bluuebunny/crossref_metadata_2025 huggingface dataset:
UV Spectra and Excitation Delocalization in DNA: Influence of the Spectral Width
Authors: Emanuele Emanuela , Markovitsi Dimitra , Millié Philippe , Zakrzewska Krystyna
Published: June 2005

The singlet excited states of the model DNA duplex (dA)10.(dT)10 are studied. Calculations are performed in the exciton theory framework. Molecular dynamics calculations provide the duplex geometry. The dipolar coupling is determined using atomic transition charges. The monomer transition energies are simulated by Gaussian functions resembling the absorption bands of nucleosides in aqueous solutions. Most of the excited states are found to be delocalized over at least two bases and result from the mixing of different monomer states. Their properties are only weakly affected by conformational changes of the double helix. On average, the highest oscillator strength is carried by the upper eigenstates. The duplex absorption spectra are shifted a few nanometers to higher energies with respect to the spectra of noninteracting monomers. The states with larger spatial extent are located close to the maximum of the absorption spectrum.
Solvation of Tetraalkylammonium Chlorides in Acetonitrile–Water Mixtures: Mass Spectrometry and Molecular Dynamics Simulations
Authors: Saielli Giacomo , Scorrano Gianfranco , Bagno Alessandro , Wakisaka Akihiro
Published: June 2005

The solvation of tetramethylammonium chloride (Me4NCl) and tetra‐n‐butylammonium chloride (Bu4NCl) in water–acetonitrile mixtures was investigated by mass spectrometry of clusters isolated from the solution. As far as the positive ions are concerned, clusters composed of alkylammonium ions and acetonitrile molecules only were observed, even for mixtures with high water content. In contrast, for the negative ions, clusters composed of chloride with both water and/or acetonitrile molecules were observed. For the smaller system (Me4NCl) we performed quantum chemical calculations and molecular dynamics simulations. It was found that even though water is present in the solvation shell of Me4N+, only acetonitrile has a strong electrostatic interaction with the cation. Water molecules around Me4N+ form hydrogen bonds with other water molecules, and they interact with Me4N+ mainly via dispersive interactions. These results indicate that Me4N+ behaves like a hydrophobic solute. On the other hand, the interaction of Cl− with water and acetonitrile is of comparable strength and, in both cases, the electrostatic interaction dominates. Herein we demonstrate experimentally and theoretically that positive and negative ions give rise to characteristic solvation structures in mixed solvents: even a relatively small organic cation, such as Me4N+, exhibits a hydrophobic‐like solvation shell.
A Study Using X‐ray Absorption and Emission Spectroscopy of Dioxygen‐Binding Xerogels Incorporating Cyclam Units Complexed with Copper Salts
Authors: Goulon José , Goulon‐Ginet Chantal , Rogalev Andrei , Wilhelm Fabrice , Jaouen Nicolas , Cabaret Delphine , Joly Yves , Dubois Géraud , Corriu Robert J. P. , David Gabriel , Brandès Stéphane , Guilard Roger
Published: June 2005

X‐ray absorption spectroscopy was used to elucidate how hybrid xerogels complexed with CuCl2 could reversibly bind molecular dioxygen. Difference EXAFS analyses at the Cu K‐edge suggest that dioxygen could bridge two Cu atoms in a μ‐η1:η1 peroxo‐like conformation with unequal Cu···O distances. Only the short distance (RCu–O1 = 1.86 ± 0.01 Å) was unambiguously determined and looks typical of a CuII site. The Cu···Cu internuclear distances would be rather long: RCu–Cu ≈ 4.0 Å (3.9 Å) for the oxygenated (oxygen‐free) xerogels. Cl K‐edge EXAFS spectra revealed the pre‐existence in the oxygen‐free xerogels of CuI sites with short Cl–Cu bonds (2.11 ± 0.03 Å). Pentacoordinate CuII sites with a longer Cl–Cu bond (2.45 ± 0.03 Å) were also identified. Another signal at a further distance (2.73 ± 0.03 Å) suggests that the Cl ions could bridge mixed‐valence {CuI,CuII} sites. In oxygenated xerogels complexed with CuCl2, ca. 75 % of the Cu atoms would be singly bound to dioxygen while the signature of the pentacoordinate CuII sites would totally vanish. Substituting CuBr2 for CuCl2 yields xerogels with a poor capability to bind dioxygen. This is remarkably correlatedwith a decrease of the signatures at RCu–O1 = 1.86 Å and RCu–Cu 4.0 Å. EXAFS spectra of the oxygen‐free xerogel complexed with CuBr2 again exhibit signatures assigned to short (2.30 Å)/long (2.49 Å) Cu–Br bonds as expected for mixed‐valence {CuI,CuII} systems. Inactive xerogels prepared with metallated cyclams seem to undergo a structural change during hydrolysis and polycondensation. Deconvoluted XANES spectra of the active xerogels exhibit a strong pre‐edge resonance which is characteristic of mixed‐valence CuI sites. This interpretation was supported by ab initio XANES simulations carried out beyond the muffin‐tin approximation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Detection of Trace Phenol Based on Mesoporous Silica Derived Tyrosinase‐Peroxidase Biosensor
Authors: Dai Zhihui , Xu Xiaoxing , Wu Lina , Ju Huangxian
Published: June 2005

A novel electrochemical biosensor for phenol based on immobilization of tyrosinase‐peroxidase on mesoporous silica is described. The enhanced sensitivity of the tyrosinase‐horseradish peroxidase based biosensor to phenol was observed on comparing with tyrosinase or horseradish peroxidase monoenzyme modified electrodes. Two enzymes retained their enzymatic activities for phenol determination without any mediator. The preparation conditions of the biosensor are discussed. Optimization of the experimental parameters was performed with regard to pH and operating potential. The phenol sensor exhibited a fast response of less than 10 seconds. The sensitivity of the biosensor for phenol was 14 μA μM−1 cm−2 with a linear range from 2×10−7 to 2.3×10−4 M and a detection limit of 4.1×10−9 M. The biosensor showed a good stability and reproducibility.
The Solid State Electrochemistry of Dysprosium(III) Hexacyanoferrate(II)
Authors: Wu Ping , Cai Chenxin
Published: June 2005

A new electroactive polynuclear inorganic compound of rare earth metal hexacyanoferrate, dysprosium hexacyanoferrate (DyHCF), was prepared chemically and characterized using techniques of FTIR spectroscopy, thermogravimetric analysis (TGA), UV‐vis spectrometry and X‐ray photoelectron spectroscopy (XPS) etc. The cyclic voltammetric behavior of DyHCF mechanically attached to the surface of graphite electrode was well defined and exhibited a pair of redox peaks with the formal potential of 217 mV (vs. SCE) at a scan rate of 100 mV/s in 0.2 M NaCl solution and the redox peak currents increased linearly with the square root of the scan rates.
Chemically Polymerized Polyaniline Films for the Mass‐Production of Biosensor Devices
Authors: Grennan Kathleen , Killard Anthony J. , Smyth Malcolm R.
Published: June 2005

The widespread use of screen‐printed electrodes in biosensor applications has meant that mass‐production of disposable, inexpensive sensors has become feasible. However, the complexity of surface coatings that require difficult and time‐consuming deposition procedures do not lend themselves to the same production conveniences. This article describes moves towards the development of an alternative to the electrochemical deposition of polyaniline on electrode surfaces for incorporation into an established sensor format. Chemical rather than electrochemical polymerization of the conducting polymer polyaniline enables a multitude of electrodes to be coated simultaneously, without the need for complex instrumentation. The aim of this work was to control the coating parameters such that a coating of polymer was deposited that displayed the optimum thickness and electrochemical properties of that previously optimized electrochemically. Deposition procedures were found to depend on the hydrophilicity of the underlying carbon paste electrode as well as on a variety of polymerization parameters.
Electrochemical Responses of Thiolated Oligodeoxynucleotides in Cobalt‐Containing Solutions
Authors: Ostatná Veronika , Jelen František , Hianik Tibor , Palecek Emil
Published: June 2005

We show for the first time that thiol end‐labeled oligodeoxynucleotides (ODN) produce specific voltammetric signals at mercury and solid amalgam electrodes in cobalt‐containing solutions (usually used in polarographic and voltammetric analysis of peptides and proteins). Most of the measurements were performed by adsorptive transfer stripping (ex situ) method. 21‐mer ODN HS(CTT)7 was attached to the hanging mercury drop electrode (HMDE) and the DNA‐modified electrode was immersed in the cobalt‐containing empty background electrolyte. This ODN produced several differential pulse voltammetric signals which are not observed in absence of cobalt. The most negative signal (peak 3) of submicromolar HS(CTT)7 attained much larger heights than the catalytic (Brdicka) peaks of about 10‐fold more concentrated cysteine‐containing peptide. The peak 3 and a less negative peak 2 of the HSODN increased with increasing buffer concentration suggesting that, similarly to cysteine‐containing peptides and proteins, for both SH–ODN peaks catalytic hydrogen evolution was responsible. Since peak 3 appeared at less negative potentials than the peptide Brdicka peaks it was possible to measure the ODN and peptide signals separately. This new possibility of measuring signals of thiolated DNA in the media, which proved suitable for protein analysis, can be utilized in the development of sensors for DNA‐protein interactions, important in biomedicine and proteomics.
Combined modelling of TCP and multi‐RED in DiffServ networks
Authors: Baumann Matthias , Marandin Dmitry , Sulaiman Samer
Published: June 2005

This paper presents a new numerical method to analyse steady‐state TCP throughputs in DiffServ networks. Different TCP models are briefly reviewed, and a Markov chain is used to capture the behaviour of a multi‐random early detection (RED) queue. The established closed network model couples models for TCP, marking device and multi‐RED queue. We assess accuracy and limits of the technique, and apply it for a discusion of parameter settings for marking devices. Copyright © 2005 AEIT.
Approximate state probabilities in large shared multirate loss systems with an application to trunk reservation
Authors: Bziuk Wolfgang
Published: June 2005

The saddle‐point method of integration is used to derive a non‐recursive approximation for the distribution of occupied bandwidth units of the multirate loss system with complete sharing, which achieves complexity O(1) per state. For the multirate finite sources model an asymptotic scaling is assumed in which the capacity and the number of sources are large and as an application the tail probability is approximated in the region 10− 4–10− 10. The limits for the infinite sources model are obtained as well and the approximate distribution is used to initialise a partial recursion, which transforms the state probabilities into an approximate distribution of the same system with trunk reservation. As a result the blockings are obtained with a low numerical complexity, which scales independent of the capacity. Numerical results show the accuracy and efficiency of the approximations. The estimate of the tail probability is shown to be superior if compared to the modified Chernoff bound. Copyright © 2005 AEIT.
Resilient dimensioning of proportionally fair networks
Authors: Pióro Michał , Kubilinskas Eligijus , Nilsson Pål
Published: June 2005

The notion of proportional fairness has recently gained considerable interest as a potential means for a fair allocation of bandwidth between the end nodes of demands in the networks carrying elastic traffic. The issue of proportionally fair allocation of bandwidth for the nominal state of the network has been studied before, both in the capacitated (link capacities given) and the uncapacitated (link capacities are also subject to optimisation) cases. In the presented paper, we address a more complicated uncapacitated problem—optimisation of link capacities for a proportionally fair network robust to failures. We formulate a relevant optimisation problem and propose efficient solution algorithms. Efficiency of the algorithms is illustrated with numerical examples including large networks. The design approach is applicable to IP/MPLS networks based on leased transmission capacity. Copyright © 2005 AEIT.
Load balancing in IP networks by optimising link weights
Authors: Mulyana Eueung , Killat Ulrich
Published: June 2005

We present a hybrid genetic algorithm (GA) approach to optimise link weights used for routing inside an autonomous system in IP networks. This method can be seen as an alternative to metaheuristic‐based approaches previously proposed in the literature. However, our approach is based on a simple but powerful GA, which utilises a plain but flexible objective function, taking both maximum link utilisation and weight reconfiguration into account. Furthermore, the population‐based feature of the GA is enhanced with a search heuristic representing an individual‐based search method to form a hybrid GA (HGA). We demonstrate our method in a case of a small network and compare the results with the linear programming (LP) lower bound of general optimal routing. Afterwards we show the results for a bigger network with increasing traffic demands, compared with the results of some conventional weight settings as well as with the LP lower bound. Copyright © 2005 AEIT.
AC algorithms in AQUILA QoS IP network
Authors: Brandauer Christof , Burakowski Wojciech , Dabrowski Marek , Tarasiuk Halina , Koch Berthold
Published: June 2005

This paper presents the admission control (AC) algorithms that are implemented in the prototype multi‐service AQUILA QoS IP network4. The discussed algorithms were developed for regulating traffic submitted to network services (NS) dedicated for handling: (1) real‐time streaming traffic of variable bit rate (VBR) type and (2) elastic traffic, produced by greedy TCP sources. For the former NS, named Premium VBR, the measurement‐based AC (MBAC) scheme is proposed. The applied approach employs the well‐known Hoeffding bound formula2for calculating required link capacity to assure packet loss ratio at a predefined level. Moreover, this method is supported by the declarations about the peak bit rate as well as by the measurements of mean bit rate on aggregate flow level. For the latter NS, named premium multimedia, two alternative AC algorithms are investigated, both designed for assuring requested TCP throughput. While the first of them follows the token bucket marking (TBM) concept12, the second one adjusts the advertised TCP window size to enable an ideal TCP behaviour (i.e. lossless packet transfer). The simulation results are included for illustrating the advantages of the discussed algorithms. Copyright © 2005 AEIT.
Heuristic methods for topological design of telecommunication networks
Authors: Karaś Piotr , Mysłek Andrzej
Published: June 2005

The paper addresses a generic topological network design problem. The target of the optimisation is to determine a network structure and a demand allocation pattern that would minimise the cost of the network, given a list of potential node locations and a list of admissible interconnections between these nodes. Since the problem is known to be NP‐hard, use of specialised heuristic algorithms is proposed. Presented approaches encompass original ideas as well as selected methods described in literature and their enhancements. The algorithms are based on the following concepts and methods: individual and bulk flow shifting, methods based on Minoux and Yaged heuristics, Simulated Allocation, cost function modification and Hybrid GRASP. A numerical study enables us to draw conclusions on the efficiency of the methods. Copyright © 2005 AEIT.
PAX5/IGH rearrangement is a recurrent finding in a subset of aggressive B‐NHL with complex chromosomal rearrangements
Authors: Poppe Bruce , De Paepe Pascale , Michaux Lucienne , Dastugue Nicole , Bastard Christian , Herens Christian , Moreau Els , Cavazzini Francesco , Yigit Nurten , Van Limbergen Heidi , De Paepe Anne , Praet Marleen , De Wolf‐Peeters Chris , Wlodarska Iwona , Speleman Frank
Published: June 2005

We present an extensive characterization of 10 B‐cell lymphomas with a t(9;14)(p13;q32). The presence of the PAX5/IGH gene rearrangement was demonstrated by fluorescence in situ hybridization (FISH) using a validated probe set, whereas complex karyotypic changes were reassessed by multiplex‐FISH (M‐FISH). Pathologic and clinical review revealed the presence of this rearrangement in 4 histiocyte‐rich, T‐cell‐rich B‐cell lymphomas (HRTR‐BCLs) and 2 posttransplantation diffuse large B‐cell lymphomas (PTLD‐DLBCLs). In contrast to initial observations describing this translocation in lymphoplasmacytic lymphoma (LPL) and LPL‐derived large B‐cell lymphoma, our data showed a wide morphologic and clinical spectrum associated with the PAX5/IGH rearrangement, pointing to an association between this aberration and a subset of de novo DLBCLs presenting with advanced disease and adverse prognosis. In addition, the recurrent incidence of this rearrangement in both HRTR‐BCL (4 cases) and PTLD‐DLBCL (2 cases) was previously unrecognized and is intriguing. © 2005 Wiley‐Liss, Inc.
Molecular characterization of the spectrum of genomic deletions in the mismatch repair genes MSH2, MLH1, MSH6, and PMS2 responsible for hereditary nonpolyposis colorectal cancer (HNPCC)
Authors: van der Klift Heleen , Wijnen Juul , Wagner Anja , Verkuilen Paul , Tops Carli , Otway Robyn , Kohonen‐Corish Maija , Vasen Hans , Oliani Cristina , Barana Daniela , Moller Pal , DeLozier‐Blanchet Celia , Hutter Pierre , Foulkes William , Lynch Henry , Burn John , Möslein Gabriela , Fodde Riccardo
Published: June 2005

A systematic search by Southern blot analysis in a cohort of 439 hereditary nonpolyposis colorectal cancer (HNPCC) families for genomic rearrangements in the main mismatch repair (MMR) genes, namely, MSH2, MLH1, MSH6, and PMS2, identified 48 genomic rearrangements causative of this inherited predisposition to colorectal cancer in 68 unrelated kindreds. Twenty‐nine of the 48 rearrangements were found in MSH2, 13 in MLH1, 2 in MSH6, and 4 in PMS2. The vast majority were deletions, although one previously described large inversion, an intronic insertion, and a more complex rearrangement also were found. Twenty‐four deletion breakpoints have been identified and sequenced in order to determine the underlying recombination mechanisms. Most fall within repetitive sequences, mainly Alu repeats, in agreement with the differential distribution of deletions between the MSH2 and MLH1 genes: the higher number and density of Alu repeats in MSH2 corresponded with a higher incidence of genomic rearrangement at this disease locus when compared with other MMR genes. Long interspersed nuclear element (LINE) repeats, relatively abundant in, for example, MLH1, did not seem to contribute to the genesis of the deletions, presumably because of their older evolutionary age and divergence among individual repeat units when compared with short interspersed nuclear element (SINE) repeats, including Alu repeats. Moreover, Southern blot analysis of the introns and the genomic regions flanking the MMR genes allowed us to detect 6 novel genomic rearrangements that left the coding region of the disease‐causing gene intact. These rearrangements comprised 4 deletions upstream of the coding region of MSH2 (3 cases) and MSH6 (1 case), a 2‐kb insertion in intron 7 of PMS2, and a small (459‐bp) deletion in intron 13 of MLH1. The characterization of these genomic rearrangements underlines the importance of genomic deletions in the etiology of HNPCC and will facilitate the development of PCR‐based tests for their detection in diagnostic laboratories. © 2005 Wiley‐Liss, Inc.
Evidence for a single‐step mechanism in the origin of hyperdiploid childhood acute lymphoblastic leukemia
Authors: Paulsson Kajsa , Mörse Helena , Fioretos Thoas , Behrendtz Mikael , Strömbeck Bodil , Johansson Bertil
Published: June 2005

High hyperdiploidy (>50 chromosomes) in childhood acute lymphoblastic leukemia (ALL) is characterized by nonrandom multiple trisomies and tetrasomies involving in particular chromosomes X, 4, 6, 8, 10, 14, 17, 18, and 21. This characteristic karyotypic pattern, the most common in pediatric ALL, may arise via a tetraploid state with subsequent loss of chromosomes, by sequential gains of chromosomes in consecutive cell divisions, or by simultaneous gain of chromosomes in a single mitosis. These alternatives may be distinguished by investigation of the allelic ratios of loci on the tetrasomic and disomic chromosomes. Previous studies of tetrasomy 21 and of the occurrence of uniparental disomies (UPDs) have suggested that the most likely mechanism is simultaneous gain. However, the other pathways have not been definitely excluded because complete analyses of all disomies and tetrasomies have never been performed. In the present study, we investigated 27 hyperdiploid ALLs by using 58 polymorphic microsatellite markers mapped to 23 of the 24 human chromosomes. Twenty‐six tetrasomies were analyzed (involving chromosomes X, 8, 10, 14, 18, and 21), and the frequency of UPDs was determined in 10 cases. In total, 200 chromosomes were studied. Equal allele dosage was observed in 24 of 26 tetrasomies, and only 7 UPDs were found. These data strongly suggest that hyperdiploidy in childhood ALL generally arises by a simultaneous gain of all additional chromosomes in a single abnormal mitosis. © 2005 Wiley‐Liss, Inc.
Semiparametric Bayesian inference in multiple equation models
Authors: Koop Gary , Poirier Dale J. , Tobias Justin
Published: June 2005

This paper outlines an approach to Bayesian semiparametric regression in multiple equation models which can be used to carry out inference in seemingly unrelated regressions or simultaneous equations models with nonparametric components. The approach treats the points on each nonparametric regression line as unknown parameters and uses a prior on the degree of smoothness of each line to ensure valid posterior inference despite the fact that the number of parameters is greater than the number of observations. We develop an empirical Bayesian approach that allows us to estimate the prior smoothing hyperparameters from the data. An advantage of our semiparametric model is that it is written as a seemingly unrelated regressions model with independent normal–Wishart prior. Since this model is a common one, textbook results for posterior inference, model comparison, prediction and posterior computation are immediately available. We use this model in an application involving a two‐equation structural model drawn from the labour and returns to schooling literatures. Copyright © 2005 John Wiley & Sons, Ltd.
Distribution approximations for cointegration tests with stationary exogenous regressors
Authors: Boswijk H. Peter , Doornik Jurgen A.
Published: June 2005

The distribution of a functional of two correlated vector‐Brownian motions is approximated by a Gamma distribution. This functional represents the limiting distribution for cointegration tests with stationary exogenous regressors, but also for cointegration tests based on a non‐Gaussian likelihood. The approximation is accurate, fast and easy to use in comparison with both tabulated critical values and simulated p‐values. The proposed procedure is applied to a UK model investigating purchasing power parity. Copyright © 2005 John Wiley & Sons, Ltd.
A bivariate count data model for household tourism demand
Authors: Hellström Jörgen
Published: June 2005

Households' choice of the number of leisure trips and the total number of overnight stays is empirically studied using Swedish tourism data. A bivariate hurdle approach separating the participation (to travel and stay the night or not) from the quantity (the number of trips and nights) decision is employed. The quantity decision is modelled with a bivariate mixed Poisson lognormal model allowing for both positive as well as negative correlation between count variables. The observed endogenous variables are drawn from a truncated density and estimation is pursued by simulated maximum likelihood. The estimation results indicate a negative correlation between the number of trips and nights. In most cases own price effects are as expected negative, while estimates of cross‐price effects vary between samples. Copyright © 2005 John Wiley & Sons, Ltd.
A note on group colorings
Authors: Král' Daniel , Pangrác Ondřej , Voss Heinz‐Jürgen
Published: June 2005

We study a concept of group coloring introduced by Jaeger et al. We show that the group chromatic number of a graph with minimum degree δ is greater than δ/(2, ln δ) and we answer several open questions on the group chromatic number of planar graphs: a construction of a bipartite planar graph with group chromatic number four and a 3‐colorable planar graph with group chromatic number five are presented. We also observe that several upper bounds on the choice number for various subclasses of planar graphs also translate to the concept of group colorings. © 2005 Wiley Periodicals, Inc. J Graph Theory
An improved synthesis of substituted [11C]toluenes via Suzuki coupling with [11C]methyl iodide
Authors: Hostetler Eric D. , Terry Garth E. , Donald Burns H.
Published: June 2005

Toluene derivatives are often found in drug‐like molecules, and are therefore desirable as radiolabelled moieties. The desire for an alternate to the Stille coupling led us to investigate the feasibility of the Suzuki coupling. We have found the Suzuki coupling route to be a robust alternative to the Stille coupling for the synthesis of functionalized [11C]toluene derivatives from [11C]methyl iodide. The avoidance of potentially toxic tin‐containing by‐products is an added advantage. The products synthesized via Suzuki coupling with [11C]methyl iodide were isolated in generally high yields (56–92%), with high radiochemical purity (>95%) and specific radioactivity (>4000 Ci/mmol) in less than 20 min following production of [11C]methyl iodide. Copyright © 2005 John Wiley & Sons, Ltd.
Synthesis of 2‐[(2‐chloro‐2′‐[18F]fluoroethyl)amino]‐2H‐1,3,2‐oxazaphosphorinane‐2‐oxide (18F‐fluorocyclophosphamide), a potential tracer for breast tumor prognostic imaging with PET
Authors: Lacan Goran , Kesner Amanda L. , Gangloff Anne , Zheng Lei , Czernin Johannes , Melega William P. , Silverman Daniel H. S.
Published: June 2005

A fluorine‐18 labeled analog of the widely used chemotherapeutic agent cyclophosphamide was synthesized as a tracer for prognostic imaging with positron emission tomography. 2‐[(2‐Chloro‐2′‐[18F]fluoroethyl)amino]‐2H‐1,3,2‐oxazaphosphorinane‐2‐oxide (18F‐fluorocyclophosphamide), was prepared by direct halogen exchange reaction from the parent cyclophosphamide. In small‐scale syntheses, radiochemical yields of up to 4.9% and specific activities of 960 Ci/mmol were achieved in a total synthesis time of 60–75 min. The [18F]‐labeled cyclophosphamide analog with radioactive purity >99% and chemical purity >96% was suitable for in vivo (microPET imaging) and ex vivo studies of a murine model of human breast tumors. Copyright © 2005 John Wiley & Sons, Ltd.
Purinergic mediated changes in Ca2+ mobilization and functional responses in microglia: Effects of low levels of ATP
Authors: McLarnon James G.
Published: June 2005

Microglia, the immune effector cells of the brain, are stimulated by a diversity of agents to transiently increase levels of intracellular calcium ([Ca2+]i). Changes in [Ca2+]i induced by compounds such as adenosine triphosphate (ATP) serve important roles in cellular signal transduction linking stimuli with cellular functional responses. Purinergic responses in microglia, like that in other cells, are mediated by two families of receptors classified as P2Y and P2X. Activation of metabotropic receptors (P2YR) leads to increased [Ca2+]i due to depletion of intracellular stores, a process that can trigger activation of Ca2+ entry through plasmalemmal store‐operated channels (SOC). Activation of ionotropic receptors (P2XR) is associated with influx of Na+ and Ca2+ and efflux of K+ through nonselective cationic channels, leading to cellular depolarization. An intriguing property of purinergic stimulation of microglia is the dependence of cellular responses on agonist concentration. As one example, activation of the subtype P2X7R by higher levels of ATP (millimolar range), leads to a marked enhancement in microglial secretion of inflammatory mediators. Other members of the ionotropic P2XR family sensitive to lower levels of ATP, however, are also important in mediating microglial inflammatory responses in brain. At lower concentrations of ATP (100 μM), activation of SOC in human microglia is not only coupled to P2YR‐dependent depletion of internal stores, but is also modulated by ATP binding to a P2XR (not P2X7R). The modulation is consistent with a P2XR‐mediated influx of Na+ and inhibition of SOC by depolarization. In this review, a primary focus is placed on the effects of low concentrations of ATP (≤100 μM) to induce changes in [Ca2+]i and modify functional processes in microglia. In essence, responses mediated by purinergic receptors other than P2X7R are considered. © 2005 Wiley‐Liss, Inc.
Differential effects of acute and subchronic administration on phencyclidine‐induced neurodegeneration in the perinatal rat
Authors: Wang Cheng Z. , Johnson Kenneth M.
Published: June 2005

Acute and subchronic administration of N‐methyl‐D‐aspartate antagonists to rats in the early postnatal period has been reported to produce widespread and selectively cortical neurotoxicity, respectively. To resolve this apparent discrepancy, we sought to clarify these data by determining the dose and temporal and regional characteristics of acute and subchronic phencyclidine (PCP)‐induced neurotoxicity. Measurement of degenerating neurons with the cupric silver technique following a single dose of PCP on postnatal day (PN) 7 revealed that neurodegeneration increased in all areas measured (frontal, parietal and cingulate cortices, striatum, hippocampus, subiculum, and thalamus) within 9 hr. Silver staining peaked at 9–16 hr and was then not detectable or was greatly reduced after 24 hr depending on the specific region. Dose‐response analysis at 9 hr showed that the lowest effective dose was 1, 3, and 10 mg/kg for the frontal cortex, hippocampus, and striatum, respectively. However, repeated PCP administration (10 mg/kg) on PN 7, 9, and 11 elicited an increase in silver staining only in the frontal cortex. To determine whether the loss of effect in the striatum and hippocampus was due to a “tolerance” mechanism or to a developmental phenomenon, we compared the effects of PCP given on PN 7, 9, or 11 with those of two doses given on PN 7 and 9 or three doses administered on PN 7, 9, and 11. Analysis of these experiments shows that both developmental factors and unknown mechanisms of tolerance underlie the apparent selective cortical neurotoxicity observed following subchronic PCP administration in perinatal rat pups. © 2005 Wiley‐Liss, Inc.
Study of volatile compounds of defective virgin olive oils and sensory evaluation: a chemometric approach
Authors: Procida Giuseppe , Giomo Andrea , Cichelli Angelo , Conte Lanfranco S
Published: June 2005

It is well known that olive oils are the only foods whose legal control must also involve sensory evaluation, and that a harmonised protocol is used for this purpose: EEC regulation 2568/91 and an IOOC trade norm of the 1990s introduced a standard method among those used to assess the quality of virgin oils, after which a modified method known as the ‘panel test’ was developed and adopted, firstly by the IOOC and later by the EEC. One problem in applying the panel method often depends on the lack of reference standards for training judges, in addition to, in some cases, a lack of exact knowledge of the origin of some defects; for these reasons, several judges have suggested the unification of some defects, even when these originate from different kinds of problems. In this paper we have applied headspace analyses to a number of samples of oils that were also characterised by a panel. Besides the samples, standard defective oils obtained by the IOOC and used for training sensory judges were also analysed, with the aim of obtaining a model for use in method validation. Seventy‐six peaks were detected and most of them identified by gas chromatography/mass spectrometry; their distribution was different in the samples characterised by different defects as assessed by the panel test. The well‐known compounds of virgin olive oils were detected, including the series of C6 compounds, whose importance in defining positive (‘green’ flavour) and negative (rancid) characteristics of olive oils is well known. No samples classified as extra virgin ever present peaks with magnitudes as great as those found in defective oils. Chemometric data evaluation was carried out and samples were clustered on the basis of the headspace composition; the results were found to agree with those of the panel test, so a number of compounds were related to the presence of particular defects. Copyright © 2005 Society of Chemical Industry
Application of pure and mixed probiotic lactic acid bacteria and yeast cultures for oat fermentation
Authors: Angelov Angel , Gotcheva Velitchka , Hristozova Tsonka , Gargova Stoyanka
Published: June 2005

Fermentation of a prebiotic containing oat substrate with probiotic lactic acid bacteria and yeast strains is an intriguing approach for the development of new synbiotic functional products. This approach was applied in the present work by using pure and mixed microbial cultures to ferment a heat‐treated oat mash. Results show that the strains studied were appropriate for oat fermentation and the process could be completed for 6–10 h depending on the strain. The viable cell counts achieved within this time were above the required levels of 106–107 cfu ml−1 for probiotic products. Both single lactic acid bacteria strains and mixed cultures of the same strains with yeast were found suitable for oat fermentation. However, the pure LAB cultures attributed better flavour and shelf life of the oat drinks. The content of the prebiotic oat component beta‐glucan remained within 0.30–0.36% during fermentation and storage of the drinks obtained with each of the strains used. Thus, these products would contribute diet with the valuable functional properties of beta‐glucan. Also, the viability of pure and mixed cultures in the oat products was good: levels of cell counts remained above the required numbers for probiotic products throughout the estimated shelf‐life period. Copyright © 2005 Society of Chemical Industry
Processing, Morphology, and Mechanical Properties of Liquid Pool Polypropylene with Different Molecular Weights
Authors: Stern Claudia , Frick Achim R. , Weickert Günter , Michler Goerg H. , Henning Sven
Published: June 2005

Summary: The processability, morphology, and resulting mechanical properties of novel polypropylene (PP) samples of varying molecular weight ($\overline M _{\rm w}$) were studied. A series of homopolymer PP in a wide $\overline M _{\rm w}$ range from 101 000 to 1 600 000 g · mol−1 was polymerised in a liquid pool (LP) under defined conditions. The LP‐PP with a well‐known polymerisation history was manufactured into micro dumbbell specimens by means of a micro injection‐moulding process. The morphology and mechanical properties of the samples were studied by light microscopy, transmission and scanning electron microscopy, and a quasi‐static tensile test. Simulation of the filling behaviour of the molten polymer inside the mould shows that the shear rate increases as the molecular weight increases, up to a maximum shear rate of 750 000 s−1. In addition, the present crystallisation time of the high‐molecular‐weight PP samples is clearly lower than their retardation time; the long macromolecules do not have sufficient time to retard while cooling. As a result of the shear‐induced crystallisation, a highly oriented crystalline structure is formed as a function of the acting shear rate. SEM and TEM investigations show the existence of an oriented shish kebab structure. The density of the shish kebab increases as the molecular weight increases. Evaluations of the shear rate and the morphological structure indicate a critical shear rate of about 300 000 s−1. Above this shear rate level, shish kebab structures are favourably formed. The shear‐induced crystallisation and, therefore, the preferred formation of a highly oriented shish kebab structure lead, obviously, to unusual solid‐state properties of the analysed LP‐PP samples. With a tensile strength up to 100 N · mm−2 and an attainable strain at break of more than 30%, the mechanical performance is much higher than results ever reported in literature.

True strain–stress behaviour of moulded the LP‐PP samples of different molecular weight.

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True strain–stress behaviour of moulded the LP‐PP samples of different molecular weight.
A calculus for ideal triangulations of three‐manifolds with embedded arcs
Authors: Amendola Gennaro
Published: June 2005

Refining the notion of an ideal triangulation of a compact three‐manifold, we provide in this paper a combinatorial presentation of the set of pairs (M,α), whereMis a three‐manifold andαis a collection of properly embedded arcs. We also show that certain well‐understood combinatorial moves are sufficient to relate to each other any two refined triangulations representing the same (M,α). Our proof does not assume the Matveev–Piergallini calculus for ideal triangulations, and actually easily implies this calculus. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Diff(Rn) as a Milnor–Lie group
Authors: Glöckner Helge
Published: June 2005

We describe a construction of the Lie group structure on the diffeomorphism group Diff(Rn), modelled on the space D(Rn,Rn) of Rn‐valued test functions on Rn, in John Milnor's setting of infinite‐dimensional Lie groups. New tools are introduced to simplify this task. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Retracted: Blow‐up results for evolution problems on ℝn
Authors: Hakem Ali
Published: June 2005

Retraction: The article “Blow‐up results for evolution problems on ℝn”, Math. Nachr. 278, 1033–1040 (2005); DOI 10.1002/mana.200310289 by Ali Hakem, published online on 8 June 2005 in Wiley Online Library (wileyonlinelibrary.com) has been retracted. The retraction is due to an identical publication in another journal, namely Bull. Belg. Math. Soc. – Simon Stevin, 12 (2005), no. 1, 73–82 and agreed by the author, the journal Editors‐in‐Chief and Wiley.
Second homology of Lie superalgebras
Authors: Iohara Kenji , Koga Yoshiyuki
Published: June 2005

The second homology of Lie superalgebras over a field of characteristic 0 extended over a supercommutative superalgebra A and their twisted version are obtained. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
$\bar \partial $‐energy integral and uniqueness of harmonic maps
Authors: Yao Guowu
Published: June 2005

In this paper, we introduce a new energy functional, $\bar \partial $‐energy functional, instead of the total energy functional to investigate the uniqueness of harmonic maps with respect to any given metric on the unit disk. Even in the setting that the Hopf differentials of harmonic maps are not integrable, certain uniqueness theorems of harmonic maps are obtained, which improve a result due to Marković and Mateljević in 1999. Moreover, a generalized energy‐minimizing property of harmonic maps is discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Convenient Method of Chain‐Growth Polycondensation for Well‐Defined Aromatic Polyamides
Authors: Yokozawa Tsutomu , Muroya Daichi , Sugi Ryuji , Yokoyama Akihiro
Published: June 2005

Summary: For the convenient synthesis of well‐defined poly(N‐octyl‐p‐benzamide)s with low polydispersities, the polycondensation of methyl 4‐octylaminobenzoate (1) was investigated. Methyl ester monomer 1 polymerized with lithium 1,1,1,3,3,3‐hexamethyldisilazide (LHMDS) in the presence of an initiator in tetrahydrofuran at −10 °C. The highly pure polyamide with a defined molecular weight and a low polydispersity is obtained after simple treatment of the reaction mixture with aqueous NaOH solution, followed by evaporation.

The chain‐growth polycondensation of 4‐octylaminobenzoic acid methyl ester (1) with lithium 1,1,1,3,3,3‐hexamethyldisilazide (LHMDS) to yield poly(N‐octyl‐p‐benzamide).

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The chain‐growth polycondensation of 4‐octylaminobenzoic acid methyl ester (1) with lithium 1,1,1,3,3,3‐hexamethyldisilazide (LHMDS) to yield poly(N‐octyl‐p‐benzamide).
Crosslinkable Composite Spheres and Capsules Synthesized by Heterocoagulation
Authors: Liu Xiyan , Niu Zhongwei , Xu Huifang , Guo Meili , Yang Zhenzhong
Published: June 2005

Summary: Crosslinkable composite microspheres were prepared by heterocoagulation of epoxy resin nanoparticles onto polystyrene microspheres. The corresponding hollow microspheres were created after removal of the core. The surface morphology was tunable from smooth to rough by controlling the degree of crosslinking of the shell nanoparticles. A positively charged polyelectrolyte could be easily adsorbed onto the composite microspheres to facilitate further synthesis, e.g., layer‐by‐layer deposition and a sol‐gel process to form inorganic materials.

An SEM image of the PS/EP/silica (where the EP was crosslinked slowly) microspheres after the cores have been removed.

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An SEM image of the PS/EP/silica (where the EP was crosslinked slowly) microspheres after the cores have been removed.
A Closed‐Loop Phase Diagram in a Weakly Interacting Polyolefin Copolymer Binary Blend System
Authors: Hu Haiqing , Chong Chuanbo , He Aihua , Zhang Chenggui , Fan Guoqiang , Dong Jin‐Yong , Han Charles C.
Published: June 2005

Summary: The phase behavior of poly(ethylene‐co‐styrene) (PES) and poly(ethylene‐co‐butene) (PEB) blends has been studied. A closed‐loop phase diagram was clearly observed in this weakly interacting system as the styrene content in the PES decreased to about 1 mol‐%. At higher styrene contents, the phase loop starts to interplay with the crystallization transformation at lower temperatures.

Phase diagram of PEB/PES blends. Phase boundary line is only for easy demonstration.

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Phase diagram of PEB/PES blends. Phase boundary line is only for easy demonstration.
The maximum likelihood estimate in reduced‐rank regression
Authors: Eldén Lars , Savas Berkant
Published: June 2005

In previous work by Stoica and Viberg the reduced‐rank regression problem is solved in a maximum likelihood sense. The present paper proposes an alternative numerical procedure. The solution is written in terms of the principal angles between subspaces spanned by the data matrices. It is demonstrated that the solution is meaningful also in the case when the maximum likelihood criterion is not valid. A numerical example is given. Copyright © 2005 John Wiley & Sons, Ltd.
Response of metastatic recurrent neuroblastoma to nitisinone: A modulator of tyrosine metabolism
Authors: Kobrinsky Nathan L. , Sjolander Diane E.
Published: June 2005

Nitisinone blocks the tyrosine pathway and may be effective in treating neuroblastoma. A 33‐month‐old male with heavily treated metastatic, recurrent, N‐MYC amplified neuroblastoma received nitsinone (0.8 mg/kg/day escalated to 5.0 mg/kg/day). Dramatic tumor regression and resolution of pain without toxicity were observed. At 10 weeks, the tumor progressed. Nitisinone, low dose cyclophosphamide and doxorubicin subsequently produced a very good partial response. At 18 months the disease progressed. The child succumbed 21 months after starting nitisinone. Nitisinone produced an increase in tyrosine and catecholamine metabolite (HVA, VMA, and metanephrines) levels. Nitisinone may be a promising agent in metastatic neuroblastoma. Pediatr Blood Cancer 2006, 46:517–520. © 2005 Wiley‐Liss, Inc.
Bioartificial dextran and poly[ethylene‐co‐(vinyl alcohol)] hybrid sponges as support for proteins
Authors: Silvestri D , Barbani N , Ciardelli G , Bertoni F , Coluccio ML , Cristallini C , Giusti P
Published: June 2005

A biological–synthetic hybrid material was prepared as a support for proteinic molecules. To control the conformational stability and ‘vitality’ of the entrapped compound, an enzyme, which catalyses a chemical reaction, was chosen. The physical immobilisation of α‐amylase on a novel biological–synthetic hybrid material was realised using a synthetic (poly[ethylene‐co‐(vinyl alcohol)]) and a biological (dextran) component. The supports were obtained in the form of porous sponges using the phase inversion process. The kinetic parameters of enzymatic hydrolysis of soluble starch were obtained by determining the maltose (reaction product) concentration in the test solution by a spectrophotometric method. A high amount of enzyme (10 and 15 mg per g of polymer matrix) was successfully entrapped in the polymer support and a rather good enzyme activity of entrapped α‐amylase and a constant activity for repeated use, compared with native α‐amylase, were observed. The results obtained clearly indicated that the bioartificial polymer sponges, showing an immobilisation of α‐amylase with maintenance of the catalytic function of the enzyme, can be used as suitable supports for proteins. Copyright © 2005 Society of Chemical Industry
Benzoxazine–epoxy copolymers: effect of molecular weight and crosslinking on thermal and viscoelastic properties
Authors: Rao BS , Rajavardhana Reddy K , Pathak Sandeep K , Pasala AR
Published: June 2005

Bisphenol‐A‐based benzoxazine was copolymerized with epoxy and chain‐extended epoxies in order to study the effect of molecular weight on cured resin properties. Cure behaviour of the copolymers was studied using differential scanning calorimetry, which indicated a single exothermic curing peak at 248 °C. Dynamic mechanical thermal analysis was used to study the viscoelastic properties of the cured resins. A decrease in tan δ peak position and an increase in storage modulus and tan δ peak height were observed due to chain extension. Higher char yield was observed for the copolymer chain extended with tetrabromobisphenol‐A. Copyright © 2005 Society of Chemical Industry
Mechanical properties of epoxy resin/hydroxyl‐terminated polyester blends: effect of two‐phase structure
Authors: Liu Yimin , Zhang Weidong , Zhou Hongwei
Published: June 2005

In this paper, the effect of two‐phase structure on the mechanism of rubber‐toughening of epoxy resins was studied. Three types of hydroxyl‐terminated polyesters with different molecular weights were synthesized in order to modify epoxy resins to obtain single‐phase (P‐1), critical phase separation (P‐2) and two‐phase (P‐3) structures. The results of dynamical mechanical analysis and scanning electron microscopy distinguished the dissolved and phase‐separated polyesters in the epoxy matrix. The P‐1 system showed the highest dissolved content of polyester in the epoxy matrix, while the P‐3 system exhibited the lowest content. Both dissolved and phase‐separated polyesters proved to be capable of increasing the toughness of modified epoxy resins. The phase‐separated polyester was found to contribute much more to the improvement of toughness. Copyright © 2005 Society of Chemical Industry