bluuebunny/crossref_metadata_2025 huggingface dataset:
A sequential Monte Carlo approach for marine ecological prediction
Authors: Dowd Michael
Published: December 2005

This study considers the problem of marine ecological prediction in the context of online estimation and forecasting. Process oriented dynamic ecosystem models are combined with marine observations. The nonlinear, nonGaussian state space model provides the statistical framework. The associated filtering (nowcasting) and prediction (forecasting) problems are addressed via sequential Monte Carlo methods, in this instance a sequential importance resampler combined with Metropolis‐Hastings MCMC. The specific focus is on a prototypical marine ecosystem model comprised of four interacting populations (phytoplankton, zooplankton, nutrients and detritus; PZND) whose co‐evolution is described by system of coupled nonlinear differential equations. Stochastic environmental variation is introduced through a stochastic growth parameter, as well as through dynamical noise in the state evolution equations. The dynamic behaviour of this stochastic ecosystem model is complex: it regularly transitions through a Hopf bifurcation and exhibits episodic blooms of variable magnitude and duration. The model is applied to a case with weak seasonality, that is the oceanic mixed layer in the eastern equatorial Pacific. A partially observed state is considered comprised of a five year satellite (SeaWiFS) derived time series of ocean phytoplankton concentration at 12°N 95°W. Filtering estimates for the ecosystem state and a dynamic parameter were obtained using the sequential Monte Carlo approach. These showed predictor‐corrector behaviour at observation times, including abrupt shifts in the median level after forecasts over measurement void. A corresponding variance (also skewness and kurtosis) growth and subsequent collapse was also seen. Forecasting experiments indicate some negative bias, and suggest there is predictive skill for forecasts out to 10–15 days. Copyright © 2005 John Wiley & Sons, Ltd.
Nonparametric prediction intervals for the future rainfall records
Authors: Raqab Mohammad Z.
Published: December 2005

Prediction of records plays an important role in the environmental applications, especially, prediction of rainfall extremes, highest water levels, sea surface, and air record temperatures. In this paper, based on the observed records drawn from a sequence sample of independent and identically random variables, we develop prediction intervals as well as prediction upper and lower bounds for records from another independent sequence. We extend the prediction problem to include prediction regions for joint upper records from a future sequence sample. The Bonferouni's inequality is used to choose appropriate prediction coefficients for the joint prediction. A real data set representing the records of the annual (January 1–December 31) rainfall at Los Angeles Civic Center is addressed to illustrate the proposed prediction procedures in the environmental applications. Copyright © 2005 John Wiley & Sons, Ltd.
Biostratigraphy, microfacies and depositional environments of upper Viséan limestones from the Burren region, County Clare, Ireland
Authors: Gallagher S.J. , MacDermot C.V. , Somerville I.D. , Pracht M. , Sleeman A.G.
Published: December 2005

The Burren region in western Ireland contains an almost continuous record of Viséan (Middle Mississippian) carbonate deposition extending from Chadian to Brigantian times, represented by three formations: the Chadian to Holkerian Tubber Formation, the Asbian Burren Formation and the Brigantian Slievenaglasha Formation. The upper Viséan (Holkerian–Brigantian) platform carbonate succession of the Burren can be subdivided into six distinct depositional units outlined below. (1) An Holkerian to lower Asbian unit of skeletal peloidal and bryozoan bedded limestone. (2) Lower Asbian unit of massive light grey Koninckopora‐rich limestone, representing a shallower marine facies. (3) Upper Asbian terraced limestone unit with minor shallowing‐upward cycles of poorly bedded Kamaenella‐rich limestone with shell bands and palaeokarst features. This unit is very similar to other cyclic sequences of late Asbian age in southern Ireland and western Europe, suggesting a glacio‐eustatic origin for this fourth‐order cyclicity. (4) Lower Brigantian unit with cyclic alternations of crinoidal/bryozoan limestone and peloidal limestone with coral thickets. These cycles lack evidence of subaerial exposure. (5) Lower Brigantian bedded cherty dark grey limestone unit, deposited during the maximum transgressive phase of the Brigantian. (6) Lower to upper Brigantian unit mostly comprising cyclic bryozoan/crinoidal cherty limestone. In most areas this youngest unit is truncated and unconformably overlain by Serpukhovian siliciclastic rocks. Deepening enhanced by platform‐wide subsidence strongly influenced later Brigantian cycle development in Ireland, but localized rapid shallowing led to emergence at the end of the Brigantian.

A Cf5 Zone (Holkerian) assemblage of microfossils is recorded from the Tubber Formation at Black Head, but in the Ballard Bridge section the top of the formation has Cf6 Zone (Asbian) foraminiferans. A typical upper Asbian Rugose Coral Assemblage G near the top of the Burren Formation is replaced by a lower Brigantian Rugose Coral Assemblage H in the Slievenaglasha Formation. A similar change in the foraminiferans and calcareous algae at this Asbian–Brigantian formation boundary is recognized by the presence of upper Asbian Cf6γ Subzone taxa in the Burren Formation including Cribrostomum lecomptei, Koskinobigenerina sp., Bradyina rotula and Howchinia bradyana, and in the Slievenaglasha Formation abundant Asteroarchaediscus spp., Neoarchaediscus spp. and Fasciella crustosa of the Brigantian Cf6δ Subzone. The uppermost beds of the Slievenaglasha Formation contain a rare and unusual foraminiferal assemblage containing evolved archaediscids close to tenuis stage indicating a late Brigantian age. Copyright © 2006 John Wiley & Sons, Ltd.
Estimating dynamic equilibrium economies: linear versus nonlinear likelihood
Authors: Fernández‐Villaverde Jesús , Rubio‐Ramírez Juan F.
Published: December 2005

This paper compares two methods for undertaking likelihood‐based inference in dynamic equilibrium economies: a sequential Monte Carlo filter and the Kalman filter. The sequential Monte Carlo filter exploits the nonlinear structure of the economy and evaluates the likelihood function of the model by simulation methods. The Kalman filter estimates a linearization of the economy around the steady state. We report two main results. First, both for simulated and for real data, the sequential Monte Carlo filter delivers a substantially better fit of the model to the data as measured by the marginal likelihood. This is true even for a nearly linear case. Second, the differences in terms of point estimates, although relatively small in absolute values, have important effects on the moments of the model. We conclude that the nonlinear filter is a superior procedure for taking models to the data. Copyright © 2005 John Wiley & Sons, Ltd.
The cross‐Euler equation approach to intertemporal substitution in import demand
Authors: Nishiyama Shin‐Ichi
Published: December 2005

This paper addresses the empirical dilemma in identifying and estimating the parameters governing the intertemporal elasticity of substitution (IES) for import demand. We propose a new concept, the cross‐Euler equation, for overcoming this empirical dilemma. IES parameters are estimated by exploiting the cointegrating restriction implied by the cross‐Euler equation. Further, by comparing the IES estimates from the cross‐Euler equation to those from the standard Euler equation, we test the hypothesis whether import demand is affected by nuisance factors. Using the US data, we found imported goods consumption to be robust against nuisance factors, but not for domestic goods. Copyright © 2005 John Wiley & Sons, Ltd.
Effect of storage upon material properties of lyophilized porcine extracellular matrix derived from the urinary bladder
Authors: Freytes Donald O. , Tullius Robert S. , Badylak Stephen F.
Published: December 2005

Xenogeneic extracellular matrices (ECMs) have been developed as off‐the‐shelf biologic scaffolds that have been effectively used in preclinical and clinical applications for tissue reconstruction. Such materials must be suitable for terminal sterilization and capable of storage for extended periods of time without significant changes in material properties and bioactivity. Material properties of interest for ECM scaffolds include hydrostatic permeability index (PI), uniaxial maximum load and elongation, maximum tangential stiffness (MTS), suture retention strength (SRS), and ball‐burst strength (BBS). The present study evaluated these material properties for lyophilized forms of an ECM scaffold derived from the porcine urinary bladder, termed urinary bladder matrix (UBM), that was terminally sterilized by e‐beam irradiation at 22 kGy and stored at room temperature (RT; 20–24°C) or refrigerated temperature (REFT; 4–8°C) for up to 12 months. UBM devices showed no change in SRS, BBS, and hydrostatic PI after the evaluation period. Lyophilized devices stored at RT showed an increase in maximum load and MTS while devices stored at REFT showed an increase in maximum elongation after 1 year of storage (p < 0.05). These results indicate that structural changes in the UBM device may slowly occur as a function of prolonged storage and storage temperature. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
PGF2α increases FGF‐2 and FGFR2 trafficking in Py1a rat osteoblasts via clathrin independent and importin β dependent pathway
Authors: Marchetti Luigi , Sabbieti Maria G. , Agas Dimitrios , Menghi Maura , Materazzi Giovanni , Menghi Giovanna , Hurley Marja M.
Published: December 2005

Previous studies showed that prostaglandin F2α (PGF2α) stimulated fibroblast growth factor‐2 (FGF‐2) and fibroblast growth factor receptor 2 (FGFR2) cytosolic and nuclear accumulation, however, the endocytic pathway has not been elucidated. This study demonstrates that although PGF2α increased the formation of clathrin‐coated structures in Py1a rat osteoblasts, they were not involved in FGF‐2 and FGFR2 trafficking. PGF2α increased binding of FGF‐2 and FGFR2 and co‐localization of reactive sites in addition to nuclear translocation at the nuclear pore complex level. FGF‐2 and FGFR2 were in close spatial correlation with importin β, further supporting nuclear import of the FGF‐2/FGFR2 complex. Immunogold and immunofluorescence techniques as well as Western blotting demonstrated increased importin β protein labeling in response to PGF2α. Similar to PGF2α, phorbol 12‐myristate 13‐acetate (PMA) also increased importin β protein. These data strongly suggest that prostaglandins may regulate osteoblast metabolism via FGF‐2/FGFR2/importin β nuclear trafficking. J. Cell. Biochem. 97: 1379–1392, 2006. © 2005 Wiley‐Liss, Inc.
Light‐induced exocytosis in cell development and differentiation
Authors: Henkel Andreas W. , Upmann Irene , Bartl Christina R. , Bönsch Dominikus , Reichardt Cornelia , Maler Juan Manuel , Nürnberger Michael , Umstätter Richard , Reulbach Udo , Kornhuber Johannes , Wiltfang Jens
Published: December 2005

Calcium‐dependent exocytosis of fluorescently labeled single secretory vesicles in PC12 cells and primary embryonic telencephalon cells can be triggered by illumination with visible light and imaged by TIRF or epifluorescence microscopy. Opsin 3 was identified by quantitative PCR expression analysis as the putative light receptor molecule for light‐induced exocytosis. In primary chicken telencephalon cells, light‐induced exocytosis is restricted to a specific period during embryonic development, and involves fusion of rather large vesicles. Strictly calcium‐dependent exocytosis starts after a delay of a few seconds of illumination and lasts for up to 2 min. We analyzed the frequency, time course and spatial distribution of exocytotic events. Exocytosis in PC12 cells and telencephalon cells occurs at the periphery or the interface between dividing cells, and the duration of single secretion events varies considerably. Our observation strongly supports the idea that light induced exocytosis is most likely a mechanism for building plasma membrane during differentiation, development and proliferation rather than for calcium‐dependent neurotransmitter release. J. Cell. Biochem. 97: 1393–1406, 2006. © 2005 Wiley‐Liss, Inc.
Theoretical studies on electron delocalization in diaminoguanidine
Authors: Bharatam Prasad V. , Iqbal Pansy
Published: December 2005

Ab initioMO and density functional methods have been employed to understand the electronic structure and second‐order delocalizations in diaminoguanidine. The potential energy surfaces of the three different positional isomers of diaminoguanidine (DAG1, DAG2, and DAG3) have been studied in detail, which suggest greater stability for DAG1 over the other isomers. Natural Population Analysis (NPA) has been employed to understand the primary and the secondary electron delocalizations in diaminoguanidine. The absolute proton affinity of diaminoguanidine is greater than both guanidine as well as aminoguanidine due to the extra stability from the intramolecular interactions in protonated diaminoguanidine. The increase in the electron delocalization upon protonation in diaminoguanidine is similar to that of guanidine and aminoguanidine. © 2005 Wiley Periodicals, Inc. J Comput Chem 27: 334–343, 2006
Superlinear scaling in master‐slave quantum chemical calculations using in‐core storage of two‐electron integrals
Authors: Fossgård Eirik , Ruud Kenneth
Published: December 2005

We describe the implementation of a parallel, in‐core, integral‐direct Hartree–Fock and density functional theory code for the efficient calculation of Hartree–Fock wave functions and density functional theory. The algorithm is based on a parallel master‐slave algorithm, and the two‐electron integrals calculated by a slave are stored in available local memory. To ensure the greatest computational savings, the master node keeps track of all integral batches stored on the different slaves. The code can reuse undifferentiated two‐electron integrals both in the wave function optimization and in the evaluation of second‐, third‐, and fourth‐order molecular properties. Superlinear scaling is achieved in a series of test examples, with speedups of up to 55 achieved for calculations run on medium‐sized molecules on 16 processors with respect to the time used on a single processor. © 2005 Wiley Periodicals, Inc. J Comput Chem 27: 326–333, 2006
Gaseous reaction mechanism of C2F radical with water
Authors: Wang Jian , Ding Yi‐Hong , Wu Gong‐Bing , Sun Chia‐Chung
Published: December 2005

The kinetic properties of the carbon–fluorine radicals are little understood except those of CFn (n =1–3). In this article, a detailed mechanistic study was reported on the gas‐phase reaction between the simplest π‐bonded C2F radical and water as the first attempt to understand the chemical reactivity of the C2F radical. Various reaction channels are considered. The most kinetically competitive channel is the quasi‐direct hydrogen‐abstraction route forming P5 HCCF + OH. At the CCSD(T)/6‐311+G(2d,2p)//B3LYP/6‐311G(d,p)+ZPVE, CCSD(T)/6‐311+G(3df,2p)//QCISD/6‐311G(d,p)+ZPVE and Gaussian‐3//B3LYP/6‐31G(d) levels, the overall H‐abstraction barriers (4.5, 4.7, and 4.2 kcal/mol) for the C2F + H2O reaction are comparable to the corresponding values (5.5, 3.7, and 5.7 kcal/mol) for the analogous C2H + H2O reaction. This suggests that C2F is a reactive radical like the extensively studied C2H, in contrast to the situation of the CF and CF2 radicals that have much lower reactivity than the corresponding hydrocarbon species. Thus, the C2F radical is expected to play an important role in the combustion processes of the carbon–fluorine chemistry. Furthermore, addition of a second H2O can catalyze the reaction with the H‐abstraction barrier significantly reduced to a marginally zero value (0.5 kcal/mol). This is also indicative of the potential relevance of the title reactions in the low‐temperature atmospheric chemistry. © 2005 Wiley Periodicals, Inc. J Comput Chem 27: 363–367, 2006
Common intersection designs
Authors: Lee Jooyoung , Stinson Douglas R.
Published: December 2005

Motivated by an application to sensor networks, Lee and Stinson [6] defined a new type of set system termed a “common intersection design.” Briefly, a µ‐common intersection design is a 1‐design in which no pair of points occurs in more than one block, and in which any two disjoint blocks intersect at least µ blocks in common. In general, we want to maximize µ as a function of the other parmameters of the design. In this paper, we analyze combinatorial properties of common intersection designs. We determine necessary conditions for “optimal” common intersection designs and provide several existence results. Connections with other types of designs are pointed out. © 2005 Wiley Periodicals, Inc. J Combin Designs 14: 251–269, 2006
Use of volatile and non‐volatile amines to evaluate the freshness of anchovies stored in ice
Authors: Pons‐Sánchez‐Cascado Sofía , Veciana‐Nogués M Teresa , Bover‐Cid Sara , Mariné‐Font Abel , Vidal‐Carou M Carmen
Published: December 2005

Amounts of volatile and biogenic amines, pH and microbial counts were monitored in Mediterranean anchovy (Engraulis encrasicholus) over 23 days of ice storage with the aim of examining their suitability as indicators of freshness. Counts of Enterobacteriaceae reached the maximum limits stipulated by Spanish regulations after 5 days of storage in ice, while those of mesophilic bacteria took 7 days. Levels of volatile amines hardly increased during ice storage. Amounts of biogenic amines did increase, though there were differences from one amine to the other. Cadaverine, the most abundant biogenic amine, showing the earliest increase, coinciding with the shelf‐life time as determined through Enterobacteriaceae counts. Amounts of histamine remained below the maximum levels established by both European Union and Food and Drug Administration regulations. Other biogenic amines were found at much higher levels than histamine. Results demonstrated the suitability of the biogenic amine index (as the sum of histamine + tyramine + putrescine + cadaverine) as a freshness indicator for anchovies stored in ice, with a limit of acceptability set at 15 mg kg−1. Copyright © 2005 Society of Chemical Industry
Effect of maltodextrin and emulsifiers on the viscosity of cake batter and on the quality of cakes
Authors: Lakshminarayan Sudha M , Rathinam Vetrimani , KrishnaRau Leelavathi
Published: December 2005

The effect of fat replacement by maltodextrin on cake batter viscosity and the quality of the resultant cakes was studied. The viscosity of batter was reduced significantly when fat was replaced with equal quantities of maltodextrin. Cakes prepared from this batter had low volume and firmer texture. Relatively better cakes were obtained when lower quantities of maltodextrin were used in the formulation. Viscosity of the above cake batter was relatively higher. A relationship between batter viscosity and cake volume was observed. Further improvement in cake volume could be achieved using emulsifiers. In the presence of glycerol monostearate little improvement in cake batter was observed, but the resultant cake volume was improved. However, sodium steroyl lactylate, which improved the batter viscosity, did not improve the cake volume or texture. Copyright © 2005 Society of Chemical Industry
The effects of genetic variation at r, rb and Tri loci in Pisum sativum L. on apparent ileal digestibility of amino acids in young broilers
Authors: Wiseman Julian , Al‐Marzooqi Waleed , Hedley Cliff , Wang Trevor L , Welham Tracey , Domoney Claire
Published: December 2005

The nutritional effect of genetic variation at r and rb loci was investigated by determining apparent and true amino acid digestibility of four near‐isogenic lines of pea (RRRbRb, RRrbrb, rrRbRb, rrrbrb) fed to young broilers in a metabolism study. The results demonstrated that the round‐seeded line (RRRbRb) generally had the lowest amino acid content with, for example, 2.5 g cystine kg−1 dry matter (DM) and 1.6 g methionine kg−1 DM, compared with contents in the three wrinkled‐seeded lines (rrRbRb, RRrbrb and rrrbrb). The double mutant line (rrrbrb) generally had the highest amino acid content, with 3.2 g cystine kg−1 DM and 2.3 g methionine kg−1 DM, and an elevated amino acid content compared with the single mutant lines (RRrbrb, rrRbRb). However, the round‐seeded line (RRRbRb) consistently had the highest coefficient of true (CTID), and apparent (CAID), ileal digestibility for all amino acids (e.g. 0.959 and 0.928 respectively for CTID and CAID for methionine) when compared with the three wrinkled lines RRrbrb, rrRbRb and rrrbrb (0.853, 0.877 and 0.866, respectively, for CTID, and 0.862, 0.882 and 0.874 for CAID). A second experiment examined the digestibility of amino acids in a pair of lines, HC8 and LC8, near‐isogenic except for the locus controlling the concentration of seed trypsin inhibitor (H, high; L, low). The results showed that the CAID and CTID obtained for all amino acids were consistently higher for LC8 than for HC8 (for methionine: 0.905 and 0.709 for CTID, respectively, for LC8 and HC8; 0.887 and 0.729, respectively, for CAID), indicating the very specific effects of quantitative variation in these proteins on nutritional value of peas for poultry. Copyright © 2005 Society of Chemical Industry
Functional properties of caseinate glycoconjugates prepared by controlled heating in the ‘dry’ state
Authors: Oliver Christine M , Melton Laurence D , Stanley Roger A
Published: December 2005

Glucose, ribose, fructose, lactose, fructo‐oligosaccharide (inulin) and a mixture of inulin and fructose were conjugated with caseinate via the Maillard reaction using controlled heating and low water activity conditions in order to improve the functional properties of caseinate for food purposes. Conjugation with ribose and glucose increased the viscosity of caseinate 28‐fold over that of the unmodified caseinate control but also produced the most browning. Glycoconjugates of caseinate–fructose reacted at a substrate ratio of 1:0.2 w/w and 60 °C at 67% relative humidity for 48 h increased the viscosity of caseinate 24‐fold with less browning. At 80% relative humidity the reaction occurred so rapidly that, within 24 h gels containing darkly coloured particulate matter were produced. Incorporation of inulin at 1:1:0.2 w/w/w caseinate/inulin/fructose prevented formation of gels and produced glycoconjugates having 15‐fold the viscosity of unmodified caseinate with minimal browning. Copyright © 2005 Society of Chemical Industry
Organochlorine pesticide residues in poultry feed, chicken muscle and eggs at a poultry farm in Punjab, India
Authors: Aulakh Rabinder S , Gill Jatinder Paul S , Bedi Jasbir S , Sharma Jagdish K , Joia Balbir S , Ockerman Herbert W
Published: December 2005

Animals intended for human food may absorb pesticides from residues in their feed, water or during direct/indirect exposure in the course of pest control. The objective of the present investigation was to monitor organochlorine pesticide residues in poultry feed, chicken muscle and eggs at a selected poultry farm. The samples were Soxhlet extracted for 8 h in 200 mL hexane–acetone (1:1, v/v) mixture. The clean‐up of the samples was performed by silica gel column chromatography and analysis was done on a gas chromatograph equipped with an electron capture detector. The mean total hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT), endosulfan sulfate and heptachlor epoxide residues were 0.65, 0.91, 0.42 and 0.02 mg kg−1, respectively, in feed while respective values for chicken muscle were 0.11, 0.24, 0.10 and 0.07 mg kg−1. Higher residues were encountered in eggs as compared to muscle. None of the muscle samples exceeded maximum residue limits (MRL) for organochlorine pesticides, while all egg samples had values above the MRL for HCH and heptachlor epoxide and seven egg samples exceeded MRL for DDT residues. The results indicated that poultry feed could be one of the major sources of contamination for chicken and eggs. These residues are present despite complete ban on the use of technical HCH and DDT for agricultural purposes in India. Copyright © 2005 Society of Chemical Industry
Coherently controlled mesoscopic transport
Authors: Weiss C
Published: December 2005

A weakly interacting Bose-Einstein condensate is
initially situated in the first of a series of wells. Numerical
calculations show that, by adding especially designed
time-dependent potential modulations, the condensate can be
transported through the wells in a controlled way.
A method of carrier-envelope phase control for few-cycle laser pulses
Authors: Hasović E , Milošević D B , Becker W
Published: December 2005

The shape of the field of a few-cycle laser pulse strongly depends on the carrier-envelope phase. For a circularly polarized few-cycle pulse, this phase is correlated with a direction in space. Superposition of two counterrotating circularly polarized few-cycle pulses yields a linearly polarized pulse. High-energy electrons, generated through above-threshold ionization by such a combination of pulses, are emitted in a direction correlated with the carrier-envelope phase. Based on these facts, we propose two schemes for direct measurement and control of the carrier-envelope phase and the phase slip of a pulse train.
Double-resonance grating mirror for polarization control in solid-state
lasers
Authors: Ahmed M A , Graf Th
Published: December 2005

The spectral width of the polarizing effect of a
coupling grating on a standard quarter-wave multilayer laser
mirror can be increased by applying dual-duty-cycle gratings. As
an example this is discussed considering the requirements to
polarize a Yb:YAG thin-disk laser. By applying dual-duty-cycle
gratings the spectral tolerance can be widened by a factor of two
as compared to single-duty-cycle designs and at the same time
achieve a high reflectivity and low losses for the oscillating
polarized laser mode. The calculations of the structures were
carried out with the help of an exact modelling code based on the
modal method. The code simulates the interaction of a plane
electromagnetic wave with the corrugated multilayer structure to
compute amplitude and power of all reflected and transmitted
diffraction waves.
Use of lasers and light‐based therapies for treatment of acne vulgaris
Authors: Mariwalla Kavita , Rohrer Thomas E.
Published: December 2005

Over the last two decades, lasers and light‐based therapies have been developed to treat a wide variety of cutaneous maladies. Given the prevalence and number of patients who suffer from refractory acne, alternatives to existing care are constantly sought after. In this review, we discuss the evidence currently available to justify the use of laser and light‐based modalities and conclude that in combination therapy, such approaches provide a safe and effective treatment for acne vulgaris. Lasers Surg. Med. 37:333–342, 2005. © 2005 Wiley‐Liss, Inc.
Poly[(4‐hydroxybutyric acid)‐alt‐(glycolic acid)]: Synthesis by Thermal Polycondensation of Metal Salts of 4‐Chlorobutyric Acid Carboxymethyl Ester
Authors: Martínez‐Palau Meritxell , Franco Lourdes , Ramis Xavier , Puiggalí Jordi
Published: December 2005

Summary: A new sequential copolyester consisting of glycolic acid and 4‐hydroxybutyric acid units was prepared by a thermal polycondensation method that uses the formation of metal chloride salts as a driving force. The polymerization conditions (time, temperature) were studied in order to obtain appropriate molecular weights and high yields. Thermal properties and thermal stability were also determined. The polymerization kinetics of sodium, potassium and cesium monomer derivatives were studied by differential scanning calorimetry and the results compared. Non‐isothermal data and an isoconversional procedure (free model) were applied to determine the Arrhenius parameters (activation energy and pre‐exponential factor). The kinetic model was selected according to both the Coats‐Redfern method and the evaluation of isokinetic parameters.

DSC heating runs of sodium, potassium and cesium salts of 4‐chlorobutyric acid carboxymethyl ester after preheating at 100 °C.

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DSC heating runs of sodium, potassium and cesium salts of 4‐chlorobutyric acid carboxymethyl ester after preheating at 100 °C.
Multi‐Arm Star Polyglycerol‐block‐poly(tert‐butyl acrylate) and the Respective Multi‐Arm Poly(acrylic acid) Stars
Authors: Shen Zhong , Chen Yu , Barriau Emilie , Frey Holger
Published: December 2005

Summary: Well‐defined multi‐arm star block copolymers, polyglycerol‐block‐poly(tert‐butyl acrylate) (PG‐b‐PtBA), with average arm‐numbers of 17, 27, 36, 66 and 90 arms, respectively, have been prepared by atom transfer radical polymerization (ATRP) of tBA in acetone, using a core‐first strategy. After hydrolysis with excess concentrated HCl in refluxing dioxane, full hydrolysis of the tert‐butyl ester groups was achieved, resulting in multi‐arm star polyelectrolytes, polyglycerol‐block‐poly(acrylic acid) (PG‐b‐PAA). The hyperbranched macroinitiators employed were prepared on the basis of hyperbranched polyglycerols via esterification with 2‐bromoisobutyryl bromide. Both CuBr/PMDETA and CuBr/Me6TREN catalyst systems have been employed for ATRP of tBA. CuBr/PMDETA was found to permit good control. Polydispersity indices for the new multi‐arm stars were mainly in the range of 1.22 to 1.4, and the absolute $\overline M _{\rm n}$ data were in agreement with the calculated values. Moreover, kinetic curves show a linear dependence of ln([M]0/[M]t) on time, confirming that the polymerizations are controlled.

Relationship between arm numbers of the multi‐arm stars and maximum conversion achieved.

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Relationship between arm numbers of the multi‐arm stars and maximum conversion achieved.
Improving Impact Poly(propylene) Morphology and Production: Selective Poisoning of Catalyst Surface Sites and the Use of Antistatic Agents
Authors: Bouzid Djallel , McKenna Timothy F. L.
Published: December 2005

Summary: Selective poisoning has been studied as a means of improving the morphology and rheological properties of high‐impact poly(propylene) copolymer particles. Two different methods of poisoning the catalyst surface in order to avoid the accumulation of ethylene‐propylene rubber (EPR) without influencing the reaction kinetics were tested: a slurry‐phase poisoning step using ethylene glycol dimethyl ether between the homopolymerisation and copolymerisation reaction steps; and direct poisoning via the use of a commercial antistatic agent during the gas‐phase copolymerisation reactor. It was observed that both methods eliminated the formation of rubber on the particle surface without noticeably influencing the kinetics. On the other hand, the use of the products directly in the gas‐phase reaction also contributed to the reduction of static electricity. It can be concluded from these experiments that industrial antistatic agents derive at least part of their effect from poisoning of the active sites on the surface of the catalyst. Furthermore, it appears that in the case of the catalyst used in this study, EPR does not appear to flow out of the growing particles. Most of the EPR found at the surface of the particles is formed close to it.

SEM images of hiPP and GLYM001.

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SEM images of hiPP and GLYM001.
Synthesis and Characterization of Poly[((maleic anhydride)‐alt‐styrene)‐co‐(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid)]
Authors: Devrim Yilser G. , Rzaev Zakir M. O. , Pişkin Erhan
Published: December 2005

Summary: Novel polyfunctional sulfone‐ and anhydride‐containing reactive terpolymers with different compositions have been synthesized by complex‐radical polymerization of the ternary MA‐St‐APMS acceptor‐donor‐acceptor monomer system. This method allows preparing terpolymers with a sufficiently high content of APMS which essentially increased polyelectrolyte, swelling, IEC and thermal stability of terpolymer films. The terpolymer structure‐composition‐properties (polyelectrolyte, thermal, swelling and cation exchange behavior) relationships were studied by FTIR and 1H{13C} NMR (DEPT‐135) spectroscopy, viscometry, DSC‐TGA methods, and by means of swelling and exchange capacity. The observed H‐bonding between sulfonic acid, amide and anhydride fragments played an important role in the formation of the physically crosslinked and self‐assembled architectures with controllable hydrophilic‐hydrophobic balance. These reactive terpolymers can be used as synthons for exchange membrane preparation and fuel cell applications.

Physically crosslinked and self‐assembled macrocomplex.

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Physically crosslinked and self‐assembled macrocomplex.
Pulsed Laser Polymerization of Alkyl Acrylates: Potential Effects of the Oxygen Presence and High Laser Power
Authors: Castignolles Patrice , Nikitin Anatoly N. , Couvreur Laurence , Mouraret Guillaume , Charleux Bernadette , Vairon Jean‐Pierre
Published: December 2005

Summary: Unexpected difficulties are encountered in the determination of propagation rate coefficients (kp) in free radical polymerization of alkyl acrylates by pulsed laser polymerization (PLP), mainly due to intramolecular transfer to polymer.1 This article is focused on the role played by the high laser power in these difficulties and the possible reactions of mid‐chain radical with residual oxygen. Removing the oxygen by simple bubbling of nitrogen is sufficient to avoid alteration of the polymerization kinetics of acrylates by residual oxygen under PLP conditions. Moreover, no degradation of polymer (or solvent) has been detected after irradiation with the high laser power typically used in PLP experiments. However, it has been shown that this high laser power completely prevents from having a temporally and spatially homogeneous radical concentration in the PLP cell. A model is proposed here to simulate the pulsed laser polymerization taking initiator consumption and laser energy absorption into account. According to our simulation results, this non‐negligible initiator consumption and laser power absorption can indeed have a positive influence, i.e., it favors the obtainment of a bimodal molar mass distribution fulfilling the IUPAC consistency criteria. This observation may contradict the idea that PLP‐SEC is not suitable to determine accurate kp values for acrylates above 20–30 °C.

Instantaneous MMDs formed after N pulses. Simulation taking initiator consumption and laser absorption into account.

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Instantaneous MMDs formed after N pulses. Simulation taking initiator consumption and laser absorption into account.
Polymer‐Polymer Interaction: Consistent Modeling in Terms of Chain Connectivity and Conformational Response
Authors: Wolf Bernhard A.
Published: December 2005

Summary:An approach developed for the modeling of polymer solutions is extended to polymer blends. It accounts explicitly for the fact that the segments of a given macromolecule cannot spread out over the entire volume of the system (chain connectivity) and that the space a polymer molecule occupies may change after contact formation between the components of a mixture (conformational responseζ). The validity of the equation obtained for the Flory‐Huggins interaction parameter between polymers is tested by means of critical data published for the system PVME/PS. The measured phase diagrams can be modeled equally well by two limiting assumptions concerning the temperature dependence of the conformational response. However, using these two different sets of parameters to calculate the phase behavior for high molar masses of both polymers, leads to fundamental differences. One of them yields double critical points and predicts well defined critical compositions in the limit of infinite molar masses of both polymers, in contrast to the original Flory‐Huggins theory. The physical meaning of the different parameters is analyzed and the composition and temperature dependencies of the Flory‐Huggins interaction parameter resulting from the present modeling are compared with corresponding data reported in the literature.

Double critical line (double critical concentrationφDCas a function ofmandn) calculated by means of Equation (12) and (13) using the system specific parameters given in row two of Table 2, and its projections into the different planes.

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Double critical line (double critical concentrationφDCas a function ofmandn) calculated by means of Equation (12) and (13) using the system specific parameters given in row two of Table 2, and its projections into the different planes.
Isoconversional Analysis of Combined Melt and Glass Crystallization Data
Authors: Vyazovkin Sergey , Dranca Ion
Published: December 2005

Summary: As proposed earlier (Macromol. Rapid Commun., 2004, 25, 733) the Kg and U* parameters of the Hoffman‐Lauritzen theory can be derived from isoconversional analysis of DSC data on melt crystallization. In this study, the analysis is extended to include both melt and glass crystallization data. The analysis of DSC data on non‐isothermal crystallization of poly(ethylene terephthalate) (PET) and poly(ethylene 2,6‐naphthalate) (PEN) demonstrates that for each of these polymers the combined melt and glass crystallization data can be described by single set of the Kg and U* values. The respective values for PET are 3.6 × 105 K2 and 7.5 kJ · mol−1 and for PEN 2.2 × 105 K2 and 6.6 kJ · mol−1. The use of combined data sets helps to improve the precision of computations.

Experimental E on T data for melt (circles) and glass (squares) crystallization of PET.

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Experimental E on T data for melt (circles) and glass (squares) crystallization of PET.
High Speed SSA Thermal Fractionation and Limitations to the Determination of Lamellar Sizes and Their Distributions
Authors: Lorenzo Arnaldo T. , Arnal Maria L. , Müller Alejandro J. , Boschetti de Fierro Adriana , Abetz Volker
Published: December 2005

Summary: The technique of successive self‐nucleation and annealing (SSA) has been applied using differential scanning calorimetry (DSC) to a model hydrogenated polybutadiene prepared by anionic polymerization and to a commercial Ziegler‐Natta ethylene/1‐butene copolymer. Here, it is shown that the use of high scanning rates (50 °C · min−1) in the SSA protocol can reduce the thermal fractionation time to only 78 min in length (if 6 fractions are produced with a fractionation window of 5 °C), taking into consideration the need to compensate the increment in heating rates by reducing the sample mass. This time is much shorter than those previously achieved by thermal fractionation in the literature, where fractionation times of 12 or 24 h are common. Potentially, much higher rates could be employed by further reducing the fractionation times by SSA. For the first time, a distribution of lamellar thicknesses has been obtained by transmission electron microscopy after SSA fractionation and compared to distributions calculated by the Thomson‐Gibbs equation. It is shown that the results are highly dependent on the equilibrium melting temperatures employed in the calculations, and it is recommended that the values of lamellar thicknesses obtained are checked by comparing with methylene sequence lengths derived from calibration measurements available in the literature. The Thomson‐Gibbs equation is useful for comparing lamellar thickness distributions obtained by SSA with different polymers only on a semi‐quantitative basis.

Rate and mass compensation as a way to reduce fractionation time employing SSA.

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Rate and mass compensation as a way to reduce fractionation time employing SSA.
11th IUPAC “International Symposium on Macromolecule‐Metal Complexes” (http://www.dcci.unipi.it/∼bea/mmc‐11/)
Authors: Ruggeri Giacomo , Ciardelli Francesco
Published: December 2005

Conference Reports: This section contains reports on topical conferences. Reports are usually written at the request of the editorial office, but unsolicited contributions are also welcome. Suggestions should be sent to the editorial office of the Macromolecular journals, preferably by E‐mail to macromol@wiley‐vch.de.
Cover Picture: Macromol. Chem. Phys. 24/2005
Authors: Li Jiang , Guo Shaoyun , Slezák Radek , Hausnerová Berenika
Published: December 2005

Cover: The figure shows that ultrasound treatment during extrusion of a polystyrene (PS)/ethylene‐propylene diene monomer (EPDM) blend can decrease the size of the dispersed phase and improve its dispersion, leading to an increase of the compatibility of the blend. This is attributed to the formation of PS‐EPDM copolymers by combination of the corresponding macroradicals. Further details can be found in the Full Paper by J. Li, S. Guo,* R. Slez´k, and B. Hausnerov´ on page 2429.
Dwarf Cavendish as a Source of Natural Fibers in Poly(propylene)‐Based Composites
Authors: Faria Helena , Cordeiro Nina , Belgacem Mohamed Naceur , Dufresne Alain
Published: December 2005

Summary: Composite materials were prepared by compounding and hot‐pressing PP or MAPP and lignocellulosic fibers extracted from the rachis of Musa acuminate Colla var. Dwarf Cavendish banana tree. The fibers were used as raw filler or after a chemical treatment expected to remove most of the extractible compounds. The resulting materials were characterized using SEM, DSC, DMA, tensile tests and water sorption experiments. All results show that the main aspect involved in the interfacial adhesion between the polar filler and the non‐polar matrix is the extraction of lignin and fatty substances. This results in higher values of the degree of crystallinity and crystallization temperature of the matrix, higher mechanical properties and lower water sensitivity.

Scanning electron micrograph showing the cross section of the lignocellulosic filler obtained from rachis of banana tree: (a) raw, and (b) extracted fibers.

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Scanning electron micrograph showing the cross section of the lignocellulosic filler obtained from rachis of banana tree: (a) raw, and (b) extracted fibers.
Oligomer Deposition on the Surface of PET Fiber in Supercritical Carbon Dioxide Fluid
Authors: Kawahara Yutaka , Kamo Masaki , Yamamoto Kiyoshi , Ogawa Satoshi , Terada Douhiko , Kikutani Takeshi , Tsuji Masaki
Published: December 2005

Summary: Spin‐drawing yarn (SDY) and high‐speed spun (HSS) fibers were produced from recycled poly(ethylene terephthalate) pellets, and the oligomer deposition on the surface of fiber in supercritical carbon dioxide fluid was compared. The oligomer deposition was obvious for SDY, which corresponded to the fact that the amount of imperfect small crystallites generated in amorphous regions through s‐CO2 treatment was much smaller for SDY as compared to that with HSS. The imperfect small crystallites generated in amorphous regions will work as a barrier to the oligomer migration. In order to suppress the deposition of oligomer for SDY, the combination of a heatset treatment and an alkaline etching was useful. At a heatset process, the oligomer migration to the surface layer tends to occur, and the layer becomes rich in oligomer. The following topochemical hydrolysis reaction at alkaline etching removes such layer. Accordingly, the total content of oligomer in etched fiber is reduced. As a result, the oligomer deposition in s‐CO2 treatment becomes not so serious. In addition, the heatset treatment gives the shrinkproof property to SDY, and the property is still retained after the alkaline etching.

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Large‐Scale Synthesis of Necklace‐Like Single‐Crystalline PbTiO3 Nanowires
Authors: Lu Xiaofeng , Zhang Daliang , Zhao Qidong , Wang Ce , Zhang Wanjin , Wei Yen
Published: December 2005

Summary: We show in this communication that large‐scale necklace‐like single‐crystalline tetragonal perovskite PbTiO3 nanowires can be obtained via a simple electrospinning method. The morphology and the crystal structure are investigated by SEM, XRD, and HRTEM. The length of the necklace‐like PbTiO3 nanowires is from tens to several tens of micrometers, the wider the diameter of it is between 100 and 200 nm and the thinner the part is between 20 and 50 nm. The necklace‐like PbTiO3 nanowires exhibit high surface photovoltage under the action of external electric field, which is probably applicable in displaying photoelectric devices of heterojunction structure.

SEM image of the electrospinning necklace‐like PbTiO3 nanowires.

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SEM image of the electrospinning necklace‐like PbTiO3 nanowires.
Synthesis and Characterization of Novel Mesogen‐Jacketed Liquid Crystalline Miktoarm Star Rod‐Coil Block Copolymer
Authors: Chen Jianfang , Wang Xingzhu , Liao Xiaojuan , Zhang Hailiang , Wang Xiayu , Zhou Qifeng
Published: December 2005

Summary: A series of novel mesogen‐jacketed liquid crystal miktoarm star rod‐coil block copolymers were synthesized via atom transfer radical polymerization (ATRP). Their architectures {coil conformation of styrene segment and rigid rod conformation of {2,5‐bis[(4‐methoxyphenyl)oxycarbonyl]styrene} (MPCS) segment} were confirmed by GPC, 1H NMR, and MALDI‐TOF studies. The liquid crystalline behaviors of the synthesized copolymers are evidenced from POM observation. The liquid crystalline phase depends on the molecular weights of the rigid rod arm of miktoarm star copolymers.

Miktoarm star rod‐coil block copolymer.

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Miktoarm star rod‐coil block copolymer.
Carbon Nanotubes as a Ligand in Cp2ZrCl2‐Based Ethylene Polymerization
Authors: Park Sungjin , Yoon Seung Woong , Lee Kyung‐Bok , Kim Dong Jin , Jung Young Hwan , Do Youngkyu , Paik Hyun‐jong , Choi Insung S.
Published: December 2005

Summary: We report a simple method for tuning catalytic property of a metallocene‐based catalyst, Cp2ZrCl2, for ethylene polymerization by the direct adsorption of Cp2ZrCl2 onto multi‐walled carbon nanotubes (MWCNTs). The direct interactions between MWCNTs and the Cp rings of Cp2ZrCl2 controlled the polymerization behaviors, and we could generate polyethylene with an extremely high molecular weight ($\overline M _{\rm w}$ = 1 000 000) at 30 °C and under 1 atm of ethylene gas.

Preparation of Cp2ZrCl2‐MWCNT.

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Preparation of Cp2ZrCl2‐MWCNT.
Dewetting Process of Polyelectrolyte Multilayer Films in Hot Water
Authors: Qin Sheng , Wei Dongshan , Liao Qi , Jin Xigao
Published: December 2005

Summary: We analyzed quantitatively the effects of temperature on the morphologic evolution of the desorption process in hot water measured ex situ by atomic force microscopy. The morphology of the hole that forms with immersion of the polyelectrolyte film in hot water has characteristics similar to those from polymer dewetting processes near the glass transition temperature. The hole diameter immediately reaches a maximum in the desorption process while the number of holes increases linearly with time.

AFM images of the morphology of PEM film after immersion in hot water 60 min.

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AFM images of the morphology of PEM film after immersion in hot water 60 min.
Supramolecular Thermotropic Liquid Crystalline Materials with Nematic Mesophase Based on Methylated Hyperbranched Polyethylenimine and Mesogenic Carboxylic Acid
Authors: Chen Yu , Shen Zhong , Gehringer Lionel , Frey Holger , Stiriba Salah‐Eddine
Published: December 2005

Summary: Supramolecular interaction of fully methylated hyperbranched polyethylenimines (PEI) with a mesogen‐based carboxylic acid, 5‐(p‐cyanobiphenoxy)pentanoic acid, results in the formation of supramolecular complexes exhibiting thermotropic liquid crystalline (LC) mesophases. In contrast to the common smectic mesophases of most dendritic LC polymers, nematic LC phases were observed. The complexation of PEI and the mesogen units is due to electrostatic interaction between the carboxylate groups and the ammonium end groups of PEI. LC properties were investigated by a combination of differential scanning calorimetry, polarizing light optical microscopy, and X‐ray diffractometry.

Schematic illustration of the supramolecular assembly of CBPA with PEIMe backbone.

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Schematic illustration of the supramolecular assembly of CBPA with PEIMe backbone.