bluuebunny/crossref_metadata_2025 huggingface dataset:
MRI of the brachial plexus in polyneuropathy associated with monoclonal gammopathy
Authors: Eurelings Marijke , Notermans Nicolette C. , Franssen Hessel , Van Es H. Wouter , Ramos Lino M.P. , Wokke John H.J. , Van Den Berg Leonard H.
Published: August 2002

On magnetic resonance (MR) imaging of the brachial plexus increased signal intensity and swelling of the brachial plexus has been found in chronic inflammatory demyelinating polyneuropathy (CIDP). Whether these proximal abnormalities are also present in the distal polyneuropathy associated with monoclonal gammopathy is unknown. Therefore, we performed MR imaging of the brachial plexus in 21 patients with polyneuropathy associated with IgM monoclonal gammopathy (11 IgM with anti‐MAG antibodies, 10 IgM without anti‐MAG antibodies). For comparison we studied 9 patients with polyneuropathy associated with IgG monoclonal gammopathy and 8 patients with CIDP. Among the 30 patients with monoclonal gammopathy, 24 patients had demyelinating polyneuropathy. Among these 24 patients, there was increased signal intensity of the brachial plexus on the T2‐weighted images regardless of whether clinical deficits were generalized or purely distal in location. No association was found with the isotype of the monoclonal gammopathy. Of the 8 patients with CIDP, 5 had brachial plexus abnormalities. None of the 6 patients with axonal polyneuropathy associated with monoclonal gammopathy had such abnormalities. Thus, MR imaging of the brachial plexus shows that the distal demyelinating polyneuropathy associated with monoclonal gammopathy is more generalized than presumed. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1312–1318, 2001
Comparative study of pressure‐flow parameters
Authors: Eri Lars M. , Wessel Nicolai , Tysland Ole , Berge Viktor
Published: August 2002

Methods for quantification of bladder outlet obstruction (BOO) are still controversial. Parameters such as detrusor opening pressure (pdet.open), maximum detrusor pressure (pdet.max), minimum voiding pressure (pdet.min.void), and detrusor pressure at maximum flow rate (Pdet.Qmax) separate obstructed from nonobstructed patients to some extent, but two nomograms, the Abrams‐Griffiths nomogram and the linearized passive urethral resistance relation (LinPURR), are more accepted for this purpose, along with the urethral resistance algorithm. In this retrospective, methodologic study, we evaluated the properties of these parameters with regard to test‐retest reproducibility and ability to detect a moderate (pharmacologic) and a pronounced (surgical) relief of bladder outlet obstruction. We studied the pressure‐flow charts of 42 patients who underwent 24 weeks of androgen suppressive therapy, 42 corresponding patients who received placebo, and 30 patients who had prostate surgery. The patients performed repeat void pressure‐flow examinations before and after treatment or placebo. The various parameters were compared. Among the bladder pressure parameters, Pdet.Qmax seemed to have some advantages, supporting the belief that it is the most relevant detrusor pressure parameter to include in nomograms to quantify BOO. In assessment of a large decrease in urethral resistance, such as after TURp, resistance parameters that are based on maximum flow rate as well as detrusor pressure are preferable. Neurourol. Urodynam. 21:186–193, 2002. © 2002 Wiley‐Liss, Inc.
Computational structural mechanics
Authors: Mang H. A. , Hellmich Ch. , Lackner R. , Pichler B.
Published: August 2002

The three topics selected for this paper are taken from structural engineering with special emphasis on civil engineering. The tool for numerical solutions of the respective engineering problems is the finite element method. The first topic is structural stability. From a design‐orientated viewpoint, it is frequently not necessary to perform a fully non‐linear analysis to obtain stability limits on non‐linear load–displacement paths. Instead, linear eigenvalue problems may be used to compute estimates of such limits. Based on the consistent linearization of the criterion for stability limits on non‐linear load–displacement paths, higher‐order estimation functions can be calculated. The order of the errors resulting from such estimates is defined in an asymptotic sense. An ab initio criterion for identification of the type of loss of stability is presented. The second topic is adaptive finite element analysis of reinforced concrete (RC) shells. It is based on an error estimator applicable to elasto‐plastic problems accounting for hardening as well as softening material behaviour. Essential features of the developed strategy are multi‐surface plasticity theory for constitutive modelling of concrete, consideration of the steel–concrete interaction and a time‐effective calculation scheme allowing restart of the calculation at the increment at which the prespecified error tolerance was found to be exceeded. Results from adaptive ultimate load analyses of a hyperbolic RC cooling tower subjected to dead load and quasistatic wind load are presented. The third topic is the assessment of safety degrees in shotcrete tunnel shells. A hybrid method combining 3D displacement measurements and thermochemomechanical modelling of shotcrete is presented. The material law for shotcrete is cast in the framework of thermodynamics of reactive porous media. In the course of the mentioned hybrid method, displacement fields obtained from interpolation of values measured at measurement points are prescribed as boundary conditions on the outer surface of the investigated part of the tunnel shell. Copyright © 2001 John Wiley & Sons, Ltd.
Numerical analysis of strain localization in metal powder‐forming processes
Authors: Lewis Roland W. , Khoei Amir R.
Published: August 2002

It is well known that strain localization and indeed displacement discontinuity can arise in materials exhibiting plastic behaviour. Indeed such localization is almost certain to occur if strain softening or non‐associated behaviour exists, though it can be triggered even when ideal plasticity is assumed. This study is concerned mainly with the manner in which the numerical discretization process has to be devised so as to capture the localization phenomenon. In this paper, a method is presented for applying the mixed formulation to study the prediction of localization phenomenon in powder‐forming processes. This study is focused on the performance of mixed u−π triangular elements to study their efficiency in indicating localization for various mesh refinements. An adaptive analysis using element elongation is applied in the modelling of strain localization. The numerical results are obtained for a Von Mises yield criterion applied to a multi‐level component, at the final stage of compaction. It is shown that if a correct approximation is used then both the uniform and non‐uniform mesh refinements will converge to the correct answer and clearly indicate the localization phenomenon. It is also observed that an adaptive analysis using element elongation can be effective in the modelling of such phenomena. Copyright © 2001 John Wiley & Sons, Ltd.
Compact ADI method for solving parabolic differential equations
Authors: Dai Weizhong , Nassar Raja
Published: August 2002

A compact alternating direction implicit (ADI) method has been developed for solving two‐dimensional parabolic differential equations. In this study, the second‐order derivatives with respect to space are discretized using the high‐order compact finite differences. The Peaceman‐Rachford ADI method is then used for developing a new ADI scheme. It is shown by the discrete Fourier analysis that this new ADI scheme is unconditionally stable. The method can be generalized to the three‐dimensional case and an unconditionally stable compact Douglas ADI scheme is obtained. The method is illustrated by numerical examples. © 2002 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 18: 129–142, 2002; DOI 10.1002/num.1037
Determination of the triterpenoid, betulinic acid, in Doliocarpus schottianus by HPLC
Authors: Oliveira Brás H. de , Santos Cid A. M. , Espíndola Ana Paula D. M.
Published: August 2002

The isolation, detection and quantification of betulinic acid in Doliocarpus schottianus are described. The isolation from the plant extract was made by column chromatography and centrifugal TLC, and betulinic acid was characterized by spectrometric methods. The detection and quantification were made by HPLC using a C18 column eluted with acetonitrile:water and detected at 210 nm. The results showed that the metabolite accumulates in the bark of the plant, but very small concentrations were also found in the leaves and wood. Copyright © 2002 John Wiley & Sons, Ltd.
Hyperechogenic fetal bowel and Down syndrome. Results of a French collaborative study based on 680 prospective cases
Authors: Simon‐Bouy Brigitte , Muller Françoise ,   the French Collaborative Group
Published: August 2002

Hyperechogenic fetal bowel is prenatally detected by ultrasound during the second trimester of pregnancy in 0.1% to 1.8% of foetuses. It has been described as a normal variant and has often been associated with severe diseases, notably Down syndrome. The aim of the present study was to determine the risk of trisomy 21 in a prospective study of 680 fetuses with hyperechogenic foetal bowel.

Karyotyping was performed on amniotic cells in 632 cases, and outcome was known in 655 cases.

A 2.5% risk of Down syndrome and a 1% risk of other severe chromosomal anomalies were observed. Hyperechogenicity was isolated in 11/17 Down syndrome cases, and associated with other ultrasound anomalies in all seven cases of severe chromosomal anomalies. In conclusion, fetal bowel hyperechogenicity indicates a risk of chromosomal anomalies ten‐fold higher than that expected on the basis of maternal age, therefore justifying invasive procedures. Copyright © 2002 John Wiley & Sons, Ltd.
Sonography of fetal cerebrospinal anomalies
Authors: Pilu Gianluigi , Hobbins John C.
Published: August 2002

Congenital anomalies of the central nervous system (CNS) are among the most frequent malformations. Current ultrasound equipment can give a precise diagnosis of many of these lesions from early gestation. High‐resolution transvaginal probes play a major role both in allowing an early diagnosis and for better defining subtle details of both normal and abnormal cerebral anatomy. The diagnostic accuracy of prenatal ultrasound is, however, heavily dependent upon the expertise of the sonologist, the type of equipment employed, and the time dedicated to the scan. Fetal sonography is effective in identifying neural tube defects, although alpha‐fetoprotein screening seems to give a greater sensitivity. The accuracy of ultrasound in the identification of CNS malformations other than neural tube defects remains unclear because of the ascertainment biases of the few large prospective studies that have been conducted to date. Copyright © 2002 John Wiley & Sons, Ltd.
Low temperature thermal degradation of cellulosic insulating paper in air and transformer oil
Authors: Soares Sandra , Ricardo Nágila M P S , Heatley Frank , Rodrigues Edison
Published: August 2002

The thermal degradation of cellulose in the form of Kraft insulating paper has been studied in air for up to 140 h and in transformer oil for up to 3500 h in the temperature range 60–120 °C using measurements of the degree of polymerization (DP) and (in oil) analysis of furanic degradation products. Degradation was faster in air than in oil. The DP decreased from the original value of 1.2 × 103 to a limiting value in the range of 300–900 depending on temperature and degradation conditions. The variation of the DP with degradation time was consistent with two mechanisms, one in which the first‐order rate constant decreased exponentially with time, and another in which only a limited number of chain bonds were scissionable. The degradation rate was first order in scissionable bonds. The major furanic degradation products were 2‐furaldehyde, 5‐hydroxymethyl‐2‐furaldehyde and furfuryl alcohol. Their concentrations continually increased over the timescale of the experiments.

© 2001 Society of Chemical Industry
Synthesis and characterization of a novel oligosiloxane containing alternative ladderlike structure via charge‐transfer interaction
Authors: Yuan Quan , Ji Shengxiang , Zhang Rongben , He Chaobin , Chung Neal Taishung
Published: August 2002

A novel oligosiloxane containing alternative ladderlike structure involving viologen groups has been prepared via donor–acceptor interaction‐assisted template polymerization. The monomer used as the electron‐donor component, N,N ′‐bis(3‐methyldimethoxyl‐silylpropyl)‐4,4′‐bipyridinium dihexafluorophosphate and its precursor, N,N ′‐bis(3‐methyldimethoxyl‐silylpropyl)‐4,4′‐bipyridinium dibromide were first synthesized successfully in high yield. This oligosiloxane, which displays interesting electrochromic properties, has been characterized by FTIR, UV–vis, 1H NMR, 29Si NMR, X‐ray diffraction (XRD), and vapour pressure osmometry (VPO).

© 2001 Society of Chemical Industry
Free radical copolymerization of methyl methacrylate and allyl acetate Part 2 structure and properties
Authors: Hendrana Sunit , Hill David J T , Perera M C Senake , Pomery Peter J
Published: August 2002

The structure of the product from the free radical bulk copolymerization of methyl methacrylate (MMA) and allyl acetate (AAc) was investigated. The mole fraction of AAc plays an important role in the copolymerization of these two monomers. Molecular weight (MW) and molecular weight distribution (MWD) are completely altered when the feed composition is dominantly AAc. NMR spectroscopy confirmed the incorporation of AAc into the polymer. However, no allyl–allyl linkages were observed at low conversions. Tg was found to be affected by the incorporation of AAc into the polymer.

© 2001 Society of Chemical Industry
Radiation crosslinking of poly(vinyl chloride)/epoxidized natural rubber blend: effect of lead stabilization of the poly(vinyl chloride) phase
Authors: Ratnam Chantara Thevy
Published: August 2002

The irradiation crosslinking of 50/50 poly(vinyl chloride)/epoxidized natural rubber blend was investigated in the presence of 1–5 parts per hundred resin (phr) tribasic lead sulfate (TBLS) with blends prepared at various mixing temperatures. The blends were irradiated using a 3.0 MeV electron accelerator at 0, 100 and 200 kGy irradiation doses. Changes in tensile strength, elongation at break and stress‐strain curves of the blends with the increase TBLS content and blending temperatures were observed before and after irradiation. The results on the tensile properties revealed the inhibition of the irradiation‐induced crosslinking by the TBLS although it stabilizes the blend against thermal and irradiation‐induced degradation. The Fourier transform infrared spectroscopy studies further confirmed these observations. Control on the thermal degradation of the blend during blending found to be crucial in achieving maximum enhancement in blend properties upon irradiation. Evidence from dynamic mechanical analysis was also used to support this contention. Addition of 2 phr TBLS and blending at 150 °C found to be adequate in order to achieve the best enhancement in blend properties through irradiation‐induced crosslinking.

© 2001 Society of Chemical Industry
Synthesis of new polyesters with chelating subunits by solution and interfacial polycondensation
Authors: Ismail M , Mhenni F , Gallo R , Périchaud A
Published: August 2002

New polyesters have been prepared by solution and interfacial polycondensation of acid chlorides obtained from bis‐α,ω‐polymethylene‐[(2‐methoxy)phenoxy]acetic acids, acid‐ether siderophores AE
n (n being the number of methylene units), and diols including bisphenol A, ethylene glycol and propanediol. For interfacial polycondensation, average molecular weights range from 1000 to 4500 g mol−1; at higher temperature the molecular weights increase but the yield is smaller. Differential scanning calorimetry shows Tg ranging from −5 to + 110 °C. Polyesters are crystalline with n  = 6 and amorphous with n  = 2 and 4; in addition, increasing n in AE
n increases molecular weights and Tg values. In solution polycondensation, the average molecular weights are around 3000 g mol−1 and Tg is low.

© 2001 Society of Chemical Industry
Catalysts for the diffusion of photovoltaics — A review of selected programmes
Authors: Berger Wolfgang
Published: August 2002

The diffusion of photovoltaics still rests strongly on the availability of suitable support programmes. This suggests a closer look at their function as a catalyst for the spread of the technology. The paper defines this function, gives hints for the programme design, and identifies six different variables of a catalyst. These are then related to concrete programmes in Germany and Switzerland, the two countries showing the highest diffusion of photovoltaics in Europe. The analysis embraces the ‘1000 Roofs Programme’, ‘rate‐based incentives’, ‘utility programmes’ and ‘large scale photovoltaic programmes’. In spanning the last decade the study provides a historic perspective unfolding from the past to the present. A variety of programmes are compared so as to determine their effect on the actual installation of photovoltaics. The paper elucidates some of the inner structure of programmes and portrays their changing landscape and approaches in space and time. Thus, it may serve as a decision aid for the design of future programmes. Copyright © 2001 John Wiley & Sons, Ltd.
Multifaceted functional behavior assessment for students with externalizing behavior disorders
Authors: Olympia Daniel E. , Heathfield Lora Tuesday , Jenson Willieam R. , Clark Elaine
Published: August 2002

Recent federal mandates have increased interest in the use of functional behavior assessment as a necessary part of initial and ongoing work with students with externalizing behavior disorders. A multifaceted approach to functional behavior assessment provides a comprehensive assessment of both behavioral excesses and deficits commonly found in externalizing behavior disorders and also provides for the linkage of assessment information to educational interventions that can be implemented and monitored in educational settings for students with behavior disorders. The authors, using a variety of empirically derived methods, describe specific components of a multifaceted approach to functional behavior assessment in the context of the widely accepted behavioral excess/deficit model for students with externalizing behavior disorders. Empirically derived and validated methodologies (i.e., indirect data collection and analysis, direct observation and recording of behavior, and use of probes to establish baseline rates and measure impacts of intervention) are described. Technology‐assisted data collection and analysis using computer‐assisted functional behavior assessment interviews and direct observation of behavior using personal digital assistant (PDA) based software are also presented as a means to improve efficiency and reduce time needed to conduct adequate functional behavior assessments. Specific strategies to address academic skill and performance deficits as well as social skills deficiencies in the context of a multifaceted functional behavior assessment are also presented for students with externalizing behavior disorders. © 2002 Wiley Periodicals, Inc.
The complexation of peptides by aminocyclodextrins
Authors: Hacket Frank , Simova Svetlana , Schneider Hans‐Jörg
Published: August 2002

Four β‐cyclodextrins (CDs) were prepared bearing either an (N,N‐dimethylamino)propylamino group (1), an (N‐methyl)‐piperazino group (2) or a benzylamino group (3), or seven methylamino susbtituents (4). Association constants K in water with di‐ and tripeptides reach up to 200 M
−1, and after protection at the N‐terminus up to 680 M
−1. Appreciable binding occurs only in the presence of lipophilic amino acid side‐chains, with preference for this at the C‐terminus. A moderate sequence and side‐chain selectivity is observed with 1, 2 and 3, but less so with the highly charged 4 where ion pairing dominates. Detailed NMR analyses with advanced techniques including T‐ROESY and GHSQC allow full assigment of most 1H and 13C signals, with extraction of many substituent and complexation induced shifts changes (SIS and CIS values, respectively). The CIS values and NOE cross peaks from ROESY experiments provide for insight into the binding modes of selected complexes, indicating, e.g., the simultaneous presence of complexes with a peptide phenyl unit approaching from both the narrow and the wide side of the CD cavity. With 3 one observes self‐inclusion of the pendant phenyl ring within the cavity, and its replacement by analytes such as peptides, or by adamantanecarboxylic acid. The inclusion modes are illustrated with force field simulated structures and many NMR spectra, which are made available in electronic supplements. Copyright © 2001 John Wiley & Sons, Ltd.
Additional material for this paper is available from the epoc website at http://www.wiley.com/epoc: (NMR shift tables; 3D coordinates for molecular structures; 1D‐ and 2D‐NMR spectra)
Synthesis of phosphate end‐functional polymers and application to thermally latent polymeric initiators
Authors: Kim Moon Suk , Sanda Fumio , Endo Takeshi
Published: August 2002

Novel phosphates, O‐p‐(hydroxymethyl)benzyl O,O‐diethyl phosphate (1) and O‐(2‐bromoisobutyryloxymethyl)benzyl O,O‐diethyl phosphate (2) were synthesized by the reaction of diethyl phosphorochloridate with 1,4‐benzenedimethanol and the successive reaction with 2‐bromoisobutyryl bromide in the presence of triethylamine and submitted to the polymerization of ϵ‐caprolactone and methyl methacrylate as the initiators. They afforded phosphate end‐functional poly(ϵ‐caprolactone) and poly(methyl methacrylate) with controlled molecular weights and polydispersity ratios by living ring‐opening polymerization and samarium‐induced polymerization. The polymerization of glycidyl phenyl ether (GPE) was carried out with the phosphate end‐functional polymers as the latent polymeric initiators in the presence of ZnCl2. The polymerization of GPE did not proceed below 90 °C, but it rapidly proceeded to afford poly(GPE) above the temperature. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3832–3840, 2001
Synthesis of proton‐conducting membranes by the utilization of preirradiation grafting and atom transfer radical polymerization techniques
Authors: Holmberg Svante , Holmlund Peter , Wilén Carl‐Eric , Kallio Tanja , Sundholm Göran , Sundholm Franciska
Published: August 2002

The atom transfer radical polymerization (ATRP) of styrene onto poly(vinylidene fluoride)‐graft‐poly(vinylbenzyl chloride) (PVDF‐g‐PVBC) membranes was investigated. Novel membranes were designed for fuel‐cell applications. The benzyl chloride groups in the PVDF‐g‐PVBC membranes functioned as initiators, and a Cu‐based catalytic system with the general formula Cu(n)Xn/ligand [where X is Cl or Br and the ligand is 2,2′‐bipyridyl (bpy)] was employed for the ATRP. In addition, 10 vol % dimethylformamide was added for increased solubility of the catalyst complex in styrene. The system was homogeneous, except for the membrane, when the initiator/copper halide/ligand/monomer molar ratio was 1/1/3/500. As anticipated, the fastest polymerization rate of styrene was observed with the copper bromide/bpy‐based catalyst system. The reaction rate was strongly temperature‐dependent within the studied temperature interval of 100–130 °C. The degree of grafting increased linearly with time, thereby indicating first‐order kinetics, regardless of the polymerization temperature. Furthermore, 120 °C was the maximum polymerization temperature that could be used in practice because the membrane structure was destroyed at higher temperatures. The degree of styrene grafting reached 400% after 3 h at 120 °C. Such a high degree of grafting could not be reached with conventional uncontrolled radiation‐induced grafting methods because of termination reactions. On the basis of an Arrhenius plot, the activation energy for the homogeneous ATRP of styrene was 217 kJ/mol. The prepared membranes became proton‐conducting after sulfonation of the polystyrene grafts. The highest conductivity measured for the prepared membranes was 70 mS/cm, which is comparable to the values normally measured for commercial Nafion membranes. The scanning electron microscopy/energy‐dispersive X‐ray results showed that the membranes had to be grafted through the matrix with both PVBC and polystyrene to become proton‐conducting after sulfonation. In addition, PVDF‐g‐[PVBC‐g‐(styrene‐block‐tert‐butyl acrylate)] membranes were also synthesized by ATRP. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 591–600, 2002; DOI 10.1002/pola.10146
Synthesis and photochemical reaction of cyclic oligomers: Synthesis and photopolymerization of novel C‐methylcalix[4]resorcinarene and p‐alkylcalix[n]arene derivatives containing spiro ortho ether groups
Authors: Nishikubo Tadatomi , Kameyama Atsushi , Kudo Hiroto , Tsutsui Kousuke
Published: August 2002

New photoreactive calixarene derivatives containing spiro ortho ester groups (calixarenes 3a–3c) were synthesized by the reaction of 2‐bromomethyl‐1,4,6‐trioxaspiro[4.4]nonane with 2,8,14,20‐tetramethyl‐4,6,10,12,16,18,22,24‐octakis(carboxymethoxy)calix[4]resorcinarene, 5,11,17,23,29,35‐hexamethyl‐37,38,39,40,41,42‐hexakis(carboxymethoxy)calix[6]arene, and 5,11,17,23,29,35,41,47‐octa‐tert‐butyl‐49,50,51,52, 53,54,55,56‐octakis‐(carboxymethoxy)calix[8]arene, which were prepared by the reaction of C‐methylcalix[4]resorcinarene, p‐methylcalix[6]arene, and p‐tert‐butylcalix[8]arene, respectively. The thermal stability of the obtained calixarene derivatives containing spiro ortho ester groups was examined with thermogravimetric analysis, and it was found that these calixarene derivatives had good thermal stability. The photoinitiated cationic polymerization of spiro ortho ester groups in calixarene derivatives 3a–3c was examined with certain photoacid generators in the film state. Interestingly enough, the reaction of calixarene derivatives did not proceed with only photoirradiation; however, the reaction proceeded smoothly when the photoirradiation was followed by heating. Furthermore, calixarene 3a, composed of a C‐methylcalix[4]resorcinarene structure, showed the highest photochemical reactivity in this reaction system. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1293–1302, 2002
Synthesis of biodegradable copolymers with low‐toxicity zirconium compounds. II. Copolymerization of glycolide with ϵ‐caprolactone initiated by zirconium(IV) acetylacetonate and zirconium(IV) chloride
Authors: Dobrzynski Piotr
Published: August 2002

The aim of this article is to show a new method of copolymerizing glycolide and caprolactone with the low‐toxicity zirconium(IV) acetylacetonate and zirconium(IV) chloride as initiators. Such initiators enabled us to obtain copolymers with very good efficiency and good mechanical properties. The reactivity of the initiators was defined, and the chain‐propagation process was examined. On the basis of an NMR examination and differential scanning calorimetry thermograms, we found that the samples obtained at 100 °C with the initiators were characterized by a segmental chain microstructure, which provided good mechanical properties. When the synthesis was carried out at 150 °C, a more randomized structure was obtained, which caused crucial changes in the properties of the copolymers and decreases in the mechanical properties. Because of their properties, the obtained copolymers could be successfully applied as degradable surgical implants or drug carriers. The results show that the copolymers obtained with zirconium(IV) acetylacetonate and chloride could successfully replace ones obtained in the presence of tin compounds as far as medical applications are concerned. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1379–1394, 2002
Synthesis of fully lower‐rim, carbonate‐bridged calix[8]arenes and their curing behavior
Authors: Sugioka Takuo , Hay Allan S.
Published: August 2002

Novel fully lower‐rim, carbonate‐bridged calix[8]arene derivatives were successfully synthesized in high yield by the condensation of p‐alkyl substituted calix[8]arenes with triphosgene. Different bases and catalysts were used for the preparation depending on the p‐alkyl substituted groups of the calix[8]arenes. The conformational features of the derivatives were examined by 1H NMR analysis. Thermosetting formulations were prepared from a mixture of bisphenol A polycarbonate with calix[8]arene carbonate derivatives using sodium benzoate as a catalyst. Their crosslinking behaviors were studied using differential thermal/thermogravimetric analysis. No glass‐transition temperatures were observed after annealing at 280–300 °C. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1149–1155, 2001
Modeling the reversible addition–fragmentation chain transfer process in cumyl dithiobenzoate‐mediated styrene homopolymerizations: Assessing rate coefficients for the addition–fragmentation equilibrium
Authors: Barner‐Kowollik Christopher , Quinn John F. , Morsley David R. , Davis Thomas P.
Published: August 2002

A full kinetic scheme for the free‐radical reversible addition–fragmentation chain transfer (RAFT) process is presented and implemented into the program package PREDICI®. With the cumyl dithiobenzoate‐mediated bulk polymerization of styrene at 60 °C as an example, the rate coefficients associated with the addition–fragmentation equilibrium are deduced by the careful modeling of the time‐dependent evolution of experimental molecular weight distributions. The rate coefficient for the addition reaction of a free macroradical to a polymeric RAFT species (kβ) is approximately 5 · 105 L mol−1 s−1, whereas the fragmentation rate coefficient of the formed macroradical RAFT species is close to 3 · 10−2 s−1. These values give an equilibrium constant of K = kβ/k−β = 1.6 · 107 L mol−1. Conclusive evidence is given that the equilibrium lies well on the side of the macroradical RAFT species. The high value of kβ is comparable in size to the propagation rate coefficients reported for acrylates. The transfer rate coefficient to cumyl dithiobenzoate is close to 3.5 · 105 L mol−1 s−1. A careful sensitivity analysis was performed, which indicated that the reported rate coefficients are accurate to a factor of 2. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1353–1365, 2001
Synthesis and photoinduced deprotection of calixarene derivatives containing certain protective groups
Authors: Nishikubo Tadatomi , Kameyama Atsushi , Tsutsui Kousuke , Kishimoto Shinichi
Published: August 2002

Calixarene derivatives 1a, 1b, and 1c containing pendant tert‐butoxycarbonyl (t‐BOC) groups were synthesized in 81, 93, and 83% yields, respectively, by the reaction of C‐methylcalix[4]resorcinarene (CRA), p‐methylcalix[6]arene (MCA), and p‐tert‐butylcalix[8]arene (BCA) with di‐tert‐butyl dicarbonate using triethylamine as a base in pyridine. Calixarene derivatives 2a, 2b, and 2c containing pendant trimethylsilyl ether (TMSE) groups were obtained in 58, 50, and 82% yields, respectively, by the reaction of CRA, MCA, and BCA with 1,1,1,3,3,3‐hexamethyldisilazane using chlorotrimethylsilane as an accelerator in tetrahydrofuran. Calixarene derivatives 3a, 3b, and 3c containing pendant cyclohexenyl ether (CHE) groups were also prepared in 65, 78, and 84% yields, respectively, by the reaction of CRA, MCA, and BCA with 3‐bromocyclohexene using potassium hydroxide as a base as well as tetrabutylammonium bromide as a phase‐transfer catalyst in N‐methyl‐2‐pyrolidone. The photoinduced deprotection of calixarene derivatives 1a–c was examined with bis‐[4‐(diphenylsulfonio)phenyl]sulfide bis(hexafluorophosphate) as a photoacid generator on UV irradiation followed by heating in the film state, and it was found that the deprotection of the t‐BOC groups of 1a proceeded smoothly in high conversion. The deprotection rates of the t‐BOC groups of 1b and 1c were much lower than that of 1a under the same irradiation conditions. The photoinduced deprotection of calixarenes 2b–c containing tetramethylsilane groups as well as 3a–c containing CHE groups were also examined under similar reaction conditions in the film state, and it was found that the deprotection rates of calixarenes 2b–c and 3a–c were lower than those of the corresponding 1a–c calixarenes. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1481–1494, 2001
Rare‐earth‐metal‐initiated polymerizations of (meth)acrylates and block copolymerizations of olefins with polar monomers
Authors: Yasuda Hajime
Published: August 2002

The organo‐rare‐earth‐metal‐initiated living polymerization of methyl methacrylate (MMA) was first discovered in 1992 with (C5Me5)2LnR (where R is H or Me and Ln is Sm, Yb, Y, or La) as an initiator. These polymerizations provided highly syndiotactic (>96%) poly(methyl methacrylate) (PMMA) with a high number‐average molecular weight (Mn > 1000 × 103) and a very narrow molecular weight distribution [weight‐average molecular weight/number‐average molecular weight (Mw/Mn) < 1.04] quantitatively in a short period. Bridged rare‐earth‐metallocene derivatives were used to perform the block copolymerization of ethylene or 1‐hexene with MMA, methyl acrylate, cyclic carbonate, or ϵ‐caprolactone in a voluntary ratio. Highly isotactic (97%), monodisperse, high molecular weight (Mn > 500 × 103, Mw/Mn < 1.1) PMMA was first obtained in 1998 with [(Me3Si)3C]2Yb. Stereocomplexes prepared by the mixing of the resulting syndiotactic and isotactic PMMA revealed improved physical properties. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 1955–1959, 2001
Well‐controlled radical copolymerization of styrene with 2‐[(perfluorononenyl)oxy] ethyl methacrylate and characterization of its copolymers
Authors: Zhang Zhaobin , Ying Shengkang , Zhang Qinlai , Xu Xudong
Published: August 2002

The atom transfer radical copolymerization of styrene with 2‐[(perfluorononenyl)oxy] ethyl methacrylate was performed in benzotrifluoride at 100 °C in the presence of 1‐bromoethyl benzene (1‐BrEB), cuprous bromide (CuBr), and α,α′‐bipyridine (bpy; [1‐BrEB]0/[CuBr]0/[bpy]0 = 1/1/3). The experimental results demonstrate that this polymerization proceeded in a living fashion, producing fluorinated random copolymers with narrow polydispersities, controlled molecular weights, and desired unit ratios. The compositions of the copolymers were calculated from 1H NMR spectra. The monomer reactivity ratios were obtained with the Skeist integral method. The copolymers were characterized by gel permeation chromatography, Fourier transform infrared, and differential scanning calorimetry. The solid surface characteristics of the copolymers were evaluated with contact‐angle measurements. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2670–2676, 2001
Temporal scaling analysis: Linear and crosslinked polymers
Authors: Phillies George D. J.
Published: August 2002

An ansatz that predicts the frequency dependence of viscoelastic moduli of polymer solutions was tested against literature data on linear polymers and polymer microgels. Excellent agreement was uniformly found between the ansatz and the experiment. The ansatz does not give a simple reduction scheme or a master plot; it systematizes large amounts of data to a few parameters. The dependence of these parameters on polymer concentration and solvent quality was examined. The ansatz satisfies Kronig–Kramer's relations; transformations of G′(ω) and G″(ω) for a given system lead to the same G(t). © 2002 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 375–386, 2002; DOI 10.1002/polb.10099
Investigation of the relationship of the glass‐transition temperature and the polymer structure by fuzzy set theory
Authors: Sun Hong , Tang Yingwu , Wu Guoshi , Zhang Fushi
Published: August 2002

Fuzzy set theory can be used to study the relationship between the glass‐transition temperature (Tg) and structure of polymers. We used the method to map this relationship and obtained Tg's for 241 polymers with a standard deviation of 20 K (the confidence bound was 90%). We also used the method to predict Tg's for 15 polymers with a standard deviation of 67 K (the confidence bound was 90%). This study demonstrates that fuzzy set theory can be effectively used for determining the quantitative structure–property relationship of polymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 454–459, 2002; DOI 10.1002/polb.10105
Interfacial tension in a lower critical solution temperature blend: Effect of temperature, blend composition, and deformation of the interphase
Authors: Vinckier I. , Schweizer T. , Laun H. M.
Published: August 2002

Interfacial tension is a very important material parameter in two‐phase polymer blends. It determines the morphology development during processing, which is crucial for the end‐use properties of the material. Although different techniques for interfacial tension measurement give comparable results for immiscible polymers, the determination of the interfacial tension in lower critical solution temperature blends is not straightforward. This is illustrated for poly(α‐methyl styrene acrylonitrile)/poly(methyl methacrylate)(PαMSAN/PMMA), a slightly incompatible polymer pair. Interfacial tension has been measured with three different techniques: small‐amplitude oscillatory shear, recovery after elongation, and elongation of a multilayer sample. The large differences in these results can be attributed to the fact that most experimental techniques determine an apparent value, rather than the thermodynamic equilibrium value, of the interfacial tension. The latter is only obtained if the measurement is performed under quiescent conditions on a system that is composed of the coexisting PαMSAN‐rich and PMMA‐rich phases. The apparent interfacial tension depends on the actual composition of the phases and on the deformation of the interface. An order of magnitude approximation for such effects has been derived from theoretical considerations. Finally, each of these apparent values can be of practical importance. If a blend is prepared by melt mixing of the pure polymers, a high apparent value of interfacial tension should be considered. If, however, a blend is prepared by phase separation of a homogeneous mixture, the thermodynamic value is important. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 679–690, 2002
High‐resolution solid‐state NMR study of the domain structure and molecular motion in drawn films of a vinylidene fluoride and trifluoroethylene copolymer with 73 mol % vinylidene fluoride
Authors: Ishii Fumiaki , Ohga Toshio , Tsutsumi Akihiro , Ohigashi Hiroji
Published: August 2002

The heterogeneous higher order structure and molecular motion in a single crystalline film of a vinylidene fluoride (VDF) and trifluoroethylene (TrFE) copolymer with 73 mol % VDF was investigated with the 1H–13C cross‐polarization/magic‐angle spinning NMR technique. A transient oscillation was observed in plots of the 13C peak intensity versus the contact time for the CH2, CHF, and CF2 groups. On the basis of the extended cross‐relaxation theory of spin diffusion, we determined that the oscillation behavior was caused by the TrFE‐rich segments in the chain and that the crystal consisted of VDF‐rich and TrFE‐rich domains. The former had TrFE‐rich segments in VDF and TrFE fractions of 0.24 and 0.27, respectively, and the latter had VDF‐rich segments in a VDF fraction of 0.49. The spin–lattice relaxation time T1ρH in the rotating frame for each group was minimal in the three temperature regions of β, αb, and αc (↑) on heating and in the two temperature regions of α1D and αc (↓) on cooling. The αc (↑) and αc (↓) processes depended on the first‐order ferroelectric phase‐transition regions on heating and cooling, respectively. The motional modes for the other processes were confirmed by the T1ρH minimum behavior of the VDF and TrFE groups in the TrFE‐rich domain and the VDF‐rich segments in the VDF‐rich domain. The β and αb processes were attributed to the flip–flop motion of the TrFE‐rich segments and the competitive motion of the TrFE‐ and VDF‐rich segments in the ferroelectric phase, respectively. The α1D process was due to the one‐dimensional diffusion motion of the conformational defects along the chain in the paraelectric phase, accompanied by the trans and gauche transformation of the VDF conformers of ttg+tg− and g+tg−tt. The effect of the competitive motion of the TrFE‐rich segment on the thermal stability of the VDF‐rich segment in the chain near the Curie temperature was examined. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1026–1037, 2002
Comparative study of the mechanical relaxation behavior of polymethacrylates containing different bulky side groups
Authors: García Nuria , Compañ Vicente , Díaz‐Calleja Ricardo , Guzmán Julio , Riande Evaristo
Published: August 2002

The syntheses of poly(1,3‐dioxan‐5‐yl methacrylate), poly(cis‐2‐phenyl‐1,3‐dioxan‐5‐yl methacrylate), poly(trans‐2‐phenyl‐1,3‐dioxan‐5‐yl methacrylate), poly(cis‐2‐cyclohexyl‐1,3‐dioxan‐5‐yl methacrylate), and poly(trans‐2‐cyclohexyl‐1,3‐dioxan‐5‐yl methacrylate) are reported. The mechanical relaxation spectrum of the simplest polymer, poly(1,3‐dioxan‐5‐yl methacrylate), exhibits a prominent β relaxation centered at −98 °C, at 1 Hz, followed in increasing order of temperature by an ostensible glass–rubber relaxation process. In addition to the β relaxation, the loss curves of poly(trans‐2‐phenyl‐1,3‐dioxan‐5‐yl methacrylate) and poly(trans‐2‐cyclohexyl‐1,3‐dioxan‐5‐yl methacrylate) display in the glassy state a high activation energy relaxation, named the β* process, that seems to be a precursor of the glass–rubber relaxation of these polymers. The mechanical spectra of poly(trans‐2‐cyclohexyl‐1,3‐dioxan‐5‐yl methacrylate) and poly(cis‐2‐cyclohexyl‐1,3‐dioxan‐5‐yl methacrylate) exhibit a low activation energy process in the low‐temperature side of the spectra, which is absent in the other polymers. The molecular origin of the mechanical activity of these polymers in the glassy state is discussed in qualitative terms. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1154–1162, 2002
Thermal studies on polypropylene/polyamide‐6 blends modified by succinic anhydride and succinyl fluorescein grafted polypropylenes
Authors: Marco C. , Collar E. P. , Areso S. , García‐Martínez J. Ma.
Published: August 2002

This study investigates the role played by two different interface agents on the basis of atactic polypropylene in the continuous/disperse phase polypropylene/polyamide‐6 (PP/PA6) system. The two agents used were obtained at the authors' laboratories from an atactic polypropylene byproduct derived from industrial polymerization reactors and consist of two grafted polymers containing either succinic anhydride (a‐PP‐SA) or both succinyl‐fluorescein and succinic anhydride grafted groups (a‐PP‐SF/SA). The role of these grafted polymers as compatibilizers in PP/PA6 polymer blends has been confirmed in previous investigations on the basis of their macroscopic behavior. This work investigates the thermal study of these blends where polypropylene acts as the polymer matrix and polyamide as the dispersed phase. Under isothermal conditions, thermal analysis agrees with the changes in the overall system behavior caused by the presence of the interface agents. These aspects were confirmed by polarized light microscopy that showed the morphology of the blends before and after modification with a‐PP‐SA or a‐PP‐SF/SA. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1307–1315, 2002
Shape and position of middle‐angle scattering peaks from smectic phases of polymers
Authors: Stribeck N. , Wutz C.
Published: August 2002

A method for the quantitative analysis of isotropic middle‐angle X‐ray scattering (MAXS) from segmented polymers, which are able to form liquid‐crystalline (LC) phases, is proposed and applied to scattering curves from poly(ester imide) samples. Oriented material in the LC state shows MAXS fiber patterns with a meridional layer‐line reflection, which sometimes is split, creating a four‐point pattern. Comparing scattering data from oriented material with data from isotropic material, we can explain the asymmetry of the isotropic MAXS reflection by limited lateral correlation. Thus, for the LC state of segmented polymers, the notion of stacks built from alternating planar layers of smectic mesogens and spacers units is not generally applicable. Only in the limiting case of infinite flatness does the line profile become symmetric. A simple analytical expression for the shape of the line profile of MAXS reflections is deduced. The equation fitted to the MAXS peak of isotropic LC polymer samples in the smectic state results not only in the determination of a corrected long period but also in two additional parameters, the correlation height of the smectic stack and the flatness of its layers. Compared to established methods for line‐profile analysis in small‐angle scattering, the proposed method models the nanostructure with classical notions of a two‐phase system in one direction only, whereas the lateral contribution to the scattering intensity is characterized by a short‐range loss of correlation instead of a classical description by domain‐phase boundaries. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1749–1755, 2001
Axial correlation lengths for aromatic copolyesters
Authors: Wu Tzong‐Ming
Published: August 2002

X‐ray methods were used to investigate the structure of Vectra® and Xydar® polyesters. Xydar® is based on the aromatic polyester prepared from p‐hydroxybenzoic acid (HBA), terephthalic acid, and biphenol. Vectra® consists of HBA and 2‐hydroxy‐6‐naphthoic acid. X‐ray fiber diagrams of these materials consist of a series of nonperiodic layer lines, which are consistent with a structure consisting of parallel chains of a random comonomer sequence. The meridional peak positions are predicted accurately for fully extended, infinite chains, and the observed and calculated intensities are also in reasonably good agreement. However, there is a less adequate match between the observed and calculated peak profiles, which are predicted to be much sharper than those observed. The latter agreement is improved with a model consisting of finite chain segments with a slightly nonlinear (sinuous) conformation. The best agreement for the observed peak profiles is obtained with an ordered segment length of 90 ± 6 Å and a sinuosity of g = 3.67 ± 0.08% for Vectra® fibers and with an ordered segment length of 104 ± 6 Å and a sinuosity of g = 3.33 ±0.08% for Xydar® fibers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1839–1847, 2001
Adsorption of a single polymer chain on a surface: A molecular dynamics simulation study
Authors: Michel Andreas , Kreitmeier Stefan
Published: August 2002

We performed simulations of the physical adsorption of a single globular chain on a surface of hemispherical shape by means of molecular dynamics simulations. For the chain, we took advantage of a united atom model. Interactions within the chain were limited to stretching, bending, and torsional as well as nonbonded interactions between the nonadjacent atoms. The interaction between each chain element and the surface formation are reigned by a Lennard–Jones potential. In this article, we focused on differences in the behavior of the adsorbed globule to the free unadsorbed one particularly in two different zones of the immediate vicinity of the surface. There were strong indications for a localized acceleration of the dynamics as compared with the bulk that appears in an increase of trans–gauche switches. For explanation we came up with an adsorption scenario. Special attention was given to the shift of the percentage of trans and gauche conformations within the globule in dependence on the strength of the adsorption potential that might be related to crystallization or glass transition. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2333–2339, 2001