bluuebunny/crossref_metadata_2025 huggingface dataset:
The Low-temperature Initial Oxidation Stages of Cu(100) Investigated by in situ Ultra-high-vacuum Transmission Electron Microscopy
Authors: Sun L. , Yang J.C.
Published: July 2005

The nucleation and growth of Cu2O islands due to Cu(100) oxidation at temperatures from 200 to 350 °C have been observed by in situ ultra-high-vacuum transmission electron microscopy. For this temperature range, epitaxial Cu2O islands form a triangular shape with rounded edges when Cu(100) is exposed to dry oxygen at 5 × 10−4 Torr in situ. Our initial analysis on the nucleation and growth of these three-dimensional Cu2O islands agrees well with the heteroepitaxial model of surface diffusion of oxygen.
Evaluation of criteria used to assess the quality of aquatic toxicity data
Authors: Hobbs Dustin A. , Warne Michael St. J. , Markich Scott J. , Hobbs Dustin A.
Published: July 2005

Good quality toxicity data underpins robust hazard and risk assessments in aquatic systems and the derivation of water quality guidelines for ecosystems. Hence, an objective scheme to assess the quality of toxicity data forms an important part of this process. The variation of scores from 2 research papers using the Australasian ecotoxicity database (AED) quality assessment scheme was evaluated by 23 ecotoxicologists. The results showed that the quality class that the assessors gave each paper varied by less than 10% when compared with a quality score agreed a priori between the authors of this study. It was determined that the majority of the variation in each assessment was due to ambiguous or poorly written assessment criteria, information that was difficult to find, or information in the paper that was overlooked by the assessor. This led to refinements of the assessment criteria in the AED, which resulted in a 16% improvement (i.e., reduction) in the mean variation of scores for the 2 papers when compared with the a priori scores. The improvement in consensus among different assessors evaluating the same research papers suggests that the data quality assessment scheme proposed in this article provides a more robust scheme for assessing the quality of aquatic toxicity data than methods currently available.
Soil type-specific environmental quality standards for zinc in dutch soil
Authors: Bos Rudy , Huijbregts Mark , Peijnenburg Willie
Published: July 2005

The heavy metal zinc is an element of natural origin. Adverse effects of chemicals on soil ecosystems depend on the soil type. Therefore, soil type-specific variation in natural background concentration and toxicity data should be taken into account in the derivation of environmental quality standards for zinc. In this paper, a methodology is presented, taking the specific features of natural occurrence and soil type into account by deriving soil type-specific background concentrations as well as soil type-specific maximum permissible additions (MPAs) for zinc in Dutch soil. The strategy used to perform a soil type-specific risk assessment for zinc consisted of 6 steps: identification of soil types, determination of characteristic background concentrations, selection of characteristic organisms, determination of no-observed-effect concentrations (NOECs), and derivations of the MPA and the maximum permissible concentration (MPC). Differences in background concentrations between different Dutch soil types were up to a factor of 7.5, whereas the MPA between the soil types varied by up to a factor of 3. This resulted in MPCs for the 3 predominant soil types that vary from 44 mg/kg dry weight (dry wt) to 208 mg/kg dry wt. Although large differences in MPC were observed, the uncertainties in background concentrations hinder setting more accurate environmental quality standards for zinc. Additional measurements on remote background concentrations of zinc in Dutch soil are needed to reduce the uncertainties in the calculated MPCs. The risk assessment approach discussed here is widely applicable to naturally occurring and anthropogenic substances.
Risk of tumorigenesis in overgrowth syndromes: A comprehensive review
Authors: Lapunzina Pablo
Published: July 2005

Overgrowth syndromes (OGS) comprise a heterogeneous group of disorders in which the main characteristic is that either weight, height, or head circumference is 2–3 standard deviations (SD) above the mean for sex and age. A striking feature of OGS is the risk of neoplasms. Here, the relative frequency of specific tumors in each OGS, topographic location, and age of appearance is determined by reviewing published cases. In some OGS (Perlman, Beckwith‐Wiedemann, and Simpson‐Golabi‐Behmel syndromes and hemihyperplasia) more than 94% of tumors appeared in the abdomen usually before 10 years of age, mainly embryonal in type. In Perlman syndrome, only Wilms tumor has been recorded, whereas in Sotos syndrome, lympho‐hematologic tumors are most frequent. Based on literature review, a specific schedule protocol for tumor screening is suggested for each OGS. A schedule with different intervals and specific tests is proposed for a more rational cost/benefit program for these disorders. © 2005 Wiley‐Liss, Inc.
Effects of reactive low‐profile additives on the properties of cured unsaturated polyester resins. I. Volume shrinkage and internal pigmentability
Authors: Dong Jyh‐Ping , Lee Jeng‐Huei , Lai Duen‐Horng , Huang Yan‐Jyi
Published: July 2005

The effects of reactive poly(methyl methacrylate) (PMMA) and poly(vinyl acetate)‐block‐PMMA as low‐profile additives (LPAs) on the volume shrinkage characteristics and internal pigmentability for low‐shrink unsaturated polyester (UP) resins during curing at 110°C were investigated. These reactive LPAs, which contained peroxide linkages in their backbones, were synthesized by suspension polymerization with polymeric peroxides as initiators. Depending on the LPA composition and molecular weight, the reactive LPAs led to a considerable volume reduction or even to a volume expansion after the curing of styrene (ST)/UP/LPA ternary systems; this was attributed mainly to the expansion effects of the LPAs on the ST‐crosslinked polyester microgel structures caused by the reduction in the cyclization reaction of the UP resin during curing as well as to the repulsive forces between the chain segments of UP and LPAs within the microgel structures. The experimental results were explained by an integrated approach of measurements for the static phase characteristics of the ST/UP/LPA system, reaction kinetics, cured sample morphology, and microvoid formation with differential scanning calorimetry, scanning electron microscopy, optical microscopy, and image analysis. With the aid of the Takayanagi mechanical model, the factors leading to both a good volume shrinkage control and acceptable internal pigmentability for the molded parts were also explored. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 264–275, 2005
Structural properties of sodium ion implanted poly(vinyl alcohol) films
Authors: Bhat Narendra V. , Nate Mandar M. , Bambole Vaishali A. , Kurup M. B.
Published: July 2005

Poly(vinyl alcohol) (PVA) films were implanted with sodium ions at various energies and total doses. Modified films were characterized by Fourier transform IR (FTIR), UV–visible (UV–vis), X‐ray diffraction (XRD), and scanning electron microscopy (SEM). From FTIR studies, it was evident that scission of the main chain occurred together with removal of hydrogen and hydroxyl groups. Sodium ions formed weak bonds with oxygen from the neighboring chains. UV–vis studies of implanted PVA showed increases in the absorbance values with the various energies and total doses. XRD studies revealed that, as the energy and total dose increased overall, the crystallinity decreased and new peaks at different 2θ values appeared. Changes in the crystallinity were also studied for thermally annealed PVA films in order to correlate and understand the phenomena of recrystallization due to ion implantation. The morphological features of the films were investigated by SEM. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 276–283, 2005
Physical, mechanical, and thermal properties of polyurethanes based on hydroxyalkylated cardanol–formaldehyde resins
Authors: Mythili C. V. , Malar Retna A. , Gopalakrishnan S.
Published: July 2005

Polyurethanes are synthesized using three different hydroxyalkylated cardanol–formaldehyde resins, diphenylmethane diisocyanate (MDI), and a commercial polyol (PPG‐2000). These polyurethanes are found to be tough and crosslinked. A polyurethane prepared using a higher mole ratio of cardanol/formaldehyde of hydroxyalkylated cardanol–formaldehyde resin is found to possess better thermal and mechanical properties than the polyurethane prepared from a lower mole ratio. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 284–288, 2005
Studies on the poly(styrene‐b‐butadiene‐b‐styrene)/clay nanocomposites prepared by melt intercalation
Authors: Xu Hongde , Li Yang , Yu Dingsheng
Published: July 2005

Two types of SBS/OMMT composites are prepared by melt blending using a twin‐screw extruder. An X‐ray diffractometer indicates that polymer chains have intercalated into the gallery of the clay. It is shown in TEM photos that the thickness of the layer aggregate in the SBS1301 matrix is approximately 200 Å, but in the SBS4402 matrix the size of the filler particle is in micrometers. When SBS1301 is intermingled into SBS4402/OMMT, the particle size is reduced obviously. The tensile strength and elongation at break of the nanocomposite, SBS1301/OMMT, increase with the addition of OMMT; and when addition is 5phr, they achieve maximum. A small content of OMMT (less than 5phr) can prevent the deterioration of the mechanical properties of the SBS1301/MMT. In addition, a small content of SBS4402 (less than 20 wt %) can improve the mechanical properties of the SBS1301/OMMT composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 146–152, 2005
Theoretical and experimental analysis of interfacial instabilities in coextrusion flows
Authors: Zatloukal M. , Kopytko W. , Lengálová A. , Vlček J.
Published: July 2005

Interfacial instabilities developed during two‐layer flows of LDPE melts were investigated theoretically through viscoelastic FEM analysis as well as experimentally on a flat multi‐manifold coextrusion die. During continuous reduction of the minor layer, the wave type appears in the film first whereas the zig‐zag type is only visible later, at the much thinner minor layer, which is an opposite order compared to film blowing coextrusion. Moreover, extensional viscosity of the minor layer was found to play a significant role from the interfacial instability point of view. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 153–162, 2005
Sorption/diffusion of aqueous mixtures of 1,4‐dioxane/tetrahydrofuran through blend membranes of poly(vinyl alcohol) and sodium alginate: Their compatibility and pervaporation separation studies
Authors: Kurkuri M. D. , Nayak J. N. , Aralaguppi M. I. , Naidu B. V. K. , Aminabhavi T. M.
Published: July 2005

Blend membranes of poly(vinyl alcohol) (PVA) and sodium alginate (NaAlg) were prepared by solution casting and crosslinked with glutaraldehyde (GA). Polymer blend compatibility was studied in water by measuring solution viscosity at 30°C. From the viscosity data, interaction parameters were determined to find the blend compatibility. Thickness of the membranes ranged between 35 and 40 μm. Circular disc‐shaped samples were cut from the thin membranes to perform gravimetric sorption experiments in water + 1,4‐dioxane and water + tetrahydrofuran mixtures at 30°C. Diffusion coefficients were calculated using Fick's equation. Concentration profiles of liquids were computed by solving Fick's equation under suitable boundary conditions. Diffusion coefficients show a dependence on the composition of the blends as well as composition of binary mixtures. A correlation was attempted between concentration profiles and diffusion coefficients of the transporting liquids. Degree of swelling and sorption coefficients were calculated from the gravimetric sorption data. Sorption kinetics was studied using an empirical equation to understand the nature of sorption–diffusion anomalies. Membrane selectivity for water + 1,4‐dioxane and water + tetrahydrofuran mixtures were calculated from the pervaporation experiments. A correlation between sorption and membrane selectivity was attempted. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 178–188, 2005
Influence of the reaction conditions on the solid‐state graft copolymerization of methyl methacrylate and polyethylene/polypropylene in situ alloys
Authors: Fu Zhi‐Sheng , Xu Jun‐Ting , Jiang Guo‐Xin , Zhang Yan‐Zhong , Fan Zhi‐Qiang
Published: July 2005

Graft copolymers of poly(methyl methacrylate) (PMMA) with spherical, high‐porosity polyethylene (PE)/polypropylene (PP) in situ alloys were synthesized by a solid‐state reaction. The effects of the amount of the free‐radical initiator, the feed ratio of the methyl methacrylate (MMA) monomer, the reaction temperature, and the composition of the alloys on the grafting degree of PMMA were studied. A greater amount of the initiator and a higher reaction temperature led to a higher grafting degree. The grafting degree first increased with the feed ratio of MMA but leveled off at a higher feed ratio. The obtained graft copolymer was fractionated by temperature gradient extraction fractionation into six fractions, and each fraction was characterized by Fourier transform infrared and differential scanning calorimetry. The structures of these fractions were ungrafted ethylene–propylene random copolymers and ethylene–propylene segmented copolymers, ethylene–propylene block copolymers having PE and PP segments of different lengths and grafted by PMMA, PP grafted by PMMA, and nearly pure PP. Most PMMA was grafted on propylene segments, and thus the grafting degree decreased as the content of ethylene units in the alloys increased. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 195–202, 2005
Effects of the oxidation temperature on the structure and properties of polyacrylonitrile‐based activated carbon hollow fiber
Authors: Sun Junfen , Wang Qingrui
Published: July 2005

Polyacrylonitrile (PAN) hollow fibers were pretreated with ammonium dibasic phosphate, oxidized in air, carbonized in nitrogen, and activated with carbon dioxide. The effects of the oxidation temperature of the PAN hollow fiber precursor on the microstructure, specific surface, pore size distribution, and adsorption properties of PAN‐based activated carbon hollow fiber (PAN‐ACHF) were studied. When PAN hollow fibers were oxidized at 270°C, because of drastic oxidation, chain scission occurred, and the number of pores within and on the surface of the resultant PAN‐ACHF increased, but the pores were just in the thinner region of the skin of PAN‐ACHF. The surface area of PAN‐ACHF reached a maximum when the oxidation temperature was 270°C. The adsorption ratios to creatinine were all higher than 90% at all oxidation temperatures, and the adsorption ratio to VB12 reached a maximum (97%) at 230°C. The dominant pore sizes of the mesopores in PAN‐ACHF ranged from 2 to 5 nm. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 203–207, 2005
Synthesis and characterization of low‐molecular‐weight hydrogenated polybutadiene‐b‐poly(ethylene glycol) block copolymers
Authors: Xu Jun‐Ting , Jin Wei , Fan Zhi‐Qiang
Published: July 2005

Low‐molecular‐weight hydrogenated polybutadiene‐b‐poly(ethylene glycol) (HPBd‐b‐PEG) block copolymers with double crystallizable blocks were synthesized by the coupling of hydroxyl‐end‐group‐containing hydrogenated polybutadiene and poly(ethylene glycol) with terephthaloyl chloride as a coupling reagent. The block structure was confirmed by 1H‐NMR, and the molecular weights of the blocks were determined as well. Gel permeation chromatography showed that the HPBd‐b‐PEG block copolymers had narrow molecular weight distributions. The crystallization and superstructures of the HPBd‐b‐PEG block copolymers were studied with differential scanning calorimetry, wide‐angle X‐ray diffraction (WAXD), and polarized optical microscopy. The results revealed that the crystallization of both blocks was suppressed mutually, especially for the shorter block. WAXD patterns showed that the crystal structures remained unchanged for both blocks. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 208–215, 2005
Preparation and characterization of linear low‐density polyethylene/low‐density polyethylene/TiO2 membranes
Authors: Wang Xuyun , Wang Zhaobo , Wang Xin
Published: July 2005

Because of their special functions, the application of nanoscale powders has recently attracted both industrial and theoretical interest. In this study, nanoscale TiO2, which exhibited a special UV absorption and consequent antibacterial function, was added to a low‐density polyethylene/linear low‐density polyethylene hybrid by melt compounding to yield functional composite membranes. TiO2 exhibited an apparent induced nucleation effect on the crystallization of polyethylene, and the size of the crystallites decreased while the number increaed with the introduction of TiO2; however, the crystallinity of polyethylene changed little. Also, TiO2 exhibited an ideal dispersion in the membrane with an average size less than 100 nm, and this excellent dispersion provided the membranes extra UV absorption; moreover, the transparency of the membranes was maintained to satisfy common requirements. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 216–221, 2005
New method for preparing polybutadiene rubber/clay composites
Authors: Wang Shaohui , Zhang Yong , Peng Zonglin , Zhang Yinxi
Published: July 2005

Polybutadiene rubber (BR)/clay/dimethyl dihydrogenatetallow ammonium chloride (DDAC) composites were prepared by a new preparation method named in situ organic modification. That is, BR, pristine clay, and quaternary ammonium salt were directly melt‐mixed without the usual pretreatment of the pristine clay with an intercalatant. BR/pristine clay, BR/organoclay DK4 (modified with DDAC), and BR/clay/DDAC composites were analyzed with X‐ray diffraction, scanning electron microscopy, and thermogravimetric analysis. The vulcanization characteristics and mechanical properties of the BR/pristine clay, BR/DK4, and BR/clay/DDAC composites were investigated. Finally, the effects of the processing conditions, clay/DDAC ratio, and clay content on the structure and properties of the BR/clay/DDAC composites were investigated. The results showed that intercalated BR/clay/DDAC composites were prepared. Organoclay DK4 and clay/DDAC effectively accelerated the vulcanization reaction of BR, which was attributed to the existence of the intercalatant used to modify the clay. The tensile strength, elongation at break, and tear strength of the BR/clay/DDAC vulcanizates were greatly improved in comparison with those of gum BR and BR/pristine clay vulcanizates but were somewhat lower than those of BR/DK4 vulcanizates. The dispersion of clay particles in the BR/clay/DDAC and BR/DK4 composites was much better than that in the BR/pristine clay composite. The temperature at the thermal degradation peak of the BR/clay/DDAC composite obviously increased in comparison with those of the gum BR, BR/clay and BR/DK4 composites. The mixing temperature and rotor speed had remarkable effects on the structure and properties of the BR/clay/DDAC composite. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 227–237, 2005
Composition distributions of different particles of a polypropylene/poly(ethylene‐co‐propylene) in situ alloy analyzed by temperature‐rising elution fractionation
Authors: Xu Jun‐Ting , Jin Wei , Fu Zhi‐Sheng , Fan Zhi‐Qiang
Published: July 2005

Fragmentation was observed in the polymerization process for the preparation of a polypropylene (PP)/poly(ethylene‐co‐propylene) (EPR) in situ alloy. Composition distributions of different polymer particles were analyzed by preparative temperature‐rising elution fractionation. The fractions eluted at room temperature and 96, 110, and 117°C were selected for 13C‐NMR characterization. There was more propylene homopolymer and ethylene–propylene block copolymer in the large particles, whereas the small particles contained more ethylene–propylene random copolymer and copolymer with a transition microstructure. On the basis of the formation mechanism of various components in the PP/EPR alloy, we inferred that the fragmentation of the polymer particles mainly took place in the copolymerization step. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 243–246, 2005
Parsing the public domain
Authors: Maxwell Terrence A.
Published: July 2005

This article explores the use of the term public domain in the American context and finds that the symbol is subject to multiple meanings. Using historical and content analysis, the analysis explores the various uses of the term and provides a preliminary taxonomy for subsequent analysis and theory building. In conclusion, it suggests that more coherent information policies regarding national and international information access, creativity, governance, and private property rights will require a better understanding and delineation of the use of public domain in legislative and common practice.
Structural properties of polyC–scleroglucan complexes
Authors: Sletmoen Marit , Stokke Bjørn T.
Published: July 2005

Successive changes of solvent conditions can be used to dissociate and reassociate the triple‐helical structure of (1,3)‐β‐D‐glucans. Ultramicroscopic techniques have revealed a blend of circular and other structures following renaturation. When this solvent exchange process is carried out in the presence of certain polynucleotides, the process creates a novel macromolecular complex. Here, we use size exclusion chromatography (SEC) to study such (1,3)‐β‐D‐glucan‐polynucleotide complexes. Online multiangle laser‐light scattering (MALLS) and refractive index (RI) detectors allowed determination of molecular weight and radius of gyration of the molecules. An ultraviolet (UV) detector allowed specific detection of the polynucleotide. The poly‐cytidylic acid (polyC) shifted to coelution with the linear fraction of the scleroglucan following the renaturation of polyC–scleroglucan blends, indicating that polyC is incorporated in linear, but not in circular, structures of scleroglucan. This conclusion was consistent with AFM topographs that revealed a decreased fraction of circular structures upon addition of polyC during the renaturation process. The combined information about radius of gyration (Rg) and molecular weight (Mw) allowed us to conclude that the polyC–scleroglucan complexes are more dense and have a higher persistence length than linear scleroglucan triple helixes. The experimentally determined mass per unit length was used as a basis for elucidating possible molecular arrangements within the polyC–scleroglucan complex. © 2005 Wiley Periodicals, Inc. Biopolymers 79: 115–127, 2005

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Highly Productive Autocondensation and Transglycosylation Reactions with Sulfolobus solfataricus Glycosynthase
Authors: Trincone Antonio , Giordano Assunta , Perugino Giuseppe , Rossi Mosè , Moracci Marco
Published: July 2005

Transglycosylation reactions (autocondensation of the substrate or transfer of the glycon donor moiety to different acceptors) with the hyperthermophilic glycosynthase from Sulfolobus solfataricus acting in dilute sodium formate buffer at pH 4.0 are reported; the use of 4‐nitrophenyl β‐glucopyranoside as both donor and acceptor in the self‐transfer reaction and a highly productive reaction with 1.1 M 2‐nitrophenyl β‐glucopyranoside were possible. Interesting effects, governed by the anomeric configuration and lipophilicity of heteroacceptors, on the regioselectivity and yield of reactions were found for the first time with this enzyme and are discussed. The results demonstrate the unexplored synthetic potential of this glycosynthase; the tuning of the reaction conditions and the choice of different donors/acceptors can lead to products of applicative interest.
Multiparameter Imaging for the Analysis of Intracellular Signaling
Authors: Schultz Carsten , Schleifenbaum Andreas , Goedhart Joachim , Gadella Theodorus W. J.
Published: July 2005

In biological experimentation and especially in drug discovery there is a trend towards more complex test systems. Cell‐based assays are replacing conventional binding or enzyme assays more and more. This development is strongly driven by novel fluorescent probes that give insight into cellular processes. Target proteins are studied in their natural environment; this gives much more realistic test results, especially with respect to enzyme location and kinetics. However, in the complex environment of cells, many parameters contribute to the performance of the protein of interest. Therefore, it would be desirable to monitor simultaneously as many of the relevant cellular processes as possible. Here, we discuss the possibilities and limitations provided by multiparameter monitoring of cellular events with fluorescent probes. Some novel examples of the use of fluorescent probes and multiparameter imaging are shown.
Mechanism‐Based Fluorescent Reporter for Protein Kinase A Detection
Authors: Law Benedict , Weissleder Ralph , Tung Ching‐Hsuan
Published: July 2005

A novel mechanism‐based fluorescent reporter was designed for the detection of protein kinase A (PKA), which is known to mediate a variety of cellular responses in most eukaryotic cells. The probe consists of a specific binding peptide sequence, LRRRRFAFC, conjugated with 2′‐thioethyl‐5‐(or ‐6)‐carboxyfluoresceinamide (FAMS; 2) and 5‐(or 6‐)carboxytetramethylrhodamine (TAMRA) at the cysteine and leucine residues, respectively. In the absence of PKA, the two fluorophores associate by hydrophobic interactions, forming an intramolecular ground‐state dimer; this results in fluorescein quenching (>93 %). Upon PKA addition, the reporter reacts with the sulfhydryl functionality at Cys199 through a disulfide‐exchange mechanism. FAMS is subsequently released, resulting in significant fluorescence amplification. The remaining peptide sequence, which acts as an inhibitor, is attached covalently to the enzyme. Our results suggest that this type of sensors could have far‐reaching applications in the molecular sensing of enzymes.
Surface‐Grafted Multiporphyrin Arrays as Light‐Harvesting Antennae to Amplify Photocurrent Generation
Authors: Morisue Mitsuhiko , Yamatsu Shigeru , Haruta Noriko , Kobuke Yoshiaki
Published: July 2005

Organized multiporphyrin arrays were developed on the conductive surface by a novel coordination‐directed molecular architecture aiming at efficient photoelectric conversion. The basic strategy employs the mutual coordination of two imidazolylporphyrinatozinc(II) units to form a cofacial dimer. Thus, meso,meso‐linked bis(imidazolylporphyrinatozinc) (Zn2(ImP)2) was organized onto imidazolylporphyrinatozinc on the gold substrate as a self‐assembled monolayer. The organized Zn2(ImP)2 bearing allyl side chains was covalently linked by ring‐closing olefin metathesis catalyzed with Grubbs catalyst. Alternating coordination/metathesis reactions allow the stepwise accumulation of multiporphyrin arrays on the gold electrode. A successive increase in absorption over a wide wavelength range occurred after each accumulation step of Zn2(ImP)2 on the gold electrode, and cathodic photocurrent generation was enhanced in the aqueous electrolyte system, containing viologen as an electron carrier. The significant increase of the photocurrent indicates that the multiporphyrin array works as a “light‐harvesting antenna” on the gold electrode.
A Multinuclear NMR Relaxometry Study of Ternary Adducts Formed between Heptadentate GdIII Chelates and L‐Lactate
Authors: Terreno Enzo , Botta Mauro , Boniforte Patrizia , Bracco Chiara , Milone Luciano , Mondino Bruna , Uggeri Fulvio , Aime Silvio
Published: July 2005

Dramatic relaxation enhancements of L‐lactate resonances have been observed upon formation of ternary adducts with GdIII complexes of heptadentate DO3A and DO3A‐like ligands (DO3A=1,4,7,10‐tetraazaciclododecane‐1,4,7‐triacetic acid). Detailed 1H and 17O NMR relaxometry investigations allow us to obtain structural, dynamic and thermodynamic information on the ternary complexes in which L‐lactate acts as a bidentate ligand replacing two water molecules in the inner coordination sphere of the GdIII ion. It has been found that the exchange rate of the coordinated L‐lactate is modulated by the structural and electronic properties of the parent Gd‐heptacoordinated macrocyclic chelate. In addition to the characterisation of the relaxation behaviour of the 1H methyl resonance of L‐lactate, this study has been extended to its 13C isomer (fully enriched at the three positions) and to the trifluoro‐L‐lactate. The obtained results may be relevant to the development of relaxation agents able to promote the relaxation enhancement of specific substrates detectable by in vivo magnetic resonance spectroscopy.
On the Oxidation of Gallium and Indium: Characterization of the Cyclic and Linear GaO2 and InO2 Molecules Generated by the Spontaneous and Photoinduced Reaction of Ga and In Atoms with O2 and Determination of the Reaction Mechanism
Authors: Köhn Andreas , Gaertner Benjamin , Himmel Hans‐Jörg
Published: July 2005

In this work, the spontaneous and photolytically activated reactions of Ga and In atoms (M) with O2 (in Ar and solid O2) are studied with the aid of the matrix‐isolation technique and the use of IR, Raman, and UV/Vis spectroscopy in combination with detailed quantum‐chemical calculations. Vibrational spectra were recorded for several different isotopomers (69Ga, 71Ga, 16O2, 18O2, 16O18O). The results show that the spontaneously formed cyclic MO2 molecules photoisomerize to give the linear OMO molecules. The collected vibrational data were then used to characterize the bond properties of the linear OMO molecules in detail. The results are compared to those obtained for CO2+ and neutral OEO compounds, where E is an element of Group 14. Quantum‐chemical calculations were carried out at various levels of theory for GaO2. These calculations indicate that linear OMO is slightly more stable than its cyclic isomer. These calculations were also used to obtain information about the reaction mechanism, and show that the formation of the cyclic isomer from Ga atoms and O2 occurs without a significant barrier. Abrupt changes of the dipole moment and the OO bond length during the approach of the O2 molecule toward the Ga atom mark the point on the potential energy surface at which one electron jumps from the Ga atom onto the O2 unit. The isomerization of cyclic GaO2 to the linear global minimum structure is accompanied by a significant barrier, which explains why this reaction requires photoactivation.
Chelation‐Controlled Radical Chain Reactions Studied by Electrospray Ionization Mass Spectrometry
Authors: Fürmeier Sven , Griep‐Raming Jens , Hayen Ahlke , Metzger Jürgen O.
Published: July 2005

Electrospray ionization mass spectrometry (ESI‐MS) is a novel tool for the investigation of chemical reactions in solution and for the direct detection and identification of reactive intermediates. The tributyltin hydride mediated addition of tert‐butyl iodide to dimethyl 2‐cyclohexyl‐4‐methyleneglutarate (2) in the presence of Lewis acids was investigated by ESI‐MS using a microreactor coupled on‐line to an ESI mass spectrometer. For the first time we have been able to show that transient radicals in radical chain reactions can be detected unambiguously under steady‐state conditions in the reaction solution and can be characterized by ESI‐MS/MS and accurate mass determination. The detection of different heterodimer radical complexes by ESI‐MS/MS has provided new insights into the mechanism of Lewis acid controlled radical chain reactions. Dimeric chelate complexes of glutarates, such as 2 and 3, and Lewis acids, like Sc(OTf)3, MgBr2⋅OEt2 and LiClO4, were observed as well as higher aggregates with additional equivalents of Lewis acid. Evidence for a dynamic equilibrium of the complexes in solution was found by NMR spectroscopy. The ESI‐MS investigation of the chelation of glutarate 2 with various Lewis acids has led to the conclusion that the tendency for Lewis acids to form dimeric chelate complexes and higher aggregates has an important effect on the stereoselective outcome of the radical reactions.
Synthesis of a Dimeric Lewis Antigen and the Evaluation of the Epitope Specificity of Antibodies Elicited in Mice
Authors: Buskas Therese , Li Yanhong , Boons Geert‐Jan
Published: July 2005

The Lewisy–Lewisx heptasaccharide, modified by an artificial aminopropyl spacer, was synthesized by an approach that employed two orthogonally protected lactosamine building blocks. A p‐(benzoyl)‐benzyl glycoside was used as a novel anomeric protecting group, which could be selectively removed at a late stage in the synthesis, thus offering the benefit of enhanced flexibility. The artificial aminopropyl moiety was modified by a thioacetyl group, which allowed an efficient conjugation to keyhole limpet hemocyanin (KLH) that had been activated with electrophilic 3‐(bromoacetamido)‐propionyl groups. Mice were immunized with the LeyLex–BrAc–KLH antigen. Analysis of the sera by ELISA established that a strong helper T‐cell immune response was raised against the LeyLex saccharide. Further ELISA analysis showed that the titer for monomeric Ley tetrasaccharide was tenfold lower whereas recognition of the Lex trisaccharide was negligible.
Interaction of Ru(II) Complex with Yeast tRNA Studied by Isothermal Titration Calorimetry
Authors: Hong Xu , Jian‐Hong Liu , Zhi‐Gang Liu , Yi Liang , Peng Zhang , Fen Du , Bing‐Rui Zhou , Liang‐Nian Ji
Published: July 2005

The interaction of metal complex with RNA has been studied by isothermal titration calorimetry (ITC) for the first time. ITC experiments show that complex [Ru(phen)2MPIP]2+ {phen=1,10‐phenanthroline, MPIP=2‐(4‐methylphenyl)imidazo[4,5‐f]‐1,10‐phenanthroline} interacts with yeast tRNA in terms of a model for a single set of identical sites through intercalation, which is consistent with our previous observation obtained from spectroscopic methods, and this binding process was driven by a moderately favorable enthalpy decrease in combination with a moderately favorable entropy increase, suggesting that ITC is an effective method for deep studying the interactions of metal complexes with RNA.
Effect of Comonomer Ethylene on Plateau Modulus of Crystal‐line Ethylene‐propylene Random Copolymer with Broad Molecular Weight Distribution
Authors: Jian Ding , Ri‐Wei Xu , Xue‐Jia Ding , Ding‐Sheng Yu
Published: July 2005

Ethylene‐propylene random copolymer with ultra‐high molecular weight (UHPPR) and broad molecular weight distribution (MWD) was prepared with Ziegler‐Natta catalyst. The viscoelastic behavior of UHPPR has been investigated by means of oscillatory rheometer at 180, 200 and 220 °C. The loss modulus (G″ curves of 180 and 200 °C present a pronounced maximum at 38.10 and 84.70 r/s, respectively. For the first time, this makes it possible to directly determine the plateau modulus ($G^{0}_{N} $) of crystalline ethylene‐propylene random copolymer with broad MWD in a certain experimental temperature G″(ω) curve. The plateau modulus of UHPPR is 4.51×105 and 3.67×105 Pa at 180 and 200 °C respectively, increasing with random incorporation of comonomer ethylene into the molecular chains and being independent of molecular weight.
Synthesis, Characterization of Neutral Nickel Complexes Bearing N‐Fluorophenylsalicylaldimine Chelate Ligands and Their Catalytic Activity to Ethylene Oligomerization
Authors: Li‐Ping Song , Wei Zhao , Ji‐Ling Huang , Shi‐Zheng Zhu
Published: July 2005

A series of neutral nickel complexes featuring N‐fluorophenylsalicylaldimine chelate ligands was synthesized, and the molecular structure of complex 4 was further confirmed by X‐ray crystallographic analysis. The neutral nickel complexes showed high activity up to 4.22×105 g oligomers/(mol Ni·h) and high selectivity to C6 olefins in catalyzing ethylene oligomerization using methylaluminoxane (MAO) as cocatalyst.
Preparation and Characterization of Novel Choline and L‐Glutamic Acid Mixed Monolayer Covalently Modified Glassy Carbon Electrode and Its Analytical Application to Nitrite Determination
Authors: Guan‐Ping Jin , Xiang‐Qin Lin
Published: July 2005

A choline and L‐glutamic acid mixed monolayer covalently modified glassy carbon electrode (Ch‐Glu/GCE) was fabricated and characterized by X‐ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). It provided an excellent example of mixed covalent monolayer modification of carbon electrodes with alkanol and amino acid, and also a facile means for altering the interfacial architecture. The Ch‐Glu/GCE displayed good catalytic activity toward the oxidation of nitrite anions. Differential pulse voltammetry was used for determination of nitrite at the Ch‐Glu/GCE. The Ch‐Glu/GCE showed higher capability for restraint of pollutions than a simple Ch modified electrode or a simple Glu modified electrode.
Hydrolysis of p‐Nitrophenyl Picolinate Catalyzed by Mono‐ and Binuclear Transition Metal Complexes with Polyether Bridged Dihydroxamic Acid
Authors: Jian‐Zhang Li , Hong‐Bo Li , Fa‐Mei Feng , Jia‐Qing Xie , Shen‐Xin Li , Bo Zhou , Sheng‐Ying Qin
Published: July 2005

Two polyether bridged dihydroxamic acids and their mono‐ and binuclear manganese(II), zinc(II) complexes have been synthesized and employed as models to mimic hydrolase in catalytic hydrolysis of p‐nitrophenyl picolinate (PNPP). The reaction kinetics and the mechanism of hydrolysis of PNPP have been investigated. The kinetic mathematical model for PNPP cleaved by the complexes has been proposed. The effects of the different central metal ion, mono‐ and binuclear metal, the pseudo‐macrocyclic polyether constructed by polyethoxy group of the complexes, and reactive temperature on the rate for catalytic hydrolysis of PNPP have been examined. The results showed that the transition metal dihydroxamates exhibited high catalytic activity to the hydrolysis of PNPP, the catalytic activity of binuclear complexes was higher than that of mononuclear ones, and the pseudo‐macrocyclic polyether might synergetically activate H2O coordinated to metal ion with central metal ion together and promote the catalytic hydrolysis of PNPP.
Effect of Al2O3 on the Structure and Photoluminescence Properties of Sol‐gel Glass Doped with Rare Earth Organic Complex
Authors: Jing Xiao , Gui‐Jun Fu , Han‐Xing Liu , Shi‐Xi Ouyang
Published: July 2005

Both silica glass materials singly doped with rare earth organic complex and co‐doped with Al3+ were prepared by in situ sol‐gel method respectively. XRD and SEM measurements were performed to verify the non‐crystalline structure of the glass. The excitation spectra, emission spectra and IR spectra were measured to analyze the influence of the glass contents on the structure of the glass and the energy level of the doped Eu(III) ions. The effect of Al3+ on the photoluminescence properties of rare earth organic complex in silica glass was investigated. The IR spectra indicated that the in situ synthesized europium complex molecule was confined to the micropores of the host and the vibration of the ligands was frozen. When Al2O3 was doped into the silica host gel, the rare earth ions in the silica network were wrapped up and dispersed by Al2O3, so the distribution of Eu(III) complex in the host was more homogeneous, and the luminescence intensity of 5D0‐7F2 transition emission of the Eu3+ ions was improved. The results showed that an appropriate amount of Al3+ added to the gel glass improved the emission intensity of the complex in the silica glass, and when the content of Al2O3 reached 4 mol%, the maximum emission intensity could be obtained compared with that of other samples containing different Al2O3 contents.
Fully Accessible Ag Nanoparticles within Three‐dimensionally Ordered Macroporous SiO2
Authors: Quan‐Zhou Wu , Qiang Yin , Ju‐Fang Liao , Jing‐Heng Deng , Yu‐Guang Li
Published: July 2005

A multi‐step process was used for preparation of three‐dimensionally ordered macroporous (3DOM) SiO2, in which fully accessible Ag nanoparticles are incorporated. The method involves the processes of assembly of polystyrene colloidal crystal, preparation of 3DOM SiO2, and incorporation of Ag nanoparticles within 3DOM SiO2 through in situ Tollens' reaction. XRD, SEM and EDXS determination show that the Ag particles deposited on the macroporous walls in nano dimension. The results indicate that lower concentration of silver ammoniate and formaldehyde in the solution is favorable for forming a very narrow size distribution and uniform shape of nanoparticles. However, the higher the concentration of the solution and the more the loading times, the larger the possibility to form un‐uniform particles. Ag nanoparticles can be sintered into larger and spheral particles by calcination at 600 °C, but can resist sintering owing to their high dispersivity when loading amount is small. The study provided a simple approach to tailor Ag/3DOM SiO2 composite materials with desired morphology and size of Ag particles within the macropores.
Electrical Properties and Dilatometric Measurements of La2Mo2O9under Low Oxygen Partial Pressure
Authors: Tian Xia , Jia‐Yan Li , Xin Luo , Qin Li , Jian Meng , Xue‐Qiang Cao
Published: July 2005

The electrical conductivity and thermal expansion of La2Mo2O9under low oxygen partial pressure were studied with the help of thermoelectric power and dilatometric measurements, respectively. The ionic conduction of La2Mo2O9was predominant with the electronic transference number less than 0.05 above an oxygen partial pressure of aboutp=10‐7Pa at 700°C, and below this pressure the electronic conduction became obvious. The defect reaction and small polaron hopping among molybdenum sites were proposed to explain the electronic conduction. Accompanying the phase transition, there was a sharp increase of thermal expansion, which became more serious under low oxygen partial pressure. The substitution of lanthanum by neodymium led to the increase of electrical conductivity but the decrease of phase stability.
Two Novel μ‐Oxo Diiron(III) Schiff Base Complexes: X‐ray Diffraction Analyses, IR, UV‐Vis, CD spectra, Magnetic Susceptibility and Electrochemistry
Authors: Wen‐Juan Ruan , Guo‐Hang Hu , Shu‐Jun Wang , Jian‐Hua Tian , Qing‐Lun Wang , Zhi‐Ang Zhu
Published: July 2005

The novel μ‐oxo diiron(III) Schiff base complexes, {[Fe(tbusalphn)]2(μ‐O)} (1) [tbusalphn = N,N′‐o‐pheny‐lenebis(3,5‐di‐tert‐butylsalicylideneiminato)] and {[Fe(R,R‐salchxn)]2(μ‐O)}(2) [R,R‐salchxn = N,N′‐R,R‐cyclo‐hexanebis(salicylideneiminato)] have been synthesized and characterized by elemental analyses, spectroscopy, magnetic susceptibility, electrochemical measurements and X‐ray diffraction techniques. X‐ray analyses revealed that the complex 1·CH3OH has nearly linear Fe‐O‐Fe angle of 176.5(2)° due to their steric crowding of ligands owing bulky substitute group, while fairly bent Fe‐O‐Fe angle was allowed by the reduced steric crowding of the ligands in 2·C4H6N2·0.5C2H5OH [149.6(1)°]. FT‐IR, UV‐Vis, CD spectra, magnetic susceptibility and cyclic voltammogram (CV) of complexes 1 and 2 have been further investigated.
Enthalpic Pair Interaction of Rubidium Chloride with α‐Amino Acid in Water at 298.15 K
Authors: Man‐Cheng Hu , Qian Yang , Yu‐Cheng Jiang , Shu‐Ping Xia
Published: July 2005

The mixing enthalpies of aqueous heavy rare alkali metal chloride RbCl solutions with aqueous α‐amino acid (L‐glycine, L‐alanine and α‐aminobutyric acid) solutions, as well as the dilution enthalpies of RbCl and α‐amino acid solutions in pure water had been measured at 298.15 K. The transfer enthalpies of RbCl from pure water to aqueous α‐amino acid solutions could be obtained from these data. The enthalpic pair interaction parameters of RbCl with α‐amino acid in water have been evaluated according to the McMillan‐Mayer theory and discussed in terms of the electrostatic interaction, structure interaction and Savage‐wood group additivity mode.
NaSO2Ph Induced Exclusive Isomerization of 1,2‐Allenyl Sulfoxides to 2‐Alkynylic Phenyl Sulfoxides
Authors: Chun‐Ling Fu , Sheng‐Ming Ma
Published: July 2005

The clean isomerization of 1,2‐allenyl sulfoxides in the presence of NaSO2Ph afforded 2‐alkynylic phenyl sulfoxides in good yields and selectivities. Although strong base‐catalyzed isomerization of allenes to alkynes is known, the mechanism for the current reaction is interesting for the obvious reason that NaSO2Ph is a weak base.
Study on the Reaction of Salicylic Acid with Dialkyl Phosphite by NMR and Electrospray Ionization Mass Spectrometry
Authors: Xiao‐Lan Chen , Ling‐Bo Qu , Lei Guo , Jian‐Sha Lu , Yan Liu , Jian‐Li Wu , Yu‐Fen Zhao
Published: July 2005

The reaction between salicylic acid and dialkyl phosphite was traced by electrospray ionization mass spectrometry and 31P NMR. All reactants, unstable intermediates and products were detected. The mechanism was proposed based on ESI‐MS results and 31P NMR profiles.
Crystal Structures of Two Calix[4]arene Isomers with Benzaldehyde Moiety and Their Photophysical Properties with Terbium(III) Ions
Authors: Hao Wang , Heng‐Yi Zhang , Yu Liu
Published: July 2005

Two calix[4]arene isomers with benzaldehyde moieties,i.e., 5,11,17,23‐tetra‐tert‐butyl‐25,27‐bis[2‐(o‐formyl‐phenoxy)ethoxy]‐26,28‐dihydroxycalix[4]arene (3) and 5,11,17,23‐tetra‐tert‐butyl‐25,27‐bis[2‐(p‐formylphenoxy)‐ ethoxy]‐26,28‐dihydroxycalix[4]arene (4), were synthesized according to a newly designed route in high yields, and their crystal structures have been determined by X‐ray crystallographic study. The photophysical behavior on com‐plexation of calix[4]arene derivatives3and4with terbium(III) nitrate was investigated in anhydrous acetonitrile at 25°C by UV‐Vis and fluorescence spectroscopies. The crystallographic structure of3indicated that the eight oxygen atoms formed a preorganized ionophoric cavity due to intramolecular π‐π stacking, which could encapsulate lanthanide ions tightly. In sharp contrast, the compound4formed a linear array by intermolecular π‐π stacking, hence the oxygen atoms of pendant arms could not coordinate with metal ions, giving a poor binding ability to Tb3+. The absorption spectra of3with Tb3+showed clearly a new broad intense absorption at 385 nm. Interestingly, the narrow emission line spectrum has also been observed for compound3with Tb3+, and the results obtained were discussed from the viewpoint of energy transfer mechanism between host structures and the properties of lanthanide ions.
Reaction of (Ph2N)2Sm(THF)4with Azobenzene: Synthesis, X‐ray Structure and Catalytic Behavior of [(Ph2N)(DME)Sm]2(μ‐η2:η2‐N2Ph2)2
Authors: Fu‐Gen Yuan , Xiu‐Juan Liu , Yong Zhang
Published: July 2005

Reaction of divalent (Ph2N)2Sm(THF)4with 1 equiv. of azobenzene in THF and then crystallization of the product in DME‐Et2O mixed solvent produced the complex of [(Ph2N)(DME)Sm]2(μ‐η2:η2‐N2Ph2)2(1) in 65.0% yield. In complex1, azobenzene molecules were reduced to be dianionic Ph2${\rm N}^{2-}_{2} $ligands, bridging two samarium ions in two η2:η2fashions. One samarium ion was bonded to a DME molecule and a diphenyl amido ligand besides two Ph2${\rm N}^{2-}_{2} $ligands. The unusual Ln‐η2‐arene close interaction was found for the first time for diphenyl amido lanthanides. Complex1could catalyze the polymerization of methyl methacrylate and acrylonitrile