bluuebunny/crossref_metadata_2025 huggingface dataset:
Human evolution at the Matuyama‐Brunhes boundary
Authors: Manzi Giorgio
Published: February 2004

The cranial morphology of fossil hominids between the end of the Early Pleistocene and the beginning of the Middle Pleistocene provides crucial evidence to understand the distribution in time and space of the genus Homo. This evidence is critical for evaluating the competing models regarding diversity within our genus. The debate focuses on two alternative hypotheses, one basically anagenetic and the other cladogenetic. The first suggests that morphological change is so diffused, slow, and steady that it is meaningless to apply species names to segments of a single lineage. The second is that the morphological variation observed in the fossil record can best be described as a number of distinct species that are not connected in a linear ancestor‐descendant sequence. Today much more fossil evidence is available than was in the past to test these alternative hypotheses, as well as intermediate variants. Special attention must be paid to Africa because this is the most probable continental homeland for both the origin of the genus Homo (around 2.5–2 Ma),1 as well as the site, two million or so years later, of the emergence of the species H. sapiens.2 However, the African fossil record is very poorly represented between 1 Ma and 600 ka. Europe furnishes recent discoveries in this time range around the Matuyama‐Brunhes chron boundary (780,000 years ago), a period for which, at present, we have no noteworthy fossil evidence in Africa or the Levant. Two penecontemporaneous sources of European fossil evidence, the Ceprano calvaria (Italy)3 and the TD6 fossil assemblage of Atapuerca (Spain)4 are thus of great interest for testing hypotheses about human evolution in the fundamental time span bracketed between the late Early and the Middle Pleistocene. This paper is based on a phenetic approach to cranial variation aimed at reviewing the Early‐to‐Middle Pleistocene trajectories of human evolution. The focus of the paper is on neither the origin nor the end of the story of the genus Homo, but rather its chronological and phylogenetic core. Elucidation of the evolutionary events that happened around 780 ka during the transition from the Early to Middle Pleistocene is one of the new frontiers for human paleontology, and is critical for understanding the processes that ultimately led to the origin of H. sapiens.
The Atapuerca sites and their contribution to the knowledge of human evolution in Europe
Authors: Bermúdez de Castro J. M. , Martinón‐Torres M. , Carbonell E. , Sarmiento S. , Rosas A. , van der Made J. , Lozano M.
Published: February 2004

Over the last two decades, the Pleistocene sites of the Sierra de Atapuerca (Spain) have provided two extraordinary assemblages of hominin fossils that have helped refine the evolutionary story of the genus Homo in Europe. The TD6 level of the Gran Dolina site has yielded about one hundred remains belonging to a minimum of six individuals of the species Homo antecessor. These fossils, dated to the end of the Lower Pleistocene (800 kyr), provide the earliest evidence of hominin presence in Western Europe. The origin of these hominins is unknown, but they may represent a speciation event from Homo ergaster/Homo erectus. The TD6 fossils are characterized by a significant increase in cranial capacity as well as the appearance of a “sapiens” pattern of craniofacial architecture. At the Sima de los Huesos site, more than 4,000 human fossils belonging to a minimum of 28 individuals of a Middle Pleistocene population (ca. 500–400 kyr) have been recovered. These hominins document some of the oldest evidence of the European roots of Neanderthals deep in the Middle Pleistocene. Their origin would be the dispersal out of Africa of a hominin group carrying Mode 2 technologies to Europe. Comparative study of the TD6 and Sima de la Huesos hominins suggests a replacement model for the European Lower Pleistocene population of Europe or interbreeding between this population and the new African emigrants.
The frog in taffeta pants
Authors: Weiss Kenneth
Published: February 2004

What is the magic that makes dead flesh fly?
The effect of information overload on consumer choice quality in an on‐line environment
Authors: Lee Byung‐Kwan , Lee Wei‐Na
Published: February 2004

As more and more consumers become part of the net population, retailers and manufacturers as well as dot‐com storefronts are touting consumers by providing an ever‐increasing amount of product information. Their long‐term survival and profitability may be determined by how much and how well their product information is presented to and processed by the consumers. By combining both the traditional and structural approaches to the information‐overload phenomenon, this study investigates the impact of Web site information on consumer choice and psychological states in an on‐line environment. Varying the number of alternatives and attributes (traditional measure) and attribute level distribution across alternatives (structural measure), this study asks subjects to choose the best (dominant) CD player in a given set. Their subjective states such as satisfaction, confidence, and confusion are also measured. Results show that the number of attributes and attribute level distribution are good predictors of the effect of information overload on consumer choice. In addition, the study finds that on‐line information overload results in less satisfied, less confident, and more confused consumers. Implications and suggestions for future research are provided. © 2004 Wiley Periodicals, Inc.
The effects of consumer knowledge on responses to event sponsorships
Authors: Roy Donald P. , Cornwell T. Bettina
Published: February 2004

Research into consumer responses to event sponsorships has grown in recent years. However, the effects of consumer knowledge on sponsorship response have received little consideration. Consumers' event knowledge is examined to determine whether experts and novices differ in information processing of sponsorships and whether a sponsor's brand equity influences perceptions of sponsor–event fit. Six sponsors (three high equity/three low equity) were paired with six events. Results of hypothesis testing indicate that experts generate more total thoughts about a sponsor–event combination. Experts and novices do not differ in sponsor–event congruence for high‐brand‐equity sponsors, but event experts perceive less of a match between sponsor and event for low‐brand‐equity sponsors. © 2004 Wiley Periodicals, Inc.
Same or different? How distance and variation affect similarity judgments
Authors: Yoo Changjo , MacInnis Deborah J.
Published: February 2004

The effects of distance and variation on product‐category similarity judgments are examined in two studies. Distance between product categories is characterized as the mean difference in the average scores of all brands in one category with all brands in another on a comparison attribute. Variation is characterized as a degree of spread of brands along that comparison attribute. Study 1 finds that both distance and variation influence the perceived similarity of two product categories. An interaction between distance and variation is also observed. Study 2 is designed to replicate and extend these results, determining if distance and variation also affect similarity judgments when brands in the two product categories are not described by the same attribute—but instead where a comparison attribute must be abstracted. The results confirm the main effects of distance and variation. However, the interaction effects between distance and variation disappear, suggesting that subjects lose some information about distribution knowledge in the abstraction process. Both studies support consumers' use of distribution knowledge about brands (distance and variation) in product‐category similarly judgment tasks. © 2004 Wiley Periodicals, Inc.
Improving product instruction compliance: “If you tell me why, I might comply”
Authors: Taylor Valerie A. , Bower Amanda B.
Published: February 2004

Although prior research into product instructions has been limited to investigating the effect of warnings such that people might avoid possible product dangers by heeding warnings, this research considers methods of improving consumer product instruction compliance when noncompliance with a product instruction does not necessarily lead to a hazardous situation. In particular, this research investigates the impact of providing instructions that specify the process by which compliance with the instructions will lead to the desired end state (e.g., product outcome), called process‐cause information. The results of a first field experiment indicate that intention to comply with product instructions is enhanced when people are told how compliance with the instructions will lead to the desired outcome (i.e., when process‐cause information is included in a product instruction). This finding is substantiated by results of a follow‐up laboratory experiment where subject compliance with an instruction‐based behavior was observed. The importance of the present research is discussed in terms of the potential impacts on customer satisfaction, service recovery, product returns, product liability, and warranties. © 2004 Wiley Periodicals.
Total assignment of 1H and 13C NMR data for the sesquiterpene lactone 15‐deoxygoyazensolide
Authors: Heleno Vladimir Constantino Gomes , Crotti Antônio Eduardo Miller , Constantino Mauricio Gomes , Lopes Norberto Peporine , Lopes João Luis Callegari
Published: February 2004

We describe a complete analysis of the 1H and 13C spectra of the anti‐inflamatory, schistossomicidal and trypanosomicidal sesquiterpene lactone 15‐deoxygoyazensolide. This lactone, with a structure similar to other important ones, was studied by NMR techniques such as COSY, HMQC, HMBC, Jres and NOE experiments. The comparison of the data with some computational results led to an unequivocal assignment of all hydrogen and carbon chemical shifts, even eliminating some previous ambiguities. We were able to determine all hydrogen coupling constants (J) and signal multiplicities and to confirm the stereochemistry. A new method for the determination of the relative position of the lactonization and the position of the ester group on a medium‐sized ring by NMR was developed. Copyright © 2004 John Wiley & Sons, Ltd.
Physicochemical characterization of the dimeric lanthanide complexes [en{Ln(DO3A)(H2O)}2] and [pi{Ln(DTTA)(H2O)}2]2−: a variable‐temperature 17O NMR study
Authors: Lee Tzu‐Ming , Cheng Tsan‐Hwang , Ou Ming‐Hung , Chang C. Allen , Liu Gin‐Chung , Wang Yun‐Ming
Published: February 2004

The Gd(III) complexes of the two dimeric ligands [en(DO3A)2] {N,N′‐bis[1,4,7‐tris(carboxymethyl)‐1,4,7,10‐tetraazacyclododecan‐10‐yl‐methylcarbonyl]‐N,N′‐ethylenediamine} and [pi(DTTA)2]8− [bisdiethylenetriaminepentaacetic acid (trans‐1,2‐cyclohexanediamine)] were synthesized and characterized. The 17O NMR chemical shift of H2O induced by [en{Dy(DO3A)}2] and [pi{Dy(DTTA)}2]2− at pH 6.80 proved the presence of 2.1 and 2.2 inner‐sphere water molecules, respectively. Water proton spin–lattice relaxation rates for [en{Gd(DO3A)(H2O)}2] and [pi{Gd(DTTA)(H2O)}2]2− at 37.0 ± 0.1° C and 20 MHz are 3.60 ± 0.05 and 5.25 ± 0.05 mM−1 s−1 per Gd, respectively. The EPR transverse electronic relaxation rate and 17O NMR transverse relaxation time for the exchange lifetime of the coordinated H2O molecule and the 2H NMR longitudinal relaxation rate of the deuterated diamagnetic lanthanum complex for the rotational correlation time were thoroughly investigated, and the results were compared with those reported previously for other lanthanide(III) complexes. The exchange lifetimes for [en{Gd(DO3A)(H2O)}2] (769 ± 10 ns) and [pi{Gd(DTTA)(H2O)}2]2− (910 ± 10 ns) are significantly higher than those of [Gd(DOTA)(H2O)]− (243 ns) and [Gd(DTPA)(H2O)]2− (303 ns) complexes. The rotational correlation times for [en{Gd(DO3A)(H2O)}2] (150 ± 11 ps) and [pi{Gd(DTTA)(H2O)}2]2− (130 ± 12 ps) are slightly greater than those of [Gd(DOTA)(H2O)]− (77 ps) and [Gd(DTPA)(H2O)]2− (58 ps) complexes. The marked increase in relaxivity (r1) of [en{Gd(DO3A)(H2O)}2] and [pi{Gd(DTTA)(H2O)}2]2− result mainly from their longer rotational correlation time and higher molecular weight. Copyright © 2004 John Wiley & Sons, Ltd.
Broadband and band‐selective IMPRESS–gHMBC: compensation of refocusing inefficiency with synchronized inversion sweep
Authors: Crouch Ronald , Boyer Robert D. , Johnson Ross , Krishnamurthy Krish
Published: February 2004

Compensation of refocusing inefficiency in a gHMBC experiment by replacing the rectangular π pulse with a pair of adiabatic pulses with synchronized inversion sweep (CRISIS) significantly improves the performance of the gHMBC experiment. The CRISIS–gHMBC experiment retains the pure absorptive shapes in F1 and hence results in better lineshape and higher resolution than the current versions of magnitude mode gHMBC spectra. When used as a broadband experiment, CRISIS–gHMBC, owing to better refocusing efficiency of the adiabatic pulse pairs, gives improved performance across the 13C spectral width. Moreover, it is shown that CRISIS–gHMBC is a robust and improved alternative and when used along with the IMPRESS (Improved Resolution using Symmetrically Shifted pulses) technique further increases the sensitivity and resolution without additional experimental time. The IMPRESS–CRISIS combination is demonstrated for broadband gHMBC and band‐selective gHMBC experiments. The ICbs–gHMBC [IMPRESS–CRISIS–band‐selective gHMBC] experiment is an attractive and better alternative to individual band‐selective gHMBC. Copyright © 2004 John Wiley & Sons, Ltd.
Conformational study of a guaiacyl β‐O‐4 lignin model compound by NMR. Examination of intramolecular hydrogen bonding interactions and conformational flexibility in solution
Authors: Besombes Stéphane , Utille Jean‐Pierre , Mazeau Karim , Robert Danielle , Taravel François R.
Published: February 2004

Intramolecular H‐bonding interactions were investigated in solution for the threo and erythro diastereomeric forms of a guaiacyl β‐O‐4 lignin model compound by using the NMR data obtained from hydroxyl protons. Temperature coefficients of the chemical shifts (dδ/dT) and coupling constants (3JHCOH) were measured in aprotic and protic solutions: DMSO‐d6, acetone‐d6 and acetone‐d6–water. The NMR parameters do not support the existence of strong and persistent intramolecular H‐bonds that could participate in the stabilization of the guaiacyl β‐O‐4 structure in solution, but instead indicate that intermolecular H‐bonds to solvent predominate. 1D NOE experiments nevertheless revealed the presence of a direct chemical exchange between the hydroxyl protons, suggesting the possible existence of weak and transient intramolecular H‐bonding interactions. The conformational flexibility of the threo structure was also investigated in acetone solution from the measurement of long‐range 1H, 1H and 1H, 13C coupling constants and from NOESY experiments. The NMR data are not consistent with any single conformation, indicating that different conformers co‐exist in solution. The experimental results support the conformational flexibility predicted by molecular dynamics simulations performed in a previous study. Finally, both experimental and theoretical approaches indicate that weak intramolecular H‐bonds can exist transiently in solution, breaking and reforming as the β‐O‐4 molecule undergoes conformational interconversion, but cannot be invoked as possible means of conferring rigidity to the β‐O‐4 structure. Copyright © 2004 John Wiley & Sons, Ltd.
Complete 1H and 13C NMR spectral assignment of 17‐hydroxy epimeric sterols with planar A or A and B rings
Authors: Ciuffreda P. , Casati S. , Manzocchi A.
Published: February 2004

Complete 1H and 13C spectral assignments of 17β‐ and 17α‐hydroxy epimers of three biologically active sterols (boldenone, 3‐methoxyestradiol and 3‐methoxydihydroequilenin) were achieved making use of one‐ and two‐dimensional NMR techniques (1D‐HOHAHA, DEPT, COSY, NOESY, TOCSY, HSQC and COLOC). Copyright © 2004 John Wiley & Sons, Ltd.
Gs‐HSQC‐NOESY versus gs‐NOESY‐HSQC experiments: signal attenuation due to diffusion; application to symmetrical molecules
Authors: Gschwind Ruth M. , Xie Xiulan , Rajamohanan Pattuparambil R.
Published: February 2004

Gradient‐selected (gs) HSQC‐NOESY type experiments are often applied in order to obtain NOE cross peaks in symmetrical molecules or in complex organic molecules, e.g. carbohydrates. Since the coherence‐selecting gradients in these pulse sequences are separated by several delays, including the mixing time, the gs‐HSQC‐NOESY spectra exhibit severe signal attenuation due to diffusion effects. The respective NOE information unaffected by diffusion effects can be obtained by X‐half‐filtered gs‐NOESY‐HSQC spectra. In this paper, an X‐half‐filtered version of the gs‐NOESY‐HSQC experiment is presented and the NOE cross peak integrals of its spectra are compared with those of a standard gs‐HSQC‐NOESY experiment. With phenanthrene as an example of symmetrical molecules, it is shown that the relative signal attenuation of gs‐HSQC‐NOESY cross peaks versus gs‐NOESY‐HSQC cross peaks is caused by diffusion effects and follows the Stejskal–Tanner equation. In contrast, the X‐half‐filtered gs‐NOESY‐HSQC experiment provides NOE cross peaks with reasonable signal‐to‐noise ratios even for long‐range interactions in the presence of quadrupolar relaxation. This is demonstrated by the spectra of lithium dimethylcuprate. Copyright © 2004 John Wiley & Sons, Ltd.
ESR study of MoY and PdMoY reduction
Authors: Saïd Zina Mongia , Ghorbel Abdelhamid
Published: February 2004

This paper deals with the reduction of MoY and PdMoY using ESR in order to study the effect of molybdenum on the reducibility of palladium ions. The evolution of signals of paramagnetic species of palladium (Pd3+ in 4d7 and Pd+ in 4d9) and molybdenum (Mo5+ in 4d1) was followed by EPR spectroscopy. Two paramagnetic species of Mo5+ were observed after reduction under hydrogen, the first with g// = 1.87 and the second with g// = 1.89. However, the Mo5+ ion on the zeolite exhibited various coordination symmetries upon reduction or other treatments, depending on the preparation method. The analysis of the g tensors allowed these signals to be attributed to molybdenyl ions in penta‐ $(\hbox{Mo}_{\rm 5c}^{5+})$ and hexacoordination $(\hbox{Mo}_{\rm 6c}^{5+})$ symmetries. Copyright © 2004 John Wiley & Sons, Ltd.
Improved method for unambiguous amino acid side‐chain 1H and 13C resonance assignment
Authors: Löhr Frank , Betz Marco , Rüterjans Heinz
Published: February 2004

Side‐chain proton and carbon‐13 resonance assignments of [13C;15N]‐enriched proteins usually rely on combinations of several multi‐dimensional experiments. Here, we describe a four‐dimensional pulse sequence, H(C)C–COSY–TOCSY–(CACO)NH, which provides the information required to assign completely aliphatic side‐chain resonance frequencies. As in widely used HCC(CO)NH–TOCSY experiments, problems due to spectral crowding are alleviated by exploiting the dispersion of backbone amide 1H and 15N signals. The modification introduced here allows signals from different side‐chains to be distinguished even in the case of overlap in the 1HN–15N plane of the spectra. For illustration, the new method is applied to two proteins with molecular masses of 11 and 23 kDa. Copyright © 2004 John Wiley & Sons, Ltd.
Complete 1H and 13C NMR assignments of two phytosterols from roots of Piper nigrum
Authors: Wei Kun , Li Wei , Koike Kazuo , Pei Yuping , Chen Yingjie , Nikaido Tamotsu
Published: February 2004

Using modern NMR techniques, including DQF‐COSY, NOESY, HETCOR and HMBC, the full assignments of all 1H and 13C chemical shifts were made for stigmastane‐3,6‐dione and stigmast‐4‐ene‐3,6‐dione, isolated from the roots of Piper nigrum (Piperaceae). Their stereochemistry was resolved by a combination of 2D NOESY data and analysis of coupling constants. The two compounds were isolated from the genus Piper for the first time. Copyright © 2004 John Wiley & Sons, Ltd.
Effects of polymorphic differences for sulfanilamide, as seen through 13C and 15N solid‐state NMR, together with shielding calculations
Authors: Portieri Alessia , Harris Robin K. , Fletton Richard A. , Lancaster Robert W. , Threlfall Terence L.
Published: February 2004

We recorded both carbon‐13 and nitrogen‐15 NMR spectra of the three solid forms of sulfanilamide most commonly known. This study led to an interpretation of the solid‐state effects seen in cross‐polarization magic angle spinning spectra. Relaxation times for the different forms were measured. These show different behaviour for the three forms, arising from mobility variations. To obtain information on local environments, static spectra and spinning sideband manifolds were recorded and analysed for the 15N resonances, using isotopically enriched samples. Shielding asymmetries and anisotropies for the two nitrogen nuclei were obtained, showing very different behaviour for the two sites. Shielding calculations were carried out for both 13C and 15N nuclei, and the results are discussed in relation to the experimental values. Copyright © 2004 John Wiley & Sons, Ltd.
A universal index formula suitable to multiparameter water quality evaluation
Authors: Peng Lihong
Published: February 2004

Based on hypothesis of “base value” of water quality parameter, a universal index suitable to multi‐parameter water quality evaluation was presented, as the monitoring values of parameters in the water quality index formula in logarithm function form were replaced by their relative values, and optimizing the parameters of different indices in the formula was carried out by Genetic Algorithms. Each index of water quality can be weighted into comprehensive index by compromise active function. The correctitude of formula was verified by using this method to asses the water quality states of many spots. The formula has shown its simplicity of calculation, practicability, generality, comparability and objectivity. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 20: 368–373, 2004
A domain decomposition method on nested domains and nonmatching grids
Authors: Flemisch Bernd , Wohlmuth Barbara I.
Published: February 2004

A one directionally coupled problem on two nested domains is analyzed. The global domain and the subdomain are discretized by two triangulations that do not match on the subdomain. The connection between the two grids is established by using a stable projection operator onto the interface. An a priori error analysis is carried out and several numerical examples are given. The method is ideally suited for the case of a moving subdomain. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 20: 374–387, 2004.
Domain decomposition for radial basis meshless methods
Authors: Li Jichun , Hon Y. C.
Published: February 2004

Both overlapping and nonoverlapping domain decomposition methods (DDM) on matching and nonmatching grid have been developed to couple with the meshless radial basis function (RBF) method. Example shows that overlapping DDM with RBF can achieve much better accuracy with less nodal points compared to FDM and FEM. Numerical results also show that nonmatching grid DDM can achieve almost the same accuracy within almost the same iteration steps as the matching grid case; hence our method is very attractive, because it is much easier to generate nonmatching grid just by putting blocks of grids together (for both overlapping and nonoverlapping), where each block grid can be generated independently. Also our methods are showed to be able to handle discontinuous coefficient. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 20: 450–462, 2004.
A posteriori error estimates for a compressible Stokes system
Authors: Kweon Jae Ryong
Published: February 2004

A linearized compressible viscous Stokes system is considered. The a posteriori error estimates are defined and compared with the true error. They are shown to be globally upper and locally lower bounds for the true error of the finite element solution. Some numerical examples are given, showing an efficiency of the estimator. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 20: 412–431, 2004.
Conservative semi‐Lagrangian advection on adaptive unstructured meshes
Authors: Iske Armin , Käser Martin
Published: February 2004

A conservative semi‐Lagrangian method is designed in order to solve linear advection equations in two space variables. The advection scheme works with finite volumes on an unstructured mesh, which is given by a Voronoi diagram. Moreover, the mesh is subject to adaptive modifications during the simulation, which serves to effectively combine good approximation quality with small computational costs. The required adaption rules for the refinement and the coarsening of the mesh rely on a customized error indicator. The implementation of boundary conditions is addressed. Numerical results finally confirm the good performance of the proposed conservative and adaptive advection scheme. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 20: 388–411, 2004
Parameterized families of finite difference schemes for the wave equation
Authors: Bilbao Stefan
Published: February 2004

This article is devoted to an analysis of simple families of finite difference schemes for the wave equation. These families are dependent on several free parameters, and methods for obtaining stability bounds as a function of these parameters are discussed in detail. Access to explicit stability bounds such as those derived here may, it is hoped, lead to optimization techniques for so‐called spectral‐like methods, which are difference schemes dependent on many free parameters (and for which maximizing the order of accuracy may not be the defining criterion). Though the focus is on schemes for the wave equation in one dimension, the analysis techniques are extended to two dimensions; implicit schemes such as ADI methods are examined in detail. Numerical results are presented. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 20: 463–480, 2004.
On a finite element method for three‐dimensional unsteady compressible viscous flows
Authors: Liu Biyue
Published: February 2004

In this article we analyze a finite element method for three‐dimensional unsteady compressible Navier‐Stokes equations. We prove the existence and uniqueness of the numerical solution, and obtain a priori error estimates uniform in time. Numerical computations are carried out to test the orders of accuracy in the error estimates. Blend function interpolations are applied in the calculation of numerical integrations. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 20: 432–449, 2004.
Polymer light‐emitting electrochemical cell based on a novel poly(aryleneethynylene) consisting of ethynylfluorene and tetraphenyldiaminobiphenyl units
Authors: Sun Qingjiang , Zhan Xiaowei , Zhang Bin , Yang Chunhe , Liu Yunqi , Li Yongfang , Zhu Daoben
Published: February 2004

The photo‐ and electro‐luminescence properties of a novel light‐emitting poly(aryleneethynylene) (PAE) consisting of ethynylfluorene and hole‐transporting tetraphenyldiaminobiphenyl units have been reported. The emission color of this polymer changes from blue to yellowish green when going from the solution to the film, which is assigned to the formation of aggregates. The light‐emitting electrochemical cell (LEC) based on this PAE type polymer has been demonstrated. Light emission is observed from the LEC in both forward and reverse bias modes. The LEC shows the turn‐on voltage of 2.9 V and the maximum electroluminescence efficiency of 0.47 cd/A under the forward bias. Introduction of the hole‐transporting moiety into the main chain can improve the electroluminescence properties of the PAE type polymer. The a.c. impedance measurements indicate that the operation of the LEC corresponds to the electrochemical doping mechanism. Copyright © 2004 John Wiley & Sons, Ltd.
Nylon‐6 film grafted with acrylic acid for dissepiment in alkaline storage batteries
Authors: Liu Minying , Zhao Qingxiang , Wang Yudong , Niu Junfeng , Cao Shaokui
Published: February 2004

A grafted nylon‐6 membrane that can be used in alkaline storage batteries was prepared by grafting acrylic acid onto nylon‐6 film using (NH4)2Ce(NO3)6/H2SO4 as initiator. The nylon‐6 films to be grafted were pre‐swelled in 20% formic acid solution, activated with an aqueous solution containing ceric ammonium nitrate and sulfuric acid. The grafting efficiency was greatly affected by the reaction temperature, the concentration of (NH4)2Ce(NO3)6/H2SO4, and the swelling time in formic acid. The degree of grafting that could be achieved under optimized conditions was up to 312%. Through infrared spectroscopy (IR) and X‐ray photoelectron spectroscopy (XPS) analysis, it was realized that graft reaction took place on the nitrogen atom of the amide group and the density of grafting point increased with an increase in the degree of grafting in a certain range. The highest density of grafting point was found to be 51.3% in a given set of reaction conditions. X‐ray diffraction illustrated that the crystallinity of the grafted membranes decreases with the increase of the degree of grafting. A membrane with 173% degree of grafting showed electric resistance of 0.11 Ω/cm2, and ion exchange capacity (IEC) of 8.7 mmol/g, which can meet the requirement for the electric discharge of storage batteries with strong power. Copyright © 2004 John Wiley & Sons, Ltd.
Fluorescence from fluorescent dye‐based polyurethane ionomer(II)
Authors: Wang C. L. , Zhang Z. J. , Kuo Y. M. , Chao D. Y.
Published: February 2004

The reaction of 6‐amino‐2(2‐hydroxy‐2‐phenyl‐ethyl)benzo[de]isoquinoline‐1,3‐dione with toluene diisocyanate and other additives to form the structure of the fluorescent dye‐based polyurethane (PU) ionomer has been proven by infrared (IR) spectroscopy. In aqueous solution, the fluorescence performance for the fluorescent dye‐based PU ionomer molecule appears at 516 nm, and its quantum yield is calculated to be 0.804. It is important to point out that increased concentration of the reactive fluorescent dye employed to prepare the fluorescent dye‐based PU ionomer molecule will not enhance the fluorescence performance of this ionomer molecule. This is probably the result of increased intra molecular interaction between ionomer molecules themselves, which may substantially reduce the excitation of the ionomer molecule by absorbing UV light. However, 6‐amino‐2‐(2‐hydroxy‐2‐phenyl‐ethyl)benzo[de]isoquinoline‐1,3‐dione is considered to be a good fluorescent dye for use in resins. Furthermore, the addition of a reactive fluorescent dye to prepare the fluorescent dye‐based PU ionomer molecule will significantly enhance the tensile strength but, however, will appreciably decrease the elongation of this ionomer molecule. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis of well‐defined chain‐end‐functionalized polystyrenes with four, eight, and sixteen perfluorooctyl groups and their surface characterization
Authors: Hirao Akira , Sakai Shiko , Sugiyama Kenji
Published: February 2004

We have successfully synthesized a series of novel well‐defined chain‐end‐functionalized polystyrenes with a definite number of four, eight, and sixteen perfluorooctyl (C8F17) groups, via living anionic polymerization, by the coupling reaction of chain‐end‐functionalized polystyrenes with dendritic benzyl bromide moieties with the functionalized 1,1‐diphenylalkylanion prepared from sec‐BuLi and 1,1‐bis(4‐tert‐butyldimethylsilyloxyphenyl)ethylene, deprotection, and a Williamson reaction with C8F17(CH2)3Br. The resulting polymers were precisely controlled in molecular weight and molecular weight distribution as well as well‐defined in chain‐end‐functionality. Surface structures of the annealed films cast from such chain‐end‐functionalized polystyrenes with C8F17 groups have been characterized by contact angle and angle‐dependent X‐ray photoelectron spectroscopy (XPS) measurements. It has been clearly observed by both measurements that the C8F17 groups are preferentially segregated from their polystyrene main chains and significantly enriched at the surfaces. However, the degree of enrichment of C8F17 group increased only to a small extent by increasing the C8F17 group from four, eight, and even sixteen in number. We have compared the present results with the previous ones obtained by using chain‐end‐functionalized polystyrenes with one, two, three, and four C8F17 groups and the structurally analogous block copolymers and discussed in more detail in terms of the dependence of enrichment degree on number of C8F17 group. Copyright © 2004 John Wiley & Sons, Ltd.
Modification of end‐groups of aliphatic hyperbranched polyester
Authors: Qiu Teng , Tang Liming , Fu Zhiwei , Tuo Xinlin , Li Yi , Liu Deshan , Yang Wantai
Published: February 2004

Aliphatic hyperbranched polyester (P1) synthesized from 2,2‐bis(methylol)propionic acid and tris(methylol)propane was reacted with phthalic anhydride and trimellitic anhydride to form modified polymers P2 and P3, respectively. The reaction kinetics and the effect of different end‐groups on the polymer properties were studied. Contrast to P1, both P2 and P3 could form global aggregates in dimethylformamide/water mixture due to their amphiphilic structures. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and properties of fluoropolyacrylate coatings
Authors: Tang Liming , Li Yi , Wu Xiaomin , Shan Xiaofeng , Wang Weicheng
Published: February 2004

Hydroxylic fluoropolyacrylates were prepared by solution copolymerization of styrene (St), 2‐hydroxypropyl acrylate (2‐HPA), butyl acrylate (BA) and fluoroacrylate under various compositions. They were further cured with hexamethylene diisocyanate (HMDI) to obtain hydrophobic coatings under ambient condition. The curing reaction was identified by differential scanning calorimetry (DSC) and gel content analysis. The properties, especially the anti‐frosting performance, of the cured coatings were measured. The results indicated that the anti‐frosting property was improved by the prescence of the hydrophobic coating. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and ionic conductivity of a polysiloxane containing quaternary ammonium groups
Authors: Kang Jun‐Jie , Li Wei‐Ying , Lin Yuan , Li Xue‐Ping , Xiao Xu‐Rui , Fang Shi‐Bi
Published: February 2004

A novel quaternary ammonium salt, polysiloxane containing quaternary ammonium groups, was designed and synthesized. Thermogravimetric results showed that the polymer maintained stable below 250°C. Ambient conductivities higher than 10−4 S cm−1 could be observed when appropriate amounts of suitable plasticizers were incorporated into the present quaternary ammonium salt. A dye‐sensitized solar cell fabricated using a plasticized electrolyte showed a fill factor of 0.50 and an energy conversion efficiency of 7.7%. Copyright © 2004 John Wiley & Sons, Ltd.
Study of cobalt(II)‐chitosan coordination polymer and its catalytic activity and selectivity for vinyl monomer polymerization
Authors: Huai‐min Guan , Xian‐su Cheng
Published: February 2004

A cobalt(II)‐chitosan coordination polymer has been prepared by soaking a chitosan film in CoCl2 aqueous solution. The results have been investigated by means of X‐ray photoelectron spectroscopy (XPS), Fourier Transform infrared FT‐IR spectroscopy, thermal analysis and electrical conductivity measurements. The XPS and FT‐IR spectra reveal that the chitosan coordinated with cobalt(II) through both oxygen and nitrogen atoms in the chitosan chain. The XPS results show that the coordination polymer possess the same shake‐up peaks with CoCl2, indicating that the cobalt(II)‐chitosan coordination polymer is high spin and the coordination number of cobalt(II) centers is four, and the electrical conductivity measurements confirm this result. Also, cobalt(II) coordination polymer can be used as a catalyst, and the polymerization of vinyl acetate was carried out in the presence of the coordination polymer/Na2SO3/H2O at pH 7 and normal temperature. The polyvinyl acetate possessed a random structure. Copyright © 2004 John Wiley & Sons, Ltd.
Organic emissive materials and devices for photonic communication
Authors: Suzuki Hiroyuki , Yokoo Atsushi , Notomi Masaya
Published: February 2004

This article describes our recent progress on the development of organic emissive materials and devices for photonic communication applications. Luminescence properties in the infrared (IR) region were examined for two types of organic emissive material, an organic rare earth complex and an organic ionic dye, and their potential for use as emissive materials in photonic communication applications was discussed. The luminescence mechanism elucidated in this study suggested a guideline for the future development of organic IR emissive materials. Novel organic emissive devices were fabricated by combining organic emissive materials with various types of photonic crystal structure utilizing nanotechnology. These devices utilize the advantages and unique properties of organic materials, and so signal the way towards the breakthroughs needed to realize emissive devices for the photonic communication networks of the future. Copyright © 2004 John Wiley & Sons, Ltd.
Study on the synthesis and application of salt‐resisting polymeric hydrogels
Authors: Li Yanfeng , Li Xianzhen , Zhou Lincheng , Zhu Xiaoxia , Li Bonian
Published: February 2004

A kind of hydrogel of semi‐2 interpenetrating polymer network (IPN) consisting of poly(sodium acrylate) (PSA) and poly(vinyl alcohol) (PVA), i.e. semi‐2 IPN PVA/PSA hydrogel, was synthesized by interpenetrating polymerization of sodium acrylate and N,N′‐methylene bisacrylamide into a solution of PVA, using potassium persulfate and sodium bisulfite as initiators. The synthetic conditions affecting the properties of the resulting hydrogel and optimal conditions were investigated, while the resulting IPN hydrogel used as an agent for holding‐water was employed in the planting of trees in an arid soil containing a higher amount of saline. Experimental results indicate that the semi‐2 IPN PVA/PSA hydrogel has an absorbency of 700–800 and 70–90 ml/g for distilled water and saline solution, respectively, as well as showing a better salt‐resistance and water‐absorbing rate compared to polymeric hydrogels based on PSA due to the introduction of the PVA segment. The results showed the surviving ratio of the planted saplings could reach 100% and be raised to 70% compared with those without hydrogel. Copyright © 2004 John Wiley & Sons, Ltd.
Preparation and catalytic oxidation properties of inorganic polymer encapsulated metal complexes
Authors: Wang Rong‐Min , Zhang Zhen‐Lin , Lou Jian‐Fang , Wang Yun‐Pu , Song Peng‐Fei , Xia Chun‐Gu
Published: February 2004

An inorganic polymer supporter, such as molecular sieve MCM‐41, was used as a support for encapsulating metal complex catalysts. The metal complex was prepared with L‐glutamic acid and Co(OAc)2 · 4H2O. Their catalytic activity in oxidation of cyclohexene with H2O2 was studied. The major products of this reaction were hexanedial, 2‐cyclohexen‐1‐one, 2‐cyclohexen‐1‐hydropenoxide and epoxide, which is different from typical oxidation of cyclohexene. The effect of temperature, solvent, additive, the amount of catalyst and oxidant were also discussed. The catalyst shows high catalytic activity. Copyright © 2004 John Wiley & Sons, Ltd.
Condensation polymers of dicyclopentadienyl iron with aromatic diazoium salts and magnetism
Authors: Chai Chun‐Peng , Wang Yun‐Pu , Wang Rong‐Min , Ren Hong‐Xia , Hao Cheng‐Jun
Published: February 2004

Five kinds of condensation polymers of dicyclopentadienyl iron with aromatic diazoium salts were firstly composed. Using inductively coupled plasma (ICP) and FT‐IR their structures were characterized. Their thermal stability was discussed using TG and DTA. The electronic structure of iron was studied by Mössbauer spectra and electron spin resonance (ESR) spectra. Measurement of temperature dependence of the magnetic property (M–T curve) of the condensation polymers indicates that they have stronger magnetism. At a temperature of T = 1.5 K, the loop of magnetic hysteresis was obtained. The strongest magnetic condensation polymer was benzyl ferrocene making 1/χm − T, obtaining a condensation temperature of Tc = 20.5 K, when T < Tc, the condensation polymer shows ferromagnetism. Copyright © 2004 John Wiley & Sons, Ltd.
Hydrogenation of five‐membered heterocycles of polymer‐supported palladium catalyst at normal temperature and pressure
Authors: Guo Zhen , Feng Hua , Ma Heng‐chang , Kang Qiao‐Xiang , Yang Zhi‐Wang
Published: February 2004

To modify the surface of aminomethyl polystyrene, grafting of hyperbranched dendritic polyamidoamine, a new class of topological macromolecules, onto the surface was investigated. It was found that hyperbranched dendritic polyamidoamine was propagated from aminomethyl polystyrene surface by repeating two processes: (1) Michael addition; (2) amidation. Furthermore, salicylal (SA) readily postgrafted to the hyperbranched dendritic polyamidoamine‐grafted‐aminomethyl polystyrene. Finally, catalytic hydrogenations of pyrrole, furan and thiophene were investigated by the modifying polyamidoamine‐grafted aminomethyl polystyrene with SA (MPGAPS)‐supported palladium catalyst. The double‐bond of the ring was hydrogenated to single‐bond ring of tetrahydro‐compound at first, then the ring is broken directly. In general, these reactions were degradation under reduction. UV absorbance spectroscopy, gas chromatography (GC), and power of hydrogen (PH) detection were used to analyze the reactants and products, and infrared (IR), X‐ray photoelectron spectroscopy (XPS) and inductively coupled plasma‐atomic emission spectrometry (ICP‐AES) characterized the catalyst. Copyright © 2004 John Wiley & Sons, Ltd.
Preparation of a multifunctional bacterial fertilizer by living azospirillum simplex cells immobilized on poly(sodium acrylate)
Authors: Wang Yun‐Pu , Chen Na‐Li , Wang Rong‐Min , Xiong Yu‐Bing , Zha Rui‐Tao
Published: February 2004

A living azospirillum simplex cell (LASSC) was immobilized on poly(sodium acrylate) (PSA). The method of preparation of the immobilized‐cell (LASSC‐PSA) was studied. LASSC was immobilized on PSA in an immobilizing medium of Na2HPO4 · 12H2O‐NaH2PO4 · 2H2O (pH 7.0) buffer, sterile water, a solution of NaCl (0.85% m/m), cultured medium (pH 7.0), respectively. The desorption capacity of LASSC on LASSC‐PSA in sterile water was measured and when the Na2HPO4 · 12H2O‐NaH2PO4 · 2H2O (pH 7.0) buffer served as the immobilizing medium, the desorption capacity of LASSC on LASSC‐PSA was the highest. The rate (m/m) of PSA and LASSC (wet weight) also affected considerably the desorption capacity of LASSC on LASSC‐PSA in sterile water, and the best rate was 1 : 0.5. The desorption capacity of LASSC on LASSC‐PSA was 50% of that at the beginning and that was still 109 cfu/g on storage for 5 months when the rate (m/m) of PSA and LASSC (wet weight) was 1 : 0.5, using Na2HPO4 · 12H2O‐NaH2PO4 · 2H2O (pH 7.0) buffer as immobilizing medium. Copyright © 2004 John Wiley & Sons, Ltd.
Preparation and adsorption properties of modified chitosan
Authors: Wang Rong‐Min , Xie Xin , Wang Jin‐Qing , Pan Su‐Juan , Wang Yun‐Pu , Xia Chun‐Gu
Published: February 2004

Chitosan has been modified by polyacrylate sodium or acrylate sodium in the presence of glutaraldehyde, which afforded four kinds of modified chitosan (CTS‐PA) with different ratios of reacting substance. They are used as an environmentally benign polymer adsorbent. The adsorption properties of these CTS‐PA to Pb2+ have been measured. The best adsorption to Pb2+ was CTS‐PA4, the removal efficiency was higher in higher concentration solution than in a lower one, the value of the removal efficiency is approximate 99.991%. Copyright © 2004 John Wiley & Sons, Ltd.
Studies of waterborne emulsion of chemically modified epoxy resin
Authors: Zhang Zhaoying , Huang Yuhui , Liao Bing , Cong Guangmin
Published: February 2004

The bisphenol‐A type epoxy resin was modified by p‐aminobenzoic acid. The modified resins were characterized using IR spectroscopy and differential scanning calorimetry (DSC). The progress of emulsification process was characterized by measuring the variations of conductivity and viscosity while dropping water into the modified resin solution. The factors influencing the emulsion particle size of the waterborne coating films of the modified resins were investigated. Copyright © 2004 John Wiley & Sons, Ltd.
A novel hyperbranched conjugated polymer for light emitting devices
Authors: He Qingguo , Huang Hongmin , Sun Qingjiang , Lin Hongzhen , Yang Junlin , Bai Fenglian
Published: February 2004

A novel hyperbranched conjugated polymer with benzene as core, phenylene vinylene as connecting groups and dimethylamino benzene as end groups (DMA‐HPV) was synthesized and characterized. It shows excellent solubility, film‐forming ability and very high thermal stability Tg = 255°C, TID = 398°C). Its fluorescence quantum efficiency in film is almost as large as that in solution (∼50%). The light emitting diodes and the light emitting cells were fabricated. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and photophysical properties of a novel semiconducting polymer
Authors: Huang Hongmin , He Qingguo , Lin Hongzhen , Bai Fenglian , Sun Zhi , Li Qingshan
Published: February 2004

An alternating copolymer containing triphenylamine (TPA) and cyano‐substituted benzene moieties, TPA‐CNPPV was synthesized using the Wittig reaction. The monomers and polymer were characterized by H‐NMR, FT‐IR and mass spectroscopy (MS). The polymer shows good solubility in common organic solvents and excellent film‐forming ability. Thermogravimetric analysis (TGA) demonstrates that the polymer has a degradation temperature (TD) of 600°C; differential scanning calorimetry (DSC) result indicates that the glass transition temperature (Tg) of TPA‐CNPPV is 160°C, suggesting high thermal stability. The photophysical properties of the light‐emitting material were investigated in both solution and spin‐coated film. Photo‐isomerization of the polymer was investigated by UV‐vis and fluorescence spectra. The interaction between TPA‐CNPPV and C60 was studied by fluorescence quenching. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and characterization of a copolymer containing 1,1′‐binaphthyl‐2,2′‐diamino and carbazolyl units
Authors: Zhang Caihong , Chen Zhaobin , Bai Fenglian
Published: February 2004

A novel copolymer has been synthesized by copolymerization of 2,2′‐dimethacrylamido‐1,1′‐binaphthyl (DMBN) with vinylcarbazole (VCZ) and its fluorescence characterization has been studied. The results show that the copolymer (DMBN‐VCZ) is soluble in some common organic solvents and the fluorescence of the copolymer (DMBN‐VCZ) can be quenched by both electron donors and electron acceptors where the quenching effects follow the Stern–Volmer equation. The dimolecular exciplexes between copolymer (DMBN‐VCZ) and strong electron donor or electron acceptor are formed. Moreover, the interaction between copolymer (DMBN‐VCZ) and C60 is also studied by fluorescent quenching. Copyright © 2004 John Wiley & Sons, Ltd.
Design and synthesis of functional polymers by in vitro selection
Authors: Ito Yoshihiro
Published: February 2004

Combinatorial chemistry, in which targeting molecules are selected from a random molecular library, has recently developed. Among the methods devised by combinatorial chemistry, the recent progress in functional polymers that have molecular recognition ability and catalysis ability, and in bio‐device polymers based on these functionalities is reviewed. Copyright © 2004 John Wiley & Sons, Ltd.