bluuebunny/crossref_metadata_2025 huggingface dataset:
Asymmetric Cobaltacarboranes [6,6'-μ-R-S(1,7-C2B9H10)2-2-Co] with a Monosulfur Bridge between Ligands and HPLC Resolution of the Enantiomers
Authors: Plešek Jaromír , Grüner Bohumír , Fusek Jiří , Votavová Hana
Published: April 2003

On treatment of the [2-Co-(1,7-C2B9H11)2- ion with elemental sulfur and AlCl3 only the racemic form of the [6,6'-μ-S(1,7-C2B9H10)2-2-Co] ion is obtained in high yield. Methylation of this ion proceeds at the sulfur bridge giving rise to the zwitterionic complex [6,6'-μ-MeS(1,7-C2B9H10)2-2-Co]. Constitution of both species has been established by high-field NMR methods and confirmed by resolution to enantiomers by HPLC on chiral stationary phase.
Synthesis and Antiviral Activity of Acyclic Nucleoside Analogues of 5-Methoxymethyl-6-methyluracil and 4-Alkylamino-5-methoxymethyl-6-methyl-2(1H)-pyrimidinones
Authors: Bhat Sunita
Published: April 2003

The uracil derivatives 1-(2-hydroxyethoxymethyl/allyl/2,3-dihydroxypropyl)-5-methoxymethyl-6-methyluracils (Vb, VIII, XI) and 4-alkylamino-1-(2- hydroxyethoxymethyl/allyl/2,3-dihydroxypropyl)-5-methoxymethyl-6-methyl-2(1H)-pyrimidinone (VIa - VIc, IXa - IXc, XIIa - XIIc) were synthesized from versatile intermediates 1-(2-benzoyloxyethoxymethyl/allyl/2,3-dihydroxypropyl)-4-methoxy-5-methoxymethyl-2(1H)-pyrimidinone (IVa, Vii, X), respectively. The compounds IVb, Vb, VIa - VIc, VIII, IXa - IXc, XIIa - XIIc were evaluated against Ranikhet disease virus (RDV) at the dose of (0.1 μg/ml); compounds VIa, VIb, IXa, XIIb showed 57, 100, 40, 80% inhibition, respectively.
Acrylate Side Chain Derivatives of 5β-Steroids
Authors: Pouzar Vladimír , Černý Ivan , Drašar Pavel
Published: April 2003

Steroids with 5β-configuration and acrylate 17β-side chain, namely (20E)-3β-hydroxy-5β-pregnane-21-carboxylate (XVI), its 3α-epimer XXVI, and homological ethyl ester XVIII were prepared from 3β-(2-tetrahydropyranyloxy)-21-norpregn-5-en-20-ol (I). The stereoselectivity of key steps was checked. Whereas hydrogenation of 4-en-3-one derivative IV gave exclusively 5β-derivative VI, the subsequent borohydride reduction yielded 3β- and 3α-hydroxy derivatives VII and XI in 1 : 4 ratio. The 3-hydroxy derivatives prepared (XVI, XVIII, and XXVI) were converted to the corresponding hemisuccinates (XX and XXVIII) and β-D-glucopyranosides (XXII, XVIV, and XXX) for latter use in biological studies.
Linear stochastic fluid networks
Authors: Kella Offer , Whitt Ward
Published: April 2003

We introduce open stochastic fluid networks that can be regarded as continuous analogues or fluid limits of open networks of infinite-server queues. Random exogenous input may come to any of the queues. At each queue, a c.d.f.-valued stochastic process governs the proportion of the input processed by a given time after arrival. The routeing may be deterministic (a specified sequence of successive queue visits) or proportional, i.e. a stochastic transition matrix may govern the proportion of the output routed from one queue to another. This stochastic fluid network with deterministic c.d.f.s governing processing at the queues arises as the limit of normalized networks of infinite-server queues with batch arrival processes where the batch sizes grow. In this limit, one can think of each particle having an evolution through the network, depending on its time and place of arrival, but otherwise independent of all other particles. A key property associated with this independence is the linearity: the workload associated with a superposition of inputs, each possibly having its own pattern of flow through the network, is simply the sum of the component workloads. As with infinite-server queueing models, the tractability makes the linear stochastic fluid network a natural candidate for approximations.
The Brownian excursion multi-dimensional local time density
Authors: Gittenberger Bernhard , Louchard Guy
Published: April 2003

Expressions for the multi-dimensional densities of Brownian excursion local time are derived by two different methods: a direct method based on Kac's formula for Brownian functionals and an indirect one based on a limit theorem for Galton–Watson trees.
Recurrent ring dynamics in two-dimensional excitable cellular automata
Authors: Gravner Janko
Published: April 2003

TheGreenberg–Hastings model(GHM) is a simple cellular automaton which emulates two properties of excitable media: excitation by contact and a refractory period. We study two ways in which external stimulation can makeringdynamics in the GHM recurrent. The first scheme involves the initial placement of excitation centres which gradually lose strength, i.e. each time they become inactive (and then stay inactive forever) with probability 1 −pf. In this case, the density of excited sites must go to 0; however, their long–term connectivity structure undergoes a phase transition aspfincreases from 0 to 1. The second proposed rule utilizes continuous nucleation in that new rings are started at every rested site with probabilityps. We show that, for smallps, these dynamics make a site excited about everyps−1/3time units. This result yields some information about the asymptotic shape of a closely related random growth model.
Modelling hierarchical systems by a continuous-time homogeneous Markov chain using two-wave panel data
Authors: Carette Philippe
Published: April 2003

An open hierarchical (manpower) system divided into a totally ordered set of k grades is discussed. The transitions occur only from one grade to the next or to an additional (k+1)th grade representing the external environment of the system. The model used to describe the dynamics of the system is a continuous-time homogeneous Markov chain with k+1 states and infinitesimal generator R = (rij) satisfying rij = 0 if i > j or i + 1 < j ≤ k (i, j = 1,…,k+1), the transition matrix P between times 0 and 1 being P = expR. In this paper, two-wave panel data about the hierarchical system are considered and the resulting fact that, in general, the maximum-likelihood estimated transition matrix cannot be written as an exponential of an infinitesimal generator R having the form described above. The purpose of this paper is to investigate when this can be ascribed to the effect of sampling variability.
On some equalities of laws for Brownian motion with drift
Authors: Imhof J. P.
Published: April 2003

A trivariate equality of laws given by Doney and Yor is extended to a quadrivariate version. Some related explicit density calculations are carried out. It is shown that a bivariate case which has been used to establish the Dassios–Port–Wendel equality of laws is in fact equivalent to it.
The random triangle model
Authors: Jonasson Johan
Published: April 2003

The random triangle model is a Markov random graph model which, for parametersp∊ (0,1) andq≥ 1 and a graphG= (V,E), assigns to a subset, η, ofE, a probability which is proportional top|η|(1-p)|E|-|η|qt(η), wheret(η) is the number of triangles in η. It is shown that this model has maximum entropy in the class of distributions with given edge and triangle probabilities.

Using an analogue of the correspondence between the Fortuin-Kesteleyn random cluster model and the Potts model, the asymptotic behavior of the random triangle model on the complete graph is examined forpof ordern−α, α > 0, and different values ofq, whereqis written in the formq= 1 +h(n) /n. It is shown that the model exhibits an explosive behavior in the sense that ifh(n) ≤clognforc< 3α, then the edge probability and the triangle probability are asymptotically the same as for the ordinaryG(n,p) model, whereas ifh(n) ≥c' lognforc' > 3α, then these quantities both tend to 1. For critical values,h(n) = 3α logn+o(logn), the probability mass divides between these two extremes.

Moreover, ifh(n) is of higher order than logn, then the probability that η =Etends to 1, whereas ifh(n) =o(logn) and α > 2/3, then, with a probability tending to 1, the resulting graph can be coupled with a graph resulting from theG(n,p) model. In particular these facts mean that for values ofpin the range critical for the appearance of the giant component and the connectivity of the graph, the way in which triangles are rewarded can only have a degenerate influence.
Partial orders and minimization of records in a sequence of independent random variables
Authors: Gouet Raúl , San Martín Jaime
Published: April 2003

Given independent random variables X1,…,Xn, with continuous distributions F1,…,Fn, we investigate the order in which these random variables should be arranged so as to minimize the number of upper records. We show that records are stochastically minimized if the sequence F1,…,Fn decreases with respect to a partial order, closely related to the monotone likelihood ratio property. Also, the expected number of records is shown to be minimal when the distributions are comparable in terms of a one-sided hazard rate ordering. Applications to parametric models are considered.
Approximations of boundary crossing probabilities for a Brownian motion
Authors: Novikov Alex , Frishling Volf , Kordzakhia Nino
Published: April 2003

Using the Girsanov transformation we derive estimates for the accuracy of piecewise approximations for one-sided and two-sided boundary crossing probabilities. We demonstrate that piecewise linear approximations can be calculated using repeated numerical integration. As an illustrative example we consider the case of one-sided and two-sided square-root boundaries for which we also present analytical representations in a form of infinite power series.
Rearing in different photic and spectral environments changes the optomotor response to chromatic stimuli in the cichlid fish Aequidens pulcher
Authors: Kröger Ronald H. H. , Knoblauch Bettina , Wagner Hans-Joachim
Published: April 2003

Developmental plasticity of spectral processing in vertebrates was investigated in fish by using an innate behavior, the optomotor response. Rearing blue acara (Aequidens pulcher; Cichlidae) under white lights of different intensities as well as deprivation of long wavelengths induced significant changes in the animals' responses to chromatic stimuli. Deprivation of short wavelengths had no effect. With this and previous studies on animals reared under similar conditions, we have demonstrated that developmental plasticity in spectral processing is present at a wide range of neural levels, spanning from photoreceptors to behavior. We hypothesize that earlier studies did not reveal such effects because of the rearing and testing conditions used.
Polyamines as olfactory stimuli in the goldfish Carassius auratus
Authors: Rolen S. H. , Sorensen P. W. , Mattson D. , Caprio J.
Published: April 2003

Electrophysiological responses of goldfish olfactory receptor neurons(ORNs) and goldfish behavioral responses to polyamines were investigated in vivo. Electro-olfactogram (EOG) recordings indicated that polyamines (putrescine, cadaverine and spermine) are potent olfactory stimuli for goldfish with estimated electrophysiological thresholds of 10–8–10–7 mol l–1,similar to that for L-arginine, the most stimulatory amino acid. Although thresholds were similar, the magnitude of the EOG responses to intermediate(10–5–10–4 mol l–1)and high (10–3 mol l–1) concentrations of polyamines dwarfed the responses to amino acids and related single amine containing compounds (amylamine and butylamine). The EOG responses to 0.1 mmol l–1 putrescine, cadaverine and spermine were, respectively,4.2×, 4.3× and 10.3× the response of the standard, 0.1 mmol l–1 L-arginine. Electrophysiological cross-adaptation experiments indicated that polyamine receptor sites are independent from those to L-amino acids (alanine, arginine, glutamate, lysine, methionine and ornithine), bile salts (sodium taurocholate and taurolithocholate), the single amine containing compounds (amylamine and butylamine) and ATP. Further, the cross-adaptation experiments revealed the existence of independent receptor sites for the different polyamines tested. Pharmacological experiments suggested that polyamine odorant transduction does not primarily involve the cyclic AMP and IP3 second messenger pathways. Behavioral assays indicated that polyamines are attractants that elicit feeding behavior similar to that elicited by L-amino acids.
Thermal windows on the trunk of hauled-out seals: hot spots for thermoregulatory evaporation?
Authors: Mauck Björn , Bilgmann Kerstin , Jones Daryl D. , Eysel Ulf , Dehnhardt Guido
Published: April 2003

Seals have adapted to the high heat transfer coefficient in the aquatic environment by effective thermal insulation of the body core. While swimming and diving, excess metabolic heat is supposed to be dissipated mainly over the sparsely insulated body appendages, whereas the location of main heat sinks in hauled-out seals remains unclear. Here, we demonstrate thermal windows on the trunk of harbour seals, harp seals and a grey seal examined under various ambient temperatures using infrared thermography. Thermograms were analysed for location, size and development of thermal windows. Thermal windows were observed in all experimental sessions, shared some common characteristics in all seals and tended to reappear in similar body sites of individual seals. Nevertheless, the observed variations in order and location of appearance,number, size and shape of thermal windows would imply no special anatomical site for this avenue of heat loss. Based on our findings, we suggest that, in hauled-out seals, heat may be transported by blood flow to a small area of the wet body surface where the elevation of temperature facilitates evaporation of water trapped within the seals' pelages due to increased saturation vapour pressure. The comparatively large latent heat necessary for evaporation creates a temporary hot spot for heat dissipation.
Sustainable Network Design: A Commercial Fabric Case Study
Authors: Mehalik Matthew M.
Published: April 2003

I use an actor-network perspective to analyze a case study of an environmentally sustainable, commercial textile fabric design. Susan Lyons of DesignTex, Inc., William McDonough of William McDonough and Partners, and Albin Käin of Rohner Textil AG constructed and maintained a network of people and objects with an environmental focus by anticipating contingencies that continually threatened their network, such as waste disposal, credibility, and financial problems. In response to these contingencies, they developed and implemented environmental tools, such as an environmental design protocol, a life-cycle development (LCD) methodology, environmental cost accounting procedures, product-evaluation metrics, and employee-management systems. The success of their efforts rests on their ability to recruit network allies by integrating these environmental tools.
Just-in-Time Manufacturing and Pollution Prevention Generate Mutual Benefits in the Furniture Industry
Authors: Klassen Robert D.
Published: April 2003

Managing the natural environment is becoming increasingly important to manufacturing firms; yet managers are also being asked to simultaneously make changes to improve their firms' competitiveness. Just-in-time (JIT) manufacturing has long emphasized reducing waste. Similarly, pollution prevention stresses reducing pollutants before they are created. During field work in five furniture manufacturing firms and a subsequent survey in 1994, I observed links between investment in JIT and improved environmental performance. More surprising, I also found that an emphasis on pollution prevention, instead of pollution control, improved delivery performance. Thus, production and environmental managers should pursue JIT and pollution prevention as complementary initiatives that can improve performance along multiple dimensions.
A Decision Support System for Planning Remanufacturing at Nortel Networks
Authors: Linton Jonathan D. , Johnston David A.
Published: April 2003

We developed a decision support system (DSS) for Nortel Networks, an international digital and internet network equipment manufacturer, to improve its planning of its remanufacturing operations for circuit assemblies. This has resulted in economic benefits to the company during the past three years. The system embodies a reverse-logistics model that allows decision makers to better plan the outbound and inbound product flows involved in making design changes. Careful modeling of the decision-making process and its embodiment in appropriate information technology were keys to the successful implementation of the project in Nortel's operations.
A female case of Sedaghatian type spondylometaphyseal dysplasia
Authors: Foulds Nicola , Fairhurst Jo , Temple I. Karen , Cade Steven , Groves Charlotte , Lancaster Tessa
Published: April 2003

Sedaghatian type spondylometaphyseal dysplasia is a rare osteochondrodysplasia first described in 1980. The original report describes an Iranian infant with mild rhizomelic limb shortening, severe metaphyseal cupping and irregularity and platyspondyly who died shortly after birth. The baby was born to a consanguineous couple who had reportedly had two similarly affected infants, one male and one female. No documented radiology is available on the female infant. Since this publication, 10 further case reports of male infants with this condition have appeared in the literature all of whom have died shortly after birth. We report a fully documented female case of Sedaghatian type spondylometaphyseal dysplasia providing further evidence to support an autosomal recessive mechanism of inheritance. © 2003 Wiley‐Liss, Inc.
Portal hypertension in Williams syndrome: Report of two patients
Authors: Casanelles Miguel Del Campo , Gil‐Fernández Juan José , Casero Luis F. Magano , Bengoechea Manuel García , Serrano Rosario , Rañada José María Fernández , Jurado Luis Alberto Pérez
Published: April 2003

Williams or Williams‐Beuren syndrome (WBS) is a developmental disorder with multisystemic manifestations characterized by distinctive facial features, mental disability with unique cognitive and personality profiles, vascular stenoses, growth retardation, and occasional infantile hypercalcemia, caused by haploinsufficiency for genes deleted in chromosome band 7q11.23. However, with the exception of arterial stenoses caused by haploinsufficiency for the elastin gene (ELN), no specific implication of any other gene in the phenotype has been established. We present two patients with portal hypertension leading to splenomegaly and pancytopenia carrying the common 1.5 Mb WBS deletion. We propose this is an additional severe vascular complication of ELN deficiency and discuss the specific characteristics of the portal venous tract that could explain the impact of ELN deficiency in that venous territory. This complication is potentially lethal and should thus be considered in any patient with WBS and splenomegaly. © 2003 Wiley‐Liss, Inc.
Deletion 12q: A second patient with 12q24.31q24.32 deletion
Authors: Plotner Pamela L. , Smith Janice L. , Northrup Hope
Published: April 2003

We report on a 20‐month‐old patient with facial dysmorphisms, microcephaly, cardiac septal defects, global developmental delay, and failure to thrive. Karyotypic evaluation revealed an interstitial deletion of the long arm of one chromosome 12, del(12)(q24.31q24.32). Only one other patient with a similar deletion has been reported previously. By comparing the two patients, we can begin to identify a characteristic phenotypic pattern. © 2003 Wiley‐Liss, Inc.
Bayes' theorem in paleopathological diagnosis
Authors: Byers Steven N. , Roberts Charlotte A.
Published: April 2003

The utility of Bayes' theorem in paleopathological diagnoses is explored. Since this theorem has been used heavily by modern clinical medicine, its usefulness in that field is described first. Next, the mechanics of the theorem are discussed, along with methods for deriving the prior probabilities needed for its application. Following this, the sources of these prior probabilities and their accompanying problems in paleopathology are considered. Finally, an application using prehistoric rib lesions is presented to demonstrate the utility of this method to paleopathology. Am J Phys Anthropol 121:000–000, 2003. © 2003 Wiley‐Liss, Inc.
Synthesis and characterization of some dibutylbis{5‐[(E)‐2‐(aryl)‐1‐diazenyl]‐2‐hydroxybenzoato}tin(IV) compounds. Toxicity studies of di‐ and tri‐organotin complexes on the second instar of Aedes aegypti mosquito larvae
Authors: Basu Baul Tushar S. , Dhar Sushmita , Rivarola Eleonora , Smith Frank E. , Butcher Ray , Song Xueqing , McCain Melodie , Eng George
Published: April 2003

The preparation and spectroscopic characterization of some complexes of the type Bu2Sn(LH)2 (LH = 5‐[(E)‐2‐(aryl)‐1‐diazenyl]‐2‐hydroxybenzoate) are reported. On the basis of spectroscopic evidence (1H, 13C, 119Sn NMR, IR and 119mSn Mössbauer) the compounds were judged to adopt the usual dicarboxylato structural type with a skew trapezoidal arrangement. This was further confirmed by X‐ray crystallography in the case of Bu2Sn(L5H)2 (L5H = 5‐[(E)‐2‐(4‐chlorophenyl)‐1‐diazenyl]‐2‐hydroxybenzoate). Toxicity studies of the di‐ and tri‐organotin compounds on the second larval instar of Aedes aegypti mosquito larvae are reported. Copyright © 2003 John Wiley & Sons, Ltd.
Crystallographic report: Crystal and molecular structure of tetramethylammoniumdiisothiocyanatotriphenyltin(IV), [NMe4SnPh3(NCS)2]
Authors: Okio Kochikpa Y. A. , Diop Libasse , Barry Aliou H. , Jouini Tahar , Ortega Simòn H.
Published: April 2003

The structure of NMe4SnPh3(NCS)2 is molecular, without any significant intermolecular contacts in the lattice. The trigonal plane around the tin atom is defined by three carbon atoms from the phenyl groups and the axial positions occupied by the NCS groups. Copyright © 2003 John Wiley & Sons, Ltd.
Crystallographic report: Crystal structure of tetra(4‐methyl‐5‐imidazole‐carboxyaldehyde)zinc(II) diperchlorate
Authors: Long La‐Sheng , Ren Yan‐Ping , Huang Rong‐Bin , Zheng Lan‐Sun
Published: April 2003

The central zinc(II) atom in the title complex is tetrahedrally coordinated by four nitrogen atoms derived from 4‐methyl‐5‐imidazolecarboxyaldehyde ligands with Zn N in the range 2.007(3) to 2.026(4) Å. Copyright © 2003 John Wiley & Sons, Ltd.
Pendant functional group copolyether sulfones: III. Modified copolyether sulfones with bisphenolic copper chelate
Authors: Cozan Vasile , Butuc Elena , Avram Ecaterina , Airinei Anton
Published: April 2003

New copolyether sulfones having copper(II) chelate units as pendant groups were synthesized by a chemical modification reaction of chloromethylated polysulfones with the sodium salt of copper(II) bis(2,4‐dihydroxybenzaldehyde) in dichloromethane/dimethyl sulfoxide as solvent system, at room temperature. The resulting copolymers were confirmed by IR absorption spectra and characterized by softening points, solubilities, differential scanning calorimetry and thermogravimetric analysis measurements. A slow increase of glass transition temperature values was observed in comparison with the starting chloromethylated polysulfones, and the thermal stability in air showed a slow, but insignificant, decrease. A significant increase in solvent resistance was observed. The glass transition temperature values, which do not exceed 200 °C, provide processing possibilities. Copyright © 2003 John Wiley & Sons, Ltd.
New organotin(IV) derivatives of dipeptides as models for metal–protein interactions: in vitro anti‐tumour activity
Authors: Nath Mala , Pokharia Sandeep , Song Xueqing , Eng George , Gielen Marcel , Kemmer Martine , Biesemans Monique , Willem Rudolph , de Vos Dick
Published: April 2003

New organotin(IV) derivatives with general formulae R2SnL, where R = n−Bu and L is the dianion of glycyltyrosine (H2L‐1), glycyltryptophane (H2L‐2), leucyltyrosine (H2L‐3), leucylleucine (H2L‐4), valylvaline (H2L‐5) and alanylvaline (H2L‐6) have been synthesized in 1 : 1 molar ratio by the reaction of Bu2SnO with the respective dipeptide under azeotropic removal of water. Triphenyltin glycylleucinate was obtained by reacting Ph3SnCl and sodium glycylleucinate with filtration of NaCl formed. The bonding and coordination behaviour in these derivatives are discussed on the basis of IR, multinuclear 1H, 13C and 117Sn magnetic resonance and 119Sn Mössbauer spectroscopic studies. These investigations suggest that all the ligands in R2SnL act as dianionic tridentates coordinating through the COO−, NH2 and Npeptide groups, whereas in Ph3Sn(HL) the ligand acts as a bidentate coordinating through the COO− and NH2 groups. The 119Sn Mössbauer studies, together with the NMR data, indicate that, for the 1 : 1 monomeric derivatives, the polyhedron around tin in R2SnL is a trigonal bipyramid with the butyl groups and Npeptide in the equatorial positions, while the axial positions are occupied by a carboxylic oxygen and the amino nitrogen atom. In Ph3Sn(HL) the structure is intermediate between pseudotetrahedral and cis‐trigonal bipyramidal, with the Namino and two phenyl groups in the equatorial plane and the carboxylate oxygen and the third phenyl group in axial positions. All the complexes have been screened against seven cancer cell lines of human origin, viz. MCF‐7, EVSA‐T, WiDr, IGROV, M19, MEL A498 and H226. Ph3Sn(HL) displays the lowest ID50 values of the tin compounds tested and reported in this paper. Its activity is comparable to those of methotrexate and 5‐fluorouracil. All the di‐n‐butyltin compounds exhibit lower in vitro anti‐tumour activities than Ph3Sn(HL); however, they do provide significantly better activities than etoposide and cis‐platin. Copyright © 2003 John Wiley & Sons, Ltd.
Kinetics of thermal decomposition of unsaturated polyester resins with reduced flammability
Authors: Kicko‐Walczak Ewa
Published: April 2003

In this article, the kinetics of thermal decomposition of unsaturated maleic–phthalic polyester resins, flame‐retarded with zinc hydroxystannate, was studied by thermogravimetric analysis at different heating rates. At the first stage, it was found, on the basis of isoconversional analysis by the methods of Friedman and of Ozawa–Flynn–Wall, that the value of the (apparent) activation energy (E) characteristically changes in three steps during the degradation. Further kinetic studies using nonlinear regression methods revealed the best fits for both pristine and stabilized resins. It was observed that the course of E versus the degree of conversion (α) during degradation of zinc hydroxystannate‐containing resins (α > 0.8) was characterized by higher values of E—this phenomenon can be explained in terms of the flame‐retardation action of zinc hydroxystannate, which is believed to operate primarily in the condensed phase. At the next stage, kinetic analysis by the nonregression method was performed to find the kinetic model [f(α) function] of the decomposition process; hence, for pristine resin, the best fit was found for the Avrami–Yerofeeyev model (nuclei growth), and for stabilized samples, the nth‐order function with catalysis proved to be the best approximation. The obtained kinetic parameters in the form of E, the preexponential factor A, and the model function f(α) allow a prediction of the polyester resin's thermal behavior in an extrapolated range of degree of conversion, time, and temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2851–2857, 2003
Preparation of asymmetric PVA membranes using ternary system composed of polymer and cosolvent
Authors: Kim Sang‐Gyun , Kim Yong‐Il , Yun Hyung‐Gu , Lim Gyun‐Taek , Lee Kew‐Ho
Published: April 2003

Integrally skinned PVA membranes have been prepared from PVA/NMP/water system by the phase inversion method in 2‐propanol bath, and the pervaporation characteristics of these membranes were investigated. With an increase in the NMP content in the polymer solution, the formation of skin layer depended on the NMP content in the cosolvent, and the overall morphology of membranes changed from porous to dense structure. Particularly, PVA membranes showed an asymmetric structure composed of a dense skin layer and a porous sublayer with finger‐like type and cellular structure in solvents of 50–60% NMP compositions. The experimental results from the pervaporation separation of MTBE and methanol mixtures were also in good agreement with the morphology for the formation of skin layer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2884–2890, 2003
The effect of reaction time and temperature during heterogenous alkali deacetylation on degree of deacetylation and molecular weight of resulting chitosan
Authors: Tsaih Ming Larng , Chen Rong H.
Published: April 2003

The objective of the study is to elucidate the effect of reaction time and temperature during heterogenous alkali reaction on degree of deacetylation (DD) and molecular weight (MW) of the resulting chitosans, and to establish the reaction conditions to obtain desired DD and MW chitosan products. Chitin was extracted from red shrimp process waste. DDs and MWs were determined by infrared spectroscopy (IR) and static light scattering, respectively. The results are as follow: The DD and MW of chitin obtained were 31.9% and 5637 kDa, respectively. The DD of the resulting chitosan increased along with reaction time and/or reaction temperature. The DDs of the resulting chitosan that were obtained from 140°C were higher than those reacted at 99°C. The highest DD of the resulting chitosans after alkali deacetylation at 99 and 140°C were 92.2 and 95.1%, respectively. The DDs of chitosans increased fast at the beginning of reaction process then slowed over time. The reaction rate and rate constant of the deacetylation reaction decreased with increasing DD of the reactant. The MWs of chitosans decreased along with the deacetylation time. MW of those chitosans reacted at 140°C are smaller than those at 99°C. The rate of chitosan degradation was above 43.6%/h in the initial stage, then decreased to about 20%/h. The degradation rate constants raised substantially in the late stage. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2917–2923, 2003
Dynamic mechanical properties of styrene‐butadiene rubber vulcanizate filled with electron beam modified surface‐treated dual‐phase filler
Authors: Shanmugharaj A. M. , Bhowmick Anil K.
Published: April 2003

The influence of the electron beam modification of a dual‐phase filler on the dynamic mechanical properties of styrene‐butadiene rubber (SBR) is investigated in the presence and absence of trimethylol propane triacrylate or triethoxysilylpropyltetrasulfide. Electron beam modification of the filler results in reduction of the tan δ at 70°C, a parameter for rolling resistance, and an increase in the tan δ at 0°C, a parameter for wet skid resistance of SBR vulcanizates. These modified fillers give significantly better overall performance in comparison with the control dual‐phase filler. This variation in properties is explained in terms of filler parameters such as the filler structure that leads to rubber occlusion and filler networking. These results are further corroborated using the master curves obtained by the time–temperature superposition principle. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2992–3004, 2003
Dielectric properties and morphology of polymer composites filled with dispersed iron
Authors: Zois Haralampos , Apekis Lazaros , Mamunya Yevgen P.
Published: April 2003

The dielectric properties and the structure of various metal–polymer composites, based on a polymer matrix of polyamide (PA), polyethylene (PE), polyoxymethylene (POM), or blend PE/POM filled with dispersed iron (Fe) particles, have been investigated in this work. In PE–Fe, PA–Fe, and POM–Fe composites the filler spatial distribution is random. In the PE/POM–Fe composites, the polymer matrix is two‐phase and the filler particles are localized only in the POM phase, resulting in an ordered distribution of the dispersed filler particles within the blend. The concentration and frequency dependence of the dielectric permittivity, ε′, and the dielectric loss tangent, tanδ, are described in terms of the percolation theory. The experimental values of the critical exponents (namely, s, r, and y) are in good agreement with those predicted by the theory for the composites with random filler distribution. The PE/POM–Fe composites demonstrate low value of the percolation threshold, PC, and high values of the critical exponents r and y. This is attributed to the specific structure of these composites. A schematic model for the morphology of the composites studied has been proposed. This model explains the peculiar behavior of the PE/POM–Fe composites by assuming ordered distribution of the filler particles in a binary polymer matrix. The proposed model is in good agreement with the results of optical microscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3013–3020, 2003
Network characterization and swelling behavior of chemical hydrogels based on acid‐containing poly(vinyl alcohol)
Authors: Ruiz J. , Mantecón A. , Cádiz V.
Published: April 2003

Poly(vinyl alcohol) (PVA) was modified with phthalic and succinic anhydrides to give vinyl alcohol–vinyl ester copolymers that contain carboxylate groups. These half‐esters were then crosslinked by using the poly‐ (ethylene glycol) (PEG) 400 diglycidylether. Low crosslinker/carboxylate ratios were used to obtain low degrees of crosslinking, so the capacity of the resulting hydrogel to absorb water was high. Water absorption was determined gravimetrically as a function of time at room temperature. The equilibrium swelling ratio and compressive modulus were characterized for all the resulting PVA hydrogels and related to the network structure. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3026–3031, 2003
Age and sex differences in hip joint space among asymptomatic subjects without structural change: Implications for epidemiologic studies
Authors: Lanyon Peter , Muir Kenneth , Doherty Sally , Doherty Michael
Published: April 2003

Objective

The prevalence of hip osteoarthritis (OA) increases significantly with age. Although it is not clear whether joint space loss at the hip is a feature of normal aging or a reflection of the OA process, epidemiologic criteria for OA are based on narrowing alone. The aim of this study was to determine whether changes in joint space width occur with age, and whether there are sex differences, in asymptomatic subjects without hip OA.

Methods

We identified a total of 1,806 subjects who had undergone intravenous urography between 1994 and 1996 and sent a questionnaire to the 1,527 of these subjects who were alive in 1998; 1,031 replies (68%) were received. All radiographs were read by an observer blinded to age, sex, and pain status. Individual radiographic features of OA (narrowing, osteophyte, sclerosis, and cysts) were graded, and an overall qualitative grade was allocated, according to a standard atlas. Minimum joint space width (JSW) was measured by metered caliper to within 0.1 mm. A total of 276 women (mean age 63 years) and 257 men (mean age 64 years) were identified who had never had hip pain (defined as having ever had pain on most days for at least 1 month) and who had no evidence of either joint space narrowing or osteophyte (grade 0, no structural changes). The minimum JSW in either hip was tabulated according to age.

Results

JSW measurement was reproducible (95% confidence limits of agreement) to within ±0.5 mm. At all ages, men had larger JSW than women (3.85 mm in women, 4.19 mm in men, mean difference 0.34 mm; 95% confidence interval [95% CI] 0.24, 0.44). A significant decline in JSW with age was seen in women, with a mean difference between ages 45–54 and 75–84 years of 0.36 mm (95% CI 0.15, 0.58; P = 0.001). No significant change in JSW with age was seen in men (mean difference 0.16 mm; 95% CI −0.11, 0.43). Analysis of an additional 64 women and 61 men who were without hip pain and had overall qualitative grade 1–2 changes gave similar results. Implementing these results to alter the threshold for definition of hip OA in women from ≤2.5 mm to ≤2.2 mm reduced the prevalence of hip OA from 10.6% to 5.6%.

Conclusion

These sex differences in joint space have significant implications in terms of the major emphasis on joint space narrowing in definitions of hip OA. Women also have a significant progressive decline in joint space with age that is not seen in men. This suggests that in women, loss of cartilage may be an age‐related phenomenon that is independent of other aspects of structural change. Consideration should be given to the development of sex‐specific definitions of hip “OA.”
Cellular microchimerism as a lifelong physiologic status in parous women: An immunologic basis for its amplification in patients with systemic sclerosis
Authors: Burastero Samuele E. , Galbiati Silvia , Vassallo Antonia , Sabbadini Maria Grazia , Bellone Matteo , Marchionni Lucia , Smid Maddalena , Ferrero Elisabetta , Ferrari Augusto , Ferrari Maurizio , Cremonesi Laura
Published: April 2003

Objective

To quantitatively measure male DNA in blood from women with systemic sclerosis (SSc) and from controls and to evaluate in vitro the modulation of the microchimeric cell population size following immunologic stimuli that were expected to trigger antigen‐specific T cells.

Methods

A real‐time polymerase chain reaction for a Y chromosome sequence was used to measure male DNA in blood from women with SSc and from controls who gave birth to sons. The in vitro change in the microchimeric cell population size was measured following immunologic stimuli, which were expected to trigger antigen‐specific T cells.

Results

Cellular microchimerism was found in SSc patients and controls, but the absolute amount of male DNA was higher in the patients, and the in vitro addition to blood mononuclear cells of an anti‐CD28 costimulatory signal acted as a powerful amplification of microchimeric cells in 3 patients with SSc but not in controls.

Conclusion

Cellular microchimerism is a physiologic phenomenon in parous women. In SSc patients, cellular microchimerism is accounted for by a higher number of cells that have the characteristics of T lymphocytes specific to maternal allogeneic antigens.
Modifications and oxidation of lipids and proteins in human serum detected by thermochemiluminescence
Authors: Shnizer Sergei , Kagan Tamara , Lanir Amos , Maor Irit , Reznick Abraham Z.
Published: April 2003

Detection of electronically excited species (EES) in body fluids may constitute an important diagnostic tool in various pathologies. Examples of such products are triplet excited carbonyls (TEC), which can be a source for photon emission in the 400–550 nm range. The aim of the present study was to determine the actual contribution of lipid and protein components (protein carbonyls) to photon emission generated by thermochemiluminescence (TCL) during the heating of biological fluids. In this study, a new TCL Photometer device, designed by Lumitest Ltd, Israel, was used. Samples were heated to a constant temperature of 80 ± 0.5°C for 280 s and photon emission was measured at several time points. In order to compare the results of TCL measurements to conventional methods of detecting lipid and protein oxidation, each examined sample was also heated in a waterbath at 80°C for 10–280 s. Lipid and protein oxidation were subsequently measured using conventional methods. The TCL of four polyunsaturated fatty acids (PUFA) with three to six double bonds was measured. The elevation of the PUFA TCL amplitude correlated with the increase in the number of double bonds of PUFA. A correlation between the increase in TCL intensity and protein carbonyl generation in bovine serum albumin (BSA) was also observed. In the venous blood serum, our study showed that an increase of TCL intensity during heating reflected the cleavage of TEC of lipid origin. Our study suggests that biological molecules such as proteins, lipids and other molecules, which may become unstable during heating, are capable of generating EES. We demonstrated that a TCL curve can be used as a kinetic model for measuring oxidative processes, which reflects modifications of different molecules involved in the oxidative stress phenomena. Copyright © 2003 John Wiley & Sons, Ltd.
Engineering a chemical implementation device and an imaging device for detecting chemiluminescence with a Polaroid™ high‐speed detector film: application to influenza diagnostics with the ZstatFlu®‐II test
Authors: Achyuthan Komandoor E. , Pence Lisa M. , Mantell Daniel R. , Nangeroni Paul E. , Mauchan Donald M. , Aitken William M. , Appleman James R. , Shimasaki Craig D.
Published: April 2003

We describe the engineering and product development of the chemiluminescent ZstatFlu®‐II Test kit for influenza diagnostics. The reaction vessel is a chemical implementation device with a polystyrene bottom chamber and a polypropylene top chamber that screw together. The patient's specimen is dispersed in a proprietary diluent and mixed inside the bottom chamber with the influenza viral neuraminidase‐specific substrate, 1,2‐dioxetane‐4,7‐dimethoxy‐Neu5Ac. Neuraminidase catalysis releases the dioxetane. The top chamber contains 40% NaOH and is sealed at the top with an ABS plastic plug‐crush pin assembly. The top chamber floor is 85% thinner at the centre, forming a frangible flap. An automated imaging device serves as an incubator for the chemical implementation devices and also facilitates the piercing of the flap by the crush pin. This action results in NaOH flushing into the bottom chamber, initiating chemiluminescence. The imaging device also exposes the Polaroid™ high‐speed detector film to chemiluminescence. At the end of exposure, the film is automatically processed and ejected. Chemiluminescence from an influenza virus‐positive specimen produces a ‘+’‐shaped white image, archiving the diagnostic outcome. The modular ZstatFlu®‐II test kit components are easily adaptable for the chemiluminescent detection of a wide range of analytes. Copyright © 2003 John Wiley & Sons, Ltd.
Chiral aspects of metabolism of antiinflammatory drug flobufen in human hepatocytes
Authors: Skálová Lenka , Král Radim , Szotáková Barbora , Babú Yogeeta N. , Pichard‐Garcia Lydiane , Wsól Vladimír
Published: April 2003

The metabolism of the nonsteroidal antiinflammatory drug flobufen, 4‐(2′,4′‐difluorobiphenyl‐4‐yl)‐2‐methyl‐4‐oxobutanoic acid, was studied in primary cultures of human hepatocytes prepared by two‐step collagenase perfusion of livers from four donors. Racemic flobufen or its individual enantiomers, R‐(+)‐ and S‐(–)‐flobufen were used as substrates. Aliquots of culture medium were collected during 24‐h incubation. The time‐dependent disappearance of flobufen enantiomers and the formation of metabolites (stereoisomers of dihydroflobufen (DHF)) in hepatocytes were measured by chiral HPLC. The reduction of flobufen in human hepatocytes was stereoselective ((+)‐R‐flobufen was preferentially metabolized) and stereospecific ((2R;4S)‐DHF and (2S;4S)‐DHF stereoisomers were mostly formed). Although the structure of flobufen is different from the profens (2‐arylpropionates), flobufen undergoes chiral inversion in human hepatocytes. The inversion of R‐(+)‐flobufen to S‐(–)‐flobufen predominates. The individual DHF stereoisomers were incubated in hepatocyte cultures and their biotransformation studied. The unidirectional chiral inversion of (2S;4S)‐DHF to (2R;4S)‐DHF and (2R;4R)‐DHF to (2S;4R)‐DHF was observed. Stereoselective oxidation of the DHFs to flobufen was also detected. Thus, flobufen metabolism in primary cultures of human hepatocytes is much more complicated (via chiral inversion and DHF re‐oxidation) than was presumed from a preliminary achiral point of view. Chirality 15:433–440, 2003. © 2003 Wiley‐Liss, Inc.
Synaptology of trigemino‐ and spinothalamic lamina I terminations in the posterior ventral medial nucleus of the macaque
Authors: Beggs J. , Jordan S. , Ericson A.‐C. , Blomqvist A. , Craig A.D.
Published: April 2003

We used the electron microscope to examine lamina I trigemino‐ and spinothalamic (TSTT) terminations in the posterior part of the ventral medial nucleus (VMpo) of the macaque thalamus. Lamina I terminations were identified by anterograde labeling with biotinylated dextran, and 109 boutons on 38 terminal fibers were closely studied in series of ultrathin sections. Five unlabeled terminal boutons of similar appearance were also examined in detail. Three‐dimensional, volume‐rendered computer models were reconstructed from complete series of serial sections for 29 boutons on 10 labeled terminal fibers and one unlabeled terminal fiber. In addition, postembedding immunogold staining for GABA was obtained in alternate sections through 23 boutons. Lamina I TSTT terminations in VMpo generally have several large boutons (mean length = 2.16 μm, mean width = 1.29 μm) that are densely packed with vesicles and make asymmetric synaptic contacts on low‐order dendrites of VMpo neurons (mean diameter 1.45 μm). They are closely associated with GABAergic presynaptic dendrites (PSDs), and nearly all form classic triadic arrangements (28 of 29 reconstructed boutons). Consecutive boutons on individual terminal fibers make multiple contacts with a single postsynaptic dendrite and can show evidence of progressive complexity. Dendritic appendages that enwrap and invaginate the terminal bouton constitute additional anatomic evidence for secure, high‐fidelity synaptic transfer. These observations provide direct ultrastructural evidence supporting the hypothesis that VMpo is a lamina I TSTT thalamocortical relay nucleus in primates that subserves pain, temperature, itch, and other sensations related to the physiological condition of the body. J. Comp. Neurol. 459:334–354, 2003. © 2003 Wiley‐Liss, Inc.
Olivocochlear efferent innervation of the organ of corti in hypothyroid rats
Authors: Cantos Raquel , López Dolores E. , Merchán Jaime A. , Rueda Joaquín
Published: April 2003

Congenital hypothyroidism induces developmental abnormalities in the auditory receptor, causing deafness due to a poor development of the outer hair cells (OHCs) and a lack of synaptogenesis between these cells and the olivocochlear axons. This efferent innervation is formed by two separate systems: the lateral system, which originates in the lateral superior olive (LSO) and reaches the inner hair cells; and the medial system, which originates in the ventral nucleus of the trapezoid body (VNTB) and innervates the OHCs. A previous study carried out in our laboratory showed that in congenitally hypothyroid animals, the neurons which give rise to the efferent system are normal in number and distribution, although smaller in size. The aim of the present work was to study the efferent fibers in the auditory receptor of hypothyroid animals, by means of stereotaxic injections of biotinylated dextran amine in the nuclei that give rise to the olivocochlear system: LSO and VNTB. In hypothyroid animals, injections in LSO gave rise to lateral olivocochlear fibers lacking their characteristic dense terminal arbors, while injections in the VNTB‐labeled fibers terminating in the spiral bundle region, far from the OHCs with which they normally contact. In the latter case, only a small percentage of labeled fibers reached the OHCs area, giving off only two radial branches maximum. Because the number of neurons which develop into the efferent innervation was normal in hypothyroid animals, we conclude that medial fibers may contact a new target. J. Comp. Neurol. 459:454–467, 2003. © 2003 Wiley‐Liss, Inc.