bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and characterization of unsaturated poly(ester‐imide) based on 1,4‐bis[2′‐trifluoromethyl‐4′‐(4″‐glycolformate)‐trimellitimidophenoxy]benzene
Authors: Li Haiyan , Wang Desheng , Fan Lin , Yang Shiyong 
Published: March 2006

AbstractA novel diimidodialcohol monomer, 1,4‐bis[2′‐trifluoromethyl‐4′‐(4″‐glycolformate)‐ trimellitimidophenoxy]benzene (BGTB), was synthesized and characterized. It was reacted with isophthalic acid, maleic anhydride and propylene glycol to produce a novel unsaturated poly(ester‐imide) (BGTB‐UPEI) with imide and trifluoromethyl groups in the polymer backbone. The BGTB‐UPEI resin was diluted with reactive monomer (styrene) to give a low‐viscous poly(ester‐imide)/styrene (BGTB‐UPEI/St) mixed solution, which was then thermally cured to yield thermosetting BGTB‐UPEI/St composite. The effect of processing parameters such as the curing temperature and curing time, reactive monomer concentration and initiator amount on the curing reaction was systematically investigated. Experimental results indicated that the thermally cured BGTB‐UPEI/St composite exhibited much better thermal, mechanical, electrical insulating properties and chemical resistance than the standard unsaturated polyester/polystyrene composite. Copyright © 2006 Society of Chemical Industry
Gas‐phase olefin polymerization over supported metallocene/MAO catalysts: influence of support on activity and polydispersity
Authors: Hammawa Hassan , Wanke Sieghard E 
Published: March 2006

AbstractThree catalysts obtained by supporting bis(n‐butylcyclopentadienyl)zirconium dichloride/methylaluminoxane on: (1) porous crosslinked poly(2‐hydroxyethylmethacrylate‐co‐styrene‐co‐divinylbenzene) particles (CAT1); (2) swellable crosslinked poly(styrene‐co‐divinylbenzene) particles (CAT2); and (3) by evaporating the catalyst precursors solution to dry powder, CAT3 were used in gas‐phase polymerization of ethylene, and ethylene/1‐hexene in a 2 L semi‐batch reactor at 80 °C and 1.4 MPa. The average polymerization activities of the three catalysts were 12.3–15.5, 4.2–10.1, and 14.3–62.9 ton PE (mol Zr h)−1 respectively. CAT1 and CAT3 produced polyethylenes with a polydispersity range of 2.3–2.7, while that of CAT2 was 3.5–6.4. The supported catalysts produced polyolefin particles with bulk density of 0.36–0.43 g ml−1, and essentially no fines. Ethylene/1‐hexene co‐polymerization (7 mol m−3 initial 1‐hexene concentration in the reactor) increased polymerization activities and produced lower‐molar‐mass co‐polymers. At 21 mol m−3 1‐hexene the polymerization activities decreased, but the relative amount of the low‐molar‐mass co‐polymer for CAT2 increased, leading to higher polydispersity. Copyright © 2006 Society of Chemical Industry
Crystal morphology and transcrystallization mechanism of isotactic polypropylene induced by fibres: interface nucleation versus bulk nucleation
Authors: Na Bing , Guo Min , Yang Jinghui , Tan Hong , Zhang Qin , Fu Qiang 
Published: March 2006

AbstractUsing polarized optical microscopy (POM) equipped with a hot stage, morphological investigations of an isotactic polypropylene (iPP) matrix, induced by a homogeneous iPP fibre and heterogeneous pure/modified nylon 6 fibres, were carried out. With respect to transcrystallization related to heterogeneous nucleation on the surface of the fibre, the nucleation mode was found to be different for iPP fibres and nylon 6 fibres. An iPP fibre can serve as a macroscopic linear nucleus, similarly to the shish‐type structure formed in stress‐induced crystallization, to induce kebab‐like growth of lamellae, whereas numerous closely packed spherulites along nylon 6 fibres resulted in macroscopic transverse growth to form a transcrystallite owing to the limitation along the fibre axis. The difference in nature between these two transcrystallites can be further demonstrated by their optical characters related to the lamellar arrangement inside the transcrystallite. As for homogeneous iPP composites, the formation of transcrystallites results from lattice matching, in consideration of the same chemical structure and lattice parameters between fibre and matrix. The incorporation of calcium chloride into a nylon 6 fibre—to destroy its crystal structure—confirmed the role of lattice matching between nylon 6 fibre and iPP matrix. The addition of atactic polypropylene (aPP) in order to enhance the nucleation ability of the iPP matrix also greatly weakened transcrystallization. Our work demonstrates that transcrystallization is just a matter of competition between interface nucleation and bulk nucleation, namely, if interface nucleation is faster than bulk nucleation, transcrystallization will develop. If not, it will be suppressed. Copyright © 2006 Society of Chemical Industry
Synthesis, structure and properties of carbon nanotube/poly(p‐phenylene benzobisoxazole) composite fibres
Authors: Li Jinhuan , Chen Xiangqun , Li Xia , Cao Hailin , Yu Hongyan , Huang Yudong 
Published: March 2006

AbstractCarbon nanotube/poly(p‐phenylene benzobisoxazole) (CNT/PBO) composite fibres were prepared by in situ polymerization and dry‐jet wet spinning. The structure and properties of the CNT/PBO fibres were investigated. FTIR and viscosity measurements showed that the functional groups on the CNT surface took part in the polymerization and affected the chemical structure and molecular weight of the composite. CNT/PBO composites with high molecular weight could be obtained by controlling the amount and addition time of CNTs. Compared with PBO fibres containing no CNTs prepared under the same conditions, the thermal resistance of the CNT (2 wt%)/PBO fibres was higher and the tensile strength was also improved by 20–50%. WAXD and SEM measurements indicated that the orientation degree of the CNT (2 wt%)/PBO fibres was smaller than that of PBO fibres. The fracture surfaces of these two fibres were also different. CNT dispersion in the CNT (2 wt%)/PBO fibres was examined by TEM. A model of the interactions between CNTs and PBO is proposed, based on these results. Copyright © 2006 Society of Chemical Industry
Selective detection of 2‐nitrobenzenesulfenyl‐labeled peptides by matrix‐assisted laser desorption/ionization‐time of flight mass spectrometry using a novel matrix
Authors: Matsuo Ei‐ichi , Toda Chikako , Watanabe Makoto , Ojima Noriyuki , Izumi Shunsuke , Tanaka Koichi , Tsunasawa Susumu , Nishimura Osamu 
Published: March 2006

AbstractThe 2‐nitrobenzenesulfenyl (NBS) method, which is useful for quantitative proteome analysis, is based on stable isotope labeling of tryptophan residues with NBS chloride (12C6‐NBSCl or 13C6‐NBSCl). We found that 3‐hydroxy‐4‐nitrobenzoic acid (3H4NBA) is a more suitable matrix than 2,5‐dihydroxybenzoic acid (DHB) for detecting NBS‐labeled peptides by MALDI‐quadrupole IT (QIT)‐TOF MS . Furthermore, NBS‐labeled peptides were selectively ionized and detected in a mixture of NBS‐labeled and unlabeled peptides. Labeled paired peaks were easily detected without enrichment, nonpaired labeled peaks were clearly distinguished from unlabeled contaminating peptides, and nitrotyrosine‐containing peptides were also selectively detected on the 3H4NBA matrix, while by‐product‐peaks arising from nitrobenzene moieties were suppressed. The use of 3H4NBA as a comatrix with CHCA improved the sensitivity of detection while substantially retaining the selectivity of 3H4NBA. The 3H4NBA matrix offers great advantages in terms of simplicity, sensitivity, and usability when used for the NBS method and for MALDI‐TOF MS analysis applied to compounds having a nitrobenzene ring.
Star polystyrenes by anionic star–star coupling reactions with divinylbenzene
Authors: Lee Hyung‐Jae , Lee Kwanyoung , Lee Soo No 
Published: March 2006

AbstractThe incremental addition of divinylbenzene was used to generate star polystyrenes in a nearly full conversion of a living polystyrenyl anion. The dramatic increase in the molecular weight of the star polystyrenes with a limited supply of the living polystyrene supported the formation of gradient‐star polystyrenes through star–star coupling. The stoichiometric analysis of the star polymers revealed that their connection polymer had a shorter length than their branch polymer. The measured solution viscosity of the gradient‐star polymers greatly deviated from a linear correlation with the molecular weight and was in parallel to a theoretical simulation based on a highly branched structure of the gradient‐star polymer. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2579–2586, 2006
Nitro‐substituted iron(II) tridentate bis(imino)pyridine complexes as high‐temperature catalysts for the production of α‐olefins
Authors: Ionkin Alex S. , Marshall William J. , Adelman Douglas J. , Shoe Aaron L. , Spence Rupert E. , Xie Tuyu 
Published: March 2006

AbstractA new series of nitro‐substituted bis(imino)pyridine ligands {2,6‐bis[1‐(2‐methyl‐4‐nitrophenylimino)ethyl]pyridine, 2,6‐bis[1‐(4‐nitrophenylimino)ethyl]pyridine, (1‐{6‐[1‐(4‐nitro‐phenylimino)‐ethyl]‐pyridin‐2‐yl}‐ethylidene)‐(2,4,6‐trimethyl‐phenyl)‐amine, and 2,6‐bis[1‐(2‐methyl‐3‐nitrophenylimino)ethyl]pyridine} and their corresponding Fe(II) complexes [{p‐NO2o‐MePhNC(Me)PyC(Me)NPho‐ Mep‐NO2}FeCl2 (10), L2FeCl2 (11), {m‐NO2o‐MePhNC(Me)PyC(Me)NPho‐Mem‐NO2}FeCl2 (12), and {p‐NO2PhNC(Me)PyC(Me)NMes}FeCl2 (14)] were synthesized. According to X‐ray analysis, there were shortenings of the axial FeN bond lengths (up to 0.014 Å) in para‐nitro‐substituted complex 10 and (up to 0.015 Å) in meta‐nitro‐substituted complex 12 versus the Fe(II) complex without nitro groups [{o‐MePhNC(Me)PyC(Me)NPho‐Me}FeCl2 (1)]. Complexes 10, 12, and 14 afforded very active catalysts for the production of α‐olefins and were more temperature‐stable and had longer lifetimes than parent non‐nitro‐substituted Fe(II) complex 1. The reaction between FeCl2 and a sterically less hindered ligand [p‐NO2PhNC(Me)PyC(Me)NPhp‐NO2] resulted in the formation of octahedral complex 11. A para‐dialkylamino‐substituted bis(imino)pyridine ligand [p‐NEt2o‐MePhNC(Me)PyC(Me)NPho‐Mep‐NEt2] and the corresponding Fe(II) complex [{p‐NEt2o‐MePhNC(Me)PyC(Me)NPho‐Mep‐NEt2}FeCl2 (16)] were synthesized to evaluate the effect of enhanced electron donation of the ligand on the catalytic performance. According to X‐ray analysis, there was a shortening (up to 0.043 Å) of the axial FeN bond lengths in para‐diethylamino‐substituted complex 16 in comparison with parent Fe(II) complex 1. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2615–2635, 2006
Synthesis and characterization of polyimides from bis(3‐aminophenyl)‐4‐(1‐adamantyl)phenoxyphenyl phosphine oxide
Authors: Kwak S. M. , Yeon J. H. , Yoon T. H. 
Published: March 2006

AbstractA novel diamine, bis(3‐aminophenyl)‐4‐(1‐adamantyl)phenoxyphenyl phosphine oxide (mDAATPPO), was synthesized via the Williamson ether reaction of 4‐(1‐adamantyl)phenol and bis(3‐nitrophenyl)‐4‐fluorophenyl phosphine oxide, followed by reduction. The phenol group was prepared by the Friedel–Crafts reaction of 1‐bromoadamantane and phenol, whereas the phosphine oxide group was synthesized by the Grignard reaction of 1‐bromo‐4‐fluorobezene and diphenyl phosphinic chloride, followed by nitration. The monomer and its intermediate compounds were characterized with Fourier transform infrared, NMR, and melting‐point apparatus. The monomer was then used to prepare polyimides with 2,2‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride, 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride, 4,4′‐oxydiphthalic dianhydride, and pyromellitic dianhydride by the conventional two‐step synthesis: the preparation of poly(amic acid) followed by solution imidization. The molecular weights of the polyimides were controlled to 20,000 g/mol by off‐stoichiometry, and the synthesized polyimides were characterized with Fourier transform infrared, NMR, gel permeation chromatography, thermogravimetric analysis, and differential scanning calorimetry. In addition, the solubility, intrinsic viscosity, dielectric constant, and birefringence of the polyimides were evaluated. Novel polyimides with mDAATPPO exhibited good solubility, high glass‐transition temperatures (290–330 °C), excellent thermal stability (>500 °C), low dielectric constants (2.77–3.01), low refractive indices, and low birefringence values (0.0019–0.0030). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2567–2578, 2006
Photocrosslinked poly(vinylbenzophenone)‐core micelles via mild Friedel–Crafts benzoylation of polystyrene amphiphiles
Authors: Chen Ying , Tavakley Anita E. , Mathiason Tate M. , Taton T. Andrew 
Published: March 2006

AbstractPhotocrosslinkable poly(vinylbenzophenone)‐containing polymers were synthesized via a one‐step, Friedel–Crafts benzoylation of polystyrene‐containing starting materials [including polystyrene, polystyrene‐block‐poly(tert‐butyl acrylate), polystyrene‐block‐poly(ethylene oxide), polystyrene‐block‐poly(methyl methacrylate), and polystyrene‐block‐poly(n‐butyl acrylate)] with benzoyl trifluoromethanesulfonate as a benzoylation reagent. The use of this mild reagent (which required no added Lewis acid) permitted polymers with well‐defined compositions and narrow molecular weight distributions to be synthesized. Micelles formed from one of these benzoylated polymers, [polystyrene0.25‐co‐poly(vinylbenzophenone)0.75]115‐block‐poly(acrylic acid)14, were then fixed by the irradiation of the micelle cores with UV light. As the irradiation time was increased, the pendent benzophenone groups crosslinked with other chains in the glassy micelle cores. Dynamic light scattering, spectrofluorimetry, and Fourier transform infrared spectroscopy were all used to verify the progress of the crosslinking reaction. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2604–2614, 2006
Appraisal of the cancer experience by family members and survivors in long‐term survivorship
Authors: Bowman Karen F. , Rose Julia H. , Deimling Gary T. 
Published: March 2006

AbstractThis study assessed the appraisal of the stressfulness of the cancer experience and its correlates for family members and older survivors living in the long‐term survivorship phase of the disease. On average, family members appraised the cancer experience as more stressful than their surviving relatives. Beliefs about the effect of the diagnosis and treatment on family members were important correlates for both family members and survivors in the appraisal process. Cancer characteristics were not related to appraisal for survivors, but stage at diagnosis was associated with a more stressful appraisal for family members. Demographic characteristics were unrelated to appraisal for family members, but being African‐American was linked to a less stressful appraisal for survivors. These findings highlight the stressful impact of the cancer experience on family members and can help guide health care interventions which include family members from African‐American and White ethnicities. Copyright © 2006 John Wiley & Sons, Ltd.
ARTIST: An activated method in internal coordinate space for sampling protein energy landscapes
Authors: Yun Mi‐Ran , Lavery R. , Mousseau N. , Zakrzewska K. , Derreumaux P. 
Published: March 2006

AbstractWe present the first applications of an activated method in internal coordinate space for sampling all‐atom protein conformations, the activation–relaxation technique for internal coordinate space trajectories (ARTIST). This method differs from all previous internal coordinate‐based studies aimed at folding or refining protein structures in that conformational changes result from identifying and crossing well‐defined saddle points connecting energy minima. Our simulations of four model proteins containing between 4 and 47 amino acids indicate that this method is efficient for exploring conformational space in both sparsely and densely packed environments, and offers new perspectives for applications ranging from computer‐aided drug design to supramolecular assembly. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Optical quantum control using II–VI quantum dots
Authors: Henneberger F. , Akimov I. A. 
Published: March 2006

AbstractII–VI quantum dots are used to control and to manipulate single charge and spin excitations in semiconductors. Two‐photon excitation enables us to generate an entangled state and to control the emission cascade of the exciton‐biexciton system. On charged quantum dots, we demonstrate direct optical manipulation of the resident electron spin. The spin life‐times are significantly larger than 10 µs in low magnetic field. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of the number of Mn ions inside CdMnTe self assembled quantum dots
Authors: Wojnar P. , Suffczyński J. , Kowalik K. , Golnik A. , Karczewski G. , Kossut J. 
Published: March 2006

AbstractWe have grown self assembled CdMnTe/CdZnTe quantum dots with small amount of Mn ions by molecular beam epitaxy. Using atomic layer epitaxy growth mode for the deposition of the QDs layer, we were able to add the manganese ions only into the two central monolayers of six monolayers‐thick CdTe layers, thus, achieving great dilution of Mn ions. Micro‐photoluminescence measurements performed in an external magnetic field confirmed that the Mn ions are successfully incorporated in the CdTe QDs, which manifests itself by the strong circular polarization and the giant Zeeman splitting of PL‐lines coming from individual QDs. Studying the magnetic field dependencies of several QDs from our ensemble, we found that the energy shifts acquire, approximately, only few nearly discrete values. We attribute this effect to small number of Mn ions inside our QDs that contribute to the splitting of excitons and we use the saturation values of the shift it to determine this number precisely. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of sub‐gap irradiation on the time‐of‐flight current waveforms of high resistivity CdTe
Authors: Suzuki K. , Seto S. , Sawada T. , Imai K. 
Published: March 2006

AbstractEffects of IR irradiation on TOF current waveforms of a CdTe:Cl crystal with Pt electrodes on its (111) faces have been investigated. An increase of TOF current and a change in the evolution of DC photocurrent versus applied voltage by IR irradiation are observed. By taking into account an effect of surface recombination, satisfactory fits to theory are obtained for the charge collection efficiency and the DC photocurrent versus applied voltage. These results show that the observed effects are mainly explained by a reduction of surface recombination velocity rather than by an increase of bulk carrier lifetime. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High p‐type doping level of MgZnCdSe on InP substrates by inserting ZnTe thin layers
Authors: Saitoh Takumi , Nomura Ichirou , Sueoka Kan , Kikuchi Akihiko , Kishino Katsumi 
Published: March 2006

AbstractA novel p‐type doping method for MgZnCdSe on InP substrates was proposed. In this method, highly p‐type‐doped thin layers, such as N‐doped ZnTe, are inserted at proper intervals into MgZnCdSe layers. The inserted thin layer emits holes and the p‐type coduction was achieved. ZnCdSe/ZnTe superlattices (SLs), where thin p‐type‐doped ZnTe layers were periodically inserted, were grown on InP substrates by molecuar beam epitaxy. When the ratio of ZnTe layer thickness to one insertion period was 0.17, the net acceptor cocentration (NA‐ND) value reached 8.0 × 1017 cm–3. This value was more than one order of magnitude greater than that of a simple N‐doped ZnCdSe layer (3.5 × 1016 cm–3). To obtain wide bandgap p‐type materials, MgSe/ZnCdSe/ZnTe SLs were fabricated. NA‐ND values from 4.7 × 1017 to 8.0 × 1017 cm–3 were observed for samples with bandgap energies from 2.33 to 2.04 eV. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coherent control of polariton modes in pulse‐transmission and four‐wave‐mixing experiments
Authors: Kudyk I. , Wischmeier L. , Voss T. , Rückmann I. , Gutowski J. 
Published: March 2006

AbstractWe report coherent optical control of polariton modes in pulse‐transmission and four‐wave‐mixing experiments realized on a ZnSe/ZnSSe heterostructure containing a 25 nm thin active ZnSe layer. It is shown in linear pulse‐transmission at low excitation density that the modes can be separately controlled. The coherent control of nonlinear polaritonic FWM polarization is different for both directions of first‐order diffraction. The FWM signal observed in direction 2k1‐k2 shows that the polariton modes can be separately manipulated. Contrasting to that, in the direction 2k2‐k1 all polariton modes are simultaneously enhanced or diminished. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Far‐infrared spectroscopy of HgMnTe–MnSe mixture
Authors: Romčević N. , Romčević M. , Milutinović A. , Kostić R. 
Published: March 2006

AbstractFar‐infrared reflectivity spectrum of Hg0.91Mn0.09Te‐MnSe mixture, grown by Bridgman method, was measured in the 80–500 cm–1 range at room temperature. The investigated mixture consists of MnSe clusters randomly distributed in Hg0.91Mn0.09Te matrix. The analysis of the far‐infrared spectrum was made by a fitting procedure. The Maxwell‐Garnett effective medium theory is used for modeling the effective dielectric function, and by that way calculating both the electron and phonon response. There is a good agreement between the experimental results and the applied model. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence, Raman scattering and vertical transport of CdSe/CdMgSe superlattices
Authors: Reshina I. I. , Ivanov S. V. , Mirlin D. N. , Sedova I. V. , Sorokin S. V. 
Published: March 2006

AbstractPhotoluminescence and photoluminescence excitation spectra, vertical transport of photoexcited charge carriers and excitons and Raman scattering by optical phonons have been studied for the first time in low‐strained superlattices CdSe/CdMgSe grown by molecular‐beam epitaxy on InAs substrates. The vertical transport was studied by purely optical means involving an enlarged quantum well built into the superlattice. The enlarged quantum well served as a sink for the photoexcited carriers and excitons that have tunnelled through the superlattice. The measurements conducted in temperature range 2–150 K and also under in‐plane strong magnetic fields show that vertical transport occurs mainly by free heavy‐hole excitons but in superlattices with 5.9 nm and 7.3 nm periods it is not of the Bloch type. A comparison of the calculated energies of the interband transitions with the experimental data provides the valence‐band ofsett in the range 0.4–0.5. The Raman spectra indicate a two‐mode behavior of the optical phonons in CdMgSe barriers. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Shorter wavelength intersubband absorption down to λ = 1.55 µm in (CdS/ZnSe)/BeTe type‐II superlattices
Authors: Li B. S. , Akimoto R. , Akita K. , Hasama T. 
Published: March 2006

AbstractWe first present the dependence of intersubband transition (ISB‐T) on the electronic doping density in (CdS/ZnSe)/BeTe superlattices (SLs). The in situ RHEED and X‐ray diffraction measurements reveal these SLs with perfect structure. An ISB‐T energy as high as 0.787 eV is observed in this structure. The intensity of ISB absorption increases with increasing ZnCl2 flux until reaches a maximum and then decreases with further more ZnCl2 flux supplying. The ISB‐T energy slightly red shifts from 0.787 to 0.775 eV with ZnCl2 flux increasing and then blue shifts to 0.785 eV when the intensity of ISB decreases with more chlorine doping. Finially, The anneal effects on the properties in (CdS/ZnSe)/BeTe as well as CdS/ZnSe structures are studied. The explanations to result in the change in (CdS/ZnSe)/BeTe and CdS/ZnSe structures are given. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)