bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neuronal and astrocyte expression of nicotinic receptor subunit β4 in the adult mouse brain
Authors: Gahring Lorise C. , Persiyanov Karina , Rogers Scott W. 
Published: December 2003

AbstractNeuronal nicotinic acetylcholine receptor (nAChR) expression and function are customized in different brain regions through assembling receptors from closely related but genetically distinct subunits. Immunohistochemical analysis of one of these subunits, nAChRβ4, in the mouse brain suggests an extensive and potentially diverse role for this subunit in both excitatory and inhibitory neurotransmission. Prominent immunostaining included: 1) the medial habenula, efferents composing the fasciculus retroflexus, and the interpeduncular nucleus; 2) nuclei and ascending tracts of the auditory system inclusive of the medial geniculate; 3) the sensory cortex barrel field and cell bodies of the ventral thalamic nucleus; 4) olfactory‐associated structures and the piriform cortex; and 5) sensory and motor trigeminal nuclei. In the hippocampus, nAChRβ4 staining was limited to dendrites and soma of a subset of glutamic acid dehydrogenase‐positive neurons. In C57BL/6 mice, but to a lesser extent in C3H/J, CBA/J, or CF1 mice, a subpopulation of astrocytes in the hippocampal CA1 region prominently expressed nAChRβ4 (and nAChRα4). Collectively, these results suggest that the unique functional and pharmacological properties exerted by nAChRβ4 on nAChR function could modify and specialize the development of strain‐specific sensory and hippocampal‐related characteristics of nicotine sensitivity including the development of tolerance. J. Comp. Neurol. 468:322–333, 2004. © 2003 Wiley‐Liss, Inc.
Anatomical evidence for transsynaptic influences of estrogen on brain‐derived neurotrophic factor expression
Authors: Blurton‐Jones M. , Kuan P.N. , Tuszynski M.H. 
Published: December 2003

AbstractSeveral studies have demonstrated that estrogen modulates brain‐derived neurotrophic factor (BDNF) mRNA and protein within the adult hippocampus and cortex. However, mechanisms underlying this regulation are unknown. Although an estrogen response element (ERE)‐like sequence has been identified within the BDNF gene, such a classical mechanism of estrogen‐induced transcriptional activation requires the colocalized expression of estrogen receptors within cells that produce BDNF. Developmental studies have demonstrated such a relationship, but to date no studies have examined colocalization of estrogen receptors and BDNF within the adult brain. By utilizing double‐label immunohistochemistry for BDNF, estrogen receptor‐α (ER‐α), and estrogen receptor‐β (ER‐β), we found only sparse colocalization between ER‐α and BDNF in the hypothalamus, amygdala, prelimbic cortex, and ventral hippocampus. Furthermore, ER‐β and BDNF do not colocalize in any brain region. Given the recent finding that cortical ER‐β is almost exclusively localized to parvalbumin‐immunoreactive GABAergic neurons, we performed BDNF/parvalbumin double labeling and discovered that axons from cortical ER‐β‐expressing inhibitory neurons terminate on BDNF‐immunoreactive pyramidal cells. Collectively, these findings support a potential transsynaptic relationship between estrogen state and cortical BDNF: By directly modulating GABAergic interneurons, estrogen may indirectly influence the activity and expression of BDNF‐producing cortical neurons. J. Comp. Neurol. 468:347–360, 2004. © 2003 Wiley‐Liss, Inc.
A note on enrichment functions for modelling crack nucleation
Authors: Bellec J. , Dolbow J. E. 
Published: December 2003

AbstractFor particular discretizations and crack configurations, the enhanced approximations of the eXtended finite‐element method (X‐FEM) cannot accurately represent the discontinuities in the near‐tip displacement fields. In this note, we focus on the particular case where the extent of the crack approaches the support size of the nodal shape functions. Under these circumstances, the asymptotic ‘branch’ functions for each tip may extend beyond the length of the crack, resulting in a non‐conforming approximation. We explain the limitations of the standard approximation for arbitrary discontinuities, and propose a set of adjustments to remedy the deficiencies. We also provide numerical results that demonstrate the advantages of the modified approximation. Copyright © 2003 John Wiley & Sons, Ltd.
Cognitive color
Authors: Derefeldt Gunilla , Swartling Tiina , Berggrund Ulf , Bodrogi Peter 
Published: December 2003

AbstractThis report surveys cognitive aspects of color in terms of behavioral, neuropsychological, and neurophysiological data. Color is usually defined as a color stimulus or as perceived color. In this article, a definition of the concept of cognitive color is formulated. To elucidate this concept, those visual tasks are described where it is relevant: in color categorization, color coding, color naming, the Stroop effect, spatial organization of colored visual objects, visual search, and color memory. © 2003 Wiley Periodicals, Inc. Col Res Appl, 29, 7–19, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10209
Color measurements for pearlescent coatings
Authors: Nadal Maria E. , Early Edward A. 
Published: December 2003

AbstractThis article describes recent developments at the National Institution of Standards and Technology in the colorimetric characterization of pearlescent coatings. The goal of this research is to develop a measurement protocol for the accurate color characterization of these coatings using an understanding of their scattering mechanism as a guide. A large ensemble of bi‐directional reflectance measurements on a series of pearl interference pigmented coatings show general trends in the color variations with illumination and viewing angles. These measurements were used to define a set of geometries (illumination angles of 15°, 45°, and 65° and aspecular angles of 15°, 35°, 45°, 70°, and 85°) to characterize the angle dependent color travel observed in these coatings. © 2003 Wiley Periodicals, Inc. Col Res Appl, 29, 38–42, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10210
A comparison of task pools for dynamic load balancing of irregular algorithms
Authors: Korch Matthias , Rauber Thomas 
Published: December 2003

AbstractSince a static work distribution does not allow for satisfactory speed‐ups of parallel irregular algorithms, there is a need for a dynamic distribution of work and data that can be adapted to the runtime behavior of the algorithm. Task pools are data structures which can distribute tasks dynamically to different processors where each task specifies computations to be performed and provides the data for these computations. This paper discusses the characteristics of task‐based algorithms and describes the implementation of selected types of task pools for shared‐memory multiprocessors. Several task pools have been implemented in C with POSIX threads and in Java. The task pools differ in the data structures to store the tasks, the mechanism to achieve load balance, and the memory manager used to store the tasks. Runtime experiments have been performed on three different shared‐memory systems using a synthetic algorithm, the hierarchical radiosity method, and a volume rendering algorithm. Copyright © 2004 John Wiley & Sons, Ltd.
Performance and scalability of MPI on PC clusters
Authors: Luecke Glenn R. , Kraeva Marina , Yuan Jing , Spanoyannis Silvia 
Published: December 2003

AbstractThe purpose of this paper is to compare the communication performance and scalability of MPI communication routines on a Windows Cluster, a Linux Cluster, a Cray T3E‐600, and an SGI Origin 2000. All tests in this paper were run using various numbers of processors and two message sizes. In spite of the fact that the Cray T3E‐600 is about 7 years old, it performed best of all machines for most of the tests. The Linux Cluster with the Myrinet interconnect and Myricom's MPI performed and scaled quite well and, in most cases, performed better than the Origin 2000, and in some cases better than the T3E. The Windows Cluster using the Giganet Full Interconnect and MPI/Pro's MPI performed and scaled poorly for small messages compared with all of the other machines. Copyright © 2004 John Wiley & Sons, Ltd.
Kinetics of Oxidation of Azide by [Ethylenebis(biguanide)]silver(III) in Aqueous Acidic Media
Authors: Bandyopadhyay Prabir , Dhar Basab Bijayi , Bhattacharyya Jhimli , Mukhopadhyay Subrata 
Published: December 2003

AbstractIn aqueous acidic media sodium azide and the orange‐yellow title complex react quantitatively generating N2 gas along with a colourless solution of Ag+ ion and the ligand, ethylenebis(biguanide). The parent complex, [Ag(H2L)]3+, and one of its conjugate bases, [Ag(HL)]2+, participate in the reaction with N3− as the kinetically reactive reductant. Ag+ has no catalytic effect. At 25.0 °C, I = 1.0 M (NaNO3), rate constants for the reactions [Ag(H2L)]3+ + N3− and that for [Ag(HL)]2+ + N3− are (12.3±0.5) and (3.8±0.6) M−1·s−1, respectively. The high rate constants along with the very low equilibrium constant (10−15 M−1) calculated for the first reaction strongly suggest inner‐sphere redox mechanism. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
The First Stable Monomeric Triaminostannane of Composition [(Me3Si)3CSn(NHtBu)3] Containing Three Substituted NH Groups
Authors: Janssen Jörg , Schmidt Hans‐Georg , Noltemeyer Mathias , Roesky Herbert W. 
Published: December 2003

AbstractTriaminostannanes of secondary amines have been known since 1977 and are widely used in tin organic chemistry. However, the corresponding nitrogen substituted stannanes of primary amines are not cited in the literature. Herein we report on the ammonolysis reaction of [(Me3Si)3CSnCl3] with tBuNH2 in the presence of a strong base and the X‐ray structural analysis of [(Me3Si)3CSn(NHtBu)3], the first monomeric triaminostannane containing protons at the nitrogen atoms. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
The Isoelectronic Replacement of E = P+ and Si in the Trinuclear Organotin−Oxo Clusters [Ph2E(OSntBu2)2O·tBu2Sn(OH)2]
Authors: Beckmann Jens , Dakternieks Dainis , Duthie Andrew , Jurkschat Klaus , Mehring Michael , Mitchell Cassandra , Schürmann Markus 
Published: December 2003

AbstractThe trinuclear organotin−oxo cluster [Ph2P(OSntBu2)2O· tBu2Sn(OH)2][O3SCF3] (6), was prepared in good yield by the consecutive reaction of (tBu2SnO)3 with F3CSO3H and Ph2PO2H, and adopts a common tricyclic ESn3O3X2 structural motif with E = P; X = OH, similar to those found in the recently reported species [M(OSntBu2)2O·tBu2Sn(OH)2] [M = Ph2Si (1), Me2Si (2), CO (3), MesB (4)] and [Ph2Si(OSntBu2)2O·tBu2SnF2] (5) where E = Si, C, B and X = OH, F. Compound 6 was characterized by multinuclear NMR spectroscopy, IR spectroscopy, electrospray mass spectrometry and single‐crystal X‐ray diffraction analysis. A natural population analysis (NPA) performed on the B3LYP/LANL2DZ level of theory for the molecular structures of the isoelectronic species [Ph2Si(OSntBu2)2O·tBu2Sn(OH)2] (1) and [Ph2P(OSntBu2)2O·tBu2Sn(OH)2]+ (6a) suggests that the positive charge of the latter is partially delocalised over the phenyl rings. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Analysis of Coordination and Organometallic Compounds Using Photoionisation Mass Spectrometric Techniques
Authors: Dorcier Antoine , Dyson Paul J. , McIndoe J. Scott 
Published: December 2003

AbstractA range of coordination and organometallic compounds have been analysed by quadrupole ion‐trap mass spectrometry using various photoionisation methods. Atmospheric‐pressure photo ionisation (APPI), which combines atmospheric‐pressure chemical ionisation (APCI) with a photolysis lamp, was compared with the new technique photo‐assisted electrospray ionisation (PAESI). Additionally, the atmospheric‐pressure matrix‐assisted laser desorption ionisation (AP‐MALDI) was also evaluated and compared to MALDI quadrupole ion‐trap time‐of‐flight (MALDI‐QIT‐TOF) mass spectrometry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Cover Picture: Non‐Oxo Vanadium(IV) Complexes of Aminebis(phenolate) [O,N,O] Donor Ligands and Solution Studies of Isostructural VIV and MnIV Complexes (Eur. J. Inorg. Chem. 24/2003)
Authors: Paine Tapan K. , Weyhermüller Thomas , Bill Eckhard , Bothe Eberhard , Chaudhuri Phalguni 
Published: December 2003

AbstractThe cover picture shows the multiple characterization methods used to unravel the electronic and geometrical structures of the unit MAIIIMBII, in which three oximato groups (=N−O)− are present as bridging ligands. Variable‐temperature magnetic susceptibility and EPR measurements provide a consistent answer to the question of electronic ground states for different heterometallic combinations. Mößbauer spectroscopy helps to differentiate between the species CoIII(l.s.)FeII(l.s.) and FeII(h.s.)CoIII(l.s.). Details on the preparation and characterization of the species FeIIIMII and related heterometallic compounds are presented in the article by P. Chaudhuri et al. on p. 4299 ff.
Rational Design of Cesium‐Selective Ionophores: Dihydrocalix[4]arene Crown‐6 Ethers
Authors: Sachleben Richard A. , Bryan Jeffrey C. , Engle Nancy L. , Haverlock Tamara J. , Hay Benjamin P. , Urvoas Agathe , Moyer Bruce A. 
Published: December 2003

AbstractMolecular mechanics calculations performed on calix[4]arene crown‐6 ethers predict that the 1,3‐dihydro derivatives will exhibit greater complementarity for potassium and cesium ions than the parent 1,3‐bis(alkyloxy) calixcrowns. The X‐ray crystal structures of 1,3‐alt‐bis(octyloxy)calix[4]arene benzocrown‐6 ether, dihydrocalix[4]arene benzocrown‐6 ether, and the cesium nitrate complex of dihydrocalix[4]arene benzocrown‐6 ether were determined. The structure of the cesium complex corresponds closely to the structure predicted by molecular mechanics. The dihydrocalix[4]arene crown‐6 ethers exhibit enhanced cesium selectivity in the extraction of alkali‐metal salts. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Ring Contraction of 3,6‐Dihydro‐2H‐thiopyrans to Thiolanes by an Iodo‐Oxyacylation Reaction
Authors: Lucassen Andre C. B. , Zwanenburg Binne 
Published: December 2003

AbstractReaction of functionalized 3,6‐dihydro‐2H‐thiopyrans with N‐iodosuccinimide in the presence of carboxylic acids results in the stereospecific formation of poly‐functionalised thiolanes in good yield. The formation of these thiolanes is believed to proceed through either a nucleophilic or an electrophilic pathway leading to 4,5‐cis‐substituted derivatives. The use of unsymmetrical 2,2‐substituted 3,6‐dihydro‐2H‐thiopyrans gave mixtures of isomers that could be separated in several cases. From a 3‐substituted thiopyran a 2,2,3,4,5‐pentasubstituted thiolane was obtained. Attempts to use alcohols as external nucleophiles were unsuccessful with NIS, NBS, and N‐bromoacetamide. Iodo‐azidination with in situ generated IN3 was also unsuccessful. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Threefold Bridged p‐tert‐Butylcalix[9]arene Triphosphate
Authors: Gloede Jörg , Ozegowski Sigrid , Costisella Burkhard , Gutsche C. David 
Published: December 2003

Abstractp‐tert‐Butylcalix[9]arene 1 reacts with phosphorus pentachloride and then with water to give the p‐tert‐butylcalix[9]arene triphosphate 5, representing the first bridged calix[9]arene derivative to be described in the literature. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
An Efficient Method for the Large‐Scale Preparation of 3‐O‐Acetyl‐11‐oxo‐β‐boswellic Acid and Other Boswellic Acids
Authors: Jauch Johann , Bergmann Jochen 
Published: December 2003

Abstract3‐O‐Acetyl‐11‐oxo‐β‐boswellic acid (AKBA), found in incense, is a potent inhibitor of 5‐lipoxygenase, p38 and p42 MAP kinase and topoisomerases. Starting from crude extracts from incense, procedures are presented for the efficient large‐scale synthesis of AKBA and other boswellic acids (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Preparation of Multiply Protected Alkylhydrazine Derivatives by Mitsunobu and PTC Approaches
Authors: Brosse Nicolas , Pinto Maria‐Fatima , Jamart‐Grégoire Brigitte 
Published: December 2003

AbstractAlkylation reactions of hydrazine derivatives by Mitsunobu or PTC approaches are described. It has been shown that aminophthalimide derivatives are better acidic partners than their aminoimidodicarbonate (NBoc2) analogues, the presence of the phthaloyl group increasing the acidity of the sole proton and concomitantly reducing steric hindrance. Moreover, N‐aminophthalimide derivatives can be efficiently converted into the corresponding N‐amino‐imidodicarbonates by a three‐stage, one‐flask procedure under very mild conditions. These procedures can also be efficiently used for the preparation of orthogonally Nα,Nβ‐diprotected α‐hydrazino esters. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Stereoselective Synthesis of C‐ and N‐Ketosides by Lewis Acid‐Catalyzed C‐ and N‐Glycosidation of Alkynyl, Phenyl, and Methyl Ketoses
Authors: Gómez Ana M. , Uriel Clara , Jarosz Slawomir , Valverde Serafín , López J. Cristóbal 
Published: December 2003

AbstractC‐Ketosides can be prepared conveniently, in a stereoselective manner, from alkynyl, phenyl and methyl glucopyranose hemiketals by reaction with carbon nucleophiles in the presence of Lewis acids. The reaction of the hemiketals with trimethylsilyl azide provides an efficient route to the corresponding N‐ketopyranosides. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Deslipping of Ester Rotaxanes: A Cooperative Interplay of Hydrogen Bonding with Rotational Barriers
Authors: Linnartz Petra , Bitter Stephan , Schalley Christoph A. 
Published: December 2003

AbstractA series of rotaxanes has been synthesized which contain two ester groups in their axles. All rotaxanes bear the same tetralactam wheel. The kinetics of the de‐slipping reaction of these rotaxanes were monitored in tetrachloroethane (TCE) and dimethyl sulfoxide (DMSO) resulting in the observation of a significant solvent effect. In TCE, two isomeric rotaxanes that differ merely with respect to the orientation of the ester groups show a remarkable difference in their deslipping behavior. When the ester carbonyl group is directly attached to the axle center piece, the rotaxane decomposes with a half life of ca. 10 h at 100 °C. The reverse orientation with the carbonyl group attached to the stopper blocks deslipping almost completely and a lower limit for the half life at 100 °C of 25,000 h was obtained. These results can be interpreted by inferring a cooperative action of hydrogen bonding between wheel and axle and differences in rotational barriers. Molecular modeling and AM1 calculations support this interpretation. The implications of these results for the determination of steric size and the optimization of molecular machines are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Elucidation of the Solution Conformations of Loloatin C by NMR Spectroscopy and Molecular Simulation
Authors: Chen Heru , Haynes Richard K. , Scherkenbeck Jürgen , Sze Kong H. , Zhu Guang 
Published: December 2003

AbstractNMR experiments combined with molecular simulation with X‐PLOR have been employed to determine the solution conformation of the cyclic decapeptide loloatin C in three different solutions. In DMSO, the molecule possesses a hydrophobic aromatic “wall” consisting of Trp6 and Phe7, and a type I β‐turn structure involving Val1, Trp10, Asp9 and Asn8 with a hydrophobic head at Val1/Trp10 and a hydrophilic tail at Asp9 and Asn8; another type II′ β‐turn was also located between Leu3, Tyr4, Pro5, and Trp6. In 70/30 [D3]TFE/H2O, however, loloatin C possesses a dumbbell structure with all the hydrophobic side chains projecting upward on one side, forming a hydrophobic surface, and the hydrophilic side chains projecting to the other side, together with most of carbonyl oxygen atoms, thereby forming a hydrophilic surface. However, in 30:70 [D3]TFE/H2O, loloatin C possesses an inverse γ‐turn incorporating Tyr4, Pro5, and Trp6, a hydrophobic zone involving the side chains of Leu3, Trp6, Trp10, and Phe7 and a hydrophilic tail involving the hydrophilic side chains of Orn2, Asn8, and Asp9. The amphiphilicity of the dumbbell structure in 70/30 [D3]TFE/H2O is of interest in relation to the antibiotic activity of loloatin C. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of Cyclic Hexapeptides Based on the Antibiotic Cyclic Decapeptide Loloatin C by an in situ Indirect Cyclization Method
Authors: Chen Heru , Haynes Richard K. , Scherkenbeck Jürgen 
Published: December 2003

AbstractThree cyclic hexapeptide units based on the parent loloatin C scaffold have been identified by a ‘sliding window’ method as part of an expeditious SAR search for the basis of the antibiotic activity of the loloatins. Modified Fmoc‐based solid‐phase synthesis was used to prepare cyclic(L‐valyl‐Lornithyl‐D‐phenylalanyl‐L‐asparaginyl‐L‐aspartyl‐L‐tryptophanyl) and cyclic(L‐valyl‐L‐ornithyl‐L‐leucyl‐L‐tryptophanyl‐D‐phenylalanyl‐L‐asparaginyl) in overall yields of 42%−47%. A new solution method combined with an in situ indirect cyclization was specifically developed to prepare cyclic(L‐ornithyl‐L‐leucyl‐D‐tyrosyl‐L‐prolyl‐L‐tryptophanylD‐phenylalanyl), involving cyclization of the linear peptide through the amino group in leucine, liberated selectively from the Fmoc‐protected amine in situ, with the activated p‐nitrophenyl ester of ornithine. The method was also effectively used for cyclization of the linear precursors of the first two cyclic hexapeptides. NOE analyses coupled with peptide backbone modelling were used to establish conformations of the target compounds. All have helix‐like structures with γ‐turns. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis and Water Solubility of Novel Fullerene Bisadduct Derivatives
Authors: Bosi Susanna , Feruglio Luigi , Milic Dragana , Prato Maurizio 
Published: December 2003

AbstractThe synthesis of four classes of bisadduct derivatives of C60 is reported. The solubility of the new compounds in aqueous solvents is enhanced and is among the highest ever reported for fullerene derivatives. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis of Novel D‐Secoestrone Isoquinuclidines by an Unpredicted Iminium Ion‐Induced 1,5‐Hydride Shift
Authors: Wölfling János , Frank Éva , Schneider Gyula , Tietze Lutz F. 
Published: December 2003

AbstractUnique 9,13‐bridged D‐secoestrone alkaloids have been synthesized and structurally characterized. Treatment of 3‐methoxy‐16,17‐secoestra‐1,3,5(10)‐trien‐17‐al (6a) with aniline (7) or substituted aniline derivatives 8−28 in the presence of different Lewis and Brønsted acids produces the bridged azaestrone derivatives 51−67 and the alkenes 68−73 in high yields in a domino‐type process. The imines 29−50 are proposed as intermediates, undergoing 1,5‐hydride shifts via the iminium ion salts 75 to give the cations 77, which, depending on the substitution pattern on the aniline moiety, either afford the bridged compounds through a nucleophilic addition of the formed secondary amine to the benzylic carbocation or give the alkenes through the abstraction of a proton at C‐8. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)