bluuebunny/crossref_metadata_2025 huggingface dataset:
The “Nature” of Childhood: Ethnography as a Tool in Approaching Children in Archaeology
Authors: Thomas Kelly
Published: March 2006

Studying contemporary children in the United States might seem like an odd place to seek information that can help inform the archaeology of childhood. It is our very familiarity with this cultural construct of childhood, as former children and as contemporary parents, aunts, uncles, or friends of children, that often draws criticism from scholars of childhood in archaeology and anthropology. An ethnographic study of four‐year‐old children from a Chicago neighborhood taking part in an outdoor camp demonstrates, however, that looking beyond the familiar is indeed possible and certainly fruitful for archaeologists wishing to study children in the past. Particularly, this research takes a historical approach to contemporary constructions of childhood and looks at how contemporary ideals affect children's behavior through adult input and the built environment. Exploring this relationship between cultural ideals and children's behavior and the ways they are mediated provides insight into how particularistic cultural constructions of children and childhood may be represented through the behavioral traces of them in the archaeological record.
Growing Up North: Exploring the Archaeology of Childhood in the Thule and Dorset Cultures of Arctic Canada
Authors: Park Robert W.
Published: March 2006

In late prehistoric times the Canadian Arctic was occupied sequentially by the peoples known to archaeologists as the Dorset and the Thule cultures, the latter being the direct cultural and biological ancestors of the Inuit who live there today. For archaeologists interested in exploring aspects of childhood, the Thule culture has three very desirable characteristics: potentially magnificent preservation due to the effects of permafrost; a complex and varied material culture; and, from their Inuit descendants, a rich and detailed body of ethnographic information that can be drawn upon for analogy. With these advantages it is possible to identify a wide range of Thule items, especially miniature versions of implements, specifically associated with children. These can be studied to explore the roles of children in Thule society. Intriguingly, it is far more difficult to identify items associated with children of the Dorset culture, despite their material culture's being equally complex and their sites being often almost as well preserved. This chapter summarizes the results of research into childhood among the Thule and shows how the experience of childhood for Dorset children may have been somewhat different from that experienced by their Thule successors.
Children and Ceramic Innovation: A Study in the Archaeology of Children
Authors: Smith Patricia E.
Published: March 2006

Studies of the archaeological remains of children's activities have the potential to inform us not only on the lives of children but also on the lives of those around them. In this essay, I examine a class of artifacts that highlights the interactive and transformative nature of learning within prehistoric Huron society. This class of artifacts, juvenile pots, has typically been attributed to children but then summarily ignored. Stylistic analysis of these artifacts is used to address the question of whether children were innovators in prehistoric Huron society. Temporal changes in the decorative motifs applied to juvenile pots indicate that Huron children were active participants in a network of intergenerational learning/teaching interactions and in the process of creating stylistic change.
Patterns of Distribution and Abundance of Tubifex tubifex and Other Aquatic Oligochaetes in Myxobolus cerebralis Enzootic Areas in Pennsylvania
Authors: Kaeser Adam J. , Sharpe William E.
Published: March 2006

Recent outbreaks of whirling disease (caused by the myxosporean parasite Myxobolus cerebralis) among wild rainbow trout Oncorhynchus mykiss have called attention to deficiencies in the knowledge of aquatic oligochaete ecology in rivers and streams of North America. Revealing the patterns of distribution and abundance of Tubifex tubifex, an obligate host in the life cycle of M. cerebralis, is critical to understanding local and regional differences in the epizootiology of this disease. To gather fundamental information on the ecology of T. tubifex among streams in Pennsylvania, we surveyed oligochaetes and the features of their habitat. We used indirect and direct ordination techniques to search for patterns in oligochaete assemblages and their relationships to the environment. In general, higher-gradient streams with coarse substrate contained low-density oligochaete assemblages dominated by the family Enchytraeidae. Lower-gradient streams with fine-sediment habitat were dominated by Limnodrilus hoffmeisteri and contained either Ilyodrilus templetoni or T. tubifex. A key finding to emerge from this survey was that high oligochaete density, T. tubifex occurrence, and T. tubifex density were associated with proximity to obvious sources of organic enrichment. Limits on the distribution of T. tubifex in Pennsylvania relative to distributions in M. cerebralis–affected systems in the Intermountain West may be a factor in explaining why whirling disease has not been observed to cause population declines among wild rainbow trout in this region and should be further investigated.
The Asymptotic Efficiency of Largest Claims Reinsurance Treaties
Authors: Kremer Erhard
Published: March 2006

Reinsurance treaties defined as generalizations of the classical largest claims reinsurance covers are investigated with respect to the associated risk, defined as the variance of the insurer's retaining total claims amount. Instead of the unhandy variance corresponding handier asymptotic expressions are used. With these an asymptotic efficiency measure for comparing two such reinsurance covers is defined. It is shown that with respect to asymptotic efficiency the excess-of-loss treaty is better than the classical largest claims treaty. Furthermore the problem of giving optimal wheights to the ordered claims of a generalized largest claims cover is discussed.
Fuzzy Insurance
Authors: Lemaire Jean
Published: March 2006

Fuzzy set theory is a recently developed field of mathematics, that introduces sets of objects whose boundaries are not sharply defined. Whereas in ordinary Boolean algebra an element is either contained or not contained in a given set, in fuzzy set theory the transition between membership and non-membership is gradual. The theory aims at modelizing situations described in vague or imprecise terms, or situations that are too complex or ill-defined to be analysed by conventional methods. This paper aims at presenting the basic concepts of the theory in an insurance framework. First the basic definitions of fuzzy logic are presented, and applied to provide a flexible definition of a “preferred policyholder” in life insurance. Next, fuzzy decision-making procedures are illustrated by a reinsurance application, and the theory of fuzzy numbers is extended to define fuzzy insurance premiums.
Ruin Probability for Translated Combination of Exponential Claims
Authors: Chan Beda
Published: March 2006

An alternative expression for the coefficients in the ruin probability for the classical ruin model with translated combination of exponential claims is derived.
Asset Pricing Models and Insurance Ratemaking
Authors: Cummins J. David
Published: March 2006

This paper provides an introduction to asset pricing theory and its applications in non-life insurance. The first part of the paper presents a basic review of asset pricing models, including discrete and continuous time capital asset pricing models (the CAPM and ICAPM), arbitrage pricing theory (APT), and option pricing theory (OPT). The second part discusses applications in non-life insurance. Among the insurance models reviewed are the insurance CAPM, discrete time discounted cash flow models, option pricing models, and more general continuous time models. The paper concludes that the integration of actuarial and financial theory can provide major advances in insurance pricing and financial management.
Convergence of Bayes and Credibility Premiums
Authors: Schmidt Klaus D.
Published: March 2006

For a risk whose annual claim amounts are conditionally i.i.d. with respect to a risk parameter, it is known that the Bayes and credibility premiums are asymptotically optimal in terms of losses. In the present note it is shown that the Bayes and credibility premiums actually converge to the individual premium.
Minimax Estimation of a Mean Vector for Distributions on a Compact Set
Authors: Dykstra Richard
Published: March 2006

Minimax estimation procedures for the mean vector of a distribution on a compact set under squared error type loss functions are considered. In particular, a Dirichlet process prior is used to show that a linear function of is a minimax estimator in the class of all measurable estimators and all possible distributions. This effort extends some earlier work of Bühlmann to a more general setting.
Premium Calculation: Why Standard Deviation Should be Replaced by Absolute Deviation
Authors: Denneberg Dieter
Published: March 2006

Average absolute (instead of quadratic) deviation from median (instead of expectation) is better suited to determine the safety loading for insurance premiums than standard deviation: The corresponding premium functionals behave additive under the practically relevant risk sharing schemes between first insurer and reinsurer.
On Changing the Parameter of Exponential Smoothing in Experience Rating
Authors: Bonsdorff Heikki
Published: March 2006

We consider exponential smoothing Yn = αXn + (1 − α)Yn−1, 0 < α < 1, in experience rating. Here the premium Yn is determined by the policy's own claims history (Xn). In order to uniformize the fluctuation of premiums, it is appropriate to use a bigger α for the big policies than for the small ones. When the size of the policy changes with time, a need arises to change α correspondingly. It has recently been shown that changing based on the size of the premiums Yn may lead to too low a tariff level. This result is presented here and illustrated by means of simulation. Further, some general results are given how the changing can be made without a decline in the tariff level. The results are applied to a tariff system in which the linking of the smoothing parameter to the size of the policy is particularly motivated.
Bayes and Empirical Bayes Estimation for the Chain Ladder Model
Authors: Verrall R.J.
Published: March 2006

The subject of predicting outstanding claims on a porfolio of general insurance policies is approached via the theory of hierarchical Bayesian linear models. This is particularly appropriate since the chain ladder technique can be expressed in the form of a linear model. The statistical methods which are applied allow the practitioner to use different modelling assumptions from those implied by a classical formulation, and to arrive at forecasts which have a greater degree of inherent stability. The results can also be used for other linear models. By using a statistical structure, a sound approach to the chain ladder technique can be derived. The Bayesian results allow the input of collateral information in a formal manner. Empirical Bayes results are derived which can be interpreted as credibility estimates. The statistical assumptions which are made in the modelling procedure are clearly set out and can be tested by the practitioner. The results based on the statistical theory form one part of the reserving procedure, and should be followed by expert interpretation and analysis. An illustration of the use of Bayesian and empirical Bayes estimation methods is given.
Cooperative Game Theory and its Insurance Applications
Authors: Lemaire Jean
Published: March 2006

This survey paper presents the basic concepts of cooperative game theory, at an elementary level. Five examples, including three insurance applications, are progressively developed throughout the paper. The characteristic function, the core, the stable sets, the Shapley value, the Nash and Kalai-Smorodinsky solutions are defined and computed for the different examples.
Distribution of Surplus in Life Insurance
Authors: Ramlau-Hansen Henrik
Published: March 2006

This paper discusses distribution of surplus in life insurance within a general Markov chain framework. A conservative interest rate and a conservative set of transition intensities are used for reserving purposes whereas more realistic assumptions are used for the purpose of distributing surplus. The paper examines various actuarial aspects of distributing surplus through either cash bonuses, terminal bonuses or increased benefits. The results are illustrated by some examples.
Separating True IBNR and IBNER Claims
Authors: Schnieper R.
Published: March 2006

A simple model for IBNR claims is presented. Estimates for the loss reserves and for the ultimate claims rate are derived. Approximations to the mean square error of the estimators are produced. A more specific parametric model is suggested for the case that we deal with claim numbers instead of claim amounts. The general method is illustrated by a practical application to the pricing of a casualty excess of loss cover.
The Schmitter Problem and a Related Problem: A Partial Solution
Authors: Kaas R.
Published: March 2006

At the 1990 ASTIN-colloquium, Schmitter posed the problem of finding the extreme values of the ultimate ruin probability ψ(u) in a risk process with initial capital u, fixed safety margin θ, and mean μ and variance σ2 of the individual claims. This note aims to give some more insight into this problem. Schmitter's conjecture that the maximizing individual claims distribution is always diatomic is disproved by a counterexample. It is shown that if one uses the distribution maximizing the upper bound e−Ru to find a ‘large’ ruin probability among risks with range [0, b], incorrect results are found if b is large or u small.

The related problem of finding extreme values of stop-loss premiums for a compound Poisson (λ) distribution with identical restrictions on the individual claims is analyzed by the same methods. The results obtained are very similar.
Risk Theory with the Gamma Process
Authors: Dufresne François , Gerber Hans U. , Shiu Elias S. W.
Published: March 2006

The aggregate claims process is modelled by a process with independent, stationary and nonnegative increments. Such a process is either compound Poisson or else a process with an infinite number of claims in each time interval, for example a gamma process. It is shown how classical risk theory, and in particular ruin theory, can be adapted to this model. A detailed analysis is given for the gamma process, for which tabulated values of the probability of ruin are provided.
Evaluating Compound Generalized Poisson Distributions Recursively
Authors: Goovaerts M. J. , Kaas R.
Published: March 2006

In this paper we give a recursive scheme, involving Panjer's recursion, to compute the distribution of a compound sum of integer claims, when the number of summands follows a Generalized Poisson distribution. Also, an elegant derivation is given for some basic properties of this counting distribution.
Recursive Calculation of Survival Probabilities
Authors: Dickson David C. M. , Waters Howard R.
Published: March 2006

In this paper we present an algorithm for the approximate calculation of finite time survival probabilities for the classical risk model. We also show how this algorithm can be applied to the calculation of infinite time survival probabilities. Numerical examples are given and the stability of the algorithms is discussed.
Premium Calculation Implications of Reinsurance Without Arbitrage
Authors: Venter Gary G.
Published: March 2006

Constraints imposed on premium calculation principles are studied under one aspect of competitive market theory: the impossibility of systematic arbitrage. Principles based on second moments or utility theory are shown to lead to arbitrage possibilities, while some other principles do not.
Distributions de Pareto: Intérêts et limites en réassurance
Authors: Huyghues-Beaufond Par Claude
Published: March 2006

Instead of determining for a fire insurance portfolio the loss distribution purely based on the claims experience, we try to determine it based on the sums insured.
Discriminative features of type I and type III secreted proteins from Gram-negative bacteria
Authors: Zikmanis Peteris , Andersone Inara , Baltkalne Martina
Published: March 2006

The amino acid composition of sequences and structural attributes (α-helices, β-sheets) of C-and N-terminal fragments (50 amino acids) were compared to annotated (SWISS-PROT/ TrEMBL) type I (20 sequences) and type III (22 sequences) secreted proteins of Gram-negative bacteria.

The discriminant analysis together with the stepwise forward and backward selection of variables revealed the frequencies of the residues Arg, Glu, Gly, Ile, Met, Pro, Ser, Tyr, Val as a set of strong (1-P < 0.001) predictor variables to discriminate between the sequences of type I and type III secreted proteins with a cross-validated accuracy of 98.6–100 %. The internal and external validity of discriminant analysis was confirmed by multiple (15 repeats) test-retest procedures using a randomly split original set of proteins; this validation method demonstrated an accuracy of 100 % for 191 non-selected (retest) sequences.

The discriminant analysis was also applied using selected variables from the propensities for β-sheets and polarity of C-terminal fragments. This approach produced the next highest and comparable cross-validated classification accuracy for randomly selected and retest proteins (85.4–86.0 % and 82.4–84.5 %, respectively).

The proposed sets of predictor variables could be used to assess the compatibility between secretion substrates and secretion pathways of Gram-negative bacteria by means of discriminant analysis.
Chondroitin sulfate-modified LDL induces increased cholesteryl ester synthesis and down-regulation of LDL receptors in smooth muscle cells and macrophages
Authors: Tircol Magdalena , Tirziu Daniela , Simionescu Maya
Published: March 2006

Hypercholesterolemia induces increased transcytosis and accumulation of plasma lipoproteins in the arterial intima, where they interact with matrix proteins and become modified and reassembled lipoproteins. Chondroitin 6-sulfate-modified LDL (CS-mLDL) induces migration, proliferation, and lipid accumulation in human aortic smooth muscle cells (SMCs). To search for the mechanism(s) responsible for lipid accumulation, cultured SMC and macrophages were exposed to CS-mLDL, minimally modified LDL (mmLDL), and native LDL (as a control). Then the cellular uptake, degradation and expression of the LDL receptor (LDL-R) was determined using radioiodinated ligands, ACAT activity assay, fluorescence microscopy and RT-PCR. The uptake of CS-mLDL was 2-fold higher in SMC and 3-to 4-fold higher in macrophages as compared to LDL and mmLDL; the lysosomal degradation of CS-mLDL was slower in SMCs and considerably diminished in macrophages. Compared with LDL, CS-mLDL induced increased synthesis and accumulation of esterified cholesterol in SMCs (∼2-fold) and macrophages (∼10-fold) within an expanded acidic compartment. CS-mLDL and mmLDL down-regulate the gene expression of the LDL-R in the both cell types. Mechanisms of CS-mLDL-induced lipid accumulation in SMC and macrophages involve increased cellular uptake, and diminished cellular degradation that stimulates cholesterol ester synthesis and accumulation in cytoplasmic inclusions and in the lysosomal compartment in an undegraded form; modified lipoproteins induce down-regulation of LDL-R.
The ARX mutations: A frequent cause of X‐linked mental retardation
Authors: Nawara Magdalena , Szczaluba Krzysztof , Poirier Karine , Chrzanowska Krystyna , Pilch Jacek , Bal Jerzy , Chelly Jamel , Mazurczak Tadeusz
Published: March 2006

The ARX gene mutations have been demonstrated to cause different forms of mental retardation (MR). Beside FMR1, in families with X‐linked mental retardation (XLMR), the ARX dysfunction was demonstrated to be among the most frequent causes of this heterogeneous group of disorders. Nevertheless, in sporadic cases of MR, ARX mutations are extremely rare. In order to evaluate the frequency of ARX mutation in XLMR, we performed mutational analysis of ARX in 165 mentally retarded probands negative for FRAXA and belonging to families in which the condition segregates as an X‐linked condition. The same recurrent mutation, an in frame 24 bp insertion (c.428‐451dup (24 bp)), was identified in five patients. In one family, the mother of two affected boys was found not to carry the mutation detected in her sons. These data suggest the presence of germline mosaicism for the mutation in the mother. Our results confirm the significant contribution of ARX mutations in the etiology of MR, especially in this group of patients selected for XLMR (3%). These data, together with those reported in the literature, imply that screening for c.428‐451 dup (24 bp) mutation should be recommended in all patients with suspected XLMR. © 2006 Wiley‐Liss, Inc.
The effect of dopamine D2, D5 receptor and transporter (SLC6A3) polymorphisms on the cue‐elicited heroin craving in Chinese
Authors: Li YiFeng , Shao ChunHong , Zhang Dandan , Zhao Min , Lin Ling , Yan Pengrong , Xie Yuying , Jiang Kaida , Jin Li
Published: March 2006

Heroin dependence is resulted from the interaction between multiple genetic and environmental factors. Subjective craving is considered to be a central phenomenon, which contributes to the continuation of drug use in active abuser and the occurrence of relapse in detoxified abusers. Dopamine pathway has been implicated in the cue‐elicited craving for a variety of addictive substances. The objective of this study was to test the hypothesis that heroin addicts carrying specific variants in dopamine‐related genes would have higher levels of craving following exposure to a heroin‐related cue. Craving induced by a series of exposure to heroin‐related cue was assessed in a cohort of Chinese heroin abuser (n = 420) recruited from natural abstinence center at Shanghai. Significantly stronger cue‐elicited heroin craving was found in individuals carrying D2 dopamine receptor gene (DRD2) TaqI RFLP A1 allele than the non‐carriers (P < 0.001). Furthermore, we did not observed significant association of cue‐elicited craving with the nine‐repeat allelic variants in dopamine transporter gene (DAT) SLC6A3 and with the dinucleotide repeat polymorphism (DRP) 148bp allele in D5 dopamine receptor gene (DRD5). The results of our study suggest that human dopamine pathway be involved in cue‐induced heroin craving, and indicate a potential genetic risk factor for persistent heroin behavior and relapse. © 2006 Wiley‐Liss, Inc.
Evaluation of RGS4 as a candidate gene for schizophrenia
Authors: Liu Yu‐Li , Shen‐Jang Fann Cathy , Liu Chih‐Min , Wu Jer‐Yuarn , Hung Shuen‐Iu , Chan Hung‐Yu , Chen Jiahn‐Jyh , Lin Chin‐Yu , Liu Shih‐Kai , Hsieh Ming H. , Hwang Tzung‐Jeng , OuYang Wen‐Chen , Chen Chun‐Ying , Lin Jin‐Jia , Chou Frank Huang‐Chih , Chueh Ching‐Mo , Liu Wei‐Ming , Tsuang Ming‐Min , Faraone Stephen V. , Tsuang Ming T. , Chen Wei J. , Hwu Hai‐Gwo
Published: March 2006

Several studies have suggested that the regulator of G‐protein signaling 4 (RGS4) may be a positional and functional candidate gene for schizophrenia. Three single nucleotide polymorphisms (SNP) located at the promoter region (SNP4 and SNP7) and the intron 1 (SNP18) of RGS4 have been verified in different ethnic groups. Positive results have been reported in these SNPs with different numbers of SNP combinatory haplotypes. In this study, these three SNP markers were genotyped in 218 schizophrenia pedigrees of Taiwan (864 individuals) for association analysis. Among these three SNPs, neither SNP4, SNP7, SNP18 has shown significant association with schizophrenia in single locus association analysis, nor any compositions of the three SNP haplotypes has shown significantly associations with the DSM‐IV diagnosed schizophrenia. Our results fail to support the RGS4 as a candidate gene for schizophrenia when evaluated from these three SNP markers. © 2006 Wiley‐Liss, Inc.
Glutamate AMPA receptor subunit 1 gene (GRIA1) and DSM‐IV‐TR schizophrenia: A pilot case‐control association study in an Italian sample
Authors: Magri Chiara , Gardella Rita , Barlati Stefano Davide , Podavini Damiano , Iatropoulos Paraskevas , Bonomi Silvia , Valsecchi Paolo , Sacchetti Emilio , Barlati Sergio
Published: March 2006

Glutamatergic dysfunction is one of the major hypotheses for the pathogenesis of schizophrenia. The GRIA1 gene encodes for one (GluR1) of the four (GluR1–4) ionotropic AMPA receptor subunits. GRIA1 is a good candidate gene for susceptibility to schizophrenia since it maps in 5q33, a region where the presence of susceptibility loci has been suggested by independent genome‐wide scans and because its expression has been found to be decreased in the brain of some schizophrenia patients. We present data from a case‐control association study on the Italian population with eight polymorphisms spanning the whole GRIA1 gene. Single‐locus analysis revealed a significantly different allele distribution in cases and in controls of two SNPs (rs707176, 0.41 vs. 0.31, P = 0.009; rs2963944, 0.41 vs. 0.30, P = 0.007), and one microsatellite (rs10631988, allele 9: 0.40 vs. 0.29, P = 0.004). Haplotype analysis showed an increased frequency of a specific haplotype for these markers (C09CC, 0.39 vs. 0.28, P = 0.009). Therefore our data indicate that GRIA1 may be involved in susceptibility to DSM‐IV‐TR schizophrenia. © 2006 Wiley‐Liss, Inc.
Lack of association between UBQLN1 and Alzheimer disease
Authors: Slifer M.A. , Martin E.R. , Bronson P.G. , Browning‐Large C. , Doraiswamy P.M. , Welsh‐Bohmer K.A. , Gilbert J.R. , Haines J.L. , Pericak‐Vance M.A.
Published: March 2006

Alzheimer disease (AD) is heterogeneous and complex with a strong genetic diathesis. It is the most common cause of dementia affecting the elderly. Linkage studies [Kehoe et al., 1999; Hum Mol Genet 8: 237–245]; [Pericak‐Vance et al., 2000; Exp Gerontol 35: 1343–1352]; [Myers et al., 2002; Am J Med Genet 114: 235–244]; [Blacker et al., 2003; Hum Mol Genet 12: 23–32] identified chromosome 9q as a region containing a possible AD candidate gene. Functional protein studies [Mah et al., 2000; J Cell Biol 151: 847–862]; [Ko et al., 2002; J Biol Chem 277: 35386–35392] identified the UBQLN1 gene on chromosome 9q that encodes ubiquilin as a likely candidate for a role in late‐onset AD pathogenesis. A recent family‐based study by [Bertram et al., 2005; N Engl J 352: 884–894] reported genetic association and expression evidence for a putative AD risk allele of an intronic single nucleotide polymorphism (SNP) within the UBQLN1 gene. In this study, we comprehensively assessed whether any of seven polymorphisms located across the UBQLN1 gene are associated with AD in another large family‐based data set and an independent case‐control data set. We found no significant association of AD risk with any of the seven SNPs genotyped (including those SNPs previously reported by Bertram et al.) in either the family‐based or case‐control data set. Age‐specific analyses and analyses conditional on Apolipoprotein E (ApoE) genotype and sex also revealed no significant associations to AD risk in either data set. Using age at onset (AAO) as a quantitative trait revealed a modest age modifying association; however, the results were inconsistent between the data sets. Our results suggest that UBQLN1 variants do not increase risk for AD in these data. © 2006 Wiley‐Liss, Inc.
Cover Picture: Biomimetic Fluorapatite–Gelatine Nanocomposites: Pre‐Structuring of Gelatine Matrices by Ion Impregnation and Its Effect on Form Development / Intrinsic Electric Dipole Fields and the Induction of Hierarchical Form Developments in Fluorapatite–Gelatine Nanocomposites: A General Principle for Morphogenesis of Biominerals? (Angew. Chem. Int. Ed. 12/2006)
Authors: Tlatlik Harald , Simon Paul , Kawska Agnieszka , Zahn Dirk , Kniep Rüdiger , Lichte Hannes
Published: March 2006

Form development…︁…︁during growth of fluorapatite–gelatine nanocomposites is effected by pre‐structuring of gelatine matrices by ion impregnation. The cover picture shows the hierarchical fractal aggregate (background), structural details of a fanlike aggregate, and a simulation of the “stiffening” effect on a protein molecule of Ca2+ ion incorporation. This effect is discussed by R. Kniep and co‐workers in their Communication on page 1905 ff. A second paper on page 1911 ff. deals with the effect of intrinsic electric dipole fields on the form development of the nanocomposite materials.
Synthesis and evaluation of a composite crosslinked copolymer as a particulate fluid diversion agent
Authors: Lu Hongsheng , Huang Zhiyu , Li Peiwu , Ma Yong , Feng Yujun
Published: March 2006

To meet the needs for polymer particulates for the flooding of oil fields, a composite crosslinked copolymer of hydrophilic monomers [acrylamide (AM) and acrylic acid (AA)] and a hydrophobic monomer [methyl methacrylate (MMA)] was synthesized. In this study, we first added a rare‐earth thermal stabilizer and inorganic montmorillonite (MMT) clay to the copolymer; this showed that the composite crosslinked copolymer exhibited good water‐swelling performance at 200°C, with gel static grade of 5, a toughness index of 1.1170, and a salinity limit of 250,000 mg/L. It also had better injection abilities. The AM/AA/MMA ratio was 4 : 1 : 0.03 w/w, the crosslinker additive content was 0.03 wt %, the thermal stabilizer additive content was 5 wt %, and the clay (MMT) additive content was 13 wt %. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4429–4433, 2006
Photooxidation of benzil groups in the presence of hindered amine stabilizers in the polystyrene film
Authors: Kósa C. , Mosnáček J. , Lukáč I. , Hrdlovič P. , Chmela š. , Habicher W. D.
Published: March 2006

The photoperoxidation at λ > 400 nm of benzil (BZ) groups with the air oxygen to benzoyl peroxide (BP) groups in the polystyrene matrices was investigated in the presence of hindered amine stabilizer (HAS). HAS was used as a free molecule or was bound in combined molecule with BZ. HAS was in the form of parent amine as 2,2,6,6‐tetramethyl‐4‐hydroxypiperidine (TMP) and in the form of stable nitroxyl radical 1‐oxo‐2,2,6,6‐tetramethyl‐4‐hydroxypiperidine (NO). Both HAS forms effected the photooxidation of BZ structures. The main product of the photooxidation in the presence of parent amine TMP as well as in its absence is benzoyl peroxide (BP). The rate of BZ consumption increases in the presence of TMP. Irradiation of BZ in the presence of sufficient concentration of freely added NO results only in the formation of benzoic acid esters and benzoic acid, which are the main decomposition products of BP. The benzoic acid esters/benzoic acid ratio increases with the increasing concentration of NO. Bounding of BZ and TMP into one molecule (BZNH) results in slower dicarbonyl depletion, as compared with the case when mixture of BZ and TMP was used. Very slow depletion of BZ carbonyl absorption was observed in the case of bounded BZ and NO in one molecule (BZNO), in comparison with the mixture of free NO and BZ. In the case of BZNO, an effective intramolecular quenching of BZ excited triplet states with NO structures proceeds. Steady stay and dynamic emission (phosphorescence) measurements also show an effective quenching of BZ excited states by unbounded or bounded NO. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4420–4428, 2006
Effect of starch addition on compression‐molded poly(3‐hydroxybutyrate)/starch blends
Authors: Thiré Rossana M. S. M. , Ribeiro Thiago A. A. , Andrade Cristina T.
Published: March 2006

Because of their biocompatibility and total biodegradability, poly(3‐hydroxybutyrate) (PHB) and starch have attracted attention as promising raw materials for manufacture of single‐use plastic items and biomaterials. PHB/maize starch blends with starch contents in the range of 0–50 wt % were processed in an internal mixer, and their compression‐molded films were characterized by tensile tests, X‐ray diffraction, thermogravimetric analysis, wettability measurements, and scanning electron microscopy. Water and glycerol were used as plasticizers. The results indicated that the thermal degradation behavior of the blends were similar to that of pure PHB films. All the blends showed heterogeneous morphology, wherein starch granules were dispersed in continuous PHB‐rich matrix. Despite the decrease in elongation at break and tensile strength, starch incorporation of up to 30 wt % into PHB matrix resulted in materials as hard as pure PHB films, but exhibiting less crystallinity and more hydrophilic character, which might lead to a higher biodegradation rate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4338–4347, 2006
Properties of hydrophobically modified polyacrylamide with low molecular weight and interaction with surfactant in aqueous solution
Authors: Wu Shuhui , Shanks Robert A. , Bryant Gary
Published: March 2006

Hydrophobically modified polyacrylamide (HMPAM), with a molecular weight of 104 g/mol, was studied using a range of rheological methods and dynamic light scattering (DLS). DLS measurements indicate that the association of the modified polymer begins at low concentration. The modified polymer with high substitution forms transient networks below the critical concentration, but the networks are disrupted by the micelles formed by the polymer itself, and the networks do not contribute to viscosity enhancement. The modified polymers exhibited surface activity, and so they may be regarded as nonionic polymeric surfactants rather than thickeners. On the other hand, HMPAM is shown to interact with the surfactant SDS while PAM is inert to SDS. In the hydrophobic domains, it undergoes a surfactant‐induced association process; in the hydrophobe‐surfactant transition regions, the surfactant binds to the polymer in a noncooperative way and forms a polymer–surfactant complex. Contracted polymer chains begin to extend because of electrostatic repulsion, which can overcome the association at surfactant domains. The conformation of HMPAM polymer chains could be controlled by adding a specific amount of surfactant. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4348–4360, 2006
Synthesis and properties of nanosilica‐reinforced polyurethane for grouting
Authors: Xiang X. J. , Qian J. W. , Yang W. Y. , Fang M. H. , Qian X. Q.
Published: March 2006

A polyurethane/nanosilica (PU/SiO2) hybrid for grouting was prepared in a two‐step polymerization using poly(propylene glycol) diols as the soft segment, toluene 2,4‐diisocyanate (TDI) as the diisocyanate, 3,3′‐dichloro‐4,4′‐diaminodiphenylmethane (MOCA) as the chain extender, and acetone as the solvent. The size and dispersion of nanosilica, the molecular structure, mechanical properties, rheological behavior, thermal performance, and the UV absorbance characteristic of the PU/SiO2 hybrid were investigated by transmission electron microscopy (TEM), FTIR, mechanical tests, viscometry, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and UV spectroscopy. Nanosilica dispersed homogeneously in the PU matrix. The maximum values of mechanical properties such as tensile strength, elongation break, and adhesive strength showed an addition of nanosilica of about 2 wt %. Resistance to both high and low temperatures was better than with PU. And the UV absorbance of the PU/SiO2 hybrid increased in the range of 290–330 nm with increasing nanosilica content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4333–4337, 2006
Preparation of alginate/poly(N‐isopropylacrylamide) semi‐interpenetrating and fully interpenetrating polymer network hydrogels with γ‐ray irradiation and their swelling behaviors
Authors: Lee Sang Bong , Park Eun Kyoung , Lim Youn Mook , Cho Seong Kwan , Kim So Yeon , Lee Young Moo , Nho Young Chang
Published: March 2006

Semi‐interpenetrating polymer network (semi‐IPN) and fully interpenetrating polymer network (full‐IPN) hydrogels composed of alginate and poly(N‐isopropylacrylamide) were prepared with γ‐ray irradiation. The semi‐IPN hydrogels were prepared through the irradiation of a mixed solution composed of alginate and N‐isopropylacrylamide (NIPAAm) monomer to simultaneously achieve the polymerization and self‐crosslinking of NIPAAm. The full‐IPN hydrogels were formed through the immersion of the semi‐IPN film in a calcium‐ion solution. The results for the swelling and deswelling behaviors showed that the swelling ratio of semi‐IPN hydrogels was higher than that of full‐IPN hydrogels. A semi‐IPN hydrogel containing more alginate exhibited relatively rapid swelling and deswelling rates, whereas a full‐IPN hydrogel showed an adverse tendency. All the hydrogels with NIPAAm exhibited a change in the swelling ratio around 30–40°C, and full‐IPN hydrogels showed more sensitive and reversible behavior than semi‐IPN hydrogels under a stepwise stimulus. In addition, the swelling ratio of the hydrogels continuously increased with the pH values, and the swelling processes were proven to be repeatable with pH changes. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4439–4446, 2006
Anti‐ultraviolet and physical properties of woolen fabrics cured with citric acid and TiO2/chitosan
Authors: Hsieh Sung‐Huang , Zhang Fang‐Ru , Li Hui‐Si
Published: March 2006

This experiment is to research the chemical compositions of the crosslink of the woolen, oxidized with H2O2 of various concentrations and temperatures, cured with the citric acid and TiO2/chitosan liquid of different proportions, and then observed by means of Fourier Transfer Infrared Spectrometer (FT‐IR), Scanning Electronic Microscope (SEM), Energy Dispersive Spectrometer (EDS), and Thermo‐Gravity Analyzer (TGA). Its antishrinkage, antimicrobes, antiultraviolet, strength, elasticity, softness, and yellowness are also investigated to study the changes in its physical properties. From the result, we can see, under the SEM, the sign of disappearance of woolen scales owing to the destruction by H2O2 oxidization; the more H2O2 and its oxidization temperature, the more serious their destruction. The phenomenon of crosslink is not obvious after oxidization and curing treatment with TiO2/chitosan, but it somehow apparently happens to the woolen surface. Because TiO2/chitosan does not intertwine with the woolen well, which has few effects of heat, the woolen shrinks less with more H2O2 and oxidization temperatures. Its antishrinkage is better. But the more wash, the more shrinkage. However, TiO2 covered with chitosan catches less sunlight, and thus cannot suppress or even kill microbes. The woolen processed with nanometer TiO2 enhances the effect of antiultraviolet, which is better as the density of TiO2 increases. The strength and elasticity of the woolen are worse for more H2O2 and the higher temperature destroy scales and make the woolen coarse, yellow,and less soft. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4311–4319, 2006
Influence of the temperature profile in the interface on the bond strength of polyamide–polyurethane two‐component tensile bars
Authors: Pompe G. , Bräuer M. , Schweikle D. , Nagel J. , Hupfer B. , Lehmann D.
Published: March 2006

Two‐component tensile bars with polyamide 6 (PA) and thermoplastic polyurethane (TPU) unmodified and modified with 4,4′‐diphenylmethane diisocyanate (MDI) have been investigated. It is known that the bond strength of PA/TPU tensile bars can increase by about 50% if MDI‐modified polyurethane is applied. The subject of these studies is the analysis of the influence of the mass temperatures on the bond strength. The mass temperatures of the first and second injection process and the delay time between the first and second injection processes determine the temperature gradient in the interface at the moment of the second injection. There is an increase in the bond strength when there is an increasing temperature gradient; therefore, the mass temperature of the first component at the delay time has to be lower than the mass temperature of the second component. The temperature gradient can be used as a measure of the thermal annealing of the first component near the interface during the heat transfer from the second component. It can be concluded that effective thermal annealing causes an increase in the bond strength. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4297–4305, 2006
Organic–inorganic hybrid materials. II. Preparation and properties of higher silica containing polycarbonate–silica hybrid materials
Authors: Arakawa Motoomi , Sukata Kazuaki , Shimada Masayuki , Agari Yasuyuki
Published: March 2006

The sol–gel reaction of a polycarbonate (PC) oligomer having triethoxysilyl groups at both ends of the PC chain (PCS) with a tetraethoxysilane or tetramethoxysilane oligomer provided transparent or semitransparent films of higher silica containing organic–inorganic hybrid materials (HSPC‐HMs). The films were superior to those from PC and from PCS in terms of the morphological homogeneity, heat resistance, and surface hardness. The HSPC‐HM films had minimum oxygen permeability at a PCS/tetraethoxysilane ratio of 3/7. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4273–4279, 2006
Different factors in the supercritical CO2‐assisted grafting of poly(acrylic acid) to polypropylene
Authors: Hou Zhenzhong , Xu Qun , Peng Qi , Li Jianbo , Fan Haijuan , Zheng Shijun
Published: March 2006

The grafting of poly(acrylic acid) to polypropylene was realized with supercritical CO2 as a substrate swelling agent and a monomer/initiator carrier. The effects of different supercritical CO2‐assisted impregnation conditions on the substrate mass increment and grafting efficiency were studied. The original isotactic polypropylene and the grafting product were characterized through IR spectroscopy, differential scanning calorimetry, and scanning electron microscopy. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4280–4285, 2006
Role of pretreatment with potassium permanganate and urea on mechanical and degradable properties of photocured coir (Cocos nucifera) fiber with 1,6‐hexanediol diacrylate
Authors: Khan Mubarak A. , Hassan M. Masudul , Taslima Rownak , Mustafa A. I.
Published: March 2006

Coir fibers were modified with 1,6‐hexanediol diacrylate (HDDA) using ultraviolet (UV) radiation. Concentration of HDDA, soaking time, and radiation dose were optimized and found to be 30% HDDA in methanol along with photoinitiator Irgacure‐500 (2%) and 120 min of soaking time registered as the better performance (polymer loading (PL) 7%, tensile strength factor, Tf = 1.50). Urea of different concentrations (0.5–2%) were incorporated with 30% HDDA to monitor its effect on the properties and 1% urea produced the best results (PL = 25%, Tf = 1.82). For the improvement of the properties, the fibers were subjected to surface treatment with potassium permanganate (KMnO4) of different concentrations at various treating times. Enhanced properties (PL = 86%. Tf = 4.42) of the fibers treated with KMnO4 (0.05%) were obtained. The KMnO4 treated fibers were again treated with HDDA (30%) solution along with urea (1%) and found to produce the best results (PL = 100%, Tf = 4.5). Water uptake and degradable properties of the treated and virgin fibers were obtained. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4361–4368, 2006
Interfacial reaction and its influence on phase morphology and impact properties of modified‐polyacetal/thermoplastic polyurethane blends
Authors: Kawaguchi Kuniaki , Tajima Yoshihisa
Published: March 2006

The cationic polymerization of 1,3,5‐trioxane, 1,3‐dioxolane and a small amount of 2‐hydroxyacetic acid (HAA) was carried out, and the resulting modified‐polyacetal (POM) was blended with thermoplastic polyurethane (TPU) in melt. The results of 1H NMR analysis indicated that HAA was almost incorporated in the modified‐POM, and that the resulting carboxyl end‐group and hydroxyl end‐group in the modified‐POM reacted with TPU during the melt blending. There were many boundary layers between the cavities and matrix in the modified‐POM/TPU (82/18 by weight) blend that was etched with tetrahydrofuran (THF), and the diameter of the cavities became ∼0.3–1 μm long when the blending time reached 10 min. The results of scanning electron microscopic (SEM) observation and dynamic mechanical analysis (DMA) indicated that the modified‐POM/TPU blend had a good compatibility because of the interfacial reaction between the modified‐POM and TPU phase in the blend. The modified‐POM/TPU blend exhibited higher Charpy impact strength when compared with a normal‐POM/TPU blend; the toughness of the modified‐POM/TPU blend attributed to the good compatibility between the two phases. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4375–4382, 2006
Chemical silver plating on polyester/cotton blended fabric
Authors: Jiang S. Q. , Newton E. , Yuen C. W. M. , Kan C. W.
Published: March 2006

Chemical plating is a metallizing process that can impart unique properties to textile fabrics. It has great potential for use in textile production, especially in the functional and decorative aspects. The present study examined the feasibility of applying chemical silver plating to a polyester/cotton blended fabric (T/C fabric) as well as investigating the properties of the silver‐plated T/C fabric. It was found that chemical silver plating helped to produce T/C fabric with a novel appearance and to improve its performance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4383–4387, 2006
Controlled hierarchical assembly of switchable DNA–multiprotein complexes
Authors: Sroga Grazyna E. , Dordick Jonathan S.
Published: March 2006

Directed, biologically‐driven self‐assembly has the potential to yield hybrid multicomponent architectures with applications ranging from sensors and diagnostics to catalysts and responsive materials. To enable these applications, it is critical to gain control over the precise orientation and geometry of biomolecules interacting with one‐another and with surfaces. Such control has thus far been difficult to achieve in even the simplest biomolecular designs. We report a novel methodology for the design and synthesis of functional, oriented, and reversibly switchable hierarchical assemblies at the nanoscale using DNA–protein and protein–protein interactions. The biomolecular assembly relies on the highly selective recognition between transcription factors (TFs) and their cognate DNA motifs that serve as transcription factor binding sites (TFBSs) along with the calmodulin (CaM)–calmodulin binding peptide (CBP) interaction that is regulated by Ca2+. Through these two types of controllable interactions, we achieved the sequential and hierarchical self‐assembly of multiprotein complexes complete with embedded fluorescence and catalytic capabilities, which may serve as a paradigm for multifunctional assemblies. © 2006 Wiley Periodicals, Inc.