bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas phase production of [11C]methyl iodide‐d3. Synthesis and biological evaluation of S‐[N‐methyl‐11C]citalopram and deuterated analogues
Authors: Madsen Jacob , Elfving Betina , Andersen Kim , Martiny Lars , Knudsen Gitte M. 
Published: April 2004

AbstractThree 11C‐labelled tracers for the serotonin reuptake site, S‐[N‐methyl‐11C]citalopram ([11C]‐4), S‐[N‐methyl‐d3‐11C]citalopram ([11C]‐12), and S‐[N‐methyl‐11C]citalopram‐α,α‐d2 ([11C]‐13) were synthesized and the distribution of radioactivity after injection of radioligand was examined ex vivo in rats. The deuterated analogue of (S)‐desmethylcitalopram, (S)‐1‐(4‐fluorophenyl)‐1‐(3‐methylamino‐[3‐d2]‐propyl)‐1,3‐di‐hydro‐isobenzofuran‐5‐carbonitrile (11), was synthesized in a multi‐step synthesis from escitalopram (4) and used as precursor in the synthesis of [11C]‐13. In analogy with the reported gas phase synthesis of [11C]methyl iodide the first gas phase synthesis of [11C]Methyl iodide‐d3 is reported. The 1H/2H kinetic isotope effect related to the synthesized compounds were investigated in ex vivo rat studies, where the brain regions of interest to cerebellum ratios of the tracers [11C]‐4, [11C]‐12 and [11C]‐13 were compared. The ex vivo data indicated no significant differences in binding in any of the investigated brain regions after injection of the three tracers. Copyright © 2004 John Wiley & Sons, Ltd.
Syntheses of carbon‐14 labelled AJ‐9677, a specific β3‐adrenoceptor agonist
Authors: Ochi Takeshi , Toda Hiroshi , Minamida Akira , Terauchi Yoshiaki , Fujii Toshihiko 
Published: April 2004

AbstractTwo 14C‐labelled versions of AJ‐9677, a novel anti‐diabetic drug candidate, have been synthesized. The first, [acetic acid‐2‐14C]AJ‐9677, was synthesized via a four‐step process starting from 2‐chloro‐N,N‐diethyl[2‐14C]acetamide (3), and the second, [hydroxymethine‐14C]AJ‐9677, by a two step process from (R)‐3‐chloro[7‐14C]styrene oxide (8). When stored in the solid state both compounds undergo radiolytic decomposition in a similar manner, despite the labelled position being different, to give the dechlorinated derivative (12a, 12b). Purification of the required product was achieved after derivatization to the methyl esters. Copyright © 2004 John Wiley & Sons, Ltd.
Late‐glacial and Holocene river development in the Teleorman Valley on the southern Romanian Plain
Authors: Howard A. J. , Macklin M. G. , Bailey D. W. , Mills S. , Andreescu R. 
Published: April 2004

AbstractThis paper reports on a radiocarbon‐dated sequence of alluvial terraces from the Teleorman Valley in the southern Romanian Plain and represents the first Late‐glacial and well‐constrained Holocene alluvial sequence from the lower Danube Valley of southeast Europe. The two earliest and most extensive terraces (T1 and T2) are dissected by large, high‐amplitude palaeochannels, which are dated to ca. 12 800 yr BP and are comparable to large meandering palaeochannels identified from other Late glacial contexts across northern and central Europe. The remaining sequence of alluvial deposits show changes in river activity and accelerated sedimentation around 4900–4800 yr BP, 4000–3800 yr BP, 3300–2800 yr BP, 1000 yr BP and within the past 200 yr. A phase of tributary stream alluvial fan deposition is dated to ca. 2400 yr BP. All these periods of alluvial sedimentation correlate well with episodes of climatic cooling, higher rainfall and enhanced river activity, both in terms of incision and greater lateral mobility as well as increased flood frequency and magnitude identified elsewhere in central, western and northern Europe. Human activity appears to have had little effect on this river environment and significant fine‐grained sedimentation is not noted until ca. 2400 yr BP, approximately 5000 yr after the first neolithic farmers settled the area. Whether this record of river activity truly reflects the impact of prehistoric societies on this catchment will only be elucidated through further, ongoing detailed archaeological research. Copyright © 2003 John Wiley & Sons, Ltd.
The Preboreal climate reversal and a subsequent solar‐forced climate shift
Authors: van der Plicht J. , van Geel B. , Bohncke S. J. P. , Bos J. A. A. , Blaauw M. , Speranza A. O. M. , Muscheler R. , Björck S. 
Published: April 2004

AbstractAccurate chronologies are essential for linking palaeoclimate archives. Carbon‐14 wiggle‐match dating was used to produce an accurate chronology for part of an early Holocene peat sequence from the Borchert (The Netherlands). Following the Younger Dryas–Preboreal transition, two climatic shifts could be inferred. Around 11 400 cal. yr BP the expansion of birch (Betula) forest was interrupted by a dry continental phase with dominantly open grassland vegetation, coeval with the PBO (Preboreal Oscillation), as observed in the GRIP ice core. At 11 250 cal. yr BP a sudden shift to a humid climate occurred. This second change appears to be contemporaneous with: (i) a sharp increase of atmospheric 14C; (ii) a temporary decline of atmospheric CO2; and (iii) an increase in the GRIP 10Be flux. The close correspondence with excursions of cosmogenic nuclides points to a decline in solar activity, which may have forced the changes in climate and vegetation at around 11 250 cal. yr BP. Copyright © 2004 John Wiley & Sons, Ltd.
The Younger Dryas and Holocene climate record of a stalagmite from Hölloch Cave (Bavarian Alps, Germany
Authors: Wurth Georg , Niggemann Stefan , Richter Detlev K. , Mangini Augusto 
Published: April 2004

AbstractStable isotope analyses and seven U/Th dates of a stalagmite from the alpine Hölloch Cave (Germany) have yielded a palaeoclimate record for the past 14 300 yr. The δ18O record is positively correlated with relative temperature variations. The late glacial part of this record, including the Younger Dryas, exhibits a striking correlation with records from ice cores, lake sediments and marine sediments. In addition, this record suggests relatively high temperatures and distinct temperature fluctuations from 9000–4200 yr BP, if compared with the 4200–0 yr BP period, matching the regional soil formation–erosion and timberline patterns. The δ13C record appears to have been controlled mainly by soil formation (14 300–9000 yr BP) and by humidity variations (9000–0 yr BP). Copyright © 2004 John Wiley & Sons, Ltd.
Raman spectroscopic detection of wyartite in the presence of rabejacite
Authors: Frost Ray L. , Henry Dermot A. , Erickson Kristy 
Published: April 2004

AbstractRaman microscopy was used to confirm the presence of wyartite, CaU5+(UO2)2(CO3)O4(OH)(H2O)7, in the presence of rabejacite, (Ca(UO2)4(SO4)2(OH)5·6H2O), obtained from the Ranger Mine, Northern Territory, Australia. This occurrence is unusual in that it means that a uranyl carbonate has been formed under acidic conditions. Wyartite is a mineral known for the occurrence of pentavalent U5+. A band is observed at 818 cm−1 in the Raman spectrum of wyartite assigned to the ν2 symmetric bending mode of the (CO3)2− units. The presence of carbonate is confirmed by the ν1 stretching vibration at 1071 cm−1 and the ν3 stretching vibrations at 1445 and 1345 cm−1. Two bands are observed at 853 and 837 cm−1 and are assigned to the ν1 stretching modes of the UO2 units. Raman spectroscopy allows the partial band separation of the ν2 (CO3)2− and ν1 modes of UO2. The Raman spectrum of rabejacite is characterized by an intense sharp band at 1010 cm−1 assigned to the ν1 stretching mode of (SO4)2−. Three bands observed at 1086, 1123 and 1175 cm−1 are attributed to the ν3 antisymmetric stretching modes of (SO4)2−. The mineral rabejacite is also characterized by ν2 bending modes at 457 and 394 cm−1 and ν4 bending modes at 666, 605, 537 and 505 cm−1. Raman spectroscopy has proven most useful for the detection of wyartite in the presence of other mineral phases. Copyright © 2004 John Wiley & Sons, Ltd.
(Nano)structure, skin/core and tension behaviour of polyamide fibres
Authors: Marcellan Alba , Colomban Philippe , Bunsell Anthony 
Published: April 2004

AbstractThe micro/nanostructural evolution of ultrahigh‐performance and textile (containing a dispersion of TiO2 powder) polyamide 66 fibres during tensile loading and failure initiation was studied using Raman spectroscopy low‐wavenumber collective modes (∼100 cm−1) as a mechanical probe representative of the crystalline domains. The analysis of the wavenumber distribution revealed the skin/core heterogeneity. A compressive residual stress in the skin was evaluated at about 200 MPa from calibration plots. The homogeneity of the TiO2 grain dispersion was mapped on fibre sections and scanned along their lengths. In situ analysis at different strain levels shows that the amorphous region accommodates the stress up to ca 350 MPa, from which point elastic behaviour is observed. Particular attention was devoted to analysing crack formation. Copyright © 2004 John Wiley & Sons, Ltd.
Oxidation of lactic acid by water soluble (colloidal) manganese dioxide
Authors: Khan Zaheer , Raju  , Akram Mohd. , Kabir‐ud‐Din  
Published: April 2004

AbstractSpectrophotometric method has been used to characterize water‐soluble colloidal manganese dioxide obtained by the redox reaction between sodium thiosulphate and potassium permanganate in neutral aqueous medium which shows a single peak in the visible region with λmax = 425 nm. The kinetics of the oxidation of lactic acid by colloidal manganese dioxide (oxidant) has been investigated spectrophotometrically under pseudo‐first‐order conditions of excess lactic acid. The rate of the noncatalytic reaction pathway was slow which increased with increasing lactic acid concentration. The reaction was first‐order with respect to [oxidant] as well as [lactic acid]. In presence of manganase(II) and fluoride ions, the noncatalytic path disappeared completely while the oxidation rate of autocatalytic path increased and decreased, respectively with increasing [Mn(II)] and [F−]. A mechanistic scheme in conformity with the observed kinetics has been proposed with the rate‐law:

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© 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 359–366 2004
Fabrication of Temperature‐Sensitive Imprinted Polymer Hydrogel
Authors: Liu Xue‐Yong , Ding Xiao‐Bin , Guan Ying , Peng Yu‐Xing , Long Xin‐Ping , Wang Xiao‐Chuan , Chang Kun , Zhang Yong 
Published: April 2004

AbstractSummary: Weakly cross‐linked temperature sensitive gels that memorize 4‐aminopyridine molecules were designed and synthesized. The polymer gels show special selectivity, good thermo‐sensitivity and reusability, which would have an enormous potential of application in drug controlled release systems.Adsorption of Apy by the imprinted and non‐imprinted gels in the shrunken state at 60 °C.imageAdsorption of Apy by the imprinted and non‐imprinted gels in the shrunken state at 60 °C.
A note on Grzegorczyk's logic
Authors: Jeřábek Emil 
Published: April 2004

AbstractGrzegorczyk's modal logic (Grz) corresponds to the class of upwards well‐founded partially ordered Kripke frames, however all known proofs of this fact utilize some form of the Axiom of Choice; G. Boolos asked in [1], whether it is provable in plain ZF. We answer his question negatively: Grz corresponds (in ZF) to a class of frames, which does not provably coincide with upwards well‐founded posets in ZF alone. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On deciding the non‐emptiness of 2SAT polytopes with respect to First Order Queries
Authors: Subramani K. 
Published: April 2004

AbstractThis paper is concerned with techniques for identifying simple and quantified lattice points in 2SAT polytopes. 2SAT polytopes generalize the polyhedra corresponding to Boolean 2SAT formulas, Vertex‐Packing (Covering, Partitioning) and Network flow problems; they find wide application in the domains of Program verification (Software Engineering) and State‐Space search (Artificial Intelligence). Our techniques are based on the symbolic elimination strategy called the Fourier‐Motzkin elimination procedure and thus have the advantages of being extremely simple (from an implementational perspective) and incremental. We also provide a characterization of a 2SAT polytope in terms of its extreme points and derive some interesting hardness results for associated optimization problems. Finally, we provide a brief discussion on the maximum size of a subdeterminant of the linear system representing a 2SAT polytope; this parameter plays a vital role in deriving analytical bounds on the size of the search space for checking whether the polyhedron includes a lattice point. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On weakening the Deduction Theorem and strengthening Modus Ponens
Authors: Bou Félix , Font Josep Maria , García Lapresta José Luis 
Published: April 2004

AbstractThis paper studies, with techniques of Abstract Algebraic Logic, the effects of putting a bound on the cardinality of the set of side formulas in the Deduction Theorem, viewed as a Gentzen‐style rule, and of adding additional assumptions inside the formulas present in Modus Ponens, viewed as a Hilbert‐style rule. As a result, a denumerable collection of new Gentzen systems and two new sentential logics have been isolated. These logics are weaker than the positive implicative logic. We have determined their algebraic models and the relationships between them, and have classified them according to several standard criteria of Abstract Algebraic Logic. One of the logics is protoalgebraic but neither equivalential nor weakly algebraizable, a rare situation where very few natural examples were hitherto known. In passing we have found new, alternative presentations of positive implicative logic, both in Hilbert style and in Gentzen style, and have characterized it in terms of the restricted Deduction Theorem: it is the weakest logic satisfying Modus Ponens and the Deduction Theorem restricted to at most 2 side formulas. The algebraic part of the work has lead to the class of quasi‐Hilbert algebras, a quasi‐variety of implicative algebras introduced by Pla and Verdú in 1980, which is larger than the variety of Hilbert algebras. Its algebraic properties reflect those of the corresponding logics and Gentzen systems. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
EM + Ext− + ACint is equivalent to ACext
Authors: Carlström Jesper 
Published: April 2004

AbstractIt is well known that the extensional axiom of choice (ACext) implies the law of excluded middle (EM). We here prove that the converse holds as well if we have the intensional (‘type‐theoretical’) axiom of choice ACint, which is provable in Martin‐Löf's type theory, and a weak extensionality principle (Ext−), which is provable in Martin‐Löf's extensional type theory. In particular, EM is equivalent to ACext in extensional type theory. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis and Characterization of Polystyrene‐Encapsulated Laponite Composites via Miniemulsion Polymerization
Authors: Sun Qunhui , Deng Yulin , Wang Zhong Lin 
Published: April 2004

AbstractSummary: A novel polystyrene‐encapsulated laponite composite system has been developed via a miniemulsion polymerization approach. The encapsulation mechanism and process parameters have been examined in detail using light‐scattering, sedimentation analysis, wide‐angle X‐ray diffraction (WXRD), and transmission electron microscopy (TEM). The laponite was encapsulated through a miniemulsion polymerization process in which laponite was predispersed in the monomer phase. The stability of both the miniemulsion and the latex depends on initiation loci, premixing procedures, intensity and time of ultrasonification and the surfactants and co‐stabilizer used. Hydrophobicity of the laponite clay played a vital role in both the encapsulation of the clay and the stability of the latex. A quaternary ammonium salt, cetyltrimethylammonium bromide (CTAB), was mixed with the clay in the monomer phase prior to emulsification. As a result, the clay particles were hydrophobically modified and were intercalated. The hydrophobicity not only favored the clay dispersion in the oil droplets but also aided the entry of the monomer into the clay's intergalleries during polymerization. Meanwhile, CTAB helped stabilize the system when it was used in conjunction with the nonionic surfactant polyoxyethylene (40) isooctylphenyl ether (TX‐405). In this way, the laponite is effectively encapsulated within a polystyrene shell in a stable latex form. More importantly, the polymerization initiated in the intergalleries of the clay effectively expands the clay's platelet array to form an exfoliated structure.image
Solid‐State Structure and Mechanical Properties of Blends of an Amorphous Polyamide and a Poly(amino‐ether) Resin
Authors: Granado Ainhoa , Eguiazábal José I. , Nazábal Jon 
Published: April 2004

AbstractSummary: Finely dispersed blends of an amorphous polyamide (AP) and a poly(amino‐ether) (PAE) resin were obtained by direct injection moulding. The blend components reacted slightly, mainly in PAE‐rich compositions, as seen by torque increases and FT‐IR. Both negative volumes of mixing and preferential orientation were observed in blends with very high AP contents, leading to synergisms in both the modulus of elasticity and the yield stress. In PAE‐rich blends, the effects of these two structural characteristics were negative, but the higher presence of reacted products also led to an overall synergistic modulus of elasticity. With the exception of blends very rich in PAE, in which the more extensive reactions led to brittle materials, the reactions compatibilized the blends due to the presence of small amounts of reacted copolymers, probably at the interface.Cryogenically fractured surface of the skin of the AP/PAE 80/20 w/w blend.imageCryogenically fractured surface of the skin of the AP/PAE 80/20 w/w blend.
Dextran Hydrogels Containing Poly(N‐isopropylacrylamide) as Grafts and Cross‐Linkers Exhibiting Enzymatic Regulation in a Specific Temperature Range
Authors: Kumashiro Yoshikazu , Ooya Tooru , Yui Nobuhiko 
Published: April 2004

AbstractSummary: Specific temperature‐responsive biodegradable hydrogels were synthesized and characterized in terms of their regulation of enzymatic accessibility based on the physical properties of the temperature‐responsive polymers. The hydrogels consist of glycidyl methacrylate‐modified dextran grafted with the poly(N‐isopropylacrylamide) (PNIPAAm) homopolymer, and cross‐linked by co‐polymerization with NIPAAm and N,N‐dimethylacrylamide (DMAAm). The coil‐globule change in the grafted poly(NIPAAm) chains and only a slight dehydration of the poly(NIPAAm‐co‐DMAAm) cross‐linkers are effective in controlling the enzymatic degradation over a specific temperature range.The thermo‐responses of the graft chains (steric hindrance) and the crosslinkers (slight deswelling of the hydrogel networks) control the enzymatic degradation of the hydrogel.imageThe thermo‐responses of the graft chains (steric hindrance) and the crosslinkers (slight deswelling of the hydrogel networks) control the enzymatic degradation of the hydrogel.
Cationic Polymerization of 3‐Ethyl‐3‐hydroxymethyloxetane in an Ionic Liquid
Authors: Biedroń Tadeusz , Bednarek Melania , Kubisa Przemysław 
Published: April 2004

AbstractSummary: Cationic ring‐opening polymerization of 3‐ethyl‐3‐hydroxymethyloxetane (EOX) in a neutral ionic liquid (1‐butyl‐3‐methylimidazolium tetrafluoroborate, [bmim][BF4]) leading to a multihydroxyl, branched polyether proceeds readily to nearly quantitative conversion. Because of the relatively high polarity of ionic liquids, intermolecular hydrogen bonding leading to the formation of aggregates is reduced considerably. On the other hand, intramolecular hydrogen bonding facilitating intramolecular chain transfer is not significantly affected and the molecular weights of polymers are in the same range as those obtained in bulk polymerization or polymerization in organic solvents.image
Mass spectrometric approaches for the investigation of dynamic processes in condensed phase
Authors: Fabris Daniele 
Published: April 2004

Abstract

I.
Introduction
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II.
Off‐Line Sampling
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A.  Quantitative Approaches for Kinetics Determinations
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B.  Characterization of Intermediates in Chemical Reactions
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C.  Off‐Line Investigation of Catalysis in Biological Systems
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III.
Continuous On‐Line Monitoring
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IV.
Rapid Mixing
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V.
Conclusions
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VI.
Abbreviations and Acronyms
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Acknowledgments
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References
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Mass spectrometry (MS) offers many advantages over other established spectroscopic techniques employed for the investigation of processes in condensed phase. The sensitivity, specificity, and speed afforded by MS‐based methods enable to obtain very valuable insights into the mechanism of complex dynamic processes. Off‐line methods rely on quenching to halt the progress of the reaction of interest and allow for the implementation of a broad range of analytical procedures for sample fractionation, isolation, or desalting. On the contrary, on‐line methods are designed to carry out the real‐time monitoring of dynamic processes through a continuous uninterrupted analysis of reaction mixtures, with the only caveat that the sample solutions be directly amenable to the available ionization technique. The utilization of rapid mixing devices in direct connection with a mass spectrometer or included in off‐line schemes provides access to the initial moments of a reaction, which can offer very important information about the reaction mechanism. This report summarizes the different off‐ and on‐line strategies developed to study chemical and biochemical reactions in solution and obtain kinetic/mechanistic information. The merits of the various experimental designs, the characteristics of the different instrumental setups, and the factors affecting time resolution are discussed with the aid of specific examples, which highlight the contributions of MS to the different facets of the investigation of dynamic processes in condensed phase. © 2004 Wiley Periodicals, Inc.
Absence of sensory neuropathy among workers with occupational exposure to chlorpyrifos
Authors: Albers James W. , Garabrant David H. , Schweitzer Sarah , Garrison Richard P. , Richardson Rudy J. , Berent Stanley 
Published: April 2004

AbstractSeveral studies have reported the occurrence of sensory neuropathy with exposure to chlorpyrifos and other organophosphorus insecticides, at levels not associated with overt toxicity. We evaluated 113 chemical workers, including 53 of 66 (80%) eligible chlorpyrifos workers and 60 of 74 (81%) randomly selected referent workers, to identify evidence of sensory neuropathy or subclinical neuropathy. Compared to referents, chlorpyrifos subjects had significantly longer duration of work in chlorpyrifos‐exposed areas (9.72 vs. 0.01 years; P < 0.0001), greater cumulative chlorpyrifos exposure (64.16 vs. 0.69 mg/m3 · day; P < 0.0001), higher urine 3,5,6‐trichloro‐2‐pyridinol (TCP) excretion (108.6 vs. 4.3 μg/g creatinine; P < 0.0001), and lower plasma butyrylcholinesterase (BuChE) activity (7281 vs. 8176 mU/ml; P = 0.003). Despite exposures among chlorpyrifos subjects to levels at which well‐described physiological effects on B‐esterases exist, the frequency of symptoms or signs of neuropathy did not differ significantly between groups, and the only 2 subjects fulfilling criteria for confirmed neuropathy were both in the referent group. Mean nerve conduction study results were comparable to established control values and did not differ significantly between groups. We found no evidence of sensory neuropathy or isolated peripheral abnormalities among subjects with long‐term chlorpyrifos exposure at levels known to be associated with the manufacturing process. Muscle Nerve 29: 677–686, 2004