bluuebunny/crossref_metadata_2025 huggingface dataset:
An Enantioselective Polymer Prepared by the Surface Molecular-Imprinting Technique
Authors: Yoshida Masahiro , Uezu Kazuya , Goto Masahiro , Furusaki Shintaro , Takagi Makoto
Published: November 2003

An enantioselective imprinted polymer was prepared by the surface template polymerization technique. An organophosphorus extractant was effective as a functional host molecule for recognizing a certain amino acid. The imprinted polymer exhibited a high template effect toward L-tryptophan methylester compared to its D-isomer, while a reference polymer prepared without an imprinting molecule did not show any selectivity among the enantiomers.
Tribenzo-1,4,5,8,9,12-hexathiatriphenylene Dication and Dibenzo-1,4,5,8-tetrathiaphenanthrene Dication
Authors: Nakai Takeo , Kozaki Masatoshi , Sato Kazunobu , Shiomi Daisuke , Takui Takeji , Itoh Koichi , Okada Keiji
Published: November 2003

Tribenzo-1,4,5,8,9,12-hexathiatriphenylene dication (12+) and dibenzo-1,4,5,8-tetrathiaphenanthrene dication (22+) were generated in concentrated sulfuric acid. Their zero-field splitting parameters were determined as D = 0.012 cm−1, E ≈ 0.00 cm−1 for 12+, and D = 0.012 cm−1, E ≈ 0.00 cm−1 for 22+. The dication 12+ was found to be a triplet in the ground state, whereas 22+ to be a singlet ground state with the singlet-triplet energy gap of −35 ± 2 J/mol.
Drastic Selectivity Change by SMSI Effect in the CO-H2 Reaction over Pd/CeO2
Authors: Naito Shuichi , Aida Shigeru , Tsunematsu Tadao , Miyao Toshihiro
Published: November 2003

Selectivity of CO-H2 reaction over Pd/CeO2 changed drastically from methanol to methane by higher temperature reduction (SMSI effect). Facile isotopic exchange reaction of 12C18O-13C16O indicated the dissociative adsorption of CO over reduced Pd/CeO2, which corresponds to the acceleration of methane formation. Infrared spectroscopic investigation during the reaction suggested that methanol formation sites were formed by the transformation of methane formation sites.
Synthesis and Binding Affinities of Novel Spirocyclic Lactam Peptidomimetics of Somatostatin
Authors: Damour Dominique , Barreau Michel , Blanchard Jean-Charles , Burgevin Marie-Claude , Doble Adam , Pantel Guy , Labaudinière Richard , Mignani Serge
Published: November 2003

Synthesis of novel spirocyclic lactam peptidomimetics of the binding domain of somatostatin from commercially available D, L-methionine is described.
Perpendicular Magnetic Anisotropy in Co/Pd Multilayered Films Prepared by Electroplating
Authors: Sato Yuichi , Kudo Koji , Tamano Haruo , Kobayakawa Koichi
Published: November 2003

Co/Pd, Co/Pt and Co/Au multilayered films, generally prepared by dry methods such as sputtering, vacuum evaporation, and MBE method, are known to exhibit perpendicular magnetic anisotropy. We prepared Co/Pd multilayered film by electroplating from aqueous solution and first time observed that the easy axis of magnetization of the obtained film was in a direction perpendicular to the film plane.
Synthesis and Structure of SO2 Bridged Trinuclear Re Cluster (Et4N)[Re3(μ3-S)(μ-SO2)(μ-S)2Cl6(PEt3)3]
Authors: Sokolov Maxim , Imoto Hideo , Saito Taro
Published: November 2003

A SO2 bridged triangular rhenium cluster (Et4N)[Re3(μ3-S)(μ-SO2)(μ-S)2Cl6(PEt3)3] was isolated as one of the products in the reaction of Re3S7Cl7 with triethylphosphine at room temperature. The Re3(μ3-S)(μ-SO2)(μ-S)25+ cluster core is unique and differs in many points from that of closely related Re3(μ3-S)(μ-S)35+ cluster.
Enhanced Electron Transfer from Glucose Oxidase to DNA-Immobilized Electrode Aided by Ferrocenyl Naphthalene Diimide, a Threading Intercalator
Authors: Takenaka Shigeori , Uto Yoshihiro , Takagi Makoto , Kondo Hiroki
Published: November 2003

A ferrocene-modified 1,4,5,8-naphthalenetetracarboxyldiimide (1), bound to double stranded DNA by a threading intercalation mode, enhanced the electron transfer between glucose oxidase and a DNA-immobilized electrode.
Desymmetrization of meso-Diols by Acylation with Axially Chiral Twisted Amides and Its Mechanistic Studies
Authors: Yamada Shinji , Katsumata Hiroko
Published: November 2003

Desymmetrization of meso-1,2-, -1,3-, and -1,4-diols was performed by acylation with chiral twisted amides.1 The conformation of the twisted amides was studied by optimization of the PM3 method in order to elucidate the reaction mechanism. The directionality of the amide bond rotation was considered to be significantly responsible for the stereoselectivity.
Photochromic Reversible Substitution Reaction of Tridentate Schiff Base-Ruthenium(II) Complexes
Authors: Nakajima Kiyohiko , Ishibashi Satoshi , Kojima Masaaki
Published: November 2003

In acetonitrile, the chloro ligands of [RuCl2(ppb-etol)(PPh3)] (1, ppb-etol = N-(2-diphenylphosphinobenzilidene)-2-hydroxyethylamine) are substituted with the solvent molecules to yield an equilibrium mixture of [RuCl(CH3CN)(ppb-etol)(PPh3)]Cl (2) and [Ru(CH3CN)2(ppb-etol)(PPh3)]Cl2 (3) at 50°C in the dark. The reaction is accompanied by a color change from orange to yellow. Upon irradiation of UV-vis light, the color of the solution reverts to orange, and complexes 2 and 3 are converted again into complex 1. The color change can be made repeatedly and a reversible photochromic reaction system is constructed.
Music Perception and Cognition
Authors: Justus Timothy C. , Bharucha Jamshed J.
Published: November 2003

This chapter reviews the field of music perception and cognition, which is the area of cognitive psychology devoted to determining the mental mechanisms underlying our appreciation of music. The chapter begins with the study of pitch, including the constructive nature of pitch perception and the cognitive structures reflecting its simultaneous and sequential organization in Western tonal‐harmonic music. This is followed by reviews of temporal organization in music, and of musical performance and ability. Next, literature concerning the cognitive neuroscience of music is examined, including studies of neuropsychology, neuroimaging, and event‐related potentials. The chapter concludes with a discussion of developmental music cognition, cross‐cultural music cognition, and the evolutionary psychology of music.
Neural Basis of Haptic Perception
Authors: Johnson Kenneth
Published: November 2003

Haptic perception depends on four types of cutaneous mechanoreceptors. Combined psychophysical and neurophysiological research supports the idea that each of the four mechanoreceptive afferent systems innervating the hand serves a distinctly different perceptual function and that haptic perception can be understood as the sum of these functions. The evidence reviewed in this chapter supports the following synthesis: (1) SA1 mechanoreceptive afferent, which innervate the skin densely and are selectively responsive to points, edges and curvature, are responsible for form and texture perception. (2) RA mechanoreceptive afferents, which also innervate the skin densely, are responsible for motion detection. Their most important function is the provision of feedback signals about slip between the skin and an object held in the hand, which is critical for grip control. (3) Pacinian afferents, which are extremely sensitive, are responsible for the perception of distant events through vibrations transmitted to the hand through tools, objects, and probes held in the hand. (4) SA2 mechanoreceptors provide information about skin stretch. Perhaps their most important function is the provision of a neural image of skin stretch that signals the shape of the hand and fingers.
Models of Memory
Authors: Raaijmakers Jeroen G. W. , Shiffrin Richard M.
Published: November 2003

Over the past 50 years, models for human memory have developed from simple data descriptions for specific tasks to general frameworks that can and have been generalized to most of the major paradigms that are used in memory research. We argue that such a generalization across tasks becomes possible because the models specify basic mechanisms rather than simple equations that describe the data in a specific task. We illustrate this by a brief review of the developments since the 1950s, followed by a discussion of the major theoretical frameworks that have been developed over the past 25 years. The early models such as Estes’ Stimulus Sampling Theory focused on learning, but in the 1960s the emphasis gradually shifted to memory and especially the distinction between short‐term and long‐term memory. In the 1980s a number of global models were developed that dealt with data from a variety of memory tasks. Although these global memory models have been quite successful there remained some problems, most notably the explanation for the lack of list‐strength effects in recognition. Recent developments show that models based on a Bayesian or rational approach (ACT‐R, REM) may provide a unified framework for explicit as well as implicit memory.
Cognitive Development
Authors: Gelman Rochel
Published: November 2003

This chapter interleaves a review of theories of cognitive development with accounts of the nature of concepts. Of central concern is how young children come to share concepts with members of the community they join. Different classes of cognitive development make contact with different theories about the nature of concepts. Learning theories (e.g., associationist, connectionist and systems theories) and stage theories assume that infants and very young children build concepts from simple sensory and perceptual inputs. The speakers' use of words highlights relevant sensory‐perceptual input, the kind that the mind will combine into associative networks, logical structures, or connectionist networks. These in turn can support the induction or construction of true, that is abstract, concepts. Until this happens, the young child cannot help but be perception‐bound. True concepts are characterized in terms of necessary and sufficient conditions, not particular percepts. They also can be continued according to logical rules.
Perceptual Learning
Authors: Kellman Philip J.
Published: November 2003

Perceptual learning refers to experience‐induced changes in the way information is extracted. Evidence suggests that such changes are pervasive in human perception, affecting tasks from the simplest sensory discriminations to the most complex extraction of abstract relations, and that perceptual learning is not reducible to other forms of learning. In this chapter, I consider perceptual learning phenomena in terms of components of discovery; ways in which new bases of response are attained; fluency; and ways in which the speed and ease of information pickup improve. Although data from several senses are considered, I focus on vision: basic visual sensitivities, “middle vision” (perception of surfaces and objects), and high‐level visual cognition. I consider neural bases and computational models, as well as evidence about the conditions under which learning occurs and real‐world applications of perceptual learning. Perceptual learning, which comprises one of the most important foundations of human expertise, provides a window into plasticity in the nervous system and poses computational challenges in understanding how information extraction changes with experience.
Spatial Learning
Authors: Collett Thomas S.
Published: November 2003

Animals engage in an enormous variety of spatial behaviors that require accurately directed movements of either an appendage or of the whole animal towards a visible goal. Animals also plan routes to remembered places that are invisible from their starting point. Learning thus occurs for many reasons and in many different systems within the CNS. Plastic adjustments are made to make movements precise and to calibrate estimates of distance and direction. Information is acquired to aid an animal's return to significant places, to follow routes, and more generally to enable it to exploit changing resources within familiar territory. The extent to which animals, other than primates, build a map‐like representation and plan novel routes using it remains a matter of debate.
Role of Learning in Cognitive Development
Authors: Gelman Rochel , Lucariello Joan
Published: November 2003

In this chapter, we review the distinction between development and learning, showing why what is innate and what is learned cannot be treated as mutually exclusive categories. The learning that is essential to cognitive development is driven by domain‐specific skeletal structures, which seek relevant inputs and organize and structure what is revealed by experience. Different domains are defined by different sets of principles, specifying relations between different kinds of entities. The domain of sociality is structured by the principles of contingency, agency, mental states, emotional evaluation, and fittingness. These principles apply to persons in social interactions. This skeletal structure organizes the acquisition of social understanding. Special attention is given to this domain, because the account of structured learning in this domain is given de novo here.

We contrast learning in the social domain with learning in two other domains: the domain of number and the domain of causality. The numerical domain is structured by arithmetic operations (addition, subtraction, and ordination) and by the principles of nonverbal counting. These principles organize attention to and the learning of verbal counting and basic arithmetic. The central principle in the causal domain is the distinction between animate and inanimate causality. These principles organize the learning of facts about the nature of movements, interactions, and transformations of objects in the animate and inanimate spheres.
Signal Detection Theory
Authors: MacMillan Neil A.
Published: November 2003

In perceptual, cognitive, and diagnostic tasks, accuracy depends on both limited sensitivity and the application of a decision process. By making explicit assumptions about the nature of the cognitive representation, signal detection theory (SDT) measures the contributions of these two components of performance. (Other approaches to assessing accuracy also constrain possible representations, although not all are explicit about their assumptions.) Thereceiver‐operating characteristic(ROC) curve, which takes account of response bias in decision‐making by examining conditions in which this bias varies, is a valuable tool for sensitivity measurement: The ROC curve provides an assumption‐free index of accuracy, and is also used to distinguish among competing representations. The simplest form of SDT assumes that different stimulus possibilities lead to distributions of strength on a decision axis, and this model can be applied to many experimental paradigms in which a single stimulus is presented on each trial. Using more complex representations in which distributions lie in a multidimensional space, SDT predicts the relation between different paradigms for measuring accuracy (e.g., two‐alternative forced‐choice, same‐different). Multidimensional representations also describe the classification and identification of stimuli from complex stimulus sets, and are particularly useful in analyses of perceptual interaction and attention.
Parallel and Serial Processing
Authors: Logan Gordon D.
Published: November 2003

This chapter reviews theoretical and empirical progress that has been made in answering the question “Is processing parallel or serial?” Answers to the question are complicated because the distinction between parallel and serial processing interacts with other basic distinctions, including exhaustive versus self‐terminating search, limited versus unlimited capacity, discrete versus continuous processing, and stochastic versus functional independence. Because of these complications, parallel and serial models readily mimic each other's predictions. Empirical answers to the question are complicated as well because different procedures invoke parallel and serial processing in different ways, and because detailed theories of empirical phenomena often mimic each other's predictions. The chapter reviews progress in distinguishing parallel and serial models of memory search, visual search, dual‐task performance, redundant stimulation, and memory retrieval. It addresses recent alternatives to parallel processing, such as coactivation and mixture models. It ends by evaluating the amount of cumulative progress that has been made in answering the question “Is processing parallel or serial?” and by speculating about prospects for progress in the future.
Aging and Cognition
Authors: Rabbitt Patrick
Published: November 2003

Aging is indexed both by the passage of time and as the progress of biological processes occurring in time. Biological aging can be indexed by time related physiological change in sensory and motor function that directly affect cognitive competence and also act as markers for changes in the brain and central nervous system, and so in mental abilities. Cognitive and biological changes can be studied either by cross‐sectional or by longitudinal comparisons, both of which have logical and methodological advantages and difficulties. The simplicity of applied studies to understand and mitigate practical difficulties that older people encounter in their daily lives contrasts with the methodological difficulties of studies driven by contrasting general theories of cognitive aging. One, logically questionable, assumption has been that changes are driven by “global” and diffuse brain changes that modify a particular master performance parameter, such as general mental ability or information processing speed, and so affect all cognitive systems to the same extent. An alternative assumption, that aging affects some brain systems, particularly those in the frontal and prefrontal cortex that control “executive” behavior earlier and more severely than others, is better supported by logic and evidence, but encounters methodological problems in relating behavioral to neurophysiological changes.
The Effects of Material Properties on the Activity of Sol‐Gel Entrapped Perruthenate under Supercritical Conditions
Authors: Ciriminna Rosaria , Campestrini Sandro , Pagliaro Mario
Published: November 2003

Silica gels organically modified and doped with the ruthenium species tetra‐n‐propylammonium perruthenate (TPAP) are leach‐proof, selective catalysts for the aerobic oxidation of alcohols to carbonyl compounds with dioxygen at low pressure in compressed carbon dioxide. The catalytic sol‐gels are recyclable and the correlation between the reactivity of the materials and their surface polarity and textural properties suggests valuable information on the chemical behaviour of sol‐gel entrapped silica catalysts in oxidation catalysis which is of relevant interest considering the importance of heterogeneous oxidative dehydrogenation of alcohols in fine chemistry. An explanation of the structure‐activity relationship is proposed to provide guidelines for the further development of efficient solid oxidation catalysts for conversions in supercritical carbon dioxide.
Heterogeneous Enantioselective Hydrogenation of Activated Ketones Catalyzed by Modified Pt‐Catalysts: A Systematic Structure‐Selectivity Study
Authors: Exner Christian , Pfaltz Andreas , Studer Martin , Blaser Hans‐Ulrich
Published: November 2003

A systematic structure‐selectivity study was carried out for the enantioselective hydrogenation of activated ketones with chirally modified Pt/Al2O3 catalysts. For this, 18 modifiers containing an extended aromatic system able to form a strong adsorption complex with the Pt surface, and a suitable chiral group with an amino function capable to interact with the keto group of the substrate (HCd, Qd, HCn, Qn, and semi‐synthetic derivatives, as well as synthetic analogues) were prepared and tested on 8 different activated ketones in AcOH and toluene under standard conditions. It was found that relatively small structural changes of the substrate and/or modifier structures strongly affected the enantioselectivity, and that no “best” modifier exists for all substrates. The highest ees for all substrates were obtained with quinuclidine‐derived modifiers in combination with naphthalene or quinoline rings, either in AcOH (substrates 1–5 and 8, all carrying an sp3 carbon next to the keto group) or toluene (6 and 7, with an sp2 carbon next to the ketone). The presence and nature of the substituent R' at the quinuclidine significantly affected the ee (positive and negative effects). Certain combinations of an aromatic system and an amino function were preferred: For the quinuclidine moiety, quinoline and to a somewhat lesser extent naphthalene were a better match, while for the pyrrolidinylmethyl group anthracene was better suited. Methylation of the OH group often had a positive effect for hydrogenations in AcOH but not in toluene. With the exception of 8, higher ees were obtained for the Cd/Qn series [leading to (R)‐products] than for the Cn/Qd series [leading to (S)‐products]. In several cases, opposite structure‐selectivity trends were detected when comparing reactions in toluene and AcOH, indicating a significant influence of the solvent.
Chloride channels as tools for developing selective insecticides
Authors: Bloomquist Jeffrey R.
Published: November 2003

Ligand‐gated chloride channels underlie inhibition in excitable membranes and are proven target sites for insecticides. The γ‐aminobutyric acid (GABA1) receptor/chloride ionophore complex is the primary site of action for a number of currently used insecticides, such as lindane, endosulfan, and fipronil. These compounds act as antagonists by stabilizing nonconducting conformations of the chloride channel. Blockage of the GABA‐gated chloride channel reduces neuronal inhibition, which leads to hyperexcitation of the central nervous system, convulsions, and death. We recently investigated the mode of action of the silphinenes, plant‐derived natural compounds that structurally resemble picrotoxinin. These materials antagonize the action of GABA on insect neurons and block GABA‐mediated chloride uptake into mouse brain synaptoneurosomes in a noncompetitive manner. In mammals, avermectins have a blocking action on the GABA‐gated chloride channel consistent with a coarse tremor, whereas at longer times and higher concentrations, activation of the channel suppresses neuronal activity. Invertebrates display ataxia, paralysis, and death as the predominant signs of poisoning, with a glutamate‐gated chloride channel playing a major role. Additional target sites for the avermectins or other chloride channel‐directed compounds might include receptors gated by histamine, serotonin, or acetylcholine.

The voltage‐sensitive chloride channels form another large gene family of chloride channels. Voltage‐dependent chloride channels are involved in a number of physiological processes including: maintenance of electrical excitability, chloride ion secretion and resorption, intravesicular acidification, and cell volume regulation. A subset of these channels is affected by convulsants and insecticides in mammals, although the role they play in acute lethality in insects is unclear. Given the wide range of functions that they mediate, these channels are also potential targets for insecticide development. Arch. Insect Biochem. Physiol. 54:145–156, 2003. © 2003 Wiley‐Liss, Inc.
Bt: Mode of action and use
Authors: Whalon Mark E. , Wingerd Byron A.
Published: November 2003

The insecticidal toxins from Bacillus thuringiensis (Bt) represent a class of biopesticides that are attractive alternatives to broad‐spectrum “hard” chemistries. The U.S. Food Quality Protection Act and the European Economic Council directives aimed at reducing the use of carbamate and organophosphate insecticides were expected to increase the use of narrowly targeted, “soft” compounds like Bt. Here we summarize the unique mode of action of Bt, which contributes to pest selectivity. We also review the patterns of Bt use in general agriculture and in specific niche markets. Despite continued predictions of dramatic growth for biopesticides due to US Food Quality Protection Act—induced cancellations of older insecticides, Bt use has remained relatively constant, even in niche markets where Bt has traditionally been relatively high. Arch. Insect Biochem. Physiol. 54:200–211, 2003. © 2003 Wiley‐Liss, Inc.
Botanical insecticides for controlling agricultural pests: Piperamides and the Colorado potato beetle Leptinotarsa decemlineata say (Coleoptera: Chrysomelidae)
Authors: Scott I.M. , Jensen H. , Scott J.G. , Isman M.B. , Arnason J.T. , Philogène B.J.R.
Published: November 2003

The efficacy of extracts from two Piperaceae species, Piper nigrum L. and P. tuberculatum Jacq. were evaluated using larvae and adults of the Colorado Potato Beetle Leptinotarsa decemlineata (Say). Young larvae and neonates were the most susceptible; a 24‐h LD50 of 0.064% extract of P. tuberculatum was determined for 4‐day‐old larvae, while 0.05% extract of P. nigrum reduced larval survival up to 70% within one week after treatment of potato Solanum tuberosum L. (Solanaceae) plants. When an insecticide resistant strain of L. decemlineata larvae was tested with the P. tuberculatum extract, there was less than a 2‐fold tolerance ratio compared to the 22‐fold tolerance ratio to cypermethrin, a pyrethroid. Older larvae, pre‐pupal stage and adults, were less sensitive to the P. nigrum extracts; the 24‐h LD50 was 0.5% (95% C.I. = 0.36, 0.65). However, the same concentration was equally effective under field conditions. In the greenhouse, P. nigrum at 0.5% was as effective at reducing adult L. decemlineata feeding as combinations with 2 separate botanical mixtures, garlic and lemon grass oil. Under field conditions, the residual activity of the P. nigrum extracts was less than 3 h. When adult L. decemlineata were placed on treated plants exposed to full sunlight for 0, 1.5, and 3 h, leaf damage progressively increased as the main active compound, piperine, was found to degrade by 80% after 3 h. An in vitro polysubstrate monoxygenase (PSMO) enzyme assay, using the substrate methoxyresorufin O‐demethylation (MROD), determined that the principal P. nigrum active compound, piperine, is responsible for inhibition of that specific enzyme. The results suggest that Piper extracts could be used effectively as contact botanical insect control agents to protect potato plants from developing L. decemlineata larvae at concentrations less than 0.1%. There is also potential for Piper extracts to control insecticide resistant populations in conjunction with other integrated pest management (IPM) strategies used in conventional and organic agriculture. Arch. Insect Biochem. Physiol. 54:212–225, 2003. © 2003 Wiley‐Liss, Inc.
The probability distribution of side‐chain conformations in [Leu] and [Met]enkephalin determines the potency and selectivity to μ and δ opiate receptors
Authors: Nielsen Bjørn G. , Jensen Morten Ø. , Bohr Henrik G.
Published: November 2003

The structure of enkephalin, a small neuropeptide with five amino acids, has been simulated on computers using molecular dynamics. Such simulations exhibit a few stable conformations, which also have been identified experimentally. The simulations provide the possibility to perform cluster analysis in the space defined by potentially pharmacophoric measures such as dihedral angles, side‐chain orientation, etc. By analyzing the statistics of the resulting clusters, the probability distribution of the side‐chain conformations may be determined. These probabilities allow us to predict the selectivity of [Leu]enkephalin and [Met]enkephalin to the known μ‐ and δ‐type opiate receptors to which they bind as agonists. Other plausible consequences of these probability distributions are discussed in relation to the way in which they may influence the dynamics of the synapse. © 2003 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 71: 577–592, 2003
Electrochemistry of Metallofullerene Films: The Major Isomer of Dy@C82
Authors: Fan Louzhen , Yang Shangfeng , Yang Shihe
Published: November 2003

Solution‐cast films of the major isomer of Dy@C82 (Dy@C82(I)) have been studied by cyclic voltammetry (CV) in acetonitrile. The films are found to display pronounced and stable redox responses in solution. The reduction/reoxidation processes exhibit large splittings between the first two reduction and reoxidation waves. However, a pair of reversible oxidation and rereduction waves is observed after the reoxidation of a reduced film. The characteristics and the inter‐relationship of these waves are uncovered by the CV technique, scanning electron microscopy (SEM), and UV/Vis‐NIR spectra. A possible mechanism is proposed for the film electrode processes, which emphasizes the redox‐induced structural reorganization of the metallofullerene film by the incorporation and expulsion of electrolyte ions into and out of the film. The influence of the counter ion diffusivity and the ion‐pair stability on the electrochemical activity of the metallofullerene film has also been indicated.
Expanded Radialenes with Bicyclo[4.3.1]decatriene Units: New Precursors to Cyclo[n]carbons
Authors: Tobe Yoshito , Umeda Rui , Iwasa Naruhito , Sonoda Motohiro
Published: November 2003

A new method for the formation of conjugated polyynes has been developed based on both the rearrangement of vinylidenes to alkynes and the [2+1] cheletropic fragmentation of dialkynylmethylenebicyclo[4.3.1]deca‐1,3,5‐triene derivatives. A model study of the photolysis of simple dialkynylmethylenebicyclo[4.3.1]deca‐1,3,5‐trienes resulted in cheletropic fragmentation followed by 1,2‐migration to give the corresponding linear polyynes, although undesired isomerization to methylenebicyclo[5.3.0]triene derivatives took place concurrently. Expanded [3]‐, [4]‐, [5]‐, and [6]radialene derivatives with exocyclic bicyclo[4.3.1]decatriene units were prepared by oxidative coupling of the monomeric units as precursors to the corresponding cyclo[n]carbons, monocyclic forms of carbon clusters. The spectroscopic properties of the expanded radialenes were investigated in connection with cross conjugation of the core π system and with its perturbation by the extraannular bicyclic π system. In negative‐mode laser‐desorption time‐of‐flight (LD‐TOF) mass spectra, the expanded radialenes exhibited peaks due to the corresponding cyclo[n]carbon anions (n = 18, 24, 30, and 36) formed by the stepwise loss of the aromatic indane fragments.
Photoswitching of the Magnetic Interaction between a Copper(II) Ion and a Nitroxide Radical by Using a Photochromic Spin Coupler
Authors: Takayama Kohsuke , Matsuda Kenji , Irie Masahiro
Published: November 2003

Photoswitching of an intramolecular spin exchange interaction between a copper(II) ion and a nitroxyl radical by using a metal complex of diarylethene has been studied by means of ESR spectroscopy. As a coordination ligand, a diarylethene with a 1,10‐phenanthroline ring and nitronyl nitroxide radical was synthesized. Mixing the diarylethene ligand with [Cu(hfac)2] (hfac=hexafluoroacetylacetone) in toluene led to a hypsochromic shift of the absorption maxima of the closed‐ring isomer due to complexation. ESR measurement in toluene at room temperature of the open‐ring isomer of the CuII complex gave a spectrum that is a superposition of the spectra from the nitroxide radical and CuII. When the sample was irradiated with 366 nm light, a new peak due to large exchange interaction appeared between those of the nitroxyl radical and CuII. This ESR measurement revealed that the magnitude of the spin exchange interaction was changed by more than 160‐fold by photoirradiation. This is the largest magnetic photoswitching phenomenon recorded in diarylethene systems.
Gas‐Phase Detection of HSOH: Synthesis by Flash Vacuum Pyrolysis of Di‐tert‐butyl Sulfoxide and Rotational‐Torsional Spectrum
Authors: Winnewisser Gisbert , Lewen Frank , Thorwirth Sven , Behnke Markus , Hahn Josef , Gauss Jürgen , Herbst Eric
Published: November 2003

Gas‐phase oxadisulfane (HSOH), the missing link between the well‐known molecules hydrogen peroxide (HOOH) and disulfane (HSSH), was synthesized by flash vacuum pyrolysis of di‐tert‐butyl sulfoxide. Using mass spectrometry, the pyrolysis conditions have been optimized towards formation of HSOH. Microwave spectroscopic investigation of the pyrolysis products allowed—assisted by high‐level quantum‐chemical calculations—the first measurement of the rotational‐torsional spectrum of HSOH. In total, we have measured approximately 600 lines of the rotational‐torsional spectrum in the frequency range from 64 GHz to 1.9 THz and assigned some 470 of these to the rotational‐torsional spectrum of HSOH in its ground torsional state. Some 120 out of the 600 lines arise from the isotopomer H34SOH. The HSOH molecule displays strong c‐type and somewhat weaker b‐type transitions, indicating a nonplanar skew chain structure, similar to the analogous molecules HOOH and HSSH. The rotational constants (MHz) of the main isotopomer (A=202 069, B=15 282, C=14 840), determined by applying a least‐squares analysis to the presently available data set, are in excellent agreement with those predicted by quantum‐chemical calculations (A=202 136, B=15 279, C=14 840). Our theoretical treatment also derived the following barrier heights against internal rotation in HSOH (when in the cis and trans configurations) to be Vcis≈2216 cm−1 and Vtrans≈1579 cm−1. The internal rotational motion results in detectable torsional splittings that are dependent on the angular momentum quantum numbers J and Ka.
Supramolecular Control of the Template‐Induced Selective Photodimerization of 4‐Methyl‐7‐O‐hexylcoumarin
Authors: Skene William G. , Couzigné Emilie , Lehn Jean‐Marie
Published: November 2003

A symmetric ditopic molecular receptor (3), containing two identical hydrogen‐bonding recognition subunits, was designed and synthesized. These subunits are capable of binding substrates with complementary donor and acceptor sites to form a supramolecular complex through hydrogen bonding. Receptor 3 was designed to accept two guest molecules, which are held in close proximity within the supramolecular species. The substrate molecule, 4‐methyl‐7‐O‐hexylcoumarin (1 c), forms a 2:1 complex with a binding constant of 150 m−1 for the second substrate, passing first through a 1:1 complex with an affinity constant of 510 m−1. The orientation of two molecules of 1 c when bound to the template leads to the selective formation of the trans‐syn [2+2] photoproduct 2 cB upon irradiation. Other photoproducts typically produced in the absence of the template are suppressed.
A phase II study of topotecan with vincristine and doxorubicin in children with recurrent/refractory neuroblastoma
Authors: Garaventa Alberto , Luksch Roberto , Biasotti Simona , Severi Gianluca , Pizzitola Maria Rosa , Viscardi Elisabetta , Prete Arcangelo , Mastrangelo Stefano , Podda Marta , Haupt Riccardo , De Bernardi Bruno
Published: November 2003

BACKGROUND

A Phase II trial in children with advanced neuroblastoma was carried out in five Italian institutions to evaluate the antitumor activity and tolerability of topotecan followed by vincristine and doxorubicin.

METHODS

Children older than age 1 year with Stage III or Stage IV neuroblastoma, all of whom had been treated previously with chemotherapy and were diagnosed with either refractory or recurrent disease, were treated with topotecan at an intravenous dose of 1.5 mg/m2 (the dose was 0.75 mg/m2 for patients who were treated within 1 year of previous megatherapy) per day for 5 days followed by 48‐hour intravenous infusions of 2 mg/m2 vincristine and 45 mg/m2 doxorubicin. Cycles of therapy were repeated every 3 weeks.

RESULTS

Twenty‐five patients (2 with Stage III disease and 23 with Stage IV disease; 19 with refractory disease and 6 with recurrent disease) were treated with a total of 115 cycles. Four patients had complete responses, 12 patients had partial responses, 4 patients had minor responses or stable disease, and 5 patients had tumor progression. The overall response rate (including complete and partial responses) was 64% (95% confidence interval, 43–82%). Fifteen patients were alive at the time of the current report and were progression free at 4–16 months (median, 9 months) after the first course of this treatment. Toxicity generally was limited to the hematopoietic system. Dose‐limiting toxicity was observed in only 1 patient (Grade 4 liver toxicity). There were no deaths due to infectious or toxic causes.

CONCLUSIONS

The topotecan‐vincristine‐doxorubicin combination was active and well tolerated in previously treated patients with advanced neuroblastoma. Cancer 2003. © 2003 American Cancer Society.
Sustainability hijacked by the sociological wall of self‐evidence
Authors: Cerin Pontus
Published: November 2003

The nowadays commonly applied structuring of sociological theories – the four‐fielder of Burrell and Morgan (1979) – in the environmental and sustainability agenda may, unfortunately, serve as a platform for the advocators of leaving business alone to realize win–win solutions by itself – that is obstructing change by encouraging business as usual. The reason for this hijacking of environmentalism is a dichotomization of regulation and radical change along an axis describing the nature of society. By instead focusing on power along the society continuum, the tool describing sociological theory enables policy thought that promotes a societal change towards increased sustainability. Copyright © 2003 John Wiley & Sons, Ltd and ERP Environment.
Ethical investment and the incentives for corporate environmental protection and social responsibility
Authors: Aslaksen Iulie , Synnestvedt Terje
Published: November 2003

This paper addresses some interrelated questions regarding ethical investments: does ethical screening provide any incentives for improved social responsibility within firms? Are ethical screened portfolios competitive compared with conventional funds with respect to risk‐adjusted return? Does the risk‐adjusted return of a screened portfolio depend on the screening strategy applied?

Considering ethical screening as a kind of segmentation of the equity market, it is shown that screening might create incentives for changes in firms' behaviour. The strength of this incentive depends on the relative share of screened portfolios, which in turn partially depends on the financial performance of the screened portfolios. While some theoretical arguments suggest that screening imposes a handicap compared with conventional portfolios, the empirical evidence does not suggest that screened portfolios systematically under‐perform conventional portfolios. Copyright © 2003 John Wiley & Sons, Ltd and ERP Environment.
Link‐disjoint paths for reliable QoS routing
Authors: Guo Yuchun , Kuipers Fernando , Van Mieghem Piet
Published: November 2003

The problem of finding link/node‐disjoint paths between a pair of nodes in a network has received much attention in the past. This problem is fairly well understood when the links in a network are only specified by a single link weight. However, in the context of quality of service routing, links are specified by multiple link weights and restricted by multiple constraints. Unfortunately, the problem of finding link/node disjoint paths in multiple dimensions faces different conceptual problems. This paper presents a first step to understanding these conceptual problems in link‐disjoint quality of service routing and proposes a heuristic link‐disjoint QoS algorithm that circumvents these problems. Copyright © 2003 John Wiley & Sons, Ltd.
Traffic locality characteristics in a parallel forwarding system
Authors: Shi W. , MacGregor M. H. , Gburzynski P.
Published: November 2003

Due to the widening gap between the performance of microprocessors and that of memory, using caches in a system to take advantage of locality in its workload has become a standard approach to improve overall system performance. At the same time, many performance problems finally reduce to cache performance issues. Locality in system workload is the fact that makes caching possible. In this paper, we first use the reuse distance model to characterize temporal locality in Internet traffic. We develop a model that closely matches the empirical data. We then extend the work to investigate temporal locality in the workload of multi‐processor forwarding systems by comparing locality under different packet scheduling schemes. Our simulations show that for systems with hash‐based schedulers, caching can be an effective way to improve forwarding performance. Based on flow‐level traffic characteristics, we further discuss the relationship between load‐balancing and hash‐scheduling, which yields insights into system design. Copyright © 2003 John Wiley & Sons, Ltd.
Prioritized slotted multiple access protocols for bank LANs
Authors: Sklira M. , Pomportsis A. S.
Published: November 2003

Four classes of traffic are present in a bank communication system: Alarm, BSC, SNA and IP traffic, with each class of traffic having different priority requirements. In this paper, a prioritized multiple access protocol is introduced which is capable of handling the above priority classes. The proposed protocol makes use of learning automata in order to dynamically assign the available bandwidth to the priority classes. In this way, it is capable of being adapted to the traffic conditions. The proposed protocol, is applicable to a broad range of prioritized LANs, as it can be easily extended to support multiple classes of traffic. Copyright © 2003 John Wiley & Sons, Ltd.
Uncompromised generation of a specific H‐2DM‐dependent peptide‐MHC class II complex from exogenous antigen in Leishmania mexicana‐infected dendritic cells
Authors: Bennett Clare L. , Colledge Lisa , Richards Hannah E. , Reay Philip A. , Blackburn C. Clare , Aebischer Toni
Published: November 2003

Leishmania infection inhibits the capacity of macrophages (MΦ) to present antigens to CD4+ T cells. Relocation of MHC class II and H‐2DM to the parasitophorous vacuole (PV) and their subsequent degradation by the parasite may contribute to this defect. Dendritic cells (DC) are critical for initiation of primary T cell responses. DC can process Leishmania antigen and elicit Leishmania‐specific T cells, but it is unknown whether exposure to Leishmania impairs this capacity. In particular, it is not clear whether DC containing live parasites efficiently process and present antigens. We investigated the ability of mouse bone marrow‐derived DC infected with L. mexicana to generate pigeon cytochrome c (PCC) peptide‐MHC class II complexes, using the mAb D4, which recognizes PCC89–104 H‐2Ek, and the PCC‐specific T cell hybridoma 2B4. We show that H‐2DM‐dependent complex generation is not compromised by infection and that complexes are fully recognized by specific T cells. We further show that in contrast to infected MΦ, in infected DC cytoplasmic H‐2DM is not down‐regulated and not relocated to the parasite‐containing vacuole. This observation may explain the continued ability of infected DC to present PCC, and also indicates differences in the habitat of these intracellular parasites in DC compared to MΦ.
Human CD4+CD25+ regulatory cells have marked and sustained effects on CD8+ T cell activation
Authors: Câmara Niels Olsen Saraiva , Sebille Fabien , Lechler Robert I.
Published: November 2003

Amongst the many types of regulatory cells that have been described during the past few years, the spontaneously occurring population that is characterized by co‐expression of CD4 and CD25 appears to play a key role in the prevention of autoimmunity and the maintenance of transplantation tolerance. In this study we have examined the ability of CD4+CD25+ T cells to regulate human CD8+ T cells, and the behavior of CD8+ T cells following activation in the presence of regulatory CD4+CD25+ T cells. The experiments described here demonstrate that human CD4+CD25+ T cells cause pronounced and sustained inhibition of CD8+ T cell proliferation in response to polyclonal and allogeneic stimulation. The regulation of CD8+ T cell activation was cell contact‐dependent and included inhibition of perforin, granzyme B and IFN‐γ cytokine production at the transcriptional level and impaired cytotoxicity. The regulated CD8+ T cell population showed sustained hyporesponsiveness and refractoriness to exogenous IL‐2. These data provide insights into the short‐ and long‐term effects of CD4+CD25+ T cells on CD8+ T cells that could be of considerable value in optimizing vaccination against tumor and viral antigens.
p300 cooperates with Smad3/4 and Runx3 in TGFβ1‐induced IgA isotype expression
Authors: Park Seok‐Rae , Lee Eun‐Kyoung , Kim Byung‐Chul , Kim Pyeung‐Hyeun
Published: November 2003

We have shown previously that Smad3 and Smad4 mediate TGF‐β1‐induced IgA expression. In the present study, we examined the involvement of Runx3 in this process. Overexpression of Runx3 in mice increased germ‐line α (GLα) transcription, and transcription was further augmented when B lymphoma and LPS‐activated murine spleen cells were co‐transfected with Smad3/4. Overexpressionof Runx3 and Smad3/4 increased IgA secretion by both cell types in response to TGF‐β1. p300, which has histone acetyltransferase activity, further augmented TGF‐β1‐induced GLα transcription promoted by Smad3/4 and Runx3. These observations were confirmed by examining the influence of Smad3/4, Runx3 and p300 on the expression of endogenous GLα and post‐switch α transcripts.E1A, an inhibitor of p300, blocked both GLα promoter activity and the enhancement of endogenous GLα transcription by Smad3/4 and Runx3. We conclude that p300 cooperates with Smad3/4 and Runx3 in stimulating TGF‐β1‐induced GLα transcription and subsequent IgA isotype expression, while E1A inhibits these cooperative effects.
OX40/OX40L interaction induces the expression of CXCR5 and contributes to chronic colitis induced by dextran sulfate sodium in mice
Authors: Obermeier Florian , Schwarz Herbert , Dunger Nadja , Strauch Ulrike G. , Grunwald Nicole , Schölmerich Jürgen , Falk Werner
Published: November 2003

Interactions between APC and T lymphocytes have been implicated as a major factor contributing to inflammatory bowel disease. To test whether OX40/OX40L interaction plays a role in chronic intestinal inflammation, we induced chronic colitis using dextran sulfate sodium and treated the mice with a murine fusion protein (OX40–IgG). Treatment resulted in a dose‐dependent and significant reduction of intestinal inflammation (46%) as measured by a histologic score. IL‐10 and IL‐5 production from mesenteric lymph node cells increased 20‐fold and 18‐fold, respectively. In colonic tissue, IL‐10 mRNA levels increased and the expression of T‐bet was decreased to 30%. IL‐10 neutralization partly inhibited the beneficial effects of OX40–IgG treatment. Surprisingly, despite the reduction of inflammation we found the number and size of colonic lymphoid follicles increased, with an accumulation of CD4+ cells in the mantle area. In contrast, the number of CD4+ cells infiltrating the mucosa was significantly reduced, as was their CXCR5 expression (24‐fold). We conclude that OX40/OX40L interaction contributes to the perpetuation of chronic colitis partly by suppressing IL‐10 production. Furthermore, our data suggest that the OX40/OX40L‐induced CXCR5 expression on CD4+ cells may be important for the inflammatory process by allowing migration to the germinal center for further differentiation of CD4+ cells before they infiltrate the chronically inflamed mucosa.