bluuebunny/crossref_metadata_2025_split huggingface dataset:
Visible light photopolymerization: Synthesis of new fluorone dyes and photopolymerization of acrylic monomers using them
Authors: Tanabe Takayoshi , Torres‐Filho Afranio , Neckers D. C. 
Published: April 2003

AbstractSeveral 3‐alkoxy‐5, 7‐diiodo‐6‐fluorones (λmax ≈ 470 nm) have been synthesized and evaluated as initiators for photopolymerization triggered with the 515.5 nm line of an Ar+ laser. 2‐Acyl‐ and 2‐alkyl‐4,5,7‐triiodo‐3‐hydroxy‐6‐fluorones were also tested at 515.5 nm. 9‐Cyano‐2‐Acyl‐ and 9‐cyano‐2‐alkyl‐4,5,7‐triiodo‐3‐hydroxy‐6‐fluorones were studied and could be excited with the 632 nm line of a He–Ne laser. Dyes with long linear carbon chain alkoxy groups at C‐6 showed larger molar extinction coefficients and formed polymers with better mechanical properties than did compounds with shorter carbon chains, or did the corresponding C‐6 phenols. The optimum side chain length of the C‐6 ether alkyl group is between 4–7 carbon atoms. With longer carbon chain alkoxy groups at C‐8, e.g., octyl, the mechanical properties of the formed polymers are inferior to systems formed with the butyl isomer as photoinitiator. In the case of alkoxy groups with branched alkyl groups (e.g., 2‐ethylbutyl), the relationship between dye structure and the properties of the polymers formed is less straightforward. Though the dyes react from their triplet state, the fluorescence quantum yields of the dyes and the performance of the dyes as photoinitiators appear directly related. © 1995 John Wiley & Sons, Inc.
Temperature‐sensitive luminescence of tris (β‐diketone) europium chelates for monitoring high‐speed cationic photopolymerizations
Authors: Crofcheck C. L. , Nelson E. W. , Jacobs J. L. , Scranton A. B. 
Published: April 2003

AbstractThe temperature‐dependent luminescence of tris (β‐diketone) chelates of europium was used for in situ temperature measurements during cationic photopolymerizations of vinyl ethers. These molecular‐level luminescent probes provided a real‐time, noninvasive method for monitoring temperature during these high‐speed polymerizations. Two specific probes, tris (benzoyl‐1, 1, 1‐trifluoroacetone) europium and tris (1,1,1,5,5,5,‐hexafluoroacetylacetone) europium, met several stringent spectral and performance requirements for application in our system. The luminescence from these probes exhibits a reproducible temperature dependence over a wide temperature range and is not sensitive to changes in viscosity. In situ temperature profiles obtained using this novel technique verified the importance of thermal effects during these highly exothermic photopolymerizations. These studies have demonstrated the utility of the tris(β‐diketone) europium chelates for characterizing the temperature during high‐speed photopolymerizations that cannot be monitored using conventional techniques. © 1995 John Wiley & Sons, Inc.
Polynucleotide analogues. VI. Synthesis and characterization of alternating copolymers of maleic anhydride and dihydropyran containing guanine derivatives
Authors: Han Man Jung , Cho Nam Shik , Cho Tae Joon , Chang Ji Young 
Published: April 2003

Abstract2‐Amino‐6‐chloropurine was reacted with 2‐(tosyloxymethyl)‐2,3‐dihydro‐2H‐pyran to give 2‐(2‐amino‐6‐chloropurin‐9‐ylmethyl)‐2,3‐dihydro‐2H‐pyran (3) and its N7‐isomer (4), which were treated with 5% aqueous trimethylamine to result in 2‐(guanin‐9‐ylmethyl)‐2,3‐dihydro‐2H‐pyran (5) and its N7‐isomer (6), respectively. 2‐(N2‐Acetylguanin‐9‐yl‐methyl)‐3,4‐dihydro‐2H‐pyran (7) and 2‐(N2‐acetylguanin‐7‐ylmethyl)‐3,4‐dihydro‐2H‐pyran (8), obtained by acetylation of compounds 5 and 6, were copolymerized with maleic anhydride to give the alternating copolymers 9 and 10, and they were hydrolyzed to result in poly[ {2‐(guanin‐9‐ylmethyl)tetrahydropyran‐5,6‐diyl} {1,2‐dicarboxyethylene}] (11) and poly[ {2‐(guanin‐7‐ylmethyl)tetrahydropyran‐5,6‐diyl} {1,2‐dicarboxyethylene}] (12), re‐spectively. Polymer 11 showed hypochromicity whereas 12 exhibited hyperchromicity in aqueous solutions. Polymers 11 and 12 in aqueous solutions showed very strong excimer fluorescence with the maximum intensities at 432 and 446 nm, respectively, at room tem‐perature. The two polymers showed polyelectrolyte effects, e.g., very high GPC molecular weights as well as reduced viscosities at low concentrations in water. Normal behavior was retained by addition of inorganic salts. Sodium salts of polymers 11 and 12 migrated to the anode by electrophoresis and both showed two bands. © 1995 John Wiley & Sons, Inc.
Emulsion polymerization of supermicron, monodisperse acrylic copolymer particles with core‐shell structures
Authors: O'Callaghan K. J. , Paine A. J. , Rudin A. 
Published: April 2003

AbstractThe emulsion polymerization of large MMA/BA copolymer particles with narrow particle size distributions and core‐shell structure is described. A series of sequential seeded growth emulsion polymerizations were used to obtain monodisperse particles with diameters of at least 3 μm, at 30% solids contents. Because the core and shell polymers used here were chemically similar, core‐shell structures could not be verified by differential staining tech‐niques. Core‐shell structure was demonstrated by minimum film‐forming temperature studies and by scanning electron microscopy in conjunction with energy dispersive x‐ray analysis, using chlorine‐labeled core polymers. © 1995 John Wiley & Sons, Inc.
Simultaneous polymerization and formation of polyphenylacetylene film by Nd(P204)3–Fe (AA)3–Al(i‐Bu)3 combined catalyst system
Authors: Yang Mujie , Zhan Xiaowei , Zhao Jian , Shen Zhiquan 
Published: April 2003

AbstractThe simultaneous polymerization and formation of polyphenylacetylene film by Nd(P204)3–Fe(AA)3–Al(i‐Bu)3 catalyst system have been investigated. The combined catalytic effects between rare earth phosphonates with MT(naph)x or Fe(AA)3 systems are first proposed and compared. The polymerization features and kinetic behaviors with Nd(P204)3–Fe(AA)3‐Al(i‐Bu)3 system are described and discussed. The combined catalytic effects have the following order, respectively: Fe ≫ Co > Cr > Mn‐Ni, Nd(P204)3‐Nd(P507)3 > Nd(P350)3 and Tb > Sm > Yb > Ho > Lu > Dy > Nd‐Er‐Pr > Y‐Tm > Ce > Gd > La. The overall polymerization activation energy was found to be 20.8 kJ/mol showing coordination‐anionic polymerization characteristic. PPA films so obtained are very similar to the rare earth ones. © 1995 John Wiley & Sons, Inc.
Thianthrene‐containing polyimides with monomer formation via nucleophilic aromatic substitution
Authors: Yoneyama Masaru , Johnson Randy A. , Mathias Lon J. 
Published: April 2003

AbstractThianthrene‐2,3,7,8‐tetracarboxylic dianhydride was synthesized via nucleophilic aromatic substitution of N‐phenyle‐4,5‐dichlorophthalimide with thiobenzamide, thioacetamide, and sodium sulfide. This monomer was then polymerized with aromatic diamines by the con‐ventional low temperature technique in N,N‐dimethylacetamide (DMAc) to yield soluble poly(amic acid)s. Polyimides were obtained by thermal cyclization of the poly(amic acid) films. Polymers obtained formed creasable thin films and had excellent thermal stability in air and nitrogen. The bent thianthrene structure limited crystallization and chain packing, as indicated by x‐ray analysis. The amorphous thianthrene‐containing polyimides were only soluble in H2SO4. © 1995 John Wiley & Sons, Inc.
Vacuum‐ultraviolet induced oxidation of the polymers polyethylene and polypropylene
Authors: Holländer A. , Klemberg‐Sapieha J. E. , Wertheimer M. R. 
Published: April 2003

AbstractThe emission from low‐pressure microwave plasmas in the vacuum‐ultraviolet (VUV) region (λ < 200 nm) was investigated in order to use these plasmas as light sources for the study of the VUV photochemistry of polyethylene (PE) and polypropylene (PP) as part of the study of plasma‐polymer interaction. These polymers, immersed in low‐presure oxygen, were exposed to radiation with wavelengths down to 112 nm, the cut off of magnesium fluoride used as a window to separate the polymer specimen from the plasma light source. Total oxygen incorporation in the surface [O], and the formation of hydroxyl, carbonyl, and carboxyl groups were measured using XPS in combination with chemical derivatizations, particularly their dependence upon the radiation spectrum and the oxygen pressure around the sample. In most experiments the surface oxygen concentration [O] attained a constant value that appears to be related to the initial oxidation rate; this suggests a competition between oxygen incorporation and chain scission reactions, followed by the removal of volatile oxidation products. PE is usually oxidized to a higher level than PP, the latter appearing to be more susceptible to reaction with atomic oxygen than PE. A general initiation mechanism for the VUV experiments is proposed that allows us to explain the observed differences in behavior between PE and PP, and the results obtained under different irradiation conditions. The nature of oxidation products is in both cases very similar to what is observed after direct plasma treatment of the polymers. We conclude that short wavelength radiation contributes very appreciably to the observed surface modification effects during plasma treatment of PE and PP. © 1995 John Wiley & Sons, Inc.
Synthesis and properties of a poly(diphenylacetylene) containing carbazolyl groups
Authors: Tachimori Hiroshi , Masuda Toshio 
Published: April 2003

Abstract1‐(p‐N‐Carbazolylphenyl)‐2‐phenylacetylene (p‐CzDPA) was polymerized by TaCl5–co‐catalyst systems (cocatalysts: n‐Bu1Sn, Et3SiH, and 9BBN) to produce acetone‐insoluble polymers in about 60‐70% yields. Poly(p‐CzDPA) was a yellowish‐orange solid, most part of which was soluble in toluene, chloroform, etc., and its weight‐average molecular weights were around 4×105. This polymer formed a tough film by solution casting, and was thermally very stable (the onset temperature of weight loss in TGA in air 470°C). The oxygen per‐meability coefficient of the polymer at 25°C was lower than two barrers. The present polymer showed photoconductivity and redox activity. © 1995 John Wiley & Sons, Inc.
Synthesis and properties of aromatic polyamides derived from 1,2‐bis(4‐aminophenoxy)benzene and aromatic dicarboxylic acids
Authors: Yang Chin‐Ping , Cherng Jeng‐Jieh 
Published: April 2003

Abstract1,2‐Bis(4‐aminophenoxy)benzene was synthesized in two steps by the preparation of 1,2‐bis(4‐itrophenoxy)benzene from 1,2‐dihydroxybenzene (catechol) and p‐chloronitrobenzene and subsequent reduction with a 10% Pd‐C catalyst and hydrazine hydrate. Aromatic polyamides with an inherent viscosity in the range of 1.08–2.00 dL/g were prepared by the direct polycondensation of this diamine with various aromatic dicarboxylic acids in N‐methyl‐2‐pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. Most of the polymers formed were soluble in aprotic solvents such as NMP and N,N‐methylacetamide (DMAc), and afforded transparent, flexible, and tough films upon casting from DMAc solutions. Most of the cast films showed obvious yield points in their stress‐strain curves and had tensile strength among 64–89 MPa, elongation at break among 5–23%, and initial modulus in 1.7–2.5 GPa. The glass transition temperatures (Tg) of these polymers were in the range of 207–278°C, and the 10% weight loss temperatures were recorded above 475°C in nitrogen and above 452°C in air. © 1995 John Wiley & Sons, Inc.
Propylene polymerization through supported metallocene/ MAO catalysts: Kinetic analysis and modelling
Authors: Bonini F. , Fraaije V. , Fink G. 
Published: April 2003

AbstractSeveral propylene polymerizations are carried out with supported metallocene catalyst, prepared by reaction of silica gel with methylaluminoxane and then with rac‐dimethylsi‐lanediylbis(indenyl)zirconiumdichloride. The rate–time curves obtained are analyzed to understand the influence of support and triisobutylaluminium on the reaction. As a first attempt to model this system we developed a partially new praticle growth model, based on a shell by shell fragmentation hypothesis (gradual break‐up from the outside to the inside of the particle), and a final multigrain structure of the particle. A kinetic scheme including the TIBA interaction with the supported catalyst is also presented. The model prediction and the experimental data are compared for the rate–time curves and polymer properties. © 1995 John Wiley & Sons, Inc.
High‐pressure synthesis of cyclic phenylacetylene oligomer
Authors: Kojima Yoshitsugu , Matsuoka Takaaki , Sato Norio , Takahashi Hideroh 
Published: April 2003

AbstractNew conjugated oligomers were prepared by reacting phenylacetylene under high pressure of 0.11 to 0.92 GPa at 100–200°C for 0–5 h. The number‐average molecular weight M̄n, the weight‐average molecular weight M̄w, and the oligomer yield increased with pressure, tem‐perature, and time. The average molecular weight of the oligomer showed the maximum value (M̄n: 830, M̄w: 2400) under 0.92 GPa, the maximum pressure, where phenylacetylene was oligomerized at a constant temperature. The structure of the oligomer was investigated from ESR, infrared, UV–VIS, field desorption mass (FDMS) spectra, and 13C NMR spec‐trum. Analysis of the FDMS spectrum revealed that the molecular weight of the oligomer was multiple of the monomer. 13C NMR spectrum of the oligomer showed the absence of sp‐carbon (C). We found that the oligomer had a cyclic structure. The cyclic oligomers of pentamer or more were new compounds. © 1995 John Wiley & Sons, Inc.
Social consequences of mining and present day solutions—Region II in Chile highlighted
Authors: Newbold Jane 
Published: April 2003

AbstractChile has been a highly successful mining country for over two centuries. Huge sums of money are generated but only a small proportion of the revenue is being directed back into the region whose natural resources are being depleted. Mining companies may not be in control of the way central government spends these funds but they have a responsibility towards the communities they impact. The environmental problems associated with mining practices have attracted most attention but the impact on the communities is proving to be a far greater challenge. This paper focuses on the social consequences and the evolving response of the mining companies to these problems and the future sustainability of the region. Copyright © 2003 John Wiley & Sons, Ltd. and ERP Environment
New Zealand fisheries management: changes in property rights structure and implications for sustainability
Authors: Stewart James M. , Callagher Peter D. 
Published: April 2003

AbstractParticipation in the New Zealand fishing industry exists on two levels: quota holding and quota ownership. This study is motivated by the desire to establish whether changes in the number and concentration of quota ownerships and quota holdings have had any impact on the sustainability of fishery in New Zealand.Of the 294 marine species commercially harvested in New Zealand the top 15 by volume and/or value are considered in this paper. Findings indicate that quota ownership and holding have become more concentrated since the inception of the individual transferable quota (ITQ) regime, with the concentration ratios CR4, CR10 and CR20 all increasing. This suggests that the introduction of the ITQ has not encouraged the entry of new market participants; rather the industry has moved toward a single ownership model.Second, this paper establishes trends in the level of total allocable commercial catch (TACC) over the study period (August 1986–June 2000). Findings suggest that, with one or two interesting exceptions, catch levels have remained remarkably constant. Prima facie, there appears to have been no adverse impact from structural change on the overall resource sustainability based on TACC. Copyright © 2003 John Wiley & Sons, Ltd. and ERP Environment
Regulating traffic with land use planning
Authors: Herala Nina 
Published: April 2003

AbstractThis article deals with integrating land use planning and traffic planning to promote sustainable development: how land use planning may be used as one of the means to reduce problems caused by traffic. The growth in car‐borne traffic has increased rapidly and consumes more and more land because of land‐extensive structure of cities and the traffic demand between human activities (home, work, services). Planning solutions emphasizing the separation of urban functions, in order to avoid health problems, have, together with the availability of inexpensive land on the outskirts of urban areas, contributed to the current generation of environmental problems, primarily from increased dependency on private cars. The OECD and EU have developed principles of sustainable transport and sustainable traffic to tackle the growth of traffic. Urban form and location of activities together with economic incentives and well organized public transport has a significant impact on traffic flows. There is not yet a general political agreement on how the reduction of traffic demand should be legally regulated, but some criteria are suggested to measure sustainable mobility in land use planning. Copyright © 2003 John Wiley & Sons, Ltd. and ERP Environment
County waste minimization programmes: a case study from Northamptonshire, UK
Authors: Phillips Paul S. , Clarkson Paul , Adams Julie , Read Adam D. , Coggins P. Chris 
Published: April 2003

AbstractThe UK Sustainable Development Strategy requires that society strive to make prudent use of natural resources so as to protect the environment and maintain high and stable levels of economic growth and employment. The Waste Strategy for England and Wales emphasizes the need to reduce the amount of waste produced through the adoption of waste minimization methodology. Waste minimization clubs have been a key element in the UK programme to introduce more sustainable practice into industry and commerce. Northamptonshire, a county in the East Midlands of England, has benefited from 14 waste minimization/resource efficiency projects, within a county programme, that have run between 1998 and 2001. This is the largest number in any county in England. This has been possible because of the formation of a large and inclusive partnership that contains all the key local and regional players. Performance indicators have been developed to direct the county programme as it strives to introduce more sustainable waste management practice. The Northamptonshire model has led to a catalysed uptake of sustainable waste management practice and has resulted in greatly improved competitiveness in some 270 companies, thereby contributing to the maintenance of stable levels of economic activity. Copyright © 2003 John Wiley & Sons, Ltd. and ERP Environment
Social interaction and the use of analogy: An analysis of preservice teachers' talk during physics inquiry lessons
Authors: Yerrick Randy K. , Doster Elizabeth , Nugent Jeffrey S. , Parke Helen M. , Crawley Frank E. 
Published: April 2003

AbstractAnalogies have been argued to be central in the process of establishing conceptual growth, making overt connections and carryover into an intended cognitive domain, and providing a generative venue for developing conceptual understanding inherent in constructivist learning. However, students' specific uses of analogies for constructing arguments are not well understood. Specifically, the results of preservice teachers' knowledge gains are not widely studied. Although we would hope that engaging preservice science teachers in exemplary lessons would assist them in using and generating analogies more expertly, it is not clear whether or how such curricula would affect their learning or teaching. This study presents an existence proof of how preservice science teachers used analogies embedded in their course materials Physics by Inquiry. This fine‐grained analysis of small group discourse revealed three distinct roles of analogies including the development of: (a) cognitive process skills, (b) scientific conceptual understanding, and (c) social contexts for problem solving. Results suggest that preservice teachers tend to overgeneralize the analogies inserted by curriculum materials, map irrelevant features of analogies into collaborative problem solving, and generate personal analogies, which counter scientific concept development. Although the authors agree with the importance of collaborative problem solving and the insertion of analogies for preservice teachers' conceptual development, we believe much more needs to be understood before teachers can be expected to construct and sustain effective learning environments that rely on using analogies expertly. Implications for teacher preparation are also discussed. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 443–463, 2003
Investigation of secondary school, undergraduate, and graduate learners' mental models of ionic bonding
Authors: Coll Richard K. , Treagust David F. 
Published: April 2003

AbstractSecondary school, undergraduate, and graduate level learners' mental models of bonding in ionic substances were explored using an interview protocol that involved the use of physical substances and a focus card containing depictions of ionic bonding and structure. Teachers and faculty from the teaching institutions were interviewed to contextualize teaching models within the educational setting for the inquiry. These data resulted in two socially negotiated consensus teaching models and a series of criterial attributes for these models: the essential qualities, all of which must be negotiated, if the model is used in a way that is acceptable to scientists. The secondary school learners see ionic bonding as consisting of attraction of oppositely charged species that arise from the transfer of electrons driven by the desire of atoms to obtain an octet of electrons. The undergraduates see the lattice structure as a key component of ionic substances and quickly identified specific ionic lattices for the physical prompts used as probes. The graduates also identified strongly with ionic lattices, were less likely to focus on particular ionic structures, and had a stronger appreciation for the notion of the ionic‐covalent continuum. The research findings suggest that learners at all educational levels harbor a number of alternative conceptions and prefer to use simple mental models. These findings suggest that teachers and university faculty need to provide stronger links between the detailed nature of a model and its intended purpose. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 464–486, 2003