bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of Acid Preconditioning for Enhanced Dewatering of Wastewater Treatment Sludges from the Pulp and Paper Industry
Authors: Mahmood Talat , Elliott Allan
Published: January 2007

In municipal and industrial practices, wastewater treatment sludges are generally conditioned with organic polymers before dewatering. The dewatering polymers are expensive and contribute significantly to the overall sludge management cost. This paper discusses a preconditioning strategy that holds great promise for enhancing dewatering properties of wastewater treatment sludges, while reducing the cost. In this approach, the waste activated sludge (WAS) is briefly preconditioned with an acid before flocculating with an organic polymer. Experimental results showed that acid preconditioning significantly enhanced dewatering. Separately acidifying WAS and subsequently combining it with primary sludge produced higher presscake solids than acidifying the combined sludge to the same final pH. Acidification exhibited the added benefit of reducing Escherichia coli counts in sludge, thus improving its biological character. This may provide flexibility in choosing a beneficial use application.
Case Report of 3 Patients with Severe Mental Illness and Chronic Hepatitis C Virus Infection Treated with Interferon-Alpha
Authors: Mistler Lisa A. , Brunette Mary F. , Rosenberg Stanley D. , Vidaver Robert M. , Luckoor Ravi , Iber Mark
Published: January 2007

We report on three patients with hepatitis C virus infection, severe mental illness, and substance use disorders that we treated successfully with interferon and ribavirin. This population has historically been refused such treatment on the grounds that they were unlikely to be adherent to treatment or would experience untoward psychiatric side effects. These case reports add support to the growing body of evidence that persons with severe mental illness and substance use disorders can be successfully treated for hepatitis C with careful monitoring and psychiatric oversight.
Open Learning Environments and the Impact of a Pedagogical Agent
Authors: Clarebout Geraldine , Elen Jan
Published: January 2007

Research reveals that in highly structured learning environments pedagogical agents can act as tools to direct students' learning processes by providing content or problem solving guidance. It has not yet been addressed whether pedagogical agents have a similar impact in more open learning environments that aim at fostering students' acquisition of complex problem solving skills. To fill this gap, this study compares two experimental conditions to a control condition. In the first experimental condition, the pedagogical agent's interventions are adapted to students' activities (APA-group). In the second experimental group, the agent interferes on fixed time intervals (NPA-group). Students work on an environmental problem in an open learning environment. It was hypothesized that the two experimental groups would outperform the control group and, additionally, that the APA-group would outperform the NPA-group. Results show that the NPA-group outperforms the control group, and that the APA-group takes a middle position, not differing from either the NPA-group or the control-group. Consequently, the second hypothesis was not confirmed. An agent providing adapted advice did not result in better performance. The discussion provides some possible explanations for these results.
Simulation versus Text: Acquisition of Implicit and Explicit Information
Authors: Taylor Roger S. , Chi Michelene T. H.
Published: January 2007

This study investigated potential differences in learning between two instructional activities: reading from a text and using a computer simulation. Participants were undergraduate students with limited knowledge of the domain topic (project management). Participants in both conditions (Simulation and Text) improved equally on a decontextualized, abstract knowledge assessment. In contrast, only the participants in the Simulation condition significantly improved on a contextualized case-based assessment. A propositional analysis revealed that participants in the Simulation condition acquired a significant amount of implicit domain information from pretest to posttest, whereas participants in the Text condition did not. These results suggest that educational computer simulations have the potential to significantly enhance the learning of implicit domain knowledge.
Autobiographical Memory and Depression in the Later Age: The Bump is a Turning Point
Authors: Gidron Yori , Alon Shirly
Published: January 2007

This preliminary study integrated previous findings of the distribution of autobiographical memories in the later age according to their age of occurrence, with the overgeneral memory bias predictive of depression. Twenty-five non-demented, Israeli participants between 65–89 years of age provided autobiographical memories to 4 groups of word cues reflecting events from childhood, adolescence, adulthood and late age. Their autobiographical responses were coded for degree of specificity of mentioning people, place and time. They additionally completed the Geriatric Depression Scale (Sheikh & Yesavage, 1986). We found that specificity of memories for adolescence cue-words (“the reminiscence bump”) was significantly and inversely correlated with depression ( r = −0.61), and this remained significant after controlling for gender and education. The study's limitations and the possibility that puberty hormones may be involved in memory and later age depression are discussed.
The Elders of the Kibbutz
Authors: Gutmann David , Shkolnik Tamar
Published: January 2007

In order to test the hypothesis that retirement would be particularly stressful for this highly motivated cohort, forty retired members of Israeli kibbutzim (22 men, 18 women) were interviewed in an open—ended fashion, concerning their early history, their decision to join the kibbutz, their working life, and their post-retirement adaptation. Little evidence of significant psychopathology was found, and those instances were for the most part traceable to traumatic rearing in the family of orientation, rather than to current, post-retirement losses and insults. These findings are discussed in terms of the Habitat-Niche model developed by Gutmann.
The Organization of Lithic Technology and the Bifurcate Occupation of the Hart Site (15La183), Lawrence County, Kentucky
Authors: Bradbury Andrew P.
Published: January 2007

Excavations at the Hart Site revealed an Early Archaic, Bifurcate Base occupation. Analysis of the lithic artifacts from this component allow for inferences concerning the organization of lithic technology at the site. Roughly forty percent of the flake debris was of non-local chert sources. A number of bifacial tools was maintained and used at the site and a staged approach to bifacial tool manufacture is indicated. Based on a high amount of use and reworking, these bifacial tools are inferred to be highly curated. Raw material percentages at the site indicate a west to east movement of people/materials.
Iconographic (Jesuit) Rings at the Utz Site
Authors: Mason Carol I.
Published: January 2007

The large and important Missouri site of Utz has produced six iconographic rings. Reviewing the means of decoration and the decorations themselves may provide a clarification of dates proposed both from radiocarbon assays and from what historic documentation is available. The rings speak of several different points of contact of the Missouris with outside, presumably French, sources; if verifiable, they may serve as another, possibly independent, means of dating.
Extrapolation designs with constraints
Authors: Fang Zhide
Published: January 2007

The author considers (asymptotically) minimax extrapolation designs for an approximately multiple linear model with the model contaminant f being restricted only by its L2norm. He splits the integrated mean squared prediction error (IMSPE) of the fitted value over the extrapolation space into two parts, namely the integrated prediction variance (IPV) and the integrated prediction bias (IPB). For a spherical design space and an annular extrapolation space, he constructs the design that minimizes the maximum value, over f, of IPB subject to bounding IPV. He also constructs the design that minimizes IPV subject to bounding the maximum IPB.
On blest's measure of rank correlation
Authors: Genest Christian , Plante Jean‐François
Published: January 2007

Blest (2000) proposed a new nonparametric measure of correlation between two random variables. His coefficient, which is dissymmetric in its arguments, emphasizes discrepancies observed among the first ranks in the orderings induced by the variables. The authors derive the limiting distribution of Blest's index and suggest symmetric variants whose merits as statistics for testing independence are explored using asymptotic relative efficiency calculations and Monte Carlo simulations.
Empirical likelihood confidence intervals for the mean of a population containing many zero values
Authors: Chen Jiahua , Chen Shun‐Yi , Rao J. N. K.
Published: January 2007

If a population contains many zero values and the sample size is not very large, the traditional normal approximation‐based confidence intervals for the population mean may have poor coverage probabilities. This problem is substantially reduced by constructing parametric likelihood ratio intervals when an appropriate mixture model can be found. In the context of survey sampling, however, there is a general preference for making minimal assumptions about the population under study. The authors have therefore investigated the coverage properties of nonparametric empirical likelihood confidence intervals for the population mean. They show that under a variety of hypothetical populations, these intervals often outperformed parametric likelihood intervals by having more balanced coverage rates and larger lower bounds. The authors illustrate their methodology using data from the Canadian Labour Force Survey for the year 2000.
Consistency of the beta kernel density function estimator
Authors: Bouezmarni Taoufik , Rolin Jean‐Marie
Published: January 2007

The authors give the exact asymptotic behaviour of the expected average absolute error of a beta kernel density estimator proposed by Chen (1999). They also prove the uniform weak consistency of this estimator for the class of continuous densities.
The historical functional linear model
Authors: Malfait Nicole , Ramsay James O.
Published: January 2007

The authors develop a functional linear model in which the values at time t of a sample of curves yi (t) are explained in a feed‐forward sense by the values of covariate curves xi(s) observed at times s ±.t. They give special attention to the case s ± [t — δ, t], where the lag parameter δ is estimated from the data. They use the finite element method to estimate the bivariate parameter regression function β(s, t), which is defined on the triangular domain s ± t. They apply their model to the problem of predicting the acceleration of the lower lip during speech on the basis of electromyographical recordings from a muscle depressing the lip. They also provide simulation results to guide the calibration of the fitting process.
Adaptive tests of regression functions via multiscale generalized likelihood ratios
Authors: Zhang Chunming M.
Published: January 2007

Many applications of nonparametric tests based on curve estimation involve selecting a smoothing parameter. The author proposes an adaptive test that combines several generalized likelihood ratio tests in order to get power performance nearly equal to whichever of the component tests is best. She derives the asymptotic joint distribution of the component tests and that of the proposed test under the null hypothesis. She also develops a simple method of selecting the smoothing parameters for the proposed test and presents two approximate methods for obtaining its P‐value. Finally, she evaluates the proposed test through simulations and illustrates its application to a set of real data.
Optimal design for the proportional odds model
Authors: Perevozskaya Inna , Rosenberger William F. , Haines Linda M.
Published: January 2007

The authors construct locally optimal designs for the proportional odds model for ordinal data. While they investigate the standard D‐optimal design, they also investigate optimality criteria for the simultaneous estimation of multiple quantiles, namely DA‐optimality and the omnibus criterion. The design of experiments for the simultaneous estimation of multiple quantiles is important in both toxic and effective dose studies in medicine. As with c‐optimality in the binary response problem, the authors find that there are distinct phase changes when exploring extreme quantiles that require additional design points. The authors also investigate relative efficiencies of the criteria.
A note on penalized minimum distance estimation in nonparametric regression
Authors: Bunea Florentina , Wegkamp Marten H.
Published: January 2007

The authors introduce a penalized minimum distance regression estimator. They show the estimator to balance, among a sequence of nested models of increasing complexity, the L1 ‐approximation error of each model class and a penalty term which reflects the richness of each model and serves as a upper bound for the estimation error.
On testing for multivariate ARCH effects in vector time series models
Authors: Duchesne Pierre , Lalancette Simon
Published: January 2007

Using a spectral approach, the authors propose tests to detect multivariate ARCH effects in the residuals from a multivariate regression model. The tests are based on a comparison, via a quadratic norm, between the uniform density and a kernel‐based spectral density estimator of the squared residuals and cross products of residuals. The proposed tests are consistent under an arbitrary fixed alternative. The authors present a new application of the test due to Hosking (1980) which is seen to be a special case of their approach involving the truncated uniform kernel. However, they typically obtain more powerful procedures when using a different weighting. The authors consider especially the procedure of Robinson (1991) for choosing the smoothing parameter of the spectral density estimator. They also introduce a generalized version of the test for ARCH effects due to Ling & Li (1997). They investigate the finite‐sample performance of their tests and compare them to existing tests including those of Ling & Li (1997) and the residual‐based diagnostics of Tse (2002).Finally, they present a financial application.
The analysis of unreplicated factorial experiments from a geometric perspective
Authors: Miller Arden E.
Published: January 2007

The author investigates the analysis of unreplicated factorial experiments from a geometric perspective. He considers more specifically a (k + 1)‐run experiment used to estimate k orthogonal contrasts. He observes that once centered and scaled to unit length, the response vector can be viewed as a point on the unit sphere in the vector space spanned by the contrasts. In this context, a model selection procedure is equivalent to a partition of the unit sphere into regions corresponding to the different models considered. The author exploits this approach to gain useful insights into the analysis of such experiments.
Best monotone M‐estimators
Authors: Kolkiewicz Adam W.
Published: January 2007

The author shows how to find M‐estimators of location whose generating function is monotone and which are optimal or close to optimal. It is easy to identify a consistent sequence of estimators in this class. In addition, it contains simple and efficient approximations in cases where the likelihood function is difficult to obtain. In some neighbourhoods of the normal distribution, the loss of efficiency due to the approximation is quite small. Optimal monotone M‐estimators can also be determined in cases when the underlying distribution is known only up to a certain neighbourhood. The author considers the e‐contamination model and an extension thereof that allows the distributions to be arbitrary outside compact intervals. His results also have implications for distributions with monotone score functions. The author illustrates his methodology using Student and stable distributions.
Self‐Rupturing and Hollow Microcapsules Prepared from Bio‐polyelectrolyte‐Coated Microgels
Authors: De Geest B. G. , Déjugnat C. , Prevot M. , Sukhorukov G. B. , Demeester J. , De Smedt S. C.
Published: January 2007

This paper reports on microcapsules obtained by layer‐by‐layer deposition of bio‐polyelectrolyte multilayers at the surface of biodegradable dextran microgels. The behavior of the layer‐by‐layer coating upon degradation of the microgel core strongly depends on the bio‐polyelectrolytes used. Two types of microcapsules, “self‐rupturing” microcapsules and “hollow” microcapsules, are presented. Self‐rupturing microcapsules are obtained when the swelling pressure of the degrading microgel core is strong enough to rupture the surrounding bio‐polyelectrolyte membrane. Self‐rupturing microcapsules could be of interest as a pulsed drug delivery system. Hollow microcapsules are obtained after applying multiple layers of bio‐polyelectrolyte that can withstand the swelling pressure of the degrading microgel core. Biomacromolecules (such as albumin and dextran) spontaneously accumulate in the hollow microcapsules prepared from dex‐HEMA microgels, which could be of interest for drug‐encapsulation purposes.
Guest‐Induced Chirality in the Ferrimagnetic Nanoporous Diamond Framework Mn3(HCOO)6
Authors: Zhang B. , Wang Z.‐M. , Kurmoo M. , Gao S. , Inoue K. , Kobayashi H.
Published: January 2007

Chiral magnets are obtained by inclusion of chiral guest molecules into the channels of an achiral nanoporous ferrimagnet consisting of the Mn3(HCOO)6 (1) framework. Insertion of the R or the S enantiomer of 2‐chloropropan‐1‐ol (CH3C*HClCH2OH) in the chiral pores of the previously emptied framework (space group P21/c) results in the two corresponding chiral solids (1R and 1S, space group P21), while insertion of a racemic mixture of the two enantiomers retains the achirality of the host for the meso solid (1RS, space group P21/c). The R guest is ordered in the M channels while the S guest is ordered in the P channels. In contrast, the R guests in the P channels and the S guests in the M channels are disordered on two crystallographic orientations. For the racemic mixture of the two enantiomers in 1RS, random disorder of guests in both channels is observed. Thus, the localization of the guest molecule depends on the nature of the surface to recognize the guest of a particular chirality. The guest inclusion compounds are thermally stable. The 1R and 1S compounds are optically active. All the compounds adopt a ferrimagnetic ground state. Compared to the host framework of 1 without guest, the Curie temperature decreases for both 1R and 1S but increases for 1RS. The additional interactions between the framework and the inserted guest alcohols strengthen the lattice via hydrogen bonds and other electrostatic forces, and it might account for the significant lowering of the lattice contribution as well as the magnetic component to the specific heat capacity upon guest loading.
Hybrid “Golden Fleece”: Synthesis and Catalytic Performance of Uniform Carbon Nanofibers and Silica Nanotubes Embedded with a High Population of Noble‐Metal Nanoparticles
Authors: Qian H.‐S. , Antonietti M. , Yu S.‐H.
Published: January 2007

Carbon nanofibers produced by hydrothermal carbonization display remarkable reactivity and the capability for in situ loading with very fine noble‐metal nanoparticles of metals such as Pd, Pt, and Au. Large quantities of uniform carbon nanofibers embedded/confined with various kinds of noble‐metal nanoparticles can be easily prepared, resulting in the formation of the so‐called uniform and well‐defined “hybrid fleece” structures. In addition, a general method has been developed to synthesize uniform silica nanotubes embedded/confined with noble‐metal nanoparticles by using the “hybrid fleece” consisting of carbon nanofibers loaded with noble‐metal nanoparticles as a template. To the best of our knowledge, the filling of silica nanotubes with a dense population of noble‐metal nanoparticles has not been demonstrated so far. These hybrid carbon structures embedded with noble‐metal nanoparticles in a heterogeneous “fleece” geometry serve as excellent catalysts for a model reaction involving the conversion of CO to CO2 at low temperatures.
Tuning the Energy Level and Photophysical and Electroluminescent Properties of Heavy Metal Complexes by Controlling the Ligation of the Metal with the Carbon of the Carbazole Unit
Authors: Yang C. L. , Zhang X. W. , You H. , Zhu L. Y. , Chen L. Q. , Zhu L. N. , Tao Y. T. , Ma D. G. , Shuai Z. G. , Qin J. G.
Published: January 2007

Four novel IrIII and PtII complexes with cyclometalated ligands bearing a carbazole framework are prepared and characterized by elemental analysis, NMR spectroscopy, and mass spectrometry. Single‐crystal X‐ray diffraction studies of complexes 1, 3, and 4 reveal that the 3‐ or 2‐position C atom of the carbazole unit coordinates to the metal center. The difference in the ligation position results in significant shifts in the emission spectra with the changes in wavelength being 84 nm for the Ir complexes and 63 nm for the Pt complexes. The electrochemical behavior and photophysical properties of the complexes are investigated, and correlate well with the results of density functional theory (DFT) calculations. Electroluminescent devices with a configuration of ITO/NPB/CBP:dopant/BCP/AlQ3/LiF/Al can attain very high efficiencies.
Raspberry‐like Gold Microspheres: Preparation and Electrochemical Characterization
Authors: Li Z. , Ravaine V. , Ravaine S. , Garrigue P. , Kuhn A.
Published: January 2007

A straightforward method to synthesize quasi‐monodisperse gold microspheres from a commercial gold plating solution is reported. The size and the surface roughness of the obtained particles can easily be tuned. In particular, raspberry‐like particles with a high active surface area are obtained. The microspheres are assembled on indium tin oxide (ITO) electrodes using the layer‐by‐layer technique and the overall electroactive surface area is increased, as characterized by cyclic voltammetry. The as‐prepared products were characterized by scanning electron microscopy (SEM), powder X‐ray diffraction (XRD), cyclic voltammetry, and light microscopy.
Determination of radionuclides in water at uranium mining remediation – a comparison of analytical methods
Authors: Laubrich Jan , Lotze Petra , Winkler Gudrun
Published: January 2007

The corporate purpose of Wismut GmbH is to decommission its former mining holdings and to rehabilitate the landscape and the environment. Sample taking and analysing the value of contaminants are necessary steps for the remediation of waste rock piles, the recycling of contaminated areas, controlled flooding of uranium mines. Main emphasis lies on the determination of heavy metals and radionuclides of natural decay chains of U‐238 and U‐235. Yearly about 60 000…70 000 determinations of radionuclides in waters were done. Facing this high output of determinations it is a permanent task for laboratory and quality management to ask: Are the results of different methods comparable to each other? Is there a preferred analytical technology? Which matrix influences exist? and What about the analytical costs? Answers to these important questions are given in this report. Summarizing our investigations done in the last few years it is possible to say that – by using different analytical methods the results of radionuclides in water samples (surface or groundwater) are comparable, – a not negligible influence of Ra‐223, Ra‐224 and Ra‐228 may exist by using the DIN 38404 C18 method to determine Ra‐226, – a preferred method cannot be defined, – the choice of the analytical method should include analytical questions (the sample matrix, the occurrence of other disturbing radionuclides, the necessary detection limit) and economical questions (costs, other parameters to be determined).
Spectroscopic investigation of humic substances in a tropical lake during a complete hydrological cycle
Authors: Oliveira Janaìna L. , Boroski Marcela , Azevedo Jùlio C. R. , Nozaki Jorge
Published: January 2007

Fluorescence and UV‐VIS techniques were employed for the investigation of natural organic matter (NOM) of a tropical lake. The relationships of absorbance/dissolved organic carbon (A/DOC), fluorescence intensity/dissolved organic carbon (FI/DOC), fluorescence ratio (FR), and peak wavelength with the highest intensity (PW) were used to distinguish the pedogenic or aquagenic origin of NOM. The values of FR, PW and A285/DOC of high waters (HW) or flooded period samples and of low waters (LW) period samples of the dry season, except for September 2002, confirm the predominance of pedogenic material. The spectra of water were similar to the standard fulvic acid (FA), and the spectra of FA from the lake were similar to the nearby soils, indicative of pedogenic predominance. The results confirm that the dissolved NOM of Patos Lagoon – MS (Brazil), in all sampling periods, predominantly consisted of humic substances (FA) of pedogenic origin.
Infanticide and cannibalism in a free‐ranging plurally breeding group of common marmosets (Callithrix Jacchus)
Authors: Bezerra Bruna Martins , Souto Antonio Da Silva , Schiel Nicola
Published: January 2007

Our study presents a detailed description of infanticide and cannibalism in a free‐ranging plurally breeding group of Callithrix jacchus. The 1‐month‐old infant was the daughter of the dominant female, and was attacked by the group's second breeding female. Two months later, the latter gave birth to twins and appeared to have become the dominant female. These findings confirm and extend previous reports of infanticide by pregnant female marmosets, and indicate that infants of dominant breeding female, as well as those of subordinate females, are vulnerable to infanticide in plurally breeding groups. With respect to the cannibalism, this act seemed to be mainly a response to the prompt availability of food, represented by the killed infant. Am. J. Primatol. 69:945–952, 2007. © 2007 Wiley‐Liss, Inc.
Ground use by northern muriquis (Brachyteles hypoxanthus)
Authors: Mourthé Ítalo M.C. , Guedes Danusa , Fidelis Janaína , Boubli Jean P. , Mendes Sérgio L. , Strier Karen B.
Published: January 2007

Many arboreal primates descend to the ground, a custom that may occur more frequently in disturbed habitats, and in the presence of researchers to whom the primates are habituated. In this paper, we describe opportunistic observations of ground use in two groups of northern muriquis (Brachyteles hypoxanthus) at the RPPN Feliciano Miguel Abdala, Minas Gerais, Brazil. Members of both groups were observed drinking, resting, feeding, playing, and traveling on the ground to different degrees, and variation in the levels of habituation of the two groups may be responsible for the differences in the distribution of their terrestrial activities. The potential increase in vulnerability to predation or disease owing to ground use has implications for the conservation of this critically endangered species. Am. J. Primatol. 69:706–712, 2007. © 2007 Wiley‐Liss, Inc.
C‐C‐Kupplungen mit Alkoholen als Elektrophilen: der Wasserstoff‐Autotransfer
Authors: Guillena Gabriela , Ramón Diego J. , Yus Miguel
Published: January 2007

Der Wasserstoff‐Autotransfer ist eine neue Art von Dominoreaktion. Die Sequenz umfasst eine einleitende oxidative Wasserstoffeliminierung, eine nachfolgende C‐C‐Kupplung verschiedenen Typs und zum Abschluss eine reduktive Wasserstoffanlagerung zur Bildung des Endprodukts. Mithilfe des Wasserstoff‐Autotransfers gelingt die Alkylierung nukleophiler Substrate mit Alkoholen als Elektrophilen unter milden Reaktionsbedingungen (schwache Basen, niedrige Temperaturen) und mit Wasser als dem einzigen Beiprodukt. Durch die Einführung verschiedener metallorganischer Katalysatoren konnte der Substratbereich deutlich erweitert werden. Dieser Kurzaufsatz fasst die neusten Fortschritte zusammen.
Alcohols as Electrophiles in CC Bond‐Forming Reactions: The Hydrogen Autotransfer Process
Authors: Guillena Gabriela , Ramón Diego J. , Yus Miguel
Published: January 2007

The hydrogen autotransfer process involves an initial oxidative hydrogen elimination, followed by different types of reactions, and is completed with a reductive hydrogen addition to give the final product. The sequence allows the alkylation of different nucleophilic agents using environmentally benign alcohols as electrophiles, mild conditions, and soft bases, with water produced as the only waste material. Recent examples of modulating the organometallic catalyst have also lent themselves to expansion of the range of available substrates, as described in this Minireview.
Degree of conversion versus the depth of polymerization of an organically modified ceramic dental restoration composite by fourier transform infrared spectroscopy
Authors: Silva Fabio F. , Mendes Luis C. , Ferreira Marysilvia , Benzi Marcia R.
Published: January 2007

The evaluation of the degree of conversion (DC) as a function of the depth (1–4 mm) of an organically modified ceramic (ormocer) dental restoration composite activated by a conventional light‐curing unit (450 nm, 21.2 J/cm2) was carried out. Fourier transform infrared spectroscopy was employed to measure DC at each depth with the ratio of the maximum height absorbance peaks at 1638 (variable band) and 1609 cm−1 (reference band) before and after the polymerization reaction. The formulation was reconstituted to understand better the composite behavior. The organic and inorganic fractions were characterized by thermogravimetric analysis, X‐ray fluorescence, proton nuclear magnetic resonance, and scanning electron microscopy. The DC values lay between 48 and 54%, seemed to be not sensitive to the depth of polymerization, and indicated a large amount of residual monomer. On the other hand, a continuous decrease in the Vickers microhardness (from 61 to 52) was observed with an increasing depth of polymerization. This behavior could be attributed to differences in the crosslinking degree on the top and bottom surfaces of the polymerized samples. The material was a conventional dental restoration composite containing 26% monomer mixture (bisphenol A/dimethacrylate and triethylene glycol dimethacrylate), a small amount (2%) of an ormocer as a compatibilizing agent, and 72% inorganic filler (barium sulfate and aluminum silicate). The low DC values could be ascribed to several factors, such as the monomer viscosities, amounts, and types, the average sizes and distributions of the fillers, and the large difference between the refractive indices of the organic and inorganic constituents. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 325–330, 2007
Thermal, mechanical, and adhesive properties of HDPE/reactive ethylene terpolymer blends
Authors: Love C. T. , Xian G. , Karbhari V. M.
Published: January 2007

Blends of high‐density polyethylene (HDPE) and a reactive ethylene terpolymer (RET) were developed as a protective coating material for steel. A morphological study with scanning electron microscopy (SEM) indicated that blends of HDPE and RET are immiscible, while high interaction between these two phases was found. Crystallization and thermomechanical behavior of the blends were investigated using differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). The crystallinity of HDPE decreased with the incorporation of RET slightly due to the disturbance of the highly viscous RET melt during crystallization. Tensile tests indicated that the addition of RET reduced both strength and modulus but increased the strain‐to‐break. Adhesion to steel substrates was improved with the incorporation of the RET component. An optimum composition of RET loading was detected to be in the range of 25–33 wt %, leading to the best adhesive performance, high tensile strength, and strain‐to‐failure of the blend material. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 331–338, 2007
The transient nature of maximum maleic anhydride grafting of polypropylene: A mechanistic approach based on a consecutive reaction model. II. A comparison of the batch solution and molten state processes
Authors: García‐Martínez J. Ma. , Areso S. , Collar E. P.
Published: January 2007

This article compares the batch solution and molten state chemical modification of an atactic polypropylene to yield a grafted polypropylene. Short reaction times appear to be sufficient and indeed necessary for the highest graft yields to be obtained if degradative processes occurring in both reaction media are to be avoided. The consecutive reactions for the optimized grafting reaction pathway were proposed for the solution process in an earlier article. The present work attempts to correlate this pathway with that of the molten state process. Grafted succinic anhydride groups react with two resorcine molecules to yield grafted succinyl‐fluorescein groups. This work considers the resorcine units as true molecular probes, to be able to stabilize and activate the complexes formed between the succinic anhydride groups and the propylene sequence. This work shows the unsteady and later dynamic character of the process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 345–351, 2007
Rheological properties of poly(methyl methacrylate)/rigid ladderlike polyphenylsilsesquioxane blends
Authors: Li Guizhi , Matsuda T. , Nishioka A. , Liang Kaiwen , Masubuchi Y. , Koyama K. , Pittman Charles U.
Published: January 2007

A series of poly(methyl methacrylate) (PMMA) blends with rigid ladderlike polyphenylsilsesquioxane (PPSQ) were prepared at weight ratios of 100/0, 95/5, 90/10, 85/15, and 80/20 by solution casting and then hot‐pressing. Their rheological properties have been studied under both dynamic shear and uniaxial elongation conditions. Their rheological properties depend on the compositions. The storage modulus, G′, loss modulus, G″, and dynamic shear viscosity, η*, of the PMMA/PPSQ 95/5 blend were slightly lower than those of pure PMMA. However, the values of G′, G″, and η* for the other PMMA/PPSQ blends are higher than those of PMMA. The G′ values increase with an increase in PPSQ content from 5% through 15% PPSQ at low frequencies and then drop as the PPSQ content increases to 20%. Uniaxial elongational viscosity (ηE) data demonstrate that PMMA/PPSQ blends exhibit slightly weaker (5% PPSQ) and much weaker (10% PPSQ) strain‐hardening than PMMA. In contrast, the PMMA/PPSQ 85/15 blend shows strain‐softening. Neither strain‐hardening nor strain‐softening was observed in the 80/20 blend. The special rheological properties for the 95/5 blend is probably due to a decrease in PMMA entanglements brought by the specific PMMA–PPSQ interactions. Rheological properties of PMMA/PPSQ blends with higher PPSQ content (≥10%) are mainly affected by formation of hard PPSQ particles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 352–359, 2007
Polymer blends of carboxylated butadiene‐acrylonitrile copolymer (nitrile rubber) and polyamide 6 developed in twin screw extrusion
Authors: Chowdhury Rajesh , Banerji M. S. , Shivakumar K.
Published: January 2007

Polymer blends of carboxylated butadiene‐acrylonitrile copolymer (nitrile rubber) and polyamide 6 (PA6) were developed in twin screw extrusion. The rubber was cured with SP 1045 methylol phenolic resin during melt mixing in twin screw. Effect of degree of carboxylation in the rubber phase on blend properties has been assessed. Phase morphologies have been characterized using transmission electron microscopy. A compatibilizing NBR‐g‐Nylon 6 graft copolymer generated in situ during melt mixing via interfacial reaction between the COOH groups in NBR and the NH2 end groups in nylon 6 has been effective in generating a fine and stable dispersion of the rubber within the polyamide matrix. The graft copolymer has been characterized by DMTA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 372–377, 2007
Investigations on the adhesion and interfacial properties of polyurethane foam/thermoplastic materials
Authors: Mahmood Nasir , Busse Karsten , Kressler Jörg
Published: January 2007

The adhesion and interfacial properties of polyurethane (PU) foams with thermoplastic (TP) materials were investigated using different techniques. The adhesion performance of PU foam with TP materials was evaluated using the peel test method, and the adhesion durability was checked after different climate treatments. X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact angle measurements were used to study the surface and interface morphology of PU foam and TP material system. Three types of PU foam samples which differ in their composition and also five commercially available TP blends systems, based on poly(carbonate), poly(styrene‐co‐maleic anhydride), poly(acrylonitrile‐butadiene‐styrene), and silicone acrylate rubber have been used. The slow reacting foam shows the best adhesion properties with all the TP materials. The climate treatments strongly effected the PU foam adhesion durability with poly(carbonate) containing TP materials (70–80% loss in adhesion), but nearly no effect with poly(styrene‐co‐maleic anhydride). The samples with lowered adhesion could be separated by peeling without visible foam residues on the TP surface. AFM, XPS, and surface tension studies have shown that the surface properties of the TP material are still governed by the PU foam. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 479–488, 2007
Preparation of Ag nanoparticles in the presence of low generational poly(ester‐amine) dendrimers
Authors: Xu Dong‐Mei , Zhang Ke‐Da , Zhu Xiu‐Lin
Published: January 2007

Stable Ag nanoparticles of 10–20 nm were prepared by reduction of AgNO3 with NaBH4 in water solution in the presence of low generational hydroxyl‐ terminated poly(ester‐amine) dendrimer G1.0 (OH)16 and amino‐terminated poly(ester‐amine) dendrimer G1.5 (NH2)8 by optimizing preparation conditions. UV–vis absorption spectra and transmission electron microscopy were adopted to characterize absorption properties of Ag+/dendrimer complex, Ag/dendrimer nanocomposite aqueous solutions, and the morphology of the formed Ag nanoparticles, respectively. The results showed that the size of the Ag particles increased with Ag+/dendrimer molar ratio, and the size of Ag nanoparticles in Ag/G1.0 (OH)16 system was larger than that of Ag nanoparticles in Ag/G1.5 (NH2)8 system, while the polydispersities of two systems were similar. Moreover, the Ag/G1.5 (NH2)8 nanocomposite system was more stable than the Ag/G1.0 (OH)16 one. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 422–426, 2007
Structure and deformation of an elastomeric propylene–ethylene copolymer
Authors: Poon B. C. , Dias P. , Ansems P. , Chum S. P. , Hiltner A. , Baer E.
Published: January 2007

The elastic behavior of a propylene–ethylene copolymer was investigated. An initial “conditioning” tensile extension up to 800% strain resulted in an elastomer with low initial modulus, strong strain hardening, and complete recovery over many cycles. Structural changes that occurred in the low crystallinity propylene–ethylene copolymer during conditioning, and that subsequently imparted elastomeric properties to the conditioned material, were investigated. Thermal analysis, wide and small angle X‐ray diffraction, and atomic force microscopy measurements were performed at various strains during the conditioning process. Conditioning transformed crystalline lamellae into shish‐kebab fibers by melting and recrystallization. The fibers, accounting for only 5% of the bulk, were interconnected by a matrix of entangled, amorphous chains that constituted the remaining 95%. It was proposed that the shish‐kebab fibers acted as a scaffold to anchor the amorphous rubbery network. Entanglements of the amorphous chain segments acted as network junctions and provided the elastic response. The stress–strain response of materials conditioned to 400% strain or more was described by the classical rubber theory with strain hardening. The extracted value of Mc, the molecular weight between network junctions, was intermediate between the entanglement molecular weights of polypropylene and polyethylene. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 489–499, 2007
Catalytic effects of copper oxides on the curing and degradation reactions of cyanate ester resin
Authors: Hong Shinn‐Gwo , Yeh Chin‐Sen
Published: January 2007

The catalytic effect of copper oxides on the curing and degradation behaviors of the cyanate ester resin is studied with infrared spectroscopy, attenuated total reflection infrared spectroscopy (ATR), differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA). The result of infrared spectroscopy and DSC analyses indicates that accelerated curing effects from different additives are in the order of zinc octoate > cuprous oxide > cupric oxide. The exothermic characteristics of the cyanate ester resin during cure are drastically affected by the presence of the copper oxides. In addition, it is obtained from TGA analyses that the thermal stability and degradation mechanism of cyanate ester resins are also significantly affected by the addition of copper oxides whereas the extent of degradation from the cupric oxide is greater than that from the cuprous oxide. These results are attributed to the differences in catalytic effects and surface areas of two copper oxides on the cyanate ester resin in contact during the thermal exposure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 442–448, 2007
New crosslinked polymer from a rapid polymerization of acrylic acid with triaziridine‐containing compound
Authors: Chen Po‐Cheng , Wang Shih‐Chieh , Huang Chia‐Yu , Yeh Jen‐Taut , Chen Kan‐Nan
Published: January 2007

A triaziridine containing compound, trimethylolpropane tris(1‐aziridinepropionate) (TMPTA‐AZ), is prepared from a Michael addition of aziridine (AZ) with trimethylolpropane triacrylate (TMPTA). A rapid polymerization of acrylic acid (AA) with TMPTA‐AZ occurred at ambient temperature without catalyst. This polymerization process involves three subsequent reactions are proposed: (1) An exothermic neutralization takes place between AA and TMPTA‐AZ. (2) That neutralization heat triggers AZ ring‐opening reaction and that carboxyl group (of AA) plays as a nucleophile and results in an amino ester bond formation. (3) A final crosslinked polymer is obtained from that amino group reacts with its acrylic double bond via an intermolecular Michael addition reaction. These new crosslinked polymers with various performance properties are obtained from a mixture of AA and TMPTA‐AZ in different ratios and post‐heating. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 809–815, 2007
Thermal analysis of merino wool fibres without internal lipids
Authors: Martí M. , Ramírez R. , Manich A. M. , Coderch L. , Parra J. L.
Published: January 2007

Merino wool is made up of cuticle and cortical cells held together by the cell membrane complex (CMC), which contains a small amount of internal lipids (IWL) (1.5% by mass). IWL have been extracted from wool on account of their considerable dermatological interest owing to their proportion of ceramides. IWL have been extracted by different methods and solvents, methanol and acetone at laboratory and pilot plant levels. Thermal analysis of these extracted wool fibers is presented using thermogravimetry (TG) and differential scanning calorimetry (DSC). TG provides a measurement of the weight loss of the sample as a function of time and temperature. DSC gives information about possible structure modification of extracted wool fibers. Thermoporometry was applied to evaluate the pore size distribution of extracted wool fibers. The results showed that the extraction process increased the pore size distribution and the cumulated pore volume, which is consistent with some changes in the extracted wool CMC. Extracted fiber becomes more hydrophilic and absorbs a large amount of water. We can conclude that the lipid extraction of wool produced no relevant changes in the crystalline fraction when extracted with acetone. However, part of the amorphous keratin material was extracted with methanol, the rest of the crystalline material becoming more stable. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 545–551, 2007
Evaluation and characterization of ammoniumpolyphosphate–pentaerythritol‐based systems for intumescent coatings
Authors: Andersson Anna , Lundmark Stefan , Maurer Frans H. J.
Published: January 2007

Intumescent coatings are increasingly used as a method of passive fire protection on steel constructions. By forming a carbon network and releasing a blowing agent, the thin intumescent film swells 100‐fold at elevated temperatures. The highly insulating foam effectively prevents the load bearing steel from reaching its critical temperature at which it looses its mechanical properties and collapses. The role of the carbon donor in intumescent coatings has been studied. Comparison in temperature development, foaming ratios, and rheological behavior has been performed between formulations containing pentaerythritol (penta), di–penta, and tri–penta. A simulated fire test, in which the temperature development during intumescence was studied, showed that the formulations containing penta were considerably more efficient in keeping a low temperature throughout the process. A more rapid temperature development was displayed when using di–penta and tri–penta as the carbon donor. Rheometer tests indicate that penta formulations enter the intumescent process at a lower temperature and stays in it for a longer time than di–penta and tri–penta formulations. Furthermore, the crossover temperature and maximum phase angle are shifted towards higher temperatures by replacing penta with di–penta and with tri–penta in the formulations, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 748–753, 2007
Polyethylenes/PET blend compatibilization with maleic anhydride modified polyethylenes obtained by a UV preirradiation process
Authors: Martínez J. G. , Benavides R. , Guerrero C.
Published: January 2007

The compatibilization of HDPE/LDPE/LLDPE/PET blend during reactive extrusion, using compatibilizing agents, such as modified high, low, and lineal low density polyethylenes with maleic anhydride, was carried out. The agents were prepared in our laboratory by using a UV preirradiation process, containing different grafting and crosslinking degrees. The materials were compared with same maleic anhydride modified polyethylenes prepared by the traditional peroxide method in our laboratory and with a commercial maleic anhydride modified lineal low density polyethylene. The mechanical and thermal properties, as well as their morphology, were evaluated in the compatibilized blends and changes in crystallization phases recorded. The elongation at break and impact strengths increased with compatibilization level and morphology was markedly more homogenous. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 560–567, 2007
Dynamic mechanical properties of Al2O3/poly(ether ether ketone) composites
Authors: Goyal R. K. , Tiwari A. N. , Mulik U. P. , Negi Y. S.
Published: January 2007

The dynamic mechanical properties of high‐performance polymer matrix composites based on semicrystalline poly(ether ether ketone) (PEEK) and aluminum oxide (Al2O3) were evaluated in the temperature range of 30–250°C with a three‐point‐bending mode at a frequency of 1 Hz. The storage modulus and loss modulus changed significantly with the variation of the Al2O3 content in the PEEK matrix. The Al2O3 reinforcement was more pronounced above the glass‐transition temperature (Tg). A composite containing 60 wt % (33 vol %) Al2O3 exhibited about a 78% increase in the storage modulus at 50°C and about a 200% increase at 200°C. However, there was no significant change in the mechanical loss factor and Tg associated with the peak of the mechanical loss factor or loss modulus with the addition of Al2O3. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 568–575, 2007