking behavior, infant's salivary cotinine levels, or tobacco exposure group, and cortisol or sAA measured in infant's saliva. The findings are discussed in relation to the influence of smoking tobacco on the validity of salivary biomarkers of stress. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 692–701, 2007.
Targeting reverse tetracycline‐dependent transactivator to murine mammary epithelial cells that express the progesterone receptor
Authors: Mukherjee Atish , Soyal Selma M. , Fernandez‐Valdivia Rodrigo , DeMayo Francesco J. , Lydon John P.
Published: October 2007

Through an established gene‐targeting strategy, reverse tetracycline‐dependent transactivator (rtTA) was targeted downstream of the murine progesterone receptor (PR) promoter. Mice were generated in which one (PR+/rtTA) or both (PRrtTA/rtTA) PR alleles harbor the rtTA insertion. The PR+/rtTA and PRrtTA/rtTA knockins exhibit phenotypes identical to the normal and the progesterone receptor knockout mouse, respectively. Crossed with the TZA reporter, which carries the TetO‐LacZ responder transgene, the PR+/rtTA/TZA and PRrtTA/rtTA/TZA bigenics exhibit doxycycline‐induced β‐galactosidase activity specifically in progesterone responsive target tissues such as the mammary gland, uterus, ovary, and pituitary gland. In the case of the PR+/rtTA/TZA mammary epithelium, dual immunofluorescence demonstrated that PR expression and doxycycline‐induced β‐galactosidase activity colocalized; β‐galactosidase was not detected in the absence of doxycycline. Although both the PR+/rtTA and PRrtTA/rtTA knockins represent innovative animal models with which to further query progesterone's mechanism of action in vivo, the PRrtTA/rtTA mouse in particular promises to provide unique insight into the paracrine mechanism of action, which underpins progesterone's involvement in mammary morphogenesis with obvious implications for extending our understanding of this steroid's role in breast cancer progression. genesis 45:639–646, 2007. © 2007 Wiley‐Liss, Inc.
Viral 2A peptides allow expression of multiple proteins from a single ORF in transgenic zebrafish embryos
Authors: Provost Elayne , Rhee Jerry , Leach Steven D.
Published: October 2007

We have adapted a novel multicistronic gene expression system involving viral peptides to the zebrafish. The viral 2A peptide allows production of multiple protein products from a single transgene. Based on highly inefficient peptide bond formation between glycine and proline residues within the 2A peptide, placement of 2A peptide sequence as a linker region between tandem cDNA's allows the stoichiometric translation of multiple unfused protein products. To test this system in zebrafish, we generated two different tandem reporter constructs employing eGFP and mCherry, separated by 2A peptide sequence. Using this system, we produced transgenic zebrafish in which fluorophores were produced as independent proteins from a single transcript. The successful application of this technology in zebrafish will be valuable for visually marking transgenic embryos and transgene‐expressing cells, or in any situation where reliable expression of multiple transgenes is desired. genesis 45:625–629, 2007. © 2007 Wiley‐Liss, Inc.
Generation of conditional knockout alleles for PDGF‐C
Authors: Wu Xiaoli , Ding Hao
Published: October 2007

PDGF‐C is a newly identified member of the platelet‐derived growth factor (PDGF) family, which is involved in multiple cellular functions by signaling through PDGF receptor (PDGFR)‐αα and αβ dimers. PDGF‐C deficiency is perinatal lethal due to the formation of cleft palate. To further characterize the cellular function of PDGF‐C during both embryonic and postnatal development, we have generated two conditional alleles of the Pdgf‐c gene in which two loxP sites flank exon 5. Global Cre‐mediated excision of the floxed exon 5 in these alleles resulted in a complete loss of PDGF‐C expression and caused embryonic defects identical to those previously described for the PDGF‐C null embryos. These conditional alleles will therefore be the important genetic tools for dissecting the spatial and temporal roles of PDGF‐C during development and in adult tissues. Furthermore, from this work, we have also described a simple approach for creating mouse conditional alleles in an efficient manner. genesis 45:653–657, 2007. © 2007 Wiley‐Liss, Inc.
Application feasibility of permittivity graded FGM (functionally graded materials) for gas‐insulated equipment
Authors: Shumiya Hideki , Kato Katsumi , Okubo Hitoshi
Published: October 2007

For the size reduction of electric power equipment, the electric field stress around solid insulators is to be carefully designed. This concern will be solved by the application of FGM (Functionally Graded Materials). In this paper, we investigated an application feasibility of FGM from numerical simulation, and the fabrication technique for gas insulated equipment. Finally, we could confirm the significant effect of FGM application for gas insulated equipment. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(2): 39–45, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20363
On properties of circuit for circuit evaluation as a parallelization procedure
Authors: Seino Katsuhiro , Tanaka Ken
Published: October 2007

It is shown here that if NC = P, the NC hierarchy collapses. We give two proofs for this. From the point of view of a circuit for circuit evaluation, the assumption that NC = P implies that any polynomial size circuit can be transduced into a polynomial size and poly‐log depth circuit. Such a parallelization property can be applied not only for uniform circuits but also for nonuniform circuits. This interesting property suggests that the assumption NC = P would be false. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(2): 46–50, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20488
Development of high‐efficiency switched reluctance motor
Authors: Suzuki Takanori , Ito Shinya , Tanaka Naoki , Chiba Akira , Fukao Tadashi , Ninomiya Hironori
Published: October 2007

In this paper, several techniques of the efficiency improvement of SRM drives are described. One of these improvements is the optimization of applied voltage waveform. Drive efficiency is further increased by application of new low‐iron‐loss materials such as Super E‐Core brand steel strip. Another step of the efficiency improvement consists in optimization of components incurring iron and copper losses by using computer program PC‐SRD. As a result, the highest efficiency level achieved in the study was 94.3%. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(2): 73–82, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20523
Remote sensing system for spatial electric field strength using free space light transmission
Authors: Sakai Toshiro , Tanaka Yasuhiro , Fukao Tadashi , Takada Tatsuo , Maeno Takashi
Published: October 2007

Most of the breakdowns in an electric power system are caused by lightning to the tower used for high‐voltage transmission wires. To avoid accidents due to lightning, it would be desirable to develop a measurement system for the spatial electric field distribution around the tower. We have developed a new system that can measure the electric field around the steel tower for electric power transmission by using an optical electric sensor. In conventional methods, the sensor is generally illuminated by light transmitted by optical fibers. On the other hand, the new measurement system illuminates the Pockels sensor directly by using a laser to measure the far electric field. Furthermore, our newly proposed feedback system makes it possible to measure the spatial electric field without concern for the change of Pockels sensor's operation point influenced by temperature change. This system is applicable as a remote sensing system to monitor the spatial electric field around a high‐voltage transmission line. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(2): 10–19, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20552
Efficient Increase of DNA Cleavage Activity of a Diiron(III) Complex by a Conjugating Acridine Group
Authors: Chen Xiao‐Qiang , Peng Xiao‐Jun , Wang Jing‐Yun , Wang Yan , Wu Song , Zhang Li‐Zhu , Wu Tong , Wu Yun‐Kou
Published: October 2007

A new diferric complex, Fe2Lb, in which a DNA intercalator (acridine) is linked to a precursor diferric complex (Fe2La), has been designed and synthesised as a hydrolytic cleaving agent of DNA. Compared with Fe2La (without the DNA intercalator) (La: 2,6‐bis{[(2‐hydroxybenzyl)(pyridin‐2‐yl)methylamino]methyl}‐4‐methylphenol), Fe2Lb [Lb: 5‐(acridin‐9‐yl)‐N‐(3,5‐bis{[(2‐hydroxybenzyl)(pyridin‐2‐yl)methylamino]methyl}‐4‐hydroxybenzyl)pentanamide] leads to a 14‐fold increase in the cleavage efficiency of plasmid DNA due to the binding interaction between DNA and the acridine moiety. The interaction has been demonstrated by UV/Vis absorption, CD spectroscopy, viscidity experiments and thermal denaturation studies. The hydrolytic mechanism is supported by evidence from T4 DNA ligase assay, reactive oxygen species (ROS) quenching and BNPP [bis(4‐nitrophenyl) phosphate, a DNA model] cleavage experiments. The pH dependence of the BNPP cleavage by Fe2La in aqueous buffer media shows a bell‐shaped pH–kobs profile with an optimum point around a pH of 7.0 which is in good agreement with the maximum point of the pH‐dependent relative concentration curve of active species from the pH titration experiments. The determination of the initial rates at a pH of 7.36 as a function of substrate concentration reveals saturation kinetics with Michaelis–Menten‐like behaviour and Fe2La shows a rate acceleration increase of 4.7 × 106 times in the hydrolysis of BNPP. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis, Characterization and X‐ray Structures of [α‐Diphenylethanedione bis(4‐ethylthiosemicarbazonato)]palladium(II) and 1,2,4‐Triazine‐3‐thione–Zinc(II) Complexes Obtained by Metal‐Induced Cyclization
Authors: Matesanz Ana I. , Pastor Cesar , Souza Pilar
Published: October 2007

The new cyclic 5‐ethoxy‐4‐ethyl‐5,6‐diphenyl‐4,5‐dihydro‐2H‐[1,2,4]‐triazine‐3‐thione ligand (HTa3T‐Et) has been obtained by an intramolecular cyclization reaction of α‐diphenylethanedione bis(4‐ethylthiosemicarbazone) (H2BbTSC‐Et). The cyclization may be promoted either by hydroxylic solvents or by ZnII ions. Thus, the reaction of H2BbTSC‐Et with ZnCl2 led to the formation of [Zn(HTa3T‐Et)2Cl2] containing not the ligand H2BbTSC‐Et but the cyclic HTa3T‐Et ligand that forms during the reaction. On the other hand, crystallization of H2BbTSC‐Et from DMSO/EtOH produces a cocrystal containing the open‐chain H2BbTSC‐Et ligand together with the cyclic HTa3T‐Et molecules, which are linked to a DMSO molecule by hydrogen bonds. However, reaction of the cocrystal with PdII ions yields a planar tetracoordinate complex in which only the H2BbTSC‐Et ligand, in the deprotonated form, is present. The preparation and molecular structures of these compounds are discussed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Homo‐ and Heterometallic Coordination Oligomers and Polymers Derived from the Preformed Complexes [Cu(bdmpp)(MeCN)2](ClO4)2, [Cu(bdmpp)(N3)2], and [Cu(bdmpp)(N3)(μ‐N3)]2 [bdmpp = 2,6‐bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)pyridine]: Syntheses, Structures, and Redox Properties
Authors: Liu Guang‐Fei , Ren Zhi‐Gang , Li Hong‐Xi , Chen Yang , Li Qiu‐Hong , Zhang Yong , Lang Jian‐Ping
Published: October 2007

Reactions of three CuII complexes of 2,6‐bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)pyridine (bdmpp), [Cu(bdmpp)(MeCN)2](ClO4)2 (1), [Cu(bdmpp)(N3)2]·1.5H2O (2·1.5H2O), and [Cu(bdmpp)(N3)(μ‐N3)]2·2MeOH (3·2MeOH), with 4,4′‐bipy, dicyanamide (dca), azide, and MCl2 (M = Cu, Co, Ni) yield a series of homo‐ and heterometallic coordination oligomers and polymers, [{Cu(bdmpp)(ClO4)}2(μ‐4,4′‐bipy)](ClO4)2 (4), {[Cu(bdmpp)(μ‐dca)](ClO4)}n (5), {[Cu(bdmpp)(μ‐N3)](ClO4)·MeCN}n (6), [{Cu(N3)(bdmpp)}2(μ‐N3)2Cu(N3)2] (7), and [{Cu(μ‐N3)(bdmpp)(μ‐N3)M(μ‐N3)(X)}2·eMeCN]n (8: M = Co, X = N3, e = 0; 9: M = Ni, X = Cl; e = 4). Compounds 1–9 have been characterized by elemental analysis, IR spectroscopy, and single‐crystal X‐ray crystallography. Compound 4 has a centrosymmetric dimeric dication structure in which two [Cu(bdmpp)(ClO4)]+ fragments are bridged by one 4,4′‐bipy. Compounds 5 and 6 have a 1D linear or spiral chain extending along the b axis in which each [Cu(bdmpp)]2+ fragment is linked through bridging dca or azide anions, respectively. Compound 7 has a trinuclear sandwich structure in which two molecules of 2 link a Cu(N3)2 species through two end‐on bridging azide anions. Compounds 8 and 9 have a similar 1D chain structure extending along the c axis in which [Cu(μ‐N3)(bdmpp)(μ‐N3)M(μ‐N3)(X)]2 (M = Co, Ni) molecules are linked by end‐to‐end azide anions (8) or end‐on azide anions (9). In addition, the electrochemical properties of 1–9 in DMF were investigated by cyclic voltammetry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis, Reactivity, X‐ray Crystal Structures and Electrochemical Behaviour of Water‐Soluble [Tris(pyrazolyl)borato]ruthenium(II) Complexes of 1,3,5‐Triaza‐7‐phosphaadamantane (PTA)
Authors: Bolaño Sandra , Bravo Jorge , Castro Jesus , Mar Rodríguez‐Rocha M. , Guedes da Silva M. Fátima C. , Pombeiro Armando J. L. , Gonsalvi Luca , Peruzzini Maurizio
Published: October 2007

A series of chloridoruthenium(II) complexes bearing the tripodal ligand tris(pyrazolyl)borate (Tp), the water‐soluble cage phosphane 1,3,5‐triaza‐7‐phosphaadamantane (PTA) and its N‐boranyl adduct PTA(BH3), together with PPh3, have been synthesised. The corresponding monohydrido complexes have also been obtained by treating the chlorides withNaOMe. The X‐ray crystal structures of [TpRuCl(PTA)(PPh3)] (2) and [TpRuCl(PTA)2] (3) are also described. Cyclic voltammetry (CV) studies in MeCN and dmso generally show reversible RuII/III oxidation waves and the values of E1/2ox reflect the electron‐donating character of the ligands [Tp (each arm) > PTA > PTA(BH3)], whose Lever electrochemical parameter (EL) has been estimated for the first time.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Direct Synthesis of Zr‐Containing Hybrid Periodic Mesoporous Organosilicas with Tunable Zirconium Content
Authors: Zhai Shang‐Ru , Park Sung Soo , Park Mina , Ullah M. Habib , Ha Chang‐Sik
Published: October 2007

Highly ordered Zr‐containing periodic mesoporous organosilicas (ZrPMO) with different Zr/Si ratios were successfully synthesized, for the first time, by employing a ZrOCl2/NaCl combination as the promoting agent and by simply adjusting the molar ratio of the zirconium species to the organosilica precursor; no addition of mineral acids was necessary. The effect of preparation parameters on the structural and textural properties were carefully investigated by using different ratios of NaCl/Si and Zr/Si. It was found that both salts are essential for this system and highly ordered ZrPMOs can be prepared within fairly wide Si/Zr ratios (5–100) while keeping the NaCl/Si ratio constant. To prove the effectiveness of this synthetic pathway with a higher Zr incorporation, ZrPMO materials were also synthesized under strongly acidic conditions for the purpose of comparison. The synthesized ZrPMO materials were thoroughly characterized by ICP‐AES, SAXS, N2 sorption, TEM, SEM, 13C CP/29Si MAS NMR spectroscopy, XPS, and TGA. Elemental analyses show that the amount of Zr incorporated into ZrPMO, which was synthesized under mild conditions, is greater than that obtained in a strongly acidic environment, and the Zr content, with a Si/Zr ratio up to 12, is close to that in the initial gel composition. A plausible assembly mechanism based on the synergistic effect of both “nonhydrolyzable” (NaCl) and “hydrolyzable” (ZrOCl2) inorganic salts was discussed in detail, where the “salting out” effect and self‐generated acidity from both inorganic salts, respectively, are believed to be key factors for the formation of ordered SBA‐15‐type ZrPMO materials under the synthetic conditions.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Ring‐Slipped (2,2′‐Bipyridine)(η3‐cyclopentadienyl)(η5‐cyclopentadienyl)vanadium(II) and Its Oxidation to (2,2′‐Bipyridine)bis(η5‐cyclopentadienyl)vanadium(III) Tetraphenylborate
Authors: Jordan Markus , Saak Wolfgang , Haase Detlev , Beckhaus Rüdiger
Published: October 2007

Reaction of vanadocene(II) (4) with 2,2′‐bipyridine (5) leads to (2,2′‐bipyridine)vanadocene(II) (6), exhibiting a η3,η5‐metallocene unit, proved by X‐ray diffraction. By selective one‐electron oxidation employing [Cp2Fe]BPh4 salts, the cationic (2,2′‐bipyridine)vanadocene(III) derivative 7 is formed. It is characterized by a classical bent bis(η5‐cyclopentadienyl)vanadium(III) structure. Characteristic structural details comparing changes in the oxidation states are discussed. The ring‐slip parameters are compared to those of tungsten and other vanadium complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Optimization of the Conditions for Copper‐Mediated N‐Arylation of Heteroarylamines
Authors: Liu Yifeng , Bai Yajun , Zhang Juan , Li Yangyang , Jiao Junping , Qi Xiaoli
Published: October 2007

Simple and inexpensive copper‐mediated N‐arylation ofheteroarylamines was achieved by using N,N′‐dimethylethylenediamine as a ligand and K2CO3 as a base in dioxane heated at 100 °C. In this coupling reaction, the influence of the copper species, ligand, base and solvent was investigated in detail. N‐Arylated derivatives of several heteroarylamines were synthesized under optimized reaction conditions, and all the products were isolated in good yields. By controlling the amount of CuI/DMEDA added, heteroarylamines with weak nucleophilic activity were coupled with aryl iodides or aryl bromides. The activity of the copper catalyst for this C–N bond‐forming reaction follows the order CuI > Cu0 > CuII. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Asymmetric Diels–Alder Reaction of Aminodienes with a Nonracemic Acrylate Bound to Rink Resin: A Comparison of These Reactions with Their Solution‐State Analogues
Authors: Songis Olivier , Géant Pierre Yves , Sautrey Guillaume , Martinez Jean , Calmès Monique
Published: October 2007

The asymmetric Diels–Alder reactions between (3R)‐4,4‐dimethyl‐2‐oxopyrrolidin‐3‐yl acrylate derivatives and three N‐Z‐protected 1‐aminodienes have been investigated both in solution and on a solid support. Comparable results for each reaction were observed with the formation of the corresponding constrained cyclic β‐amino acids in high yield and moderate‐to‐good selectivity when using optimized conditions. A detailed comparison of both solution and solid‐support synthesis by conventional heating and microwave activation revealed that the microwave technique is often advantageous. We have also demonstrated that reaction on a solid support offered an excellent resolution of the problem of low reactivity and instability of the reagents.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Mild Electrochemical Deprotection of N‐Phenylsulfonyl N‐Substituted Amines Derived from (R)‐Phenylglycinol
Authors: Coeffard Vincent , Thobie‐Gautier Christine , Beaudet Isabelle , Le Grognec Erwan , Quintard Jean‐Paul
Published: October 2007

The electrochemical reduction of N‐phenylsulfonyl N‐substituted amines in a protic medium under constant cathodic potential was found to be a mild desulfonylation method, which is able to challenge the chemical ones. The influence of the nature of the N‐substituents was considered in order to clarify the mechanistic aspects and to evaluate the scope of the method.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Thermochromism at Room Temperature in Overcrowded Bistricyclic Aromatic Enes: Closely Populated Twisted and Folded Conformations (Eur. J. Org. Chem. 31/2007)
Authors: Levy Amalia , Pogodin Sergey , Cohen Shmuel , Agranat Israel
Published: October 2007

The cover picture shows the phenomenon of thermochromism, i.e. a reversible, temperature‐dependent change in color in polycyclic aromatic enes (PAEs). The yellow room‐temperature folded conformations represented by the central structure exist in unimolecular equilibria with the deep‐colored twisted conformations: bianthrone, green; 1,8‐diazafluorenylideneanthrone, red; fluorenylideneanthrone, purple; benzo[b]fluorenylideneanthrone, blue. The PAEs under study exhibit thermochromic behavior at room temperature, having readily populated twisted conformations. The twisted and folded conformations interconvert rapidly. Details are discussed in the article by I. Agranat et al. on p. 5198 ff. The authors thank Dr. P. U. Biedermann (Max‐Planck‐Institut f?r Eisenforschung) for enlightening advice and suggestions.
Application of Multivariate curve resolution‐alternating least square methods on the resolution of overlapping CE peaks from different separation conditions
Authors: Zhang Fang , Chen Yan , Li Hua
Published: October 2007

Discussed in this paper is the development of a new strategy to improve resolution of overlapping CE peaks by using second‐order multivariate curve resolution with alternating least square (second‐order MCR‐ALS) methods. Several kinds of organic reagents are added, respectively, in buffers and sets of overlapping peaks with different separations are obtained. Augmented matrix is formed by the corresponding matrices of the overlapping peaks and is then analyzed by the second‐order MCR‐ALS method in order to use all data information to improve the precision of the resolution. Similarity between the resolved unit spectrum and the true one is used to assess the quality of the solutions provided by the above method. 3,4‐Dihydropyrimidin‐2‐one derivatives (DHPOs) are used as model components and mixed artificially in order to obtain overlapping peaks. Three different impurity levels, 100, 20, and 10% relative to the main component, are used. With this strategy, the concentration profiles and spectra of impurities, which are no more than 10% of the main component, can be resolved from the overlapping peaks without pure standards participant in the analysis. The effects of the changes in the components spectra in the buffer with different organic reagents on the resolution are also evaluated, which are slight and can thus be ignored in the analysis. Individual data matrices (two‐way data) are also analyzed by using MCR‐ALS and heuristic evolving latent projections (HELP) methods and their results are compared with those when MCR‐ALS is applied to augmented data matrix (three‐way data) analysis.
Optimization of the separation of ionizable compounds in micellar electrokinetic chromatography by simultaneous change of pH and SDS concentration
Authors: Téllez Adolfo , Fuguet Elisabet , Rosés Martí
Published: October 2007

A method to optimize the separation in micellar EKC (MEKC) of mixtures of acidic compounds as a function of two parameters, pH and concentration of sodium dodecyl sulfate, has been developed. The method considers the prediction of the retention time and the shape of the peaks. The retention time is predicted from the retention factor model and the peak shape by a polynomically modified Gaussian function that considers peak width, asymmetry factor, and height. An algorithm to calculate the global resolution of the separation at any experimental pH and [SDS] has been applied. This algorithm provides a 3‐D resolution map to easily detect the areas in which resolution for the separation of the compounds is maximum. Initial experiments to fit the models have been performed with a set of ten phenolic compounds with different hydrophobicities and pKa values, and therefore, expected to behave in a different way with changes of pH and surfactant concentration. The experiments encompassed a pH range from 6.7 to 11.1, and a sodium dodecyl sulfate concentration range from 40 to 80 mM. Through the proposed methodology, chromatograms have been simulated at different pH and [SDS] very accurately. Furthermore, the resolution at any experimental point within the studied ranges have been also calculated, giving an optimum resolution value at pH 6.7 and [SDS] = 72 mM.
Comparison of resolution in microemulsion EKC and MEKC employing suppressed electroosmosis: Application to bisphenol‐A‐diglycidyl ether and its derivatives
Authors: Poouthree Kieatsuda , Soonthorntantikul Wasura , Leepipatpiboon Natchanun , Petsom Amorn , Nhujak Thumnoon
Published: October 2007

The resolution (Rs) of hydrophobic analytes in microemulsion EKC (MEEKC) and MEKC with suppressed electroosmosis was investigated using bisphenol‐A‐diglycidyl ether and its derivatives (BADGEs) as test analytes. Separation scales were compared using our equation for the resolution, $\displaystyle {\tf="PS_SLFIT"R}_{{s}} {{ = }}(\sqrt {\bar {\tf="PS_SLFIT"N}} /4)(\alpha - 1)/(1 + {\tf="PS_SLFIT"k}_2 )$, where k is the retention factor, α the selectivity (α = k2/k1 for k2 ≥ k1>0), and $\displaystyle \bar {\tf="PS_SLFIT"N}$ the average efficiency. At given concentrations of SDS and organic cosolvent in the buffer, in comparison with MEKC, MEEKC was found to provide better resolution of BADGEs, mainly due to the significantly smaller k in MEEKC, but not the greater α in MEEKC, while a comparable range of $\displaystyle \bar {\tf="PS_SLFIT"N}$. Significantly improved resolution of BADGEs was obtained with increase in the concentration of organic cosolvent in the MEEKC and MEKC buffers, while small change in Rs with the SDS concentration in a range of 100–180 mM. In addition, a decrease in temperature or voltage resulted in slightly better Rs.
Determination of the microenvironment‐pH and charge and size characteristics of amino acids through their electrophoretic mobilities determined by CZE
Authors: Piaggio Maria V. , Peirotti Marta B. , Deiber Julio A.
Published: October 2007

Effective electrophoretic mobility data of 20 amino acids reported in the literature are analyzed and interpreted through simple physicochemical models, which are able to provide estimates of coupled quantities like hydrodynamic shape factor, equivalent hydrodynamic radius (size), net charge, actual pK values of ionizing groups, partial charges of ionizing groups, hydration number, and pH near molecule (microenvironment‐pH of the BGE). It is concluded that the modeling of the electrophoretic mobility of these analytes requires a careful consideration of hydrodynamic shape coupled to hydration. In the low range of pH studied here, distinctive hydrodynamic behaviors of amino acids are found. For instance, amino acids with basic polar and ionizing side chain remain with prolate shape for pH values varying from 1.99 to 3.2. It is evident that as the pH increases from low values, amino acids get higher hydrations as a consequence each analyte total charge also increases. This result is consistent with the monotonic increase of the hydrodynamic radius, which accounts for both the analyte and the quite immobilized water molecules defining the electrophoretic kinematical unit. It is also found that the actual or effective pK value of the α‐carboxylic ionizing group of amino acids increases when the pH is changed from 1.99 to 3.2. Several limitations concerning the simple modeling of the electrophoretic mobility of amino acids are presented for further research.
Temperature effects on the enantioselectivity of basic analytes in capillary EKC using sulfated β‐CDs as chiral selectors
Authors: Peng Zhen‐Lei , Yi Fei , Guo Baoyuan , Lin Jin‐Ming
Published: October 2007

The thermodynamic processes were investigated to reveal the temperature effects during chiral separation by capillary EKC with reversed polarity mode using sulfated β‐CD (S‐β‐CD) as chiral selectors. The temperature effects on enantioselectivities of basic analytes (ephedrine, norephedrine, synephrine, and epinephrine) were investigated in detail over a temperature range of 20–60°C. An increase of the capillary temperature produced the decrease of enantioselectivities for ephedrine and norephedrine, but increase of enantioselectivities for synephrine and epinephrine. The thermodynamic variations showed that the interactions between the basic analytes and chiral selectors were always enthalpy‐ driven. However, the difference in enthalpy and entropy showed that the enantioseparation was an enthalpy‐driven process for ephedrine and norephedrine, but an entropydriven process for synephrine and epinephrine. Just because of the different driving forces, there exist two kinds of temperature effects on enantioselectivities mentioned above.
Detection of microbial food contaminants and their products by capillary electromigration techniques
Authors: García‐Cañas Virginia , Cifuentes Alejandro
Published: October 2007

This work reviews the different analytical strategies based on capillary electromigration techniques developed for detecting microbial contaminants and their products in food matrices. Namely, this work presents an exhaustive and critical review, including works published till March 2007, on CE methods developed to detect and identify contaminants of microbial origin that represent a hazard to humans in foods. First, an overview on the strategies adopted for the analysis of intact microorganisms is presented. Next, CE methodologies based on the analysis of microbial constituents, including those based on genomics and proteomics approaches, are described. Finally, CE methods developed for detecting microbial toxins are discussed.
Rapid sample screening method for authenticity controlling vanilla flavors using a CE microchip approach with electrochemical detection
Authors: Ávila Mónica , González María Cristina , Zougagh Mohammed , Escarpa Alberto , Ríos Ángel
Published: October 2007

Five vanilla‐related flavors of food significance, vanillic alcohol (VOH), ethyl maltol (EMA), maltol (MAL), ethyl vanillin (EVA) and vanillin (VAN), were separated using CE microchips with electrochemical detection (CE‐ED microchips). A +2 kV driving voltage for both injection and separation operation steps, using a borate buffer (pH 9.5, 20 mM) and 1 M nitric acid in the detection reservoir allowed the selective and sensitive detection of the target analytes in less than 200 s with reproducible control of EOF (RSDmigration times<3%). The analysis in selected real vanilla samples was focusing on VAN and EVA because VAN is a basic fragrance compound of the vanilla aroma, whereas EVA is an unequivocal proof of adulteration of vanilla flavors. Fast detection of all relevant flavors (200 s) with an acceptable resolution (Rs >1.5) and a high accuracy (recoveries higher than 90%) were obtained with independence of the matrices and samples examined. These results showed the reliability of the method and the potential use of CE microchips in the food control field for fraudulent purposes.
Determination of synthetic polypeptide conformations and molecular geometrical parameters by nonaqueous CE
Authors: Plasson Raphaël , Vayaboury Willy , Giani Olivia , Cottet Hervé
Published: October 2007

The aim of this work was to study changes in homopolypeptide chain conformation as a function of the number of residues by the modeling of the electrophoretic mobility. For this purpose, the frictional coefficients of poly(Nϵ‐trifluoroacetyl‐L‐lysine) with different number of residues (up to 11) were determined from the absolute ionic mobilities and modeled by the hydrodynamic frictional coefficient of an equivalent cylinder. This approach allowed determination of geometrical parameters of the polypeptide chain in a liquid phase (nonaqueous solution of the BGE). The fact that the BGE and analyte are dissolved in mixed (methanol–ACN) organic solvent implied to take into account different effects and corrections that are generally not considered in aqueous solvent: namely, the effect of ion‐pairs between constituents of the BGE for the calculation of the ionic strength, the effect of ion‐pairs between the solutes and the electrolyte counterions and the correction due to the dielectric friction (Hubbard‐Onsager equations). In addition, the influence of the ionic strength on the electrophoretic mobility was corrected using the Pitts equation, and the effect of lateral charges due to a slight deprotonation of the –NH– group in the lateral chain was also considered. From this modeling, molecular geometrical parameters relative to the linear and helicoïdal conformations were obtained with very good correlation coefficients. Interestingly, this work also points out that the use of ionic mobility modeling for extracting molecular geometrical parameters can also be applied to end‐charged polypeptides with slightly charged lateral chains (3% of elementary charge per residue).
Transform methods for frequency‐dependent complex stiffness to time domain using real or imaginary data only
Authors: Nakamura Naohiro
Published: October 2007

The author has studied the transform method of complex stiffness, which is strongly dependent on frequency, to the time domain. In this paper, new transform methods that use only the real part or the imaginary part data are proposed. By applying them to example problems, it is confirmed that the accuracy of the proposed methods is almost high in both causal and noncausal cases. These methods can also be thought as a standby for the Hilbert transform, because the undefined part is easily calculated by the recovering complex function from the obtained impulse response. Copyright © 2007 John Wiley & Sons, Ltd.
A genetic algorithm multi‐objective approach for efficient operational planning technique of distribution systems
Authors: Lakshminarayana C. , Mohan M. R.
Published: October 2007

This paper presents a genetic algorithm multi‐objective approach for efficient operational planning technique for electrical power distribution systems (EPDS). Service restoration is a non‐linear, combinatorial, non‐differential and multi‐objective optimization problem that often has a great number of candidate solutions to be evaluated by the operators. To tackle the problem of service restoration with multiple objectives, the weighted sum strategy is employed to convert these objectives into a single objective function by giving equal weighting values. The transformer/feeders capacity in the post‐fault distribution network creates a major problem for the electrical power distribution engineers and distribution system substation operators to satisfy the operational constraints at the consumer localities while restoring power supply. The feasibility of the developed algorithm for service restoration demonstrated on several distribution networks with fast and effective convergence of the results of this technique helps to find the efficient operational planning of the EPDS. Copyright © 2007 John Wiley & Sons, Ltd.
Transmission network optimal planning based on plant growth simulation algorithm
Authors: Wang Chun , Cheng Haozhong
Published: October 2007

A new method, which employs a plant growth simulation algorithm (PGSA) as optimal means, is presented in this paper for solving the optimal planning problem of a transmission network in a single stage (horizon year). The transmission network planning is formulated as an integer programming problem subjected to the constraints such as overload, N − 1 security, and right‐of‐way, and an efficient solving approach based upon PGSA is developed. PGSA is a new and highly efficient random search algorithm, which characterizes the growth process of plant phototropism and can quickly find high quality solutions of the combinatorial optimization problems. The test results for two systems have verified the feasibility and efficiency of the developed PGSA based transmission network optimal planning method. Copyright © 2007 John Wiley & Sons, Ltd.
Antimicrobial activity of limonene enantiomers and 1,8‐cineole alone and in combination
Authors: Vuuren S. F. van , Viljoen A. M.
Published: October 2007

Two common essential oil constituents, 1,8‐cineole and limonene, were assessed for antimicrobial activity, using the minimum inhibitory concentration (MIC) microtitre plate method against eight organisms. The limonene enantiomers, i.e. (+), (−) and the racemate, singularly and in combination (1:1) with 1,8‐cineole, were investigated to establish possible interactions. The MIC values were in the ranges 3–27 mg/ml for (+)‐limonene; 2–27 mg/ml for (−)‐limonene and 23 mg/ml for 1,8‐cineole, depending on the pathogen studied. The combinations, when investigated in a 1:1 ratio, mostly indicated reduced activity. Using various ratios of limonene and 1,8‐cineole, the specific interaction was further investigated against Staphylococcus aureus (Gram‐positive), Pseudomonas aeruginosa (Gram‐negative) and a yeast, Cryptococcus neoformans. A figurative representation of the results using isobologram construction indicated that, depending on the ratio and specific enantiomer, an additive, synergistic or antagonistic interaction may be observed. Copyright © 2007 John Wiley & Sons, Ltd.
On the use of characteristic‐based split meshfree method for solving flow problems
Authors: Shamekhi Abazar , Sadeghy Kayvan
Published: October 2007

This study presents characteristic‐based split (CBS) algorithm in the meshfree context. This algorithm is the extension of general CBS method which was initially introduced in finite element framework. In this work, the general equations of flow have been represented in the meshfree context. A new finite element and MFree code is developed for solving flow problems. This computational code is capable of solving both time‐dependent and steady‐state flow problems. Numerical simulation of some known benchmark flow problems has been studied. Computational results of MFree method have been compared to those of finite element method. The results obtained have been verified by known numerical, analytical and experimental data in the literature. A number of shape functions are used for field variable interpolation. The performance of each interpolation method is discussed. It is concluded that the MFree method is more accurate than FEM if the same numbers of nodes are used for each solver. Meshfree CBS algorithm is completely stable even at high Reynolds numbers. Copyright © 2007 John Wiley & Sons, Ltd.