bluuebunny/crossref_metadata_2025_split huggingface dataset:
Teacher attributions of student failure and teacher behavior toward the failing student
Authors: Georgiou Stelios N. , Christou Constantinos , Stavrinides Panayiotis , Panaoura Georgia 
Published: October 2002

AbstractThe aim of this study was to examine the relation between teacher attributions of student school failure and teacher behavior toward the failing student. A structural equation model was proposed and its ability to fit the data was tested. It was found that teachers tend to behave in ways that indicate more pity and less anger when they attribute a student's low achievement to her or his low abilities, whereas they express more anger when attributing low achievement to the student's low effort. In contrast to previous research that argues in favor of anger as a high ability cue, this study has found that the presence of anger was associated with a teacher tendency to give‐up efforts to help the student improve. This giving‐up behavior was negatively related to the tendency of the teachers to accept some responsibility for the student failure. © 2002 Wiley Periodicals, Inc.
Ab initio analysis on metal ion catalysis in the enolization reactions of some acetylheterocycles: kinetics of the enolization reactions of 3‐acetyl‐5‐methylisoxazole, 5‐acetyl‐3‐methylisoxazole and 3(5)‐acetylpyrazole
Authors: Fontana Antonella , Maria Paolo De , Pierini Marco , Siani Gabriella , Cerritelli Simona , Macaluso Gabriella 
Published: October 2002

AbstractKinetic data on the enolization reaction of 3‐acetyl‐5‐methylisoxazole, 5‐acetyl‐3‐methylisoxazole, 3(5)‐acetylpyrazole and some previously studied acetylheterocycles have been the object of a comprehensive ab initio analysis. Enolization rate constants were measured spectrophotometrically by the halogen trapping technique at 25 °C and ionic strength of 0.3 mol dm−3 in water, in acetate buffers, in dilute hydrochloric acid, in dilute sodium hydroxide and in the presence of some metal ion salts. In the spontaneous (water) and base (acetate) catalysed reactions the ketones investigated are generally more reactive than acetophenone, according to the electron‐withdrawing effect of the heterocyclic ring compared with the benzene ring. In particular, acetylisoxazoles, 3(5)‐acetylpyrazole and acetylthiazoles are more reactive than acetylfurans, 2‐acetylpyrrole and acetylthiophenes respectively, and this can be attributed to the additional effect of the second heteroatom in the heterocyclic moiety. On the other hand, the compounds investigated are generally less reactive than acetophenone in the H3O+‐catalysed reaction. Ab initio calculations on the relative stability of the protonated and unprotonated forms of the substrates investigated have been compared with the kinetic results obtained in acid solutions. As far as the metal ion catalysis is concerned, an approach in terms of ΔΔE can give an estimate of the combined contributions of charge densities and frontier orbitals to the interaction of the substrate with the metal ion catalyst. A comparison of experimental metal activating factor values and ab initio calculations outlines the importance of charge density on the carbonyl oxygen atom of acetylheterocycles with one heteroatom. An analogous comparison for acetylheterocycles with two heteroatoms suggests the formation of a chelate complex or transition state, in which the metal ion coordinates both the carbonyl oxygen and the aza nitrogen, whenever these two atoms are suitably placed within the molecular structure of the acetylheterocycle. Copyright © 2002 John Wiley & Sons, Ltd.
Conformational dependence of substituent effects in the solvolyses of the 1,1‐diphenyl‐2,2,2‐trifluoroethyl system
Authors: Fujio Mizue , Kim Hyun‐Joong , Uddin Md. Khabir , Yoh Soo‐Dong , Rappoport Zvi , Tsuno Yuho 
Published: October 2002

AbstractThe substituent effects on the solvolysis of 1‐X‐phenyl‐1‐Y‐phenyl‐2,2,2‐trifluoroethyl tosylates were analyzed on the basis of the Yukawa–Tsuno equation. For the solvolysis of the symmetrically disubstituted X = Y subseries, an excellent linear correlation was obtained. However, in the solvolyses of series of varying X with a fixed‐Y subset, the substituent effects were found to give significantly concave Y–T correlations. The ρ value for the Y–T correlations changes significantly with the fixed Y substituent. There is a qualitative trend of a linear decrease in the ρ value as the fixed‐Y substituent of the respective subset becomes more electron donating. The non‐linearity of substituent effects was attributed to a substituent‐induced conformational change of the transition state, which could be simulated by calculation of the preferred conformation of the intermediate carbocation. A molecular orbital optimization method was applied to determine the preferred conformations of the α,α‐diarylcarbenium ions derived from the title systems. The symmetrical carbenium ions X = Y have a preferred propeller shape conformation with twist angles differing by 14° (E conformation), whereas in the unsymmetrical systems X ≠ Y the two aryl rings are much more (>30°) differently twisted in the preferred conformation (PT conformation). The linear correlation found for the symmetrical subseries is essentially an outcome of the E conformation of the transition state. In unsymmetrical cases, the substituent effect correlation in any Y subset should reflect the conformational arrangements, E
X, P
X and T
X of the variable X‐aryl group, depending on relative σ values of X and Y. The substituent effects in the Y‐subsets were successfully treated by three different Y‐independent correlations for the preferred conformational arrangements: E correlation for substituents when (σ
X − σ
Y) ≅ 0, P
X correlation when (σ
X − σ
Y) ≪0 and T
X correlation for the (σ
X − σ
Y) ≫0 class, respectively. Copyright © 2002 John Wiley & Sons, Ltd.
Formation and isomerization of C120: considerations of symmetry, kinetics and thermodynamics
Authors: Halevi Emil Amitai 
Published: October 2002

AbstractAn orbital‐symmetry analysis (OCAMS) of the dimerization of C60 to its stable (D2h) dimer 1 indicates that the reaction cannot proceed along a totally symmetric pathway but that the reaction‐path symmetry must be reduced at least to C2h. Similarly, one‐step conversion of 1 to its isomer 3 (also D2h), which has been proposed as an intermediate for the intercalation of helium atoms into C60, is also limited to a C2h pathway. As neither of these pathways is geometrically appropriate, it is predicted that both reactions proceed stepwise. Semi‐empirical computations (AM1/UHF) confirmed this prediction: in the dimerization, a transoid singlet biradical (2) is formed, and then closes readily to 1 after rotation about its newly formed bond. An intermediate (4) of C2v symmetry is detected along the pathway for isomerization of 1 to 3. THERMO computations (AM1/RHF) indicated that both dimers should be in thermal equilibrium with C60 at moderate temperatures, but that their equilibrium concentrations in the gas phase would be exceedingly small under thermally accessible conditions. The limitations of the computational method employed and their bearing on the reliability of the results are discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Study of inclusion complexes of acridine with β‐ and (2,6‐di‐O‐methyl)‐β‐cyclodextrin by use of solubility diagrams and NMR spectroscopy
Authors: Correia Isabelle , Bezzenine Nabil , Ronzani Nello , Platzer Nicole , Beloeil Jean‐Claude , Doan Bich‐Thuy 
Published: October 2002

AbstractPrevious molecular modeling studies, in our laboratory, have shown that some esters of type RCOO(CH2)
nC5H5N+Cl− are potentially active against Alzheimer's disease. We have also demonstrated that acridine, which has strong anticholinesterase activity appears to be a suitable R substituent. The main obstacle to the possible pharmaceutical application of these compounds is their limited solubility in water, which is due to the poor aqueous solubility of acridine itself (0.26 mM). Inclusion complexation with cyclodextrins may overcome this problem. Solubility diagrams and NMR spectroscopy were used to study the inclusion of acridine (Acr) within β‐cyclodextrin (βCD) and heptakis(2,6‐di‐O‐methyl)cyclomaltoheptose (DMβCD). A 1:1 complex was formed for the Acr–βCD system and both 1:1 and 2:1 complexes for the Acr–DMβCD system (apparent Ka 215 ± 20 and 1150 ± 100 M
−1, respectively). Data from 1H NMR studies corrected the assignment of the acridine H1, H8 and H4, H5 protons in D2O, which have been erroneously assigned in previous publications. 1H spin–lattice relaxation times T1 measured with selective, non‐selective and null inversion characterize the dynamics of the inclusion complexes. Geometric features of the host–guest inclusion complexes were inferred from intermolecular dipolar interactions obtained by 2D adiabatic off‐resonance ROESY experiments. A more detailed picture of the structure of the inclusion complexes was obtained by combining NMR structural data and molecular modeling (docking, dynamics under NMR constraints and energy calculations). Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis of nonlinear optical polyimides containing azodiamine derivative chromophores and their electrooptic and thermal properties
Authors: Zhou Yuming , Leng Weinan , Liu Xiaojuan , Xu Qunhua , Feng Jikang , Liu Juzheng 
Published: October 2002

AbstractSome thermally stable second‐order nonlinear optical (NLO) polyimides were synthesized. The polyimides were prepared by the ring‐opening polyaddition of 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride and pyromellitic dianhydride with two aromatic azodiamine derivatives as the NLO chromophores. These chromophores, based on a nitro group connected with azobenzene as the acceptor end of a donor–π‐bridge–acceptor chromophore and a diamine group as the donor end, had specific chemical stability. On the basis of ZERNER'S INDO methods, according to the sum‐over‐states formula, a program for the calculation of nonlinear second‐order optical susceptibilities was devised. The resulting polyimides had high number‐average and weight‐average molecular weights of up to 26,000 and 53,500, respectively, and a large glass‐transition temperature of 248 °C. With an in situ poling and temperature ramping technique, the optimal temperatures (Topt's) for corona poling were obtained for the largest second‐order NLO response. The electrooptic coefficient (γ33) of a polyimide at a wavelength of 830 nm was up to 21 pm/V after corona poling under its Topt, and the value remained at elevated temperatures (>90.6% was retained at 240 °C for >120 h). The thermal stability of the NLO polyimides was studied with UV spectrometry after poling of the films. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2478–2486, 2002
Photoimageable polyimides derived from α,α‐(4‐amino‐3,5‐dimethylphenyl)phenylmethane and aromatic dianhydride
Authors: Qian Z. G. , Pang Z. Z. , Li Z. X. , He M. H. , Liu J. G. , Fan L. , Yang S. Y. 
Published: October 2002

AbstractSoluble and inherent photoimageable polyimides with improved photopatterning features were prepared from α,α‐(4‐amino‐3,5‐dimethylphenyl)phenylmethane and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride. The polyimides possessed good combined chemical and physical properties: thermal stability was observed, with an initial thermal decomposition temperature of 565 °C and a high glass‐transition temperature of 318 °C. Homogeneous polyimide solutions in common organic solvents with solid contents as high as 20 wt % were prepared. These solutions had a shelf life greater than 3 months. The polyimides had high electric insulating properties and low dielectric constants and dissipation factors. Fine patterns were processed by direct exposure of the polyimide coatings to UV i‐line, followed by development with an organic developer. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3012–3020, 2002
Synthesis of fluorosilicone having highly fluorinated alkyl side chains based on the hydrosilylation of fluorinated olefins with polyhydromethylsiloxane
Authors: Furukawa Y. , Kotera M. 
Published: October 2002

AbstractHydrosilylation of fluorinated olefins with polyhydromethylsiloxane (PHMS) in the presence of a platinum catalyst was investigated to synthesize fluorosilicone having highly fluorinated alkyl side chains (Rf; CnF2n+1). The hydrosilylation of 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10‐heptadecafluoro‐1‐decene (C8F17CHCH2) (1) with poly(dimethylsiloxane‐co‐hydromethylsiloxane) {(CH3)3SiO[(H)CH3SiO]8[(CH3)2 SiO]18Si(CH3)3} (4) converted the hydrogen bonded to silicons into the 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10‐heptadecafluorodecyl group or fluorine bonded to silicons in the ratio of about 52:48, and the formation of the byproduct C7F15CFCHCH3 (8) was observed. The hydrosilylation of 7,7,8,8,9,9,10,10,11,11,12,12,13,13,14,14,14‐heptadecafluoro‐4‐oxa‐1‐tetradecene (C8F17CH2CH2OCH2CHCH2) (2) with 4 converted the hydrogen bonded to silicons into the 7,7,8,8,9,9,10,10,11,11,12,12,13,13,14,14,14‐heptadecafluoro‐4‐oxa‐tetradocyl group bonded to silicons, but an excess amount of 2 was required to complete the reaction because the isomerization of 2 occurred in part to form C8F17CH2CH2OCHCHCH3 (9). The hydrosilylation of 4,4,5,5,6,6,7,7,8,8,9,9, 10,10,11,11,11‐heptadecafluoro‐1‐undecene (C8F17CH2CHCH2) (3) with 4 converted the hydrogen bonded to silicons into the 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11‐heptadecafluoroundecyl group bonded to silicons. This type of fluorinated olefin was successfully applied to the hydrosilylation with other PHMS's that involved a homopolymer of PHMS and a cyclic PHMS. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3120–3128, 2002
Morphology and physical properties of polyethylene/silicate nanocomposite prepared by melt intercalation
Authors: Wang Ki Hyun , Choi Min Ho , Koo Chong Min , Xu Mingzhe , Chung In Jae , Jang Min Cheol , Choi Sun Woong , Song Hyun Hoon 
Published: October 2002

AbstractMaleated polyethylene (PEMA)/silicate nanocomposites with a different aspect ratio of silicate and maleated PEMA/SiO2 composite were prepared by melt intercalation. The nanocomposites with a high aspect ratio silicate (montmorillonite) showed a faster decrease in the terminal slope of the storage modulus and a steeper increase in complex viscosity than those with a low aspect ratio silicate (laponite) and SiO2. The addition of montmorillonite increases the crystallization and the melting temperature of PEMA but decreases above 3 vol % of the silicate content because of the increased viscosity. The nanocomposite with montmorillonite showed the highest yield strength and secant modulus among the composites because of the highest aspect ratio of the filler. It also revealed strong interfacial adhesion with the matrix and orientation during tensile deformation. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1454–1463, 2002
Dissolution and regeneration of cellulose in NaOH/thiourea aqueous solution
Authors: Zhang Lina , Ruan Dong , Gao Shanjun 
Published: October 2002

AbstractA novel cellulose solvent, 1.5 M NaOH/0.65 M thiourea aqueous solution, was used to dissolve cotton linters having a molecular weight of 10.1 × 104 to prepare cellulose solution. Regenerated cellulose (RC) films were obtained from the cellulose solution by coagulating with sulfuric acid (H2SO4) aqueous solution with a concentration from 2 to 30 wt %. Solubility of cellulose, structure, and mechanical properties of the RC films were examined by infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, 13C NMR, and tensile tests. 13C NMR analysis indicated that the novel solvent of cellulose is a nonderivative aqueous solution system. The presence of thiourea enhanced significantly the solubility of cellulose in NaOH aqueous solution and reduced the formation of cellulose gel; as a result, thiourea prevented the association between cellulose molecules, leading to the solvation of cellulose. The RC film obtained by coagulating with 5 wt % H2SO4 aqueous solution for 5 min exhibited higher mechanical properties than that with other H2SO4 concentrations and a homogenous porous structure with a mean pore size of 186 nm for free surface in the wet state. The RC film plasticized with 10% glycerin for 5 min had a tensile strength of 107 MPa and breaking elongation of 10%, and about 1% glycerin in the RC film plays an important role in the enhancement of the mechanical properties. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1521–1529, 2002
Poly(vinylidene fluoride)/clay nanocomposites prepared by melt intercalation: Crystallization and dynamic mechanical behavior studies
Authors: Priya L. , Jog J. P. 
Published: October 2002

AbstractThe preparation and properties of poly(vinylidene fluoride) (PVDF)/clay nanocomposites are reported for the first time. PVDF/clay nanocomposites were prepared by melt intercalation with organophilic clay. The composites were characterized with X‐ray diffraction, differential scanning calorimetry, and dynamic mechanical analysis. X‐ray diffraction results indicated intercalation of the polymer into the interlayer spacing. PVDF in the nanocomposites crystallized in the β form. Differential scanning calorimetry nonisothermal curves showed an increase in the melting and crystallization temperatures along with a decrease in crystallinity, as evidenced by the melting and crystallization peaks. Isothermal crystallization studies showed an enhanced rate of crystallization with the addition of clay, as evidenced by a reduction in the crystallization time. Dynamic mechanical analysis indicated significant improvements in the storage modulus over a temperature range of −100 to 150 °C. The tan δ peak signifying the glass‐transition temperature of PVDF shifted to higher temperatures. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1682–1689, 2002
Determination of the crystallinity of polyethylene/α‐olefin copolymers by thermal analysis: Relationship of the heat of fusion of 100% polyethylene crystal and the density
Authors: Mirabella Francis M. , Bafna Ayush 
Published: October 2002

AbstractThe heat of fusion measured with differential scanning calorimetry (DSC) is typically divided by a constant value of the heat of fusion of 100% polyethylene (PE) crystal (ΔH) for the estimation of the fraction crystallinity of PE copolymers, regardless of the density [i.e., the short‐chain branching (SCB) concentration]. In this work, values of ΔH of about 288 J/g were determined with a combined DSC and X‐ray diffraction (XRD) method for a series of PE copolymers containing SCB from 0 to 50 Br/1000 C (density = 0.965–0.865 g/cc). There was no systematic change in ΔH observed across this density range. This result supports the suitability of determining the fraction crystallinity of PE of any density by the simple division of the observed heat of fusion determined by DSC by a constant value of ΔH. This DSC method yielded values of PE crystallinity in good agreement with corresponding values determined by XRD for a series of PE copolymers. The determination of ΔH involved a small precision error for higher density (lower SCB) PEs, but the precision error increased for lower density (i.e., higher SCB) PEs. This was due to the difficulty in measuring the heat of fusion for lower density PEs, which exhibited low values of the heat of fusion and melted only slightly above room temperature, and due to the difficulty of measuring lower values of crystallinity by XRD. The crystal thickness measured by small‐angle X‐ray scattering for this series of PE copolymers decreased exponentially from about 280 to 6 Å. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1637–1643, 2002
Mechanism of the diffusion of sulfur mustard, a chemical warfare agent, in butyl and nitrile rubbers
Authors: Dubey Vinita , Gupta A. K. , Maiti S. N. 
Published: October 2002

AbstractThe diffusion of sulfur mustard (SM), a chemical warfare agent, through butyl (IIR) and nitrile (NBR) rubber membranes was studied with a standard spot disc breakthrough time test at temperatures ranging from 298 to 333 K. The mechanism of diffusion was interpreted on the basis of an Arrhenius relation and dynamic adsorption theory. The permeant SM was pictured to reversibly dwell at each adsorption site for about 1.5 × 10−13 s and hop randomly through the polymer matrices in small steps, with jump lengths of the order of a picometer. A comparatively lower activation energy, a solubility parameter closer to that of SM, and a lower thermodynamic interaction parameter also contributed toward faster uptake of SM by NBR in comparison with IIR. The diffusion data were also used to derive the collision diameter of SM in these polymer matrices. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1821–1827, 2002
Implications of a Middle Pleistocene ice‐wedge cast at Trimingham, Norfolk, eastern England
Authors: Whiteman Colin 
Published: October 2002

AbstractA wedge exposed at Trimingham, northeast Norfolk, UK, in 1998 is interpreted as an ice‐wedge pseudomorph indicating that permafrost was present in the surrounding Cromer Forest‐bed Formation sediments. The wedge is overlain by North Sea Drift Formation (NSDF) glacial sediments, demonstrating that the associated ice sheet deposited till in either a terrestrial or an extremely shallow glaciolacustrine/marine environment. This conclusion supports those who believe that this ice sheet was, at least initially, terrestrial at this location. If the wedge is stratigraphically equivalent to the early Anglian soil stratigraphic unit, the Barham Soil, then none of the NSDF tills can be older than the Anglian/Elsterian Stage (MIS 12). Copyright © 2002 John Wiley & Sons, Ltd.
Physical and chemical characteristics of the active layer and permafrost, Herschel Island, western Arctic Coast, Canada
Authors: Kokelj S. V. , Smith C. A. S. , Burn C. R. 
Published: October 2002

AbstractPhysical and geochemical characteristics of near‐surface permafrost and the impact of permafrost degradation on soil and water chemistry were investigated at five sites on Herschel Island, Yukon Territory. The distribution of soluble cations, moisture and organic matter content in turbic cryosols from undisturbed terrain indicated a thaw unconformity 50 to 80 cm below the base of the present active layer. Palaeoactive‐layer depth, estimated at between 90 and 100 cm, is less than at comparable sites in the Mackenzie Delta area. The difference may be due to the comparative proximity of Herschel Island to the Beaufort Sea coastline in the early Holocene. Soluble cations in permafrost and the active layer of static cryosols at recently disturbed sites were two orders of magnitude higher than in the active layer at undisturbed sites. Na+ was the dominant cation in undisturbed permafrost, recently disturbed ground, and surface runoff derived from disturbed areas. Although degradation of permafrost following terrain disturbance has resulted in surface salinization, a condition detrimental to vegetation growth, leaching of soluble salts from disturbed areas has occurred over time. These processes have produced a range of soil conditions that contribute to the floristic diversity of Herschel Island. Copyright © 2002 John Wiley & Sons, Ltd.
Multiple cavitating pulmonary nodules and clubbing in a 12‐year‐old girl
Authors: Horak Elisabeth , Olinsky A. , Chow C.W. , Waters K. , Sawyer S.M. 
Published: October 2002

AbstractWe report on a 12‐year‐old girl with a prolonged history of cough and hemoptysis on three occasions. X‐ray and computed tomography of the chest showed several cavitating lesions and mediastinal lymphadenopathy. Lung biopsy revealed nodular sclerosing Hodgkin's disease. Hodgkin's disease should be considered in the differential diagnosis of cavitating pulmonary lesions. Pediatr Pulmonol. 2002; 34:147–149. © 2002 Wiley‐Liss, Inc.