bluuebunny/crossref_metadata_2025 huggingface dataset:
Knowledge about Attention‐Deficit/Hyperactivity Disorder: A comparison of in‐service and preservice teachers
Authors: Kos Julie M. , Richdale Amanda L. , Jackson Mervyn S.
Published: March 2004

Attention‐Deficit/Hyperactivity Disorder (ADHD) is a common childhood disorder, yet relatively little research has assessed teachers' knowledge of this disorder or how teacher characteristics affect such knowledge. There also is a dearth of research comparing in‐service and preservice teachers' knowledge about ADHD. The aims of this study were (a) to investigate the relationships between various teacher characteristics and teachers' knowledge about ADHD, and (b) to compare perceived and actual ADHD knowledge across in‐service and preservice primary‐school teachers. Participants included 120 primary‐school teachers and 45 final‐year education undergraduates who were asked to complete a questionnaire. Two of the five hypotheses were supported: (a) that knowledge would be significantly correlated with experience in teaching a child with ADHD and (b) that in‐service teachers would obtain higher scores than preservice teachers on the actual knowledge (about ADHD) questionnaire. Implications stemming from this research include ensuring that teachers receive more training about ADHD and greater exposure to students with ADHD in the classroom. Overall, this study highlighted that deficits in teachers' knowledge about ADHD are common for both in‐service and preservice teachers. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 517–526, 2004.
ACADEMIC ACHIEVEMENT OF STUDENTS IN FOSTER CARE: IMPEDED OR IMPROVED?
Authors: Evans Larry D.
Published: March 2004

Foster care's impact on academic development was investigated for 392 students reentering foster care. Psychoeducational evaluation was performed at initial and return placements. Average achievement increased .22 points between placements. Students reentering care did not show differences in achievement or IQ compared to control students with a single placement. Although average achievement showed a small increase between placements, some students showed large changes. Declining achievement was directly related to above‐average initial achievement ( p < .001), and indirectly related to not being in special education ( p < .001) and nonminority race ( p < .02). Results provide evidence that overall academic development appears neither enhanced nor hindered by foster care placement, but specific groups may be at risk for poor gains. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 527–535, 2004.
The predictive validity of the Phelps Kindergarten Readiness Scale
Authors: Augustyniak Kristine M. , Cook‐Cottone Catherine P. , Calabrese Nancy
Published: March 2004

This study assesses the predictive validity of the Phelps Kindergarten Readiness Scale (PKRS) for later academic achievement and explores the utility of a domain‐specific measure of kindergarten readiness. Kindergarten readiness scores were significantly correlated with both math and language arts achievement as measured by New York State fourth‐grade assessments for 148 students in a suburban, northeastern public school. In addition, each of the PKRS domains (Verbal, Perceptual, and Auditory) was correlated with later academic achievement. Two simultaneously calculated regression analyses showed that language arts skills were best predicted by the Verbal and Auditory domains of the PKRS and that math achievement was more complexly determined by all three readiness domains. Structural equation modeling using AMOS‐4 showed that the latent construct readiness, as measured by the PKRS domain scores, was positively and significantly related to the latent construct academic achievement. Finally, this relationship held when age, gender, and behavioral indices at the time of kindergarten screening were used as moderator variables. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 509–516, 2004.
Using MMPI‐A profiles to predict success in a military‐style residential treatment program for adolescents with academic and conduct problems
Authors: Weis Robert , Crockett Thomas E. , Vieth Sasha
Published: March 2004

Military‐style residential treatment for adolescents with academic and conduct problems is an increasingly popular alternative to traditional school‐based services. However, dropout from “boot camp” programs is a primary reason for their high cost. Social‐emotional functioning before referral may differentiate adolescents who successfully complete these programs from those who withdraw. Minnesota Multiphasic Personality Inventory‐Adolescent (MMPI‐A; Butcher et al., 1992) responses of 225 adolescents (16–18 years) with histories of truancy and antisocial behavior were subjected to profile analysis prior to participation in a 22‐week, military‐style treatment program. Elevations on the F (Frequency), 1 (Hs), and 3 (Hy) scales differentiated adolescents who dropped out of these programs from those who graduated. Logistic regression showed prediction accuracy to be 75%. School psychologists may use MMPI‐A profiles, especially the 1/3 code type, to screen boot camp candidates, maximize adolescents' likelihood of success, and reduce costs due to attrition. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 563–574, 2004.
Polymerization of methyl acrylate with triphenylbismuthonium 1,2,3,4‐tetraphenylcyclopentadienylide as a new radical initiator
Authors: Tripathi Seema , Srivastava A. K.
Published: March 2004

Triphenylbismuthonium 1,2,3,4‐tetraphenylcyclopentadienylide in 1,4‐dioxan initiated radical polymerization of methyl acrylate to ∼30% conversion without gelation because of autoacceleration. The polymer had a viscosity‐average molecular weight of 200,000. The kinetic expression was Rpα[I]0.3[M]1.16, that is, the system followed nonideal kinetics because of primary radical termination and degradative chain‐transfer reactions. The values of kkt and the energy of activation were computed as 3.12 × 10−5 Lmol−1s−1 and 28 kJ/mol, respectively. The ylide dissociated to form a phenyl radical, which brought about polymerization of methyl acrylate. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2060–2065, 2004
Copolymerization of the macromonomer poly(ethylene oxide) with styryl end group and styrene in the presence of poly(ε‐caprolactone) with 2,2,6,6‐tetramethylpiperidinyl‐1‐oxy end group by controlled radical mechanism
Authors: Wang Yun , Lu Guangqiang , Huang Junlian
Published: March 2004

A copolymerization of macromonomer poly(ethylene oxide) (PEO) with a styryl end group (PEOS) and styrene was successfully carried out in the presence of poly(ε‐caprolactone) (PCL) with 2,2,6,6‐tetramethylpiperidinyl‐1‐oxy end group (PCLT). The resulting copolymer showed a narrower molecular weight distribution and controlled molecular weight. The effect of the molecular weight and concentration of PCLT and PEOS on the copolymerization are discussed. The purity of PEOS exerted a significant effect on the copolymerization; when the diol contents of PEO macromonomer were greater than 1%, the crosslinking product was found. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2093–2099, 2004
13C NMR determination of the microstructure of polypropylene obtained with the DADNi(NCS)2/methylaluminoxane catalyst system
Authors: Barrera Galland Griselda , Da Silva Luciana P. , Dias Marcos L. , Crossetti Geraldo L. , Ziglio Cláudio M. , Filgueiras Carlos A. L.
Published: March 2004

A complete 13C NMR characterization of a polymer synthesized with a new Ni‐diimine complex [DADNi(NCS)2, where DAD = 2,6‐iPrC6H3NC(Me)C(Me) N2,6‐iPrC6H3] activated by methylaluminoxane by homopolymerization of propylene is presented. The amorphous material was made up mainly of blocks of syndiotactic polypropylene and ethylene–propylene copolymer. Some degree of propylene inversion (<1.2 mol %) and of long isobutyl and 2‐methyl hexyl branching (<1 mol %) were assigned and quantified. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2171–2178, 2004
Preparation of cationic latices comprising hollow thermostable particles
Authors: Pavlyuchenko V. N. , Sorochinskaya O. V. , Primachenko O. N. , Byrdina N. A. , Ivanchev S. S. , Skrifvars M.
Published: March 2004

A method is described for the preparation of cationic latices comprising submicron hollow particles for a possible application as a thermally stable polymeric pigment in coatings or pigmented compositions on the basis of thermosetting polymers cured at temperatures up to 170–190 °C. The method is based on the deposition of melamine–formaldehyde resin in the form of cationic colloid onto anionic hollow particles resulting in the recharging of anionic hollow particles and the formation of an outer melamine shell, which provides thermal stability of the hollow particles at curing and application of pigmented coatings and compositions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2225–2234, 2004
New poly(p‐phenylene vinylene) derivatives with two oxadiazole rings per repeat unit: Synthesis, photophysical properties, electroluminescence, and metal ion recognition
Authors: Mikroyannidis John A. , Spiliopoulos Ioakim K. , Kasimis Theodoros S. , Kulkarni Abhishek P. , Jenekhe Samson A.
Published: March 2004

Two new poly(p‐phenylene vinylene) derivatives OX1‐PPV and OX2‐PPV bearing two 1,3,4‐oxadiazole rings per repeat unit and a fully conjugated backbone with solubilizing dodecyloxy side groups were synthesized and investigated. The amorphous conjugated polymers had glass‐transition temperature values of 60–75 °C and emitted intense blue or greenish‐blue light in solution with photoluminescence (PL) emission maxima at 379–492 nm and PL quantum yields of 0.41–0.52. In the solid state they emitted yellowish‐green light with PL emission maxima at 533–555 nm. Cyclic voltammetry showed that both conjugated polymers had reversible reduction and irreversible oxidation, making them n‐type materials. The electron affinity of OX2‐PPV was estimated as 2.85 eV whereas that of OX1‐PPV was 2.75 eV. Yellow electroluminescence (EL) was achieved from single‐layer light‐emitting diodes of OX2‐PPV with an EL emission maximum at 555 nm and a brightness of 70 cd/m2. Polymer OX2‐PPV, which was functionalized with 2,6‐bis(1,3,4‐oxadiazole‐2‐yl)pyridine, demonstrated sensitivity to various metal ions as a fluorescence‐mode chemosensor. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2112–2123, 2004
Synthesis of a soluble pyrrole copolymer with phenetidine
Authors: Li Xin‐Gui , Chen Run‐Feng , Huang Mei‐Rong , Zhu Mei‐Fang , Chen Qun
Published: March 2004

A new series of copolymers was synthesized through the oxidative polymerization of pyrrole (PY) and o‐phenetidine (PHT) with inorganic oxidants in acidic media. The polymerization parameters including the mixing method of the oxidant with the comonomer, the comonomer ratio, the time, the temperature, the oxidant, the organic medium, and the acid were systematically optimized for the synthesis of copolymers with high yields, intrinsic viscosities, and solubility. The resultant copolymers were characterized by elemental analysis, infrared, ultraviolet–visible, solution high‐resolution 1H NMR and solid‐state high‐resolution 13C NMR, circular dichroism spectroscopy, and cyclic voltammetry. The results showed that the PY observed content in the copolymers was much higher than the PY feed content. The regular variation of the polymerization yield, intrinsic viscosity, solubility, macromolecular structure, and electroactivity of the resulting polymers with the comonomer ratio, together with the complete solubility of a PY/PHT (10/90) polymer in highly polar solvents, indicated the formation of real random copolymers containing both PY and PHT units rather than a mixture of two homopolymers. However, the polymers containing more than 59 mol % PY were not homogeneous copolymers consisting of soluble and insoluble parts. A semiquantitative relationship between the polymerization yield or solubility of the copolymers and the polarity index of the organic solvents was examined. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2073–2092, 2004
Novel amphiphilic network polymers consisting of nonpolar, short primary polymer chains and polar, long crosslink units: Influence of characteristic dangling chains on swelling behavior of resulting amphiphilic gels
Authors: Doura Masato , Aota Hiroyuki , Matsumoto Akira
Published: March 2004

Novel amphiphilic network polymers consisting of nonpolar, short primary polymer chains and polar, long crosslink units were prepared, and the swelling behavior of resulting amphiphilic gels is discussed by focusing on the influence of characteristic dangling chains; that is, benzyl methacrylate (BzMA) was copolymerized with tricosaethylene glycol dimethacrylate [CH2C(CH3)CO(OCH2CH2)23OCOC(CH3)CH2, PEGDMA‐23] in the presence of lauryl mercaptan as a chain‐transfer agent because BzMA forms nonpolar, short primary polymer chains and PEGDMA‐23 as a crosslinker contains a polar, long poly(oxyethylene) unit. The enhanced incorporation of dangling chains into the network polymer was brought by shortening the primary polymer chain length, and copolymerization with methoxytricosaethylene glycol methacrylate, a mono‐ene counterpart of PEGDMA‐23, enforced the incorporation of flexible dangling poly(oxyethylene) chains into the network polymer, although the former dangling chains as terminal parts of primary poly(BzMA) chains were rather rigid. Then, the influence of characteristic dangling chains on the swelling behavior of amphiphilic gels was examined in mixed solvents consisting of nonpolar t‐butylbenzene and polar methanol. The profiles of the solvent‐component dependencies of the swelling ratios were characteristic of amphiphilic gels. The introduction of dangling poly(oxyethylene) chains led not only to an increased swelling ratio but also to sharpened swelling behavior of amphiphilic gels. The swelling response of amphiphilic gels was checked by changing the external solvent polarity. The dangling chains with freely mobile end segments influenced the swelling response of gels. The amphiphilic gels with less entangled, collapsed crosslink units exhibited faster swelling response than the ones with more entangled, collapsed primary polymer chains. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2192–2201, 2004
Hydrogels based on physiologically clotted fibrin–gelatin composites
Authors: Noorjahan S. E. , Sastry T. P.
Published: March 2004

Fibrin–gelatin composite (PFG) films were prepared and crosslinked with glutaraldehyde as reported by us previously. These composites were graft‐copolymerized with poly(2‐hydroxyethyl methacrylate) (PHEMA) and poly(2‐hydroxypropyl methacrylate) (PHPMA) with a potassium persulfate and sodium metabisulfite redox initiation system. The graft copolymers (PFG‐HEMA and PFG‐HPMA) were characterized for their percentage of grafting, percentage of equilibrium water content, and percentages of free water and bound water. The chemical composition and thermal, mechanical, morphological, and surface characteristics were also evaluated. The optimum conditions for obtaining a maximum percentage of grafting were standardized. PFG and its graft copolymers exhibited higher equilibrium water contents ranging from 60 to 77% when compared with those of HEMA and HPMA homopolymers. DSC studies revealed increased freezing water contents and decreased bound‐water contents for the graft copolymers when compared with those of PFG alone. These properties improved the efficacy of hydrogels. PFG demonstrated better mechanical properties as compared with its graft copolymers. This may be attributed to the alkaline reaction conditions wherein protein hydrolysis of PFG would have occurred thereby reducing the overall strength of the graft copolymers. IR and scanning electron microscopic studies confirmed the grafting of PHEMA and PHPMA onto PFG. Contact‐angle studies revealed increased polarity for graft copolymers, which is a symbol for increased hydrophilicity. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2241–2252, 2004
Solid polymer electrolytes I, preparation, characterization, and ionic conductivity of gelled polymer electrolytes based on novel crosslinked siloxane/poly(ethylene glycol) polymers
Authors: Kuo Ping‐Lin , Hou Sheng‐Shu , Lin Chung‐Yie , Chen Chi‐Chang , Wen Ten‐Chin
Published: March 2004

A series of crosslinked siloxane/poly(ethylene glycol) (Si–PEG) copolymers were synthesized from the reactive methoxy‐functional silicone resin (Si resin) and PEGs with different molecular weights via two kinds of crosslinking reactions during an in situ curing stage. One of the crosslinking reactions is the self‐condensation between two methoxy groups in the Si resin, and another one is an alkoxy‐exchange reaction between the methoxy group in the Si resin and the OH group in PEG. The synthesized crosslinked copolymers were characterized by Fourier transform infrared spectroscopy, DSC, and 13C NMR. The crosslinked copolymers were stable in a moisture‐free environment, but the SiOC linkages were hydrolyzed in humid conditions. The gel‐like solid polymer electrolytes (SPEs) were prepared by impregnating these crosslinked Si–PEG copolymers in a propylene carbonate (LiClO4/PC) solution. The highest conductivity reached 2.4 × 10−4 S cm−1 at 25 °C and increased to 8.7 × 10−4 S cm−1 at 85 °C. The conductivities of these gel‐type SPEs were affected by the content of LiClO4/PC, the molecular weights of PEGs, and the weight fraction of the Si resin. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2051–2059, 2004
Efficient and rapid synthesis of polyureas and polythioureas from the reaction of urea and thiourea with diamines under microwave irradiation
Authors: Banihashemi Ahmad , Hazarkhani Hassan , Abdolmaleki Amir
Published: March 2004

Polyureas and polythioureas were readily synthesized by the reaction of aromatic and aliphatic amines with urea and thioureas, respectively, in good to excellent yields under microwave irradiation. The effects of the microwave irradiation time and power, the nature of the solvent, and the solid content of the monomers on the inherent viscosity of the polymers were investigated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2106–2111, 2004
Nanoencapsulation of a hydrophobic compound by a miniemulsion polymerization process
Authors: Luo Yingwu , Zhou Xiangdong
Published: March 2004

The nanoencapsulation of hydrophobic compounds by miniemulsion polymerization, a convenient one‐step encapsulation technique for nanocapsules, was investigated in terms of the thermodynamics and kinetics. The encapsulation was achieved by polymerization inducing phase separation within minidroplets dispersed in an aqueous phase. Thermodynamic factors (the level and type of surfactant, the level of the hydrophilic comonomer, and the monomer/paraffin ratio), kinetic factors (the level of the crosslinking agent or chain‐transfer agent), and nucleation modes were all found to have a great influence on the latex morphology. Specifically, for a styrene/paraffin system, there were optimum levels of sodium dodecyl sulfate (1.0 wt %), the hydrophilic comonomer (1.0 wt % methyl acrylate acid), and the chain‐transfer agent (0.2 wt % n‐dodecanethiol) for obtaining well‐defined nanocapsules of paraffin with a styrene/paraffin ratio of 1:1. When the styrene/paraffin ratio was reduced, however, it was more difficult to achieve a fully encapsulated particle morphology. Homogeneous nucleation could compete with encapsulation, and this resulted in a pure polymer particle and a half‐moon morphology. Conditions were also found under which complete encapsulation could be observed with a water‐soluble initiator (potassium persulfate), contrary to certain reports. Replacing potassium persulfate with an oil‐soluble initiator (2,2‐azobisisobutyronitrile) had little influence on the morphology under those conditions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2145–2154, 2004
Crosslinkable poly(p‐phenylenevinylene) derivative
Authors: Sun Honghao , Liu Ze , Hu Yufeng , Wang Lixiang , Ma Dongge , Jing Xiabing , Wang Fosong
Published: March 2004

To simplify the fabrication of multilayer light‐emitting diodes, we prepared a p‐phenylenevinylene‐based polymer capped with crosslinkable styrene through a Wittig reaction. Insoluble poly(p‐phenylenevinylene) derivative (PPVD) films were prepared by a thermal treatment. The photoluminescence and ultraviolet–visible (UV–vis) absorbance of crosslinked films and noncrosslinked films were studied. We also studied the solvent resistance of crosslinked PPV films with UV–vis absorption spectra and atomic force microscopy. Double‐layer devices using crosslinked PPVD as an emitting layer, 2‐(4‐tert‐butylphenyl)‐5‐phenyl‐1,3,4‐oxadiazole (PBD) in poly(methyl methacrylate) as an electron‐transporting layer, and calcium as a cathode were fabricated. A maximum luminance efficiency of 0.70 cd/A and a maximum brightness of 740 cd/m2 at 16 V were demonstrated. A 12‐fold improvement in the luminance efficiency with respect to that of single‐layer devices was realized. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2124–2129, 2004
Synthesis and properties of novel polyimides derived from 2,2′,3,3′‐benzophenonetetracarboxylic dianhydride
Authors: Fang Xing‐Zhong , Li Qing‐Xuan , Wang Zhen , Yang Zheng‐Hua , Gao Lian‐Xun , Ding Meng‐Xian
Published: March 2004

A new synthetic route to 2,2′,3,3′‐BTDA (where BTDA is benzophenonetetracarboxylic dianhydride), an isomer of 2,3′,3′,4′‐BTDA and 3,3′,4,4′‐BTDA, is described. Single‐crystal X‐ray diffraction analysis of 2,2′,3,3′‐BTDA has shown that this dianhydride has a bent and noncoplanar structure. The polymerizations of 2,2′,3,3′‐BTDA with 4,4′‐oxydianiline (ODA) and 4,4′‐bis(4‐aminophenoxy)benzene (TPEQ) have been investigated with a conventional two‐step process. A trend of cyclic oligomers forming in the reaction of 2,2′,3,3′‐BTDA and ODA has been found and characterized with IR, NMR, matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry, and elemental analyses. Films based on 2,2′,3,3′‐BTDA/TPEQ can only be obtained from corresponding polyimide (PI) solutions prepared by chemical imidization because those from their polyamic acids by thermal imidization are brittle. PIs from 2,2′,3,3′‐BTDA have lower inherent viscosities and worse thermal and mechanical properties than the corresponding 2,3′,3′,4′‐BTDA‐ and 3,3′,4,4′‐BTDA‐based PIs. PIs from 2,2′,3,3′‐BTDA and 2,3′,3′,4′‐BTDA are amorphous, whereas those from 3,3′,4,4′‐BTDA have some crystallinity, according to wide‐angle X‐ray diffraction. Furthermore, PIs from 2,2′,3,3′‐BTDA have better solubility, higher glass‐transition temperatures, and higher melt viscosity than those from 2,3′,3′,4′‐BTDA and 3,3′,4,4′‐BTDA. Model compounds have been prepared to explain the order of the glass‐transition temperatures found in the isomeric PI series. The isomer effects on the PI properties are discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2130–2144, 2004
Diels–Alder reaction with anthracene and quinone derivatives on the dendritic periphery
Authors: Kim Chungkyun , Kim Hyojeong , Park Kyungrae
Published: March 2004

Diels–Alder (DA) adducts including 24, 48, and 96 bicyclo end groups on the dendritic periphery were prepared by the reaction of anthracene on the dendrimers (first to fourth generation) and 1,4‐benzoquinone as well as 1,4‐naphtoquinone in boiled toluene. The structural information of DA adducts on the dendritic periphery was received from the hyperfine structural analysis by 1H NMR spectroscopy. The gel permeation chromatography of DA products revealed very low polydispersity values and decreased regular retention time according to increasing generation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2155–2161, 2004
Microencapsulation of cholesteryl alkanoate by polymerization‐induced phase separation and its association with drugs
Authors: Kim Jin‐Woong , Lee Kwang‐Sup , Ju Hee‐Kyung , Ryu Jee‐Hyun , Han Sang‐Hoon , Chang Ih‐Seop , Kang Hak‐Hee , Oh Seong‐Geun , Suh Kyung‐Do
Published: March 2004

A new microencapsulation technique is presented in which cholesteryl nonanoate (CN)/poly(methyl methacrylate) (PMMA) microcapsules are produced by the induction of phase separation between CN and PMMA within the droplets during the polymerization. The concentration of CN is the most important factor determining the final morphology of the microcapsules. For example, a polynuclear type is obtained at a low concentration (<20 wt %), a mononuclear type is obtained at a medium concentration (20–30 wt %), and an irregular phase is obtained at a high concentration (>40 wt %). To evaluate the effectiveness of the technique for stabilizing an unstable drug, we selected retinol (vitamin A) as a model drug and loaded it into the CN/PMMA microcapsules. We used a process called solute codiffusion, in which a fine solvent emulsion containing the retinol was diffused uniformly into the CN/PMMA microcapsules. The loading efficiency of retinol was predicted successfully with the aid of a thermodynamic equation. In the thermal stability test of retinol, we found that an effective association with the CN phase was the most important factor determining the limit of its molecular stability. The technique reported in this article has great potential for the microencapsulation of soft materials via a simple process and for the stabilization of unstable drugs. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2202–2213, 2004
Three‐component, negative‐type, alkaline‐developable, thermally stable, and photosensitive polymer based on poly(2,6‐dihydroxy‐1,5‐naphthalene), a crosslinker, and a photoacid generator
Authors: Tsuchiya Kousuke , Shibasaki Yuji , Suzuki Masato , Ueda Mitsuru
Published: March 2004

A negative working and chemically amplified photosensitive polymer has been developed, which is based on poly(2,6‐dihydroxy‐1,5‐naphthalene) (PDHN), the crosslinker 4,4′‐methylenebis[2,6‐bis(hydroxymethyl)]phenol, and the photoacid generator (5‐propylsulfonyloxyimino‐5H‐thiophen‐2‐ylidene)‐(2‐methylphenyl)acetonitrile. PDHN, with a number‐average molecular weight of 25,000, was prepared by the oxidative coupling polymerization of 2,6‐dihydroxynaphthalene with di‐μ‐hydroxo‐bis[(N,N,N′,N′‐tetramethylethylenediamine)copper(II)] chloride in 2‐methoxyethanol at room temperature. The resulting PDHN showed a 5% weight loss temperature of 440 °C in nitrogen and a low dielectric constant of 2.82. The resist showed a sensitivity of 8.3 mJ cm−2 and a contrast of 11 when it was exposed to 436‐nm light, followed by postexposure baking at 100 °C for 5 min and development with a 2.38 wt % aqueous tetramethylammonium hydroxide solution at 25 °C. A fine negative image featuring 10‐μm line‐and‐space patterns was obtained on a film 3 μm thick exposed to 10 mJ cm−2 of ultraviolet light at 436 nm in the contact‐printed mode. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2235–2240, 2004
Rheological properties of multisticker associative polyelectrolytes in semidilute aqueous solutions
Authors: Kujawa Piotr , Audibert‐Hayet Annie , Selb Joseph , Candau Françoise
Published: March 2004

Multisticker associative polyelectrolytes of acrylamide (≈86 mol %) and sodium 2‐acrylamido‐2‐methylpropanesulfonate (≈12 mol %), hydrophobically modified with N,N‐dihexylacrylamide groups (≈2 mol %), were prepared with a micellar radical polymerization technique. This process led to multiblock polymers in which the length of the hydrophobic blocks could be controlled through variations in the surfactant‐to‐hydrophobe molar ratio, that is, the number of hydrophobes per micelle (NH). The rheological behavior of aqueous solutions of polymers with the same molecular weight and the same composition but with two different hydrophobic block lengths (NH = 7 or 3 monomer units per block) was investigated as a function of the polymer concentration with steady‐flow, creep, and oscillatory experiments. The critical concentration at the onset of the viscosity enhancement decreased as the length of the hydrophobic segments in the polymers increased. Also, an increase in the NH value significantly enhanced the thickening ability of the polymers and affected the structure of the transient network. In the semidilute unentangled regime, the behavior of the polymer with long hydrophobic segments (NH = 7) was studied in detail. The results were well explained by the sticky Rouse theory of associative polymer dynamics. Finally, the viscosity decreased with an increase in the temperature, mainly because of a lowering of the sample relaxation time. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1640–1655, 2004
Fourth‐order hydrodynamic contribution to the polymer self‐diffusion coefficient
Authors: Merriam S. C. , Phillies George D. J.
Published: March 2004

A hydrodynamic scattering treatment of interacting polymer chains is extended to obtain the five‐point chain–chain–chain–chain–chain hydrodynamic interaction tensor. The tensor is used to calculate the second‐order concentration correction to the self‐diffusion coefficient of a polymer in solution. The self‐similarity assumption of the hydrodynamic scaling model of polymer dynamics is tested against these calculations. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1663–1670, 2004
Toughness mechanism in polypropylene composites: Polypropylene toughened with elastomer and calcium carbonate
Authors: Zhang Ling , Li Chunzhong , Huang Rui
Published: March 2004

Polypropylene (PP) was modified with elastomer or CaCO3 particles of two different sizes (1 μm and 50 nm) in various volume fractions. The dispersion morphology and mechanical properties of the two systems were investigated as functions of the particle size and volume fraction of the modifier. The brittle‐to‐tough transition occurred when the matrix ligament thickness was less than the critical ligament thickness, which was about 0.1 μm for the PP used here, being independent of the type of modifier. At the same matrix ligament thickness, the improvement of the toughness was obviously higher with the elastomer rather than with CaCO3, but adding CaCO3 increased the modulus of PP. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1656–1662, 2004
Preparation and properties of nanocomposites based on acrylonitrile–butadiene rubber, styrene–butadiene rubber, and polybutadiene rubber
Authors: Sadhu Susmita , Bhowmick Anil K.
Published: March 2004

Nanocomposites were prepared with different grades of nitrile rubber with acrylonitrile contents of 19, 34, and 50%, with styrene–butadiene rubber (23% styrene content), and with polybutadiene rubber with Na‐montmorillonite clay. The clay was modified with stearyl amine and was characterized by X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). The XRD studies showed an increase in the gallery gap upon the modification of the filler by stearyl amine. The intercalation of the amine chains into the clay gallery gap was confirmed by the presence of some extra peaks (2928, 2846, and 1553 cm−1) in the FTIR spectra. The clay–rubber nanocomposites were characterized by TEM and XRD. The mechanical properties were studied for all the compositions. An improvement in the mechanical properties with the degree of filler loading up to a certain level was observed. The changes in the mechanical properties, with changes in the nature and polarity of the rubbers, were explained with the help of XRD and TEM results. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1573–1585, 2004
Mechanical properties of magnetically oriented epoxy
Authors: Al‐Haik M. S. , Garmestani H. , Li D. S. , Hussaini M. Y. , Sablin S. S. , Tannenbaum R. , Dahmen K.
Published: March 2004

The microstructure of an epoxy system oriented in high magnetic fields (15–25 T) has been observed to consist of highly oriented domains at the molecular level along the direction of the applied field. The changes in the microstructure have been characterized as a function of the magnetic‐field strength and have been investigated microscopically and with wide‐angle X‐ray diffraction. The mechanical properties of the epoxy have been examined in light of nanoindentation experiments at different load levels. The basic results of the experimental investigations for the effect of high magnetic fields on the structure and property of the epoxy are presented. Nanoindentation testing has revealed large differences in the nanomechanical behavior for thermomagnetically processed epoxy specimens. The differences can be ascribed to the microstructural changes (reorientation) of the polymer at the molecular level. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1586–1600, 2004
Exclusion effect of carbon dioxide on the crystallization of polypropylene
Authors: Oda Takafumi , Saito Hiromu
Published: March 2004

We investigated the crystallization growth of isotactic polypropylene under carbon dioxide (CO2) at various CO2 pressures and temperatures by in situ observation with a digital high‐fidelity microscope and a specially designed high‐pressure visualized cell. The fibrils within the spherulite were distorted and branched by crystallization under CO2 at pressures higher than 2 MPa, and this suggested the exclusion of CO2 from the growth front of the fibrils. The spherulite growth rate (G) at 140 °C increased with the CO2 pressure, attained a maximum value around 0.3 MPa, and then decreased. Above 6 MPa, it became slower than that under air at the ambient pressure. An analysis of the crystallization kinetics by the Hoffman–Lauritzen theory revealed that the pressure dependence of G could be ascribed to the change in the transportation rate of crystallizable molecules (βg) with pressure; that is, βg increased and then decreased with pressure. The increase in βg at a low pressure was caused by the plasticizing effect of CO2, whereas the decrease in βg at a high pressure was due to the exclusion of CO2 from the crystal growth front. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1565–1572, 2004
Investigation of glucose binding sites on insulin
Authors: Zoete Vincent , Meuwly Markus , Karplus Martin
Published: April 2004

Possible insulin binding sites for D‐glucose have been investigated theoretically by docking and molecular dynamics (MD) simulations. Two different docking programs for small molecules were used; Multiple Copy Simultaneous Search (MCSS) and Solvation Energy for Exhaustive Docking (SEED) programs. The configurations resulting from the MCSS search were evaluated with a scoring function developed to estimate the binding free energy. SEED calculations were performed using various values for the dielectric constant of the solute. It is found that scores emphasizing non‐polar interactions gave a preferential binding site in agreement with that inferred from recent fluorescence and NMR NOESY experiments. The calculated binding affinity of −1.4 to −3.5 kcal/mol is within the measured range of −2.0 ± 0.5 kcal/mol. The validity of the binding site is suggested by the dynamical stability of the bound glucose when examined with MD simulations with explicit solvent. Alternative binding sites were found in the simulations and their relative stabilities were estimated. The motions of the bound glucose during molecular dynamics simulations are correlated with the motions of the insulin side chains that are in contact with it and with larger scale insulin motions. These results raise the question of whether glucose binding to insulin could play a role in its activity. The results establish the complementarity of molecular dynamics simulations and normal mode analyses with the search for binding sites proposed with small molecule docking programs. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Electron ionization mass spectral fragmentation of derivatized 4,5‐ and 5,6‐epoxysterols
Authors: Rontani J.‐F. , Aubert C.
Published: March 2004

The electron ionization (EI) mass spectral fragmentation of derivatized 4,5‐ and 5,6‐epoxysterols was investigated. Interesting fragmentation processes involving a transannular cleavage of the epoxide ring after transfer of the trimethylsilyl group are significant in the case of 4,5‐epoxysterol trimethylsilyl ethers (affording abundant fragment ions at m/z 403 and 404). Different pathways, which have been substantiated by deuterium labelling, are proposed in order to explain the formation of these ions. In contrast, this transfer is not significant in the case of 5,6‐epoxysterol trimethylsilyl ethers. The EI mass spectra of these latter compounds appear to be very complex and to differ slightly according to the stereochemistry of the epoxy group. Acetate and trifluoroacetate derivatives of 4,5‐epoxysterols display interesting EI mass spectra dominated by a fragment ion at m/z 332 resulting from cleavage of the steroid ring A. Copyright © 2004 John Wiley & Sons, Ltd.
Modelling risk when binary outcomes are subject to error
Authors: McInturff Pat , Johnson Wesley O , Cowling David , Gardner Ian A
Published: March 2004

We present methods for binomial regression when the outcome is determined using the results of a single diagnostic test with imperfect sensitivity and specificity. We present our model, illustrate it with the analysis of real data, and provide an example of WinBUGS program code for performing such an analysis. Conditional means priors are used in order to allow for inclusion of prior data and expert opinion in the estimation of odds ratios, probabilities, risk ratios, risk differences, and diagnostic test sensitivity and specificity. A simple method of obtaining Bayes factors for link selection is presented. Methods are illustrated and compared with Bayesian ordinary binary regression using data from a study of the effectiveness of a smoking cessation program among pregnant women. Regression coefficient estimates are shown to change noticeably when expert prior knowledge and imperfect sensitivity and specificity are incorporated into the model. Copyright © 2004 John Wiley & Sons, Ltd.
Interval‐censored survival time data: confidence intervals for the non‐parametric survivor function
Authors: Goodall Ruth L. , Dunn David T. , Babiker Abdel G.
Published: March 2004

Survival data are described as interval censored when the failure time is not measured exactly but is known only to have occurred within a defined interval. In this paper, we describe and assess three methods for calculating pointwise confidence intervals for the non‐parametric survivor function estimated from interval‐censored data: the first based on the full information matrix, the second a modification of this approach involving deletion of rows and columns of the information matrix corresponding to zero estimates prior to inversion and the third based on likelihood ratio inference. In a simulation study the likelihood ratio method gave the most accurate confidence intervals with coverage consistently close to the nominal level of 95 per cent. Copyright © 2004 John Wiley & Sons, Ltd.
Inflation of the type I error rate when a continuous confounding variable is categorized in logistic regression analyses
Authors: Austin Peter C. , Brunner Lawrence J.
Published: March 2004

This paper demonstrates an inflation of the type I error rate that occurs when testing the statistical significance of a continuous risk factor after adjusting for a correlated continuous confounding variable that has been divided into a categorical variable. We used Monte Carlo simulation methods to assess the inflation of the type I error rate when testing the statistical significance of a risk factor after adjusting for a continuous confounding variable that has been divided into categories. We found that the inflation of the type I error rate increases with increasing sample size, as the correlation between the risk factor and the confounding variable increases, and with a decrease in the number of categories into which the confounder is divided. Even when the confounder is divided in a five‐level categorical variable, the inflation of the type I error rate remained high when both the sample size and the correlation between the risk factor and the confounder were high. Copyright 2004 John Wiley & Sons, Ltd.
Increasing the sample size when the unblinded interim result is promising
Authors: Chen Y. H. Joshua , DeMets David L. , Gordon Lan K. K.
Published: March 2004

Increasing the sample size based on unblinded interim result may inflate the type I error rate and appropriate statistical adjustments may be needed to control the type I error rate at the nominal level. We briefly review the existing approaches which allow early stopping due to futility, or change the test statistic by using different weights, or adjust the critical value for final test, or enforce rules for sample size recalculation. The implication of early stopping due to futility and a simple modification to the weighted Z‐statistic approach are discussed. In this paper, we show that increasing the sample size when the unblinded interim result is promising will not inflate the type I error rate and therefore no statistical adjustment is necessary. The unblinded interim result is considered promising if the conditional power is greater than 50 per cent or equivalently, the sample size increment needed to achieve a desired power does not exceed an upper bound. The actual sample size increment may be determined by important factors such as budget, size of the eligible patient population and competition in the market. The 50 per cent‐conditional‐power approach is extended to a group sequential trial with one interim analysis where a decision may be made at the interim analysis to stop the trial early due to a convincing treatment benefit, or to increase the sample size if the interim result is not as good as expected. The type I error rate will not be inflated if the sample size may be increased only when the conditional power is greater than 50 per cent. If there are two or more interim analyses in a group sequential trial, our simulation study shows that the type I error rate is also well controlled. Copyright © 2004 John Wiley & Sons, Ltd.
Effects of Extruder Die Nozzle Dimensions on Expansion and Micrographic Characterization During Extrusion of Acetylated Starch
Authors: Ganjyal Girish M. , Hanna Milford A.
Published: March 2004

Starch acetate (DS 2) with ethanol content of 16% (d. b.) was extruded in a twin‐screw extruder with nozzle length to diameter (L/D) ratios varying from 2.9 to 13.1, constant screw speed of 140 rpm and barrel temperature of 160°C. Effects of variation in L/D ratio and the individual effects of variations in L and D on expansion and micrographic properties were studied. With smaller D and larger L nozzles, back pressure developed in the die was immense, which resulted in high initial expansion and then collapse of extrudates, after a brief time, leading to smaller diameter extrudates. It was concluded that the pressure drop exerted tensile forces in the cell material in excess of its elastic limits. SEM results of the samples showed the effects. It is important to consider the elastic properties of the material in predicting ultimate radial expansion. The expansion phenomena have been explained in detail.
Analytical, Biochemical and Physicochemical Aspects of Starch Granule Size, with Emphasis on Small Granule Starches: A Review
Authors: Lindeboom Nienke , Chang Peter R. , Tyler Robert T.
Published: March 2004

Granule size, size distribution and shape are among the most important morphologically distinguishing factors of starches from different origins. This article provides an overview of aspects related to starch granule size, including procedures for determining the size, the impact of granule size on the physicochemical characteristics of starch, and biosynthetic and environmental determinants of granule size. The focus is on small granule starches, including their isolation and current and potential utilization.
Study on the Synthesis and Application of Starch‐graft‐Poly(AM‐co‐DADMAC) by Using a Complex Initiation System of CS‐KPS
Authors: Lu Shaojie , Lin Songbai , Yao Kangde
Published: March 2004

A graft copolymer was synthesized by graft copolymerization of starch with acrylamide (AM) and diallyldimethylammonium chloride (DADMAC). The copolymerization was carried out using a complex initiation system of cerium sulfate (CS) and potassium persulfate (KPS). The effects of reaction conditions on graft copolymerization and use of these copolymers as additives in papermaking was investigated. Experiments showed that a graft copolymer with higher grafting level, higher intrinsic viscosity and higher cationic degree could be obtained by changing the method of monomer addition and by controlling the ratio of DADMAC to AM. The graft copolymerization was more effective when the complex initiation system of CS‐KPS was used. When adding 0.05% of the grafted starch [S‐g‐P(AM‐co‐DADMAC)] to the papermaking system, a higher filler retention was obtained than with cationic starch and cationic polyacrylamide when the cationic degree of S‐g‐P(AM‐co‐DADMAC) was 22% and its intrinsic viscosity was 7.35.
Acylation of Starch with Vinyl Acetate in Water
Authors: Mormann Werner , Al‐Higari Mohamed
Published: March 2004

Acetylation of different types of starch with vinyl acetate in water in the presence of a base is described. Maximum degree of substitution under these conditions is 1.1. Vinyl esters of higher homologous acids (vinyl laurate) react very slowly giving very low degrees of substitution after long reaction times. The reaction mixture is biphasic, because vinyl esters are not miscible with water. Formation of two layers reduces loss of acylating agent due to reaction with water – which is a major problem encountered for esterification with acid anhydrides or chlorides – to less than 5%. Unlike acylation of starch in DMSO with vinyl esters, the acetates of starch obtained by the method reported do not show regioselective distribution of acetyl groups within the anhydroglucose units.
Editorial: Starch/Stärke 3‐4/2004
Authors: Elvers Barbara
Published: March 2004

No abstracts.
Crystal engineering of photochromic diarylethene single crystals
Authors: Morimoto Masakazu , Kobatake Seiya , Irie Masahiro
Published: March 2004

Photochromic performance of diarylethene single crystals was controlled by crystal engineering using non‐covalent
aromatic‐aromatic interactions as the directional intermolecular force. A diarylethene derivative with two pentafluorophenyl
groups, 1,2‐bis(2‐methyl‐5‐pentafluorophenyl‐3‐thienyl)perfluorocyclopentene
(1a), formed stoichiometric co‐crystals with benzene (Bz) and naphthalene (Np)
by aryl‐perfluoroaryl interactions. Face‐to‐face π‐stacking interactions between the pentafluorophenyl
groups of 1a and the aromatic molecules are responsible for 2 : 1 and 1 : 1 stoichiometric compositions
in 1a/Bz and 1a/Np co‐crystals, respectively. The diarylethene underwent thermally stable and photoreversible
photochromic reactions in a homo‐crystal of 1a and co‐crystals 1a/Bz and 1a/Np. The absorption
spectra of the photogenerated closed‐ring isomers varied depending on the conformation of the diarylethene molecules packed in the
crystals. The diarylethene 1a also formed 1 : 1 stoichiometric co‐crystals with different kinds of diarylethenes,
1,2‐bis(2‐ethyl‐5‐phenyl‐3‐thienyl)perfluorocyclopentene (2a) and
1,2‐bis[2‐methyl‐5‐(1‐naphthyl)‐3‐thienyl]perfluorocyclopentene
(3a). Both co‐crystals 1a/2a and 1a/3a showed photochromism. Although 1a, 2a,
and 3a underwent efficient photocyclization reactions in their homo‐crystals, highly selective photocyclization reactions
of 2a or 3a were observed in the co‐crystals. The selective reactions were confirmed by HPLC and X‐ray
crystallography. Excited energy transfers from 1a to 2a and from 1a to 3a are considered to occur and cause
the selective reactions. © 2004 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 4: 23–38; 2004: Published
online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10078