bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of gene transcription in cloned bovine embryos produced by different nuclear transfer techniques
Authors: Daniels R. , Hall V.J. , French A.J. , Korfiatis N.A. , Trounson A.O.
Published: August 2002

The efficiency of animal production using cloning technology is still relatively low and research to determine a more efficient nuclear transfer procedure is ongoing. One approach which may be informative in assessing the viability of nuclear transfer embryos is the analysis of embryonic gene expression. Using RT‐PCR techniques we have previously detected the aberrant expression of FGF4, FGFr2 and IL6 in a significant proportion of bovine granulosa cell‐derived nuclear transfer embryos, which correlated with a limited developmental potential in vivo. In order to analyse the effect of different donor cell nuclei on embryonic gene expression we have now analysed the expression of these genes in nuclear transfer embryos reconstructed with fetal epithelial cell nuclei. In addition, we have compared the expression of these genes in bovine nuclear transfer embryos produced by cell fusion or direct injection with variations in the timing of oocyte activation. In all nuclear transfer embryos analysed, FGFr2 and IL6 transcripts were detected at a similar rate to that in IVF embryos. However, the absence of FGF4 transcripts was again evident in a large proportion of nuclear transfer embryos and most significantly in those embryos whose development was activated almost immediately following the transfer of the donor nucleus. The results demonstrate the effects that different donor cell lines and different nuclear transfer procedures may have on the expression of developmentally important genes in nuclear transfer embryos. Mol. Reprod. Dev. 60: 281–288, 2001. © 2001 Wiley‐Liss, Inc.
Continuously moving table data acquisition method for long FOV contrast‐enhanced MRA and whole‐body MRI
Authors: Kruger David G. , Riederer Stephen J. , Grimm Roger C. , Rossman Phillip J.
Published: August 2002

A method is presented in which an extended longitudinal field of view (FOV), as required for whole‐body MRI or MRA peripheral runoff studies, is acquired in one seamless image. Previous methods typically either acquired 3D data at multiple static “stations” which covered the extended FOV or as a series of 2D axial sections. The method presented here maintains the benefits of 3D acquisition while removing the discrete nature of the multistation method by continuous acquisition of MR data as the patient table moves through the desired FOV. Although the technique acquires data only from a homogeneous central volume of the magnet at any point in time, by spatially registering all data it is possible to extend the FOV well beyond this volume. The method is demonstrated experimentally with phantoms, in vivo angiographic animal studies, and in vivo human studies. Magn Reson Med 47:224–231, 2002. © 2002 Wiley‐Liss, Inc.
Fast proton spectroscopic imaging with high signal‐to‐noise ratio: Spectroscopic RARE
Authors: Dreher Wolfgang , Leibfritz Dieter
Published: August 2002

A new fast spectroscopic imaging (SI) method is presented which is based on spatial localization by the fast MRI method of rapid acquisition with relaxation enhancement (RARE) and encoding of the chemical shift information by shifting the position of a refocusing 180° pulse in a series of measurements. This method is termed spectroscopic RARE. In contrast to spectroscopic ultrafast low‐angle RARE (U‐FLARE), the formation of two echo families (odd and even) is suppressed by using a train of 180° RF pulses with an internal four‐step phase cycle. By this means a high signal‐to‐noise ratio (SNR) per unit measurement time is obtained, because the separation of odd and even echoes, as well as dummy echoes to stabilize the echo amplitudes, is not needed anymore. The method is of particular interest for detecting signals of coupled spins, as effective homonuclear decoupling can be achieved by use of constant evolution time chemical shift encoding. The pulse sequence was implemented on a 4.7 T imaging system, tested on phantoms, and applied to the healthy rat brain in vivo. Spectroscopic RARE is particularly useful if T ≪ T2, which is typically fulfilled for in vivo proton SI measurements at high magnetic field strength. Magn Reson Med 47:523–528, 2002. © 2002 Wiley‐Liss, Inc.
Signal‐to‐noise ratio and absorbed power as functions of main magnetic field strength, and definition of “90°” RF pulse for the head in the birdcage coil
Authors: Collins Christopher M. , Smith Michael B.
Published: August 2002

Calculations of the RF magnetic (B1) field as a function of frequency between 64 and 345 MHz were performed for a head model in an idealized birdcage coil. Absorbed power (Pabs) and SNR were calculated at each frequency with three different methods of defining excitation pulse amplitude: maintaining 90° flip angle at the coil center (center α = π/2), maximizing FID amplitude (Max. AFID), and maximizing total signal amplitude in a reconstructed image (Max. Aimage). For center α = π/2 and Max. Aimage, SNR increases linearly with increasing field strength until 260 MHz, where it begins to increase at a greater rate. For these two methods, Pabs increases continually, but at a lower rate at higher field strengths. Above 215 MHz in MRI of the human head, the use of FID amplitude to set B1 excitation pulses may result in apparent decreases in SNR and power requirements with increasing static field strength. Magn Reson Med 45:684–691, 2001. © 2001 Wiley‐Liss, Inc.
Characterization and reduction of the transient response in steady‐state MR imaging
Authors: Hargreaves Brian A. , Vasanawala Shreyas S. , Pauly John M. , Nishimura Dwight G.
Published: August 2002

Refocused steady‐state free precession (SSFP) imaging sequences have recently regained popularity as faster gradient hardware has allowed shorter repetition times, thereby reducing SSFP's sensitivity to off‐resonance effects. Although these sequences offer fast scanning with good signal‐to‐noise efficiency, the “transient response,” or time taken to reach a steady‐state, can be long compared with the total imaging time, particularly when using 2D sequences. This results in lost imaging time and has made SSFP difficult to use for real‐time and cardiac‐gated applications. A linear‐systems analysis of the steady‐state and transient response for general periodic sequences is shown. The analysis is applied to refocused‐SSFP sequences to generate a two‐stage method of “catalyzing,” or speeding up the progression to steady‐state by first scaling, then directing the magnetization. This catalyzing method is compared with previous methods in simulations and experimentally. Although the second stage of the method exhibits some sensitivity to B1 variations, our results show that the transient time can be significantly reduced, allowing imaging in a shorter total scan time. Magn Reson Med 46:149–158, 2001. © 2001 Wiley‐Liss, Inc.
Volumetric multishot echo‐planar spectroscopic imaging
Authors: Tyszka J. Michael , Mamelak Adam N.
Published: August 2002

Rapid volumetric magnetic resonance spectroscopic imaging (MRSI) is potentially of great relevance to the diagnosis and treatment of focal cerebral diseases such as cancer and epilepsy. A strategy for volumetric multishot echo‐planar spectroscopic imaging (MEPSI) is described which allows whole‐brain metabolite mapping in approximately 20 min. A multishot trajectory is used in both the spatial and temporal domains which reduces the accumulated phase during each echo train and tolerates conventional Fourier reconstruction without regridding. Also described is a generalized correction for phase discontinuities arising from the multishot acquisition of the time domain, which is independent of the spatial k‐space trajectory and is therefore also applicable to multishot spiral MRSI. Whole‐brain, lipid‐suppressed MEPSI data were acquired from five normal subjects. The mean signal‐to‐noise ratios (SNRs) (±SE) for the n‐acetylaspartate (NAA), choline (Cho), and creatine (Cr) maps across all subjects were 21.3 ± 1.8, 11.7 ± 0.6, and 9.2 ± 0.6, respectively, with a computed voxel size of 2.33 ml. Magn Reson Med 46:219–227, 2001. © 2001 Wiley‐Liss, Inc.
Transient forearm conduction block in the median nerve
Authors: Watson Bradley V. , Parkes Anthony W. , Brown John D.
Published: August 2002

We present two cases referred for electrophysiological confirmation of carpal tunnel syndrome (CTS). Initial nerve conduction studies were normal. Approximately 20 min into the examination, both patients developed sensory symptoms and weakness in the distal median nerve territory while the elbow was extended and forearm supinated. Further studies demonstrated complete conduction block across the forearm in the median motor and sensory nerve fibers. When measurable, conduction velocities remained normal or were modestly slow. Complete clinical and electrophysiological recovery occurred within 2 min following forearm pronation, suggesting that dysfunction was probably due to focal transient ischemia. Patients describing increased sensory symptoms during routine electrophysiological assessments for CTS should be investigated to rule out the possibility of a more proximal abnormality. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000, 2002
A small dose of the immunosuppressive agent FK506 (tacrolimus) protects peripheral nerve from ischemic fiber degeneration
Authors: Kihara Mikihiro , Kamijo Mikiko , Nakasaka Yoshikuni , Mitsui Yoshiyuki , Takahashi Mitsuo , Schmelzer James D.
Published: August 2002

The immunosuppressant agent FK506 (tacrolimus) has proven to be neuroprotective against brain ischemia, but there are no data on potential neuroprotective effects of FK506 in peripheral nerve ischemia. We examined the potential effects of two doses of FK506 in protecting peripheral nerve from ischemic fiber degeneration. Ischemia in the left sciatic nerve of the rat was produced by injecting 2 × 106 microspheres (14 μm) into the left femoral, hypogastric, and superior gluteal arteries in proportions of 47%, 37%, and 17%, respectively. After embolization, FK506 was injected into the left femoral, hypogastric, and superior gluteal arteries in doses of 9.4, 7.4, and 3.4 μg, respectively, for the high‐dose group and 4.7, 3.7, and 1.7 μg, respectively, for the low‐dose group. The control rats were injected with saline. FK506 treatment resulted in dramatic behavioral improvement in nerve function, in the number of functioning nerve fibers, and in the salvage of a majority of nerve fibers from ischemic fiber degeneration in a dose‐dependent fashion. These results suggest that a small dose of FK506 protects peripheral nerve from ischemic fiber degeneration and that it may have potential in the treatment of ischemic neuropathy. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1601–1606, 2001
Wave‐induced seepage flux into anisotropic seabeds
Authors: Jeng D. S. , Li L. , Barry D. A.
Published: August 2002

Considerable effort has been devoted to quantifying the wave‐induced soil response in a porous seabed in the last few decades. Most previous investigations have focused on the analysis of pore pressure and effective stresses within isotropic sediments, despite strong evidence of anisotropic soil behaviour reported in the literature. Furthermore, the seepage flux, which is important in the context of contaminant transport, has not been examined. In this paper, we focus on water wave‐driven seepage in anisotropic marine sediments of finite thickness. The numerical results predict that the effects of hydraulic anisotropy and anisotropic soil behaviour on the wave‐driven seepage in marine sediment are significant. Copyright © 2001 John Wiley & Sons, Ltd.
Data from frequency‐volume charts versus filling cystometric estimated capacities and prevalence of instability in men with lower urinary tract symptoms suggestive of benign prostatic hyperplasia
Authors: van Venrooij Ger E.P.M. , Eckhardt Mardy D. , Gisolf Karel W.H. , Boon Tom A.
Published: August 2002

The aim was to examine associations of filling cystometric estimated compliance, capacities, and prevalence of bladder instability with data from frequency‐volume charts in a well‐defined group of men with lower urinary tract symptoms (LUTS) suggestive of benign prostatic hyperplasia (BPH). Men with LUTS suggestive of BPH were included if they met the criteria of the International Consensus Committee on BPH, i.e., they voided more than 150 mL during uroflowmetry, their residual volume and prostate size were estimated, and they completed frequency‐volume charts correctly. From the frequency‐volume charts, voiding habits, and fluid intake in the daytime and at night were evaluated. Filling cystometric studies were performed in these men as well. Decreased compliance was an exceptional finding. Cystometric capacity and especially effective capacity (cystometric capacity minus residual volume) corresponded significantly with the maximum voided volume on the frequency‐volume charts. Effective capacity was almost twice as high as the average voided volume. Minimum voided volume on frequency‐volume charts was not related to filling cystometric data. The presence of instability in the supine or sitting position or in both positions was not significantly associated with smaller voided volumes, higher nocturia, or diuria. Filling cystometric capacities were strongly associated with maximal and mean voided volumes derived from frequency‐volume charts. The presence of detrusor instability during filling cystometry did not significantly affect voided volumes, diuria, or nocturia. Neurourol. Urodynam. 21:106–111, 2002. © 2002 Wiley‐Liss, Inc.
Low‐cost minimum‐time line‐broadcasting schemes in complete binary trees
Authors: Averbuch A. , Gaber I. , Roditty Y.
Published: August 2002

Broadcasting is the process of transmitting a message from a member in a network (originator) to all other members. A line‐broadcasting scheme allows two members to communicate during one time unit as long as there is a path of lines between them and no link is used in more than one call between two members. Farley [3] showed an algorithm that accomplishes line broadcasting in any tree on n vertices in minimum time, which is ⌈log2 n⌉ time units. Since the structure of the tree is unknown in advance, the total number of communication link uses (cost) of his scheme is Θ (n − 1) ⌈log2 n⌉.

In this paper, we present line‐broadcasting schemes for complete binary trees. The cost of the algorithms is linear in the number of vertices. This answers a question raised by Fujita and Farley [5]. © 2001 John Wiley & Sons, Inc.
An implicit boundary element solution with consistent linearization for free surface flows and non‐linear fluid–structure interaction of floating bodies
Authors: Donescu Pompiliu , Virgin Lawrence N.
Published: August 2002

In this work, a new comprehensive method has been developed which enables the solution of large, non‐linear motions of rigid bodies in a fluid with a free surface. The application of the modern Eulerian–Lagrangian approach has been translated into an implicit time‐integration formulation, a development which enables the use of larger time steps (where accuracy requirements allow it). Novel features of this project include: (1) an implicit formulation of the rigid‐body motion in a fluid with a free surface valid for both two or three dimensions and several moving bodies; (2) a complete formulation and solution of the initial conditions; (3) a fully consistent (exact) linearization for free surface flows valid for any boundary elements such that optimal convergence properties are obtained when using a Newton–Raphson solver. The proposed framework has been completed with details on implementation issues referring mainly to the computation of the complete initial conditions and the consistent linearization of the formulation for free surface flows.

The second part of the paper demonstrates the mathematical and numerical formulation through numerical results simulating large free surface flows and non‐linear fluid structure interaction. The implicit formulation using a fully consistent linearization based on the boundary element method and the generalized trapezoidal rule has been applied to the solution of free surface flows for the evolution of a triangular wave, the generation of tsunamis and the propagation of a wave up to overturning. Fluid–structure interaction examples include the free and forced motion of a circular cylinder and the sway, heave and roll motion of a U‐shaped body in a tank with a flap wave generator. The presented examples demonstrate the applicability and performance of the implicit scheme with consistent linearization. Copyright © 2001 John Wiley & Sons. Ltd.
An improved partition of unity finite element model for diffraction problems
Authors: Ortiz P. , Sanchez E.
Published: August 2002

The partition of unity finite element method (PUFEM) is explored and improved to deal with practical diffraction problems efficiently. The use of plane waves as an external function space allows an efficient implementation of an approximate exterior non‐reflective boundary condition, improving the original proposed by Higdon for general diffraction problems. A ‘virtually’ analytical integration procedure is introduced for multi‐dimensional high‐frequency problems which exhibits a dramatic decrease in the number of operations for a given error compared with standard integration methods. Suitable conjugate gradient type solvers for the whole range of wavenumbers are used, including such cases in which PUFEM can produce nearly singular matrices caused by ‘round‐off’ limits. Copyright © 2001 John Wiley & Sons, Ltd.
The p‐version of the finite element method for three‐dimensional curved thin walled structures
Authors: Düster A. , Bröker H. , Rank E.
Published: August 2002

In this paper we present an implementation of a three‐dimensional p‐version for structural problems of solids with almost arbitrarily curved surfaces. Applying the blending function method, complex structures can often be modelled by a few p‐elements, being the basis for a higher order approximation. Numerical examples will demonstrate, that the p‐version with anisotropic Ansatz spaces allows to predict the structural behaviour of three‐dimensional plates and shells with approximately the same amount of degrees of freedom as in the two‐dimensional case, yet significantly more accurate due to the three‐dimensional model. Furthermore, it is advantageous to compute complex structures exclusively with three‐dimensional discretizations as no special elements are needed to model the transition from dimensionally reduced formulations like plates or shells to fully three‐dimensional solid elements. Using the p‐version with anisotropic Ansatz spaces the whole structure can be efficiently discretized with solid elements, even if the aspect ratio of the elements becomes very large. Copyright © 2001 John Wiley Sons, Ltd.
General theory of domain decomposition: Indirect methods
Authors: Herrera Ismael , Yates Robert , Diaz Martin
Published: August 2002

According to a general theory of domain decomposition methods (DDM), recently proposed by Herrera, DDM may be classified into two broad categories: direct and indirect (or Trefftz‐Herrera methods). This article is devoted to formulate systematically indirect methods and apply them to differential equations in several dimensions. They have interest since they subsume some of the best‐known formulations of domain decomposition methods, such as those based on the application of Steklov‐Poincaré operators. Trefftz‐Herrera approach is based on a special kind of Green's formulas applicable to discontinuous functions, and one of their essential features is the use of weighting functions which yield information, about the sought solution, at the internal boundary of the domain decomposition exclusively. A special class of Sobolev spaces is introduced in which boundary value problems with prescribed jumps at the internal boundary are formulated. Green's formulas applicable in such Sobolev spaces, which contain discontinuous functions, are established and from them the general framework for indirect methods is derived. Guidelines for the construction of the special kind of test functions are then supplied and, as an illustration, the method is applied to elliptic problems in several dimensions. A nonstandard method of collocation is derived in this manner, which possesses significant advantages over more standard procedures. © 2002 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 18: 296–322, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/num.10008
Effects of biologic and experiential conditions on the pattern of growth in weight of premature and full‐term infants
Authors: Pridham Karen F. , Brown Roger , Sondel Sherie , Clark Roseanne , Green Christopher
Published: August 2002

In this exploratory study we examined the contribution of biologic and experiential conditions to the pattern of growth in weight for premature and full‐term infants. The three components of the pattern were: (a) the infant's weight level; (b) the linear growth rate; and (c) the quadratic growth rate. Biologic conditions were maturity at birth and gender. Experiential conditions included variables in the mother's caregiving and the infant's feeding behavior, nutrient intake, and acuity of illness. At 1, 4, 8, and 12 months, premature infants (n = 61) weighed significantly less than full‐term infants (n = 53), but neither linear nor quadratic rates of weight gain were significantly different from the rates for the full‐term infants. Multilevel analytic models showed that female gender significantly affected weight level and linear and quadratic growth rates. Negative affect and behavior in both the mother and the infant significantly increased the linear rate of weight gain. The interaction of several experiential conditions with the two biologic conditions, birth maturity and gender, affected growth outcomes. Further exploration of the model with a larger sample is indicated to enable simultaneous testing of biologic and experiential conditions. © 2001 John Wiley & Sons, Inc. Res Nurs Health 24:283–297, 2001
Reconsideration of criteria for differentiating faunal assemblages accumulated by hyenas and hominids
Authors: Pickering Travis Rayne
Published: August 2002

Zooarchaeologists have established several criteria for differentiating hominid‐ and hyena‐derived faunal assemblages. In some cases, however, the patterns of skeletal part representation and bone surface modification on which these criteria are ultimately based have been observed in fossil bone assemblages of unknown origin, rather than in modern assemblages of known origin. When the proposed criteria are evaluated within an actualistic framework, only three are able to differentiate between hominid‐ and hyena‐created faunal assemblages. I suggest that only these three criteria—proportions of carnivores to ungulates in the assemblage, the preserved condition of long bone specimens (either as whole cylinders or as splintered shaft fragments), and the types of bone surface modifications—should be retained as important factors in a diagnosis of the ancient bone‐collector. The remaining four criteria—the relative proportion of horn pieces in the assemblage, the relative representation of podial bones, the relative representation of small and large bovid skeletal parts, and bovid mortality profiles—are not relevant or applicable to the problem of differentiating hominid‐ from hyena‐derived faunal assemblages. Copyright © 2002 John Wiley & Sons, Ltd.
Development of an efficient system for the separation of indole alkaloids by high performance liquid chromatography and its applications
Authors: Gerasimenko Irina , Sheludko Yuri , Unger Matthias , Stöckigt Joachim
Published: August 2002

An efficient system for the analysis of indole alkaloids by HPLC on a reversed‐phase column using an ion pair technique is described. The optimised chromatographic conditions allowed the successful separation of 22 standard monoterpenoid indole alkaloids (including some isomers) and tryptamine. The described HPLC system was applied to the analysis of alkaloids in intergeneric somatic hybrid cell cultures of Rauvolfia serpentina × Rhazya stricta. Copyright © 2001 John Wiley & Sons, Ltd.
Identification of the alkaloids of Galipea officinalis by gas chromatography–mass spectrometry
Authors: Jacquemond‐Collet Ingrid , Bessière Jean‐Marie , Hannedouche Sébastien , Bertrand Cédric , Fourasté Isabelle , Moulis Claude
Published: August 2002

Galipea officinalis Hancock, a Venezuelan shrubby tree which is acclaimed in folk medicine for its many healing properties, is the only species of the genus to contain tetrahydroquinoline alkaloids. A GC‐MS method has been developed in order to analyse the essential oil, hexane and chloroform extracts of the trunk bark of this plant, without prior derivatisation of the alkaloidal components. A study of the MS fragmentation patterns of the components permitted the identification of five new minor quinoline alkaloids together with the known alkaloids. In addition, the method could also be used for the characterisation of alkaloids within the genus Galipea. Copyright © 2001 John Wiley & Sons, Ltd.
Non‐mosaic trisomy 20 presenting at 21 weeks' gestation as a thoraco‐abdominal mass
Authors: Driggers Rita W. , Bernstein Helene , Lantz Michael , Stetten Gail , Escallon Cathleen S. , Perlman Elizabeth , Blakemore Karin J.
Published: August 2002

Non‐mosaic trisomy 20 is rare in fetuses surviving beyond the first trimester. We report a case of a fetus with non‐mosaic trisomy 20 in amniotic fluid cultures obtained during the prenatal evaluation of an unusual thoraco‐abdominal mass which was found at autopsy to be pulmonary sequestration. Gross inspection and autopsy of the fetus revealed multiple anomalies. Copyright © 2001 John Wiley & Sons, Ltd.
Issues and methodological challenges in developing and evaluating health care interventions for older people with diabetes mellitus – part 2
Authors: Forbes A , Berry J , While A , Hitman GA , Sinclair AJ
Published: August 2002

This review discusses a number of different issues relating to the development and evaluation of interventions for the diabetes care of older people. The review draws on the experience of a pilot study examining a new model of care for older frail people with type 2 diabetes, which comprised a specially developed clinical protocol to support district nurses in carrying out a diabetic annual review for the ‘older housebound’. The review examines the difficulties encountered in conducting research with this vulnerable subset of the population of people with diabetes and suggests how they may be overcome. Particular attention is directed at clarifying the research population, the validity of the proposed intervention, alternative approaches to the care of the older population with diabetes, sample selection and recruitment, and outcome measures. Copyright © 2002 John Wiley & Sons, Ltd.
Interaction of main‐chain polycations with sodium dodecyl sulfate
Authors: Zheng Xiaoliang , Cao Weixiao
Published: August 2002

The interaction of the main‐chain polycations 2,2‐ionene (I2,2) and 3,3‐ionene (I3,3) with sodium dodecyl sulfate (SDS) has been investigated in aqueous solution. It was confirmed that the interaction is cooperative and a stoichiometric 1:1 complex of I2,2–SDS or I3,3–SDS with regular structure forms as a precipitate irrespective of the molar ratio of the components. It is completely different from the interaction of side‐chain polycations such as the poly[(vinyl pyridine)‐co‐styrene] copolymer cation (PVSC) with SDS, in which no cooperative effect was observed. The driving force responsible for the cooperative effect is believed to be the hydrophobic attraction between the SDS molecule already linked on the ionene chain and the next SDS molecule to be entered. It was also confirmed that the structures of the complexes are very different, ie the ionene–SDS complexes exhibit high regularity whereas the PVSC–SDS complex is irregular.

© 2001 Society of Chemical Industry
Basic characterization of polypropene‐block‐poly(methylene‐1,3‐cyclopentane‐co‐propene) synthesized from propene and 1,5‐hexadiene with modified stopped‐flow method
Authors: Kono Hiroyuki , Ichiki Tomohito , Mori Hideharu , Nakatani Hisayuki , Terano Minoru
Published: August 2002

Block copolymerization of propene and 1,5‐hexadiene was carried out by a modified stopped‐flow polymerization method with an MgCl2‐supported Ziegler catalyst. The resulting polymer, polypropene‐block‐poly(methylene‐1,3‐cyclopentane‐co‐propene) (PP‐b‐(PMCP‐co‐PP)), in which the crystallizable PP part was linked with the non‐crystallizable PMCP‐co‐PP part, was characterized by optical microscopy, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and tensile testing. The block copolymer having a chemical linkage between PP and PMCP‐co‐PP showed properties different from those of homopolymer, random copolymer and blend polymer.

© 2001 Society of Chemical Industry
Syntheses, antitumour activities and antiangiogenesis of 1,2,3‐tris(ethoxycarbonyl)‐2‐propyl acrylate and its polymers
Authors: Kim Min‐Jeong , Chung Il‐Doo , Lee Sun‐Mi , Kim Seon‐Hee , Ha Chang‐Sik , Cho Won‐Jei
Published: August 2002

A new monomer, 1,2,3‐tris(ethoxycarbonyl)‐2‐propyl acrylate (TPA), was synthesized by reaction of acryloyl chloride and triethyl citrate. The homopolymer of TPA and its copolymers with acrylic acid (AA), vinyl acetate (VAc) and maleic anhydride (MAH) were prepared by polymerization using lauroyl peroxide (LPO) at 70 °C for 24 h. The structures of TPA and its polymers were identified by FTIR, 1H NMR, 13C NMR spectroscopies, and elemental analysis. The number average molecular weights and polydispersity indices of the synthesized polymers determined by GPC were in the range 4200–23 000 g mol−1 and 1.1–2.1, respectively. The IC50 values of the synthesized samples against cancer cell lines were greater than those of 5‐fluorouracil (5‐FU). The percentage inhibition values of SV40 DNA replication were 82.2 for TPA, 34.3 for poly (TPA), 81.9 for poly(TPA‐co‐AA), 82.0 for poly(TPA‐co‐VAc), 35.6 for poly(TPA‐co‐MAH) and 12.7 for 5‐FU. The inhibitions of SV40 DNA replication and antiangiogenesis for the synthesized TPA and its polymers are much greater than those of the control.

© 2001 Society of Chemical Industry
Copolymerization of methyl methacrylate and allyl acetate Part I. Rate of reaction
Authors: Hendrana Sunit , Hill David J T , Senake Perera M C , Pomery Peter J
Published: August 2002

Free radical bulk copolymerization of methyl methacrylate (MMA) and allyl acetate (AAc) has been investigated using electron spin resonance (ESR) and FT–near infrared (FTNIR) spectroscopy. Data are used to evaluate the rate constants. The mole fraction of AAc plays an important role in the copolymerization of these two monomers. AAc not only delays the Trommsdorff effect but also increases the onset of percentage total conversion at which the Trommsdorff region begins. With AAc fraction 0.5 and higher, no Trommsdorff effect was observed. Inclusion of AAc into copolymer structure mainly occurs in the Trommsdorf region or when the AAc fraction in the comonomer feed is dominant. This is associated with a drop in the concentration of propagating radicals. However, ESR spectra indicate that the MMA propagating radical is predominant during the reaction. In the comonomer mixtures where a Trommsdorff region can be observed, the addition of AAc does not produce any significant change in kp and kt in the steady state region. Major changes in kp and kt are observed after the gel point and glassy state, respectively.

© 2001 Society of Chemical Industry
Aqueous poly(urethane–urea) dispersions and cast films based on m‐TMXDL. 1. Structure–property relationships
Authors: Lahtinen Mika , Price Colin
Published: August 2002

Aqueous poly(urethane–urea) dispersions were prepared from polycaprolactone diol, α,α,α′,α′‐tetramethyl‐1,3‐xylylene diisocyanate (m‐TMXDI) and α,α‐dimethylol propionic acid (DMPA) using a prepolymer mixing process. In the process, polyurethane prepolymers were neutralised with triethylamine and the chains extended in water with either hydrazine, 1,2‐ethylene diamine or 1,2‐propylene diamine. For comparison, some samples were prepared from a more commonly used diisocyanate, isophorone diisocyanate (IPDI). Dispersion characteristics and basic structure–property relationships of the cast films were determined. m‐TMXDI provided some advantages over IPDI in the preparations since its use gave lower prepolymer viscosities and better resistance to elevated temperatures. Films prepared from m‐TMXDI dispersions exhibited considerably lower values of Young's modulus and hardness and higher elongations at break than those prepared from IPDI‐based dispersions for analogous compositions, whereas differences in the average particle sizes or viscosities of the dispersions were only small. When the DMA content was varied, the dispersions and cast films of m‐TMXDI‐based systems showed similar changes as are known to occur in IPDI‐based systems: as the DMPA content was increased, the average particle size of the dispersions decreased and the viscosity increased, and for the cast films, the Young's modulus and tensile strength increased and the maximum elongation at break decreased. Changing the chain‐extension agent from hydrazine to 1,2‐ethylene diamine, to 1,2‐propylene diamine and had little effect on the particle size of the dispersions, but increased the Young's modulus and hardness of the respective cast films. Molar masses of the chain‐extended polymers were unexpectedly low. DSC analysis of cast films indicated that the degree of crystallisation of the soft or hard domains was low.

© 2002 Society of Chemical Industry
Long‐range substituent and temperature effect on prototropic tautomerism in 2‐(acylmethyl)quinolines
Authors: Gawinecki Ryszard , Ośmiałowski Borys , Kolehmainen Erkki , Kauppinen Reijo
Published: August 2002

Tautomeric equilibria between 2‐(cinnamoylmethyl)quinoline, (Z)‐1,2‐dihydro‐2‐(cinnamoylmethylene)quinoline and (Z)‐4‐phenyl‐1‐(2‐quinolyl)‐1,3‐butadien‐2‐ol were studied by 1H, 13C and 15N NMR methods. The —CHCH— fragment conjugated with phenyl and a strong electron donor p‐(1‐pyrrolidine) substituent were found to favour the enolimine tautomer. This undergoes fast exchange (on the NMR time‐scale) with the enaminone form. The amount of the latter tautomer was found to increase at low temperatures. Copyright © 2001 John Wiley & Sons, Ltd.
Theoretical investigations on bond enthalpy additivity deviations in the formation of triplet diradicals from hetero‐substituted 1,3‐dimethylenecyclobutanes
Authors: Zhang Daisy Y.
Published: August 2002

In our continuing effort to understand better the cause of the large positive deviation from bond enthalpy additivity (BEA) observed in the formation of triplet 1,3‐dimethylenecyclobutane‐2,4‐diyl (1c) from 1,3‐dimethylenecyclobutane (1a), we performed B3LYP/6–31G* calculations on a series of 1,3‐disubstituted cyclobutanes, where the methylene groups in 1a are replaced by hetero groups, specifically O, NH, S, PH and SiH2. The size of the deviation from BEA (ΔBEA) is found to increase consistently with decreasing bond strength of the exocyclic π bonds. DFT calculations were also carried out on related hydrocarbons and the ΔBEA value in each case was found to be in close agreement with that predicted by simple Hückel theory. All of the computational results provide convincing evidence that antiaromaticity is absent in these diradicals, and the positive deviations from BEA, as large as 30.3 kcal mol−1, are due to the more substantial increase in the π electron delocalization in the monoradicals than that in the diradicals. Copyright © 2001 John Wiley & Sons, Ltd.
O‐Phosphorylated calix[4]arenes as Li+‐selective­receptors
Authors: Lukin, Oleg , Vysotsky Myroslav O. , Kalchenko* Vitaly I.
Published: August 2002

Phosphorylation of p‐tert‐butylcalix[4]arene 9 or calix[4]arene 10, having two diethoxyphosphoryl groups at distal positions on their narrow rim (phenolic oxygen atoms), by dibutyloxophosphinechloride or alkylation of 10 by methyl bromoacetate led to the corresponding tetrasubstituted calix[4]arenes 8b–d fixed in a cone conformation. The latter compounds and the similar derivative of calix[4]arene 8a with four diethoxyphosphoryl groups were found to exhibit lithium cation selectivity, which was supported by UV–Vis spectra of THF solutions of the alkali metal picrates and their water–chloroform extraction in the presence of ligands 8a–d. Calculated K/K selectivities range from 2.9 (8d) to 9.5 (8a), which are among the highest values for the calixarene‐based Li+‐selective receptors reported to date. Copyright © 2001 John Wiley & Sons, Ltd.
Mechanism and proton activating factors in the base‐induced β‐elimination reaction of N‐[2‐(2‐quinolyl)ethyl]quinuclidinium salt
Authors: Alunni S. , Orazi C.
Published: August 2002

N‐[2‐(2‐Quinolyl)ethyl]quinuclidinium salt in OH−–H2O, 50 °C, µ = 1 M KCl undergoes an elimination reaction with formation of 2‐vinylquinoline; the second‐order rate constant is kNOH = 12.8 × 10−3 dm3 mol−1 s−1. In acetohydroxamic acid–acetohydroxamate buffers at pH 8–9 the β‐elimination reaction occurs by a reversible E1cb mechanism, (E1cb)R. In this process, carbon deprotonation occurs from the conjugate acid, protonated at the nitrogen atom of the quinoline ring, NH+; this species is present at a very low concentration with respect to the unprotonated substrate N, with pKa = 3.87 at 50 °C, µ = 1 M KCl. The reason for the high reactivity of NH+ with respect to N is related to the high stability of the intermediate carbanion formed from NH+, which presents an enamine structure. Kinetic parameters from a study of acid–base catalysis can be calculated and compared with those of the related system activated by a pyridine ring. Studies of H/D exchange and solvent isotope effect are in agreement with the proposed mechanism. Copyright © 2001 John Wiley & Sons, Ltd.
Multisensitive polymers based on 2‐vinylpyridine and N‐isopropylacrylamide *
Authors: Wohlrab Sebastian , Kuckling Dirk
Published: August 2002

Poly(2‐vinylpyridine) (P2VP) containing functionalized end groups was synthesized using nitroxyl‐mediated radical polymerization with a hydroxy‐functionalized stable free radical. It was shown that P2VP could be synthesized with variable molar masses and low polydispersities. The transformation of the hydroxy groups to an acrylic ester led to the formation of macromonomers. A free‐radical copolymerization of these macromonomers with N‐isopropylacrylamide gave a graft copolymer with a poly(N‐ispopropylacrylamide) backbone and P2VP side chains. Polymers containing different amounts of the monomers were synthesized. It was possible to vary both the amount of P2VP side chains at a constant chain length of the macromonomer and the chain length at a nearly constant chain number. The behavior of the multifunctional macromolecules at different temperatures and pH values was investigated using dynamic light scattering and DSC. The macromolecules were found to retain the specific properties of the homopolymers. The hydrodynamic radii of the synthesized graft copolymers were both dependent on the temperature and pH value. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3797–3804, 2001
Synthesis and characterization of high molecular weight atactic polybutene‐1 with a monotitanocene/methylaluminoxane catalyst system
Authors: Huang Qigu , Wu Qing , Zhu Fangming , Lin Shangan
Published: August 2002

A novel catalyst precursor, the monotitanocene (η5‐pentamethylcyclopentadienyl) titanium tricinnamyloxide [Cp*Ti(OCH2CHCHC6H5)3], was synthesized and employed for butene‐1 polymerization in the presence of methylaluminoxane. The effects of the polymerization conditions on the catalytic activity, molecular weight, stereoregularity, and regioregularity of the polymer so obtained were investigated in detail. The results show that the monotitanocene is desirable for the production of atactic polybutene‐1 coupled with good yields under typical polymerization conditions, high molecular weight (weight‐average molecular weight = 5.3–9.6 × 105), and stereoirregularity with the Bernoullian factor B equal to 0.95, which indicates that chain‐end control is predominant. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4068–4073, 2001
Functional polyesters prepared by polymerization of α‐allyl(valerolactone) and its copolymerization with ε‐caprolactone and δ‐valerolactone
Authors: Parrish Bryan , Quansah Jennifer K. , Emrick Todd
Published: August 2002

We report the ring‐opening homopolymerization of α‐allyl(valerolactone), compound 2, and its copolymerization with ε‐caprolactone and δ‐valerolactone using stannous(II) catalysis. Although the polymerization of substituted δ‐valerolactones has received little attention for the preparation of functional polyesters, we found that compound 2 may be incorporated in controllable amounts into copolymers with other lactones, or simply homopolymerized to give a highly functionalized, novel poly(valerolactone). The presence of the pendant allyl substituent had a substantial impact on the thermal properties of these materials relative to conventional polyesters prepared from lactones, and most of the polymers presented here are liquids at room temperature. Dihydroxylation of the pendant allyl groups gave polyesters with increased hydrophilicity that degraded more or less rapidly depending on their extent of functionality. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1983–1990, 2002
Star‐shaped and photocrosslinked poly(1,5‐dioxepan‐2‐one): Synthesis and characterization
Authors: Ryner Maria , Valdre Alexandra , Albertsson Ann‐Christine
Published: August 2002

New star‐shaped and photocrosslinked poly(1,5‐dioxepan‐2‐one) (PDXO) has been synthesized through ring‐opening polymerization initiated by SnOct2/pentaerythritol. The star‐shaped PDXO was end‐functionalized by acrolyol chloride to form acrylate end groups. The end‐functionalized PDXO was photocrosslinked initiated by 2,2‐dimethoxy‐2‐phenylacetophenone. The gel content ranged from 80 to 99%, indicating a high degree of crosslinking. The thermal properties of the star‐shaped PDXO and the photocrosslinked PDXO were analyzed by differential scanning calorimetry. The glass‐transition temperature was determined to approximately −32 °C for the crosslinked PDXO. The viscosity numbers were determined for star‐shaped PDXO, with reference to linear homologues. The star‐shaped PDXO had lower viscosity numbers than the linear counterparts. The crosslinked PDXO showed a rather hydrophilic surface as compared with other resorbable polyesters. The advancing contact angle was 64 ± 2, and the receding angle was 57 ± 4. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2049–2054, 2002
MALDI‐TOF‐MS analysis of living cationic polymerization of vinyl ethers. III. Polymerization with SnCl4 and TiCl4 in the absence of additives
Authors: Katayama Hiroshi , Kamigaito Masami , Sawamoto Mitsuo
Published: August 2002

Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry analysis revealed that the precision control (or the living nature) of the cationic polymerization of vinyl ethers with SnCl4 or TiCl4 critically depends on the Lewis acid concentration and temperature. Specifically, at an extremely low Lewis acid concentration, for example, the polymerization with the HCl–vinyl ether adduct (an initiator) is living at −78 °C in CH2Cl2 solvent, whereas side reactions occurred at a higher concentration of SnCl4 or at a higher temperature, −15 °C. This was more pronounced with SnCl4 than with TiCl4, which was due to a stronger Lewis acidity of SnCl4 as suggested by NMR analysis of the model reactions. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1258–1267, 2001
Synthesis and specific biodegradation of novel polyesteramides containing amino acid residues
Authors: Fan Yujiang , Kobayashi Masami , Kise Hideo
Published: August 2002

Novel polyesteramides were synthesized from p‐nitrophenyl esters of sebacic or adipic acids and diamines containing α‐amino acid ester groups. The optimal polymerization condition was 60 °C in N,N‐dimethylformamide. The structures of these polymers were confirmed by IR and NMR. The number‐average molecular weights of these polyesteramides ranged from 2280 to 23,600 (except for the polymers containing glycine residues), depending on the nature of the amino acid used. The biodegradability of the polyesteramides was investigated by in vitro hydrolysis with proteases and a lipase as catalysts in borate buffer solutions. The results indicated that the polymers containing L‐phenylalanine were hydrolyzed most effectively by α‐chymotrypsin, subtilisin Carlsberg, and subtilisin BPN′. The polyesteramides containing other amino acid residues also underwent hydrolysis to different extents, reflecting the substrate specificity of the proteases. Lipase had almost no effect on the hydrolytic degradation of these polyesteramides. The polymers containing glycine residues were hardly decomposed by any of the enzymes used. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1318–1328, 2001
Design and synthesis of highly reactive photopolymerizable epoxy monomers
Authors: Crivello James V. , Ortiz Ricardo Acosta
Published: August 2002

The synthesis of a series of novel cationically photopolymerizable epoxide monomers bearing benzyl, allyl, and propargyl acetal and ether groups that can stabilize free radicals was carried out. These monomers display enhanced reactivity in cationic photopolymerization in the presence of certain onium salt photoinitiators. Specifically, this article describes schemes for the synthesis of cycloaliphatic epoxy monomers bearing free‐radical stabilizing groups. During UV irradiation of an onium salt cationic photoinitiator, the aryl radicals that are generated abstract labile protons present in such monomers to generate the corresponding carbon‐centered radicals. Subsequently, these radicals can interact with the onium salt by a redox mechanism to induce the decomposition of these salts. The overall result is that additional cationic species are generated by this mechanism that increase the rate and extent of the cationic ring‐opening polymerization of the epoxide monomer. An investigation of the photopolymerizations of the monomers prepared during this work was carried out using Fourier transform real‐time infrared spectroscopy, and conclusions were drawn with respect to the relationship between their structures and reactivity. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2385–2395, 2001
Synthesis and characterization of new soluble cardo polyesters derived from 1,1‐bis‐[4‐(4‐chlorocarboxyphenoxy)phenyl]‐4‐tert‐butylcyclohexane with various bisphenols by solution polycondensation
Authors: Liaw Der‐Jang , Hsu Jun‐Jang , Liaw Been‐Yang
Published: August 2002

A new cardo diacid chloride, 1,1‐bis‐[4‐(4‐chlorocarboxyphenoxy)phenyl]‐4‐tert‐butylcyclohexane (4), was synthesized from 1,1‐bis‐[4‐(4‐carboxyphenoxy)phenyl]‐4‐tert‐butylcyclohexane in refluxing thionyl chloride. Subsequently, various new polyesters were prepared from 4 with various bisphenols by solution polycondensation in nitrobenzene using pyridine as a hydrogen chloride quencher at 150 °C. These polyesters were produced with inherent viscosities of 0.32–0.50 dL · g−1. Most of these polyesters exhibited excellent solubility in a variety of solvents such as N,N‐dimethylformamide, tetrahydrofuran, tetrachloroethane, dimethyl sulfoxide, N,N‐dimethylacetamide, N‐methyl‐2‐pyrrolidinone, m‐cresol, o‐chlorophenol, and chloroform. These polymers showed glass‐transition temperatures (Tg's) between 144 and 197 °C. The polymer containing the adamantane group exhibited the highest Tg value. The 10% weight loss temperatures of the polyesters, measured by thermogravimetric analysis, were found to be in the range of 426–451 °C in nitrogen. These cardo polyesters exhibited higher Tg's and better solubility than bisphenol A‐based polyesters. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2951–2956, 2001