bluuebunny/crossref_metadata_2025 huggingface dataset:
Age of onset and death in inherited prion disease are heritable
Authors: Webb T.E.F. , Whittaker J. , Collinge J. , Mead S.
Published: August 2008

The common polymorphism at codon 129 of the prion protein gene (PRNP) is known to affect prion disease susceptibility, incubation period and phenotype. Mouse quantitative trait locus (QTL) studies demonstrate multiple modifiers of incubation time unlinked to Prnp, suggesting the existence of homologous human prion disease modifiers, but direct evidence of these has been lacking. We investigated the correlation of age at onset and death, expressed as a composite Z score, between parents and offspring in three large UK inherited prion disease kindreds. Our analysis suggests that overall heritability of the composite phenotype is 0.55 (95% CI 0.35–0.75). This measure may be an underestimate of the total genetic contribution to phenotypic heterogeneity as the analysis does not incorporate the effect of PRNP‐linked modifiers. Although the confidence intervals are wide, these data suggest a significant heritable component to phenotypic variability and support attempts to identify human prion disease modifier genes which would be important in understanding the epidemiology of variant Creutzfeldt–Jakob disease (vCJD) in populations with significant exposure to bovine spongiform encephalopathy (BSE) prions. © 2008 Wiley‐Liss, Inc.
Structure–properties relations of the drawn poly(ethylene terephthalate) filament sewing thread
Authors: Rudolf Andreja , Smole Majda Sfiligoj
Published: August 2008

This article presents research into draw ratio influence on the structure–properties relationship of drawn PET filament threads. Structural modification influence due to the drawing conditions, i.e., the birefringence and filament crystallinity, on the mechanical properties was investigated, as well as the shrinkage and dynamic mechanical properties of the drawn threads. Increasing draw ratio causes a linear increase in the birefringence, degree of crystallinity, filament shrinkage, and a decrease in the loss modulus. In addition, loss tangent and glass transition temperature, determined at the loss modulus peak, were increased by drawing. The observed structural changes influence the thread's mechanical properties, i.e., the breaking tenacity, elasticity modulus, and tension at the yield point increase, while breaking extension decreases by a higher draw ratio. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Covalent immobilization of an antimicrobial peptide on poly(ethylene) film
Authors: Steven Matthew D. , Hotchkiss Joseph H.
Published: August 2008

An antimicrobial film was produced by covalently attaching synthetic peptide E14LKK to poly(ethylene) film. E14LKK is a 14 residue, magainin‐class peptide with broad‐spectrum antimicrobial activity. The poly(ethylene) surface was first oxidized with chromic/sulphuric acid, then PEGylated by using carbodiimide chemistry to attach ω‐amino‐α‐carboxyl‐poly(ethylene glycol) (PEG). The peptide was covalently coupled to the free terminus of the PEG, again using carbodiimide coupling. Surface contact angles for distilled water decreased from 101° initially to 61° following oxidation and 45° following PEGylation. Film surface chemistry showed the expected changes during the modifications: dye adsorption assays indicated changes in the number of acidic and basic groups and X‐ray photoemission spectroscopy showed increasing oxygen and nitrogen levels. Antimicrobial activity was demonstrated in broth cultures against E.coli: growth was reduced by atleast 3 log cycles compared to controls. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Grafting of acrylonitrile onto allylated caesarweed fibers by potassium permanganate – N,N′‐dimethylacetamide redox pair
Authors: Eromosele I. C. , Eromosele C. O. , Funmilayo D. O.
Published: August 2008

Caesarweed fiber, Urena lobata, was modified by successive treatment with sodium hydroxide and allylchloride in diethylether to yield an average degree of substitution of 2.73 allyl moieties per anhydroglucose unit. The presence of allyl moieties on the fiber was confirmed by infrared spectroscopy. Graft copolymerization of acrylonitrile onto the unmodified and allyl‐modified fibers was initiated by potassium permanganate –N,N′‐dimethylacetamide redox pair in aqueous medium. The allyl fiber was markedly less reactive than the unmodified fiber with graft yields for the latter a factor of 2.3 higher than those of the former. This was attributed to resonance stabilization of allylic macroradicals of the fiber. The graft yield showed positive dependence on N,N′‐dimethylacetamide concentration in the range, 9.0–45.0 × 10−4M with Pg/Pgo of up to 1.39 at the highest concentration. The conversion in graft yield was however characterized by a plateau at the latter concentration and was ascribed to termination of grafted polymer chains by methylacetylaminomethyl radical initiating species. Spectroscopic evidence in support of the latter was the absorption peak at 1680 cm−1 for the graft copolymers, characteristic of CO stretching vibration for tertiary amide. Acetic acid, at concentrations in the range 0.28–2.22M, was inimical to grafting of acrylonitrile onto allylfibre with Pg/Pgo, of less than one. Grafting onto allylfiber showed positive temperature dependence in the range, 30–50°C with calculated activation energy of 12.3 kcal mol−1 for the graft polymerization reaction. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
A novel approach for improvement of the interfacial binding of ceramics for dental materials: Chemical treatment and oxygen plasma etching
Authors: Çökeliler Dilek , Erkut Selim , Shard Alex G. , Akdoğan Ebru , Özden Nehir , İmirzalıoğlu Pervin , Mutlu Mehmet
Published: August 2008

Dental ceramic is one of the most widely used materials in the dental industry because of its extensive use in resin‐bonded restorations and porcelain repair systems. In this study, two approaches were applied to dental ceramic surfaces for improvement in the wettability and surface energy of the effective resin–ceramic interfacial binding. One group of dental ceramics was treated by glow discharge with oxygen at a discharge power of 20 W and for an exposure time of 15 min. The other group was dipped onto hydrofluoric acid (HF) solution. Then, the samples were washed with distilled water and dried at the room temperature before the oxygen plasma treatment. The effectiveness of the two approaches was compared by means of changes in the surface wettability and polarity as measured by both the sessile drop and captive bubble techniques. Oxygen plasma treatment increased the surface wettability, but a greater increase was found with HF etching before the oxygen plasma treatment. This result was demonstrated by the decrease in the static contact angle as measured by the sessile drop technique (53.6 ± 4.19 to 27.7 ± 3.30). In addition, with the combination of the prechemical treatment with HF and the oxygen plasma treatment, the polarity increased more dramatically (0.706 ± 0.013 to 0.845 ± 0.008). The surface chemical composition and physical morphology were investigated by X‐ray photoelectron spectroscopy and scanning electron microscopy. Furthermore, the HF etching before oxygen plasma treatment was found to improve the shear bond strength, and it was significantly stronger than that of the groups treated with oxygen only for the resin composite materials (p < 0.05). This two‐step treatment could be a new approach for the activation of dental ceramic discs. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Wear resistance of low‐temperature plasma‐polymerized organosilica deposited on poly(ethylene terephthalate): The effect of discharge powers
Authors: Lin Yung‐Sen , Chen Ching‐Lun
Published: August 2008

An investigation was conducted into plasma polymerization of transparent organosilica (SiOxCy) onto flexible transparent polyethylene terephthalate (PET) substrates for improving wear resistance. The plasma‐polymerized SiOxCy with tetramethylsilane (TMS) and oxygen (O2) gases in room temperature (23°C) was proven to highly enhance the wear resistance from the completely worn of untreated PET substrates to no worn of TMS‐oxygen plasma‐polymerized PET substrates at higher discharge powers, while the wear test of 300 cycles at 300 g loading with a steel wool was applied. The performance of wear resistance on PET substrates was found to be strongly dependent on the surface characteristics of PET substrates. The surface hardness of PET substrates was determined by the pencil test. The surface morphology of PET substrate was observed by atomic force microscopy (AFM). The atomic compositions and chemical bondings of TMS‐oxygen plasma‐polymerized organosilicas were analyzed by means of X‐ray photoelectron spectroscopy (XPS). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Evaluation of polymethacrylic ionomer as compatibilizers for MCPA6/clay composites
Authors: Wu Tongfei , Liu Andong , Xie Tingxiu , Yang Guisheng
Published: August 2008

The compatibilization effects provided by polymethacrylic ionomer (PMMA ionomer) on monomer‐casting polyamide6 (MCPA6)/clay (pristine sodium montmorillonite) composites were studied in this work. The PMMA ionomer used in this study was sodium polymethacrylate ionomer (PMMA Na+‐ionomer), which is a copolymer of methyl methacrylate and sodium methacrylate, prepared using emulsion polymerization. MCPA6/clay/PMMA Na+‐ionomer composites were prepared by in situ anionic ring‐opening polymerization (AROP) of ε‐caprolactam (CLA). X‐ray diffraction (XRD) and transmission electron microscopy (TEM) plus rheological measurement were used to characterize those composites. The results indicated that PMMA Na+‐ionomer is a good compatibilizer for this system. With increasing PMMA Na+‐ionomer content, a better dispersion of clay layers was successfully achieved in the MCPA6 matrix. Furthermore, differential scanning calorimetry (DSC) and XRD results indicated that well dispersed silicate layers limit the mobility of the MCPA6 molecule chains to crystallize, reduce the degree crystalline, and favor the formation of the γ‐crystalline form of the MCPA6 matrix. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Improvement of the thermal stability of polyhydroxybutyrates by grafting with maleic anhydride by different methods: Differential scanning calorimetry, thermogravimetric analysis, and gel permeation chromatography
Authors: Hong Shinn‐Gwo , Lin Yi‐Che , Lin Chia‐Hau
Published: August 2008

The crystallization and thermal degradation behaviors of polyhydroxybutyrate (PHB) grafted with maleic anhydride (MA) by different techniques were analyzed with differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and gel permeation chromatography (GPC). The results of DSC, TGA, and GPC analyses indicated that the grafting method could affect the crystallization rate, crystallinity, and thermal stability of PHB because of changes in the molecular weight of PHB and the amount of MA grafted during the reaction. The reduction of the molecular weight of PHB that reacted during the processing followed this order of methods: melt grafting > solvent grafting > mechanical grafting. However, the grafting ratio of MA followed this order of methods: melt grafting > mechanical grafting > solvent grafting. All three grafting methods significantly improved the thermal stability, therefore increasing the crystallization rate and melting temperature of the as‐received PHB. A grafting ratio of MA as low as 0.07 wt % could result in a significant improvement in the heat resistance of PHB. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Influence of magnesium carbonate loading on the compound properties of polychloroprene, natural rubber, and their blends
Authors: Sae‐Oui Pongdhorn , Sirisinha Chakrit , Hatthapanit Kannika , Phewthongin Nilobon
Published: August 2008

The effect of magnesium carbonate (MgCO3) loading on the compound properties of polychloroprene (CR), natural rubber (NR), and their blends was investigated. The studied properties included Mooney viscosity, cure characteristics, and degree of filler–filler interaction. In addition to MgCO3 loading, the effect of the blend ratio on such properties was simultaneously determined. The results reveal that, regardless of the rubber type and blend ratio, increasing MgCO3 loading resulted in not only an increase in the compound viscosity, but also in the enhancements of the cure rate and state of cure. However, the effect of MgCO3 loading on the overcured behavior was strongly dependent on the rubber type and blend ratio. For CR, the presence of MgCO3 accelerated postcuring, whereas the opposite results were found for NR, in which the reversion rate was promoted. For CR/NR blends, a plateau behavior was obtained at a 50/50 blend ratio, where the degrees of postcuring and reversion were counterbalanced. The results also reveal that when MgCO3 was loaded at low concentrations (≤20 phr), the degree of filler–filler interaction was very low and had no significant effect on the compound properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effect of the phase ratio on the particle properties of poly(vinyl chloride) resins produced by suspension polymerization
Authors: Etesami N. , Esfahany M. Nasr , Bagheri R.
Published: August 2008

The effects of the dispersed phase to continuous phase ratio (weight of VCM (gr)/weight of water (gr) (φ = gVCM/gwater)) on the particle properties of a poly(vinyl chloride) (PVC) suspension were investigated experimentally. A series of experiments were performed with different φ values in a pilot‐scale reactor. The cold plasticizer absorption of the resin decreased with φ. Scanning electron micrographs showed that by the reduction of φ, many of the produced particles had a regular shape, a smooth surface, and greater porosity. An increase in φ caused a wider and multimodal particle size distribution of the produced PVC particles. The mean particle size and bulk density also increased with φ, whereas the molecular weight and polydispersity index did not change. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effect of chemical treatments on the mechanical, flow, and morphological properties of talc‐ and kaolin‐filled polypropylene hybrid composites
Authors: Abu Bakar M. B. , Leong Y. W. , Ariffin A. , Mohd Ishak Z. A.
Published: August 2008

This study was performed with commercially available phenyl trimethoxysilane (PTMS) and neoalkoxytitanate [i.e., neopentyl(diallyl)oxytri(dioctyl)phosphato titanate (LICA 12)] as coupling agents. PTMS and LICA 12 were used to treat talc and kaolin to compare their effects with untreated fillers upon incorporation into polypropylene (PP). Single‐filler PP composites (containing either talc or kaolin) and hybrid‐filler composites (containing a mix of both talc and kaolin) were compounded in a twin‐screw extruder and subsequently injection‐molded into dumbbells. The incorporation of PTMS and LICA 12 slightly decreased the tensile and flexural properties in terms of modulus and strength but increased the elongation at break for both single‐filler and hybrid‐filler composites. There was also a significant improvement in the impact strength of the composites, particularly those treated with LICA 12. The hybrid composites, through the synergistic coalescence of positive characteristics from talc and kaolin with the aid from chemical treatment provided an economically advantageous material with mechanical properties comparable to those of the single‐filler‐filled PP composites. Further investigations on flow and morphological properties were also done to correlate the mechanical properties of the single‐ and hybrid‐filler‐filled PP composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effect of the talc filler content on the mechanical properties of polypropylene composites
Authors: Lapcik Lubomir , Jindrova Pavlina , Lapcikova Barbora , Tamblyn Richard , Greenwood Richard , Rowson Neil
Published: August 2008

This research examines the effect of a microsize/nanosize talc filler on the physicochemical and mechanical properties of filled polypropylene (108MF10 and 33MBTU from Saudi Basic Industries Corp. and HE125MO grade from Borealis) composite matrices. A range of mechanical properties were measured [tensile properties, bending properties, fracture toughness, notched impact strength (at the ambient temperature and −20°C), strain at break, and impact strength] along with microhardness testing and thermal stability testing from 40 to 600°C as measured by differential thermal analysis and thermogravimetric analysis. Increasing filler content lead to an increase in the mechanical strength of the composite material with a simultaneous decrease in the fracture toughness. The observed increase in tensile strength ranged from 15 to 25% (the maximum tensile strength at break was found to be 22 MPa). The increase in mechanical strength simultaneously led to a higher brittleness, which was reflected in a decrease in the mean impact strength from the initial 18 kJ/m2 (for the virgin polypropylene sample) to 14 kJ/m2, that is, a 23% decrease. A similar dependency was also obtained for the samples conditioned at −20°C (a decrease of 12.5%). With increasing degree of filling of the talc–polypropylene composite matrix, the thermooxidative stability increased; the highest magnitude was obtained for the 20 wt % sample (decomposition temperature = 482°C, cf. 392°C for the virgin polymer). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and characterization of temperature‐responsive poly(vinyl alcohol)‐based copolymers
Authors: Pan Yuanfeng , Xiao Huining , Zhao Guanglei , He Beihai
Published: August 2008

A poly(vinyl alcohol) (PVA)/sodium acrylate (AANa) copolymer was synthesized to improve the water solubility of PVA at the ambient temperature. Furthermore, a series of temperature‐responsive acetalyzed poly(vinyl alcohol) (APVA)‐co‐AANa samples of various chain lengths, degrees of acetalysis (DAs), and comonomer contents were prepared via an acid‐catalysis process. Fourier transform infrared and 1H‐NMR techniques were used to analyze the compositions of the copolymers. The measurement of the turbidity change for APVA‐co‐AANa aqueous solutions at different temperatures revealed that the lower critical solution temperature (LCST) of the copolymers could be tailored through the control of the molecular weight of the starting PVA‐co‐AANa, DA, and comonomer ratios. Lower LCSTs were observed for APVA‐co‐AANa with a longer chain length, a higher DA, and fewer acrylic acid segments. In addition, the LCSTs of the APVA‐co‐AANa aqueous solutions appeared to be salt‐sensitive. The LCSTs decreased as the concentration of NaCl increased. Moreover, atomic force microscopy images of APVA‐co‐AANa around the LCST also proved the temperature sensitivity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
ToF‐SIMS investigation of epoxy resin curing reaction at different resin to hardener ratios
Authors: Awaja Firas , van Riessen Grant , Kelly Georgina , Fox Bronwyn , Pigram Paul J.
Published: August 2008

Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and principal components analysis (PCA) were used to analyze diglycidyl ether of bisphenol A (DGEBA) and diglycidyl ether of bisphenol F (DGEBF) epoxy resin blend cured with isophorone diamine (IPD) hardener at different resin to hardener ratios. The aim was to establish correlations between the hardener concentration and the nature and progress of the crosslinking reaction. Insights into the cured resin structure revealed using ToF‐SIMS are discussed. Three sets of significant secondary ions have been identified by PCA. Secondary ions such as C14H7O+, CHO+, CH3O+, and C21H24O4+ showed variance related to the completion of the curing reaction. Relative intensities of CxHyNz+ ions in the cured resin samples are indicative of the un‐reacted and partially reacted hardener molecules, and are found to be proportional to the resin to hardener mixing ratio. The relative ion intensities of the aliphatic hydrocarbon ions are shown to relate to the cured resin crosslinking density. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Phthalyl chitosan–poly(ethylene oxide) semi‐interpenetrating polymer network microparticles for oral protein delivery: An in vitro characterization
Authors: Rekha M. R. , Sharma C. P.
Published: August 2008

Phthalyl chitosan (PC) was synthesized and phthalyl chitosan–poly(ethylene oxide) (PCP) semi‐interpenetrating network microparticles were developed by ionic crosslinking with sodium tripolyphosphate. The characterization of PCP particles was done, and these particles were compared with PC and native chitosan (NC) microparticles. The PCP particle size was around 1.3 μm with a ζ potential of about −28.6 ± 12.6 mV and an insulin loading efficiency of 89.6%. The release studies were done at pH 1.2 and 7.4, which indicated a minimal release at pH 1.2 compared to that at pH 7.4. The degree of swelling was observed to be higher in PCP than in PC or NC particles. The in vitro mucin‐binding capacity and the intestinal mucoadhesiveness of the particles were evaluated. The PCP particles were highly mucoadhesive, and correspondingly, the mucin‐binding capacity was lower for these particles; this is necessary for any matrix to be a successful mucoadhesive. These results suggest the usefulness of these particles as a potential candidate for oral insulin‐delivery systems. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
The Primary Cilium of Connective Tissue Cells: Imaging by Multiphoton Microscopy
Authors: Donnelly Eve , Williams Rebecca , Farnum Cornelia
Published: August 2008

Three‐dimensional reconstruction of a multiphoton image stack showing primary cilia (green)
tenocyte nuclei (blue), and collagen (red) in extensor tendon. From “The Primary Cilium of Connective Tissue Cells: Imaging by Multiphoton Microscopy,” by Eve Donnelly, et al., on page 1062, in this issue. Anatomical Record 291:1062–1073.
The importance of reporting disease activity states in rheumatoid arthritis clinical trials
Authors: Aletaha Daniel , Funovits Julia , Smolen Josef S.
Published: August 2008

Objective

To compare the value of reporting treatment effects in rheumatoid arthritis (RA) as relative change from baseline (e.g., American College of Rheumatology [ACR] responder status) with the value of evaluating absolute disease activity states (e.g., remission).

Methods

We pooled data from several recent RA clinical trials and evaluated patients who had completed a 1‐year treatment period (n = 629). We compared levels of functional impairment and radiographic progression among patients meeting the ACR 50% or 70% improvement criteria (ACR50 and ACR70 responders, respectively) who attained remission of disease, low disease activity, or moderate disease activity after 1 year, as assessed by the Simplified Disease Activity Index and the Disease Activity Score in 28 joints.

Results

Within the ACR50 and ACR70 responder groups, functional disability and radiographic progression were lowest in patients who had attained disease remission at 1 year, compared with those who had attained low or moderate disease activity. When patients attained the same disease activity category, physical function and radiographic progression did not differ significantly with different response states.

Conclusion

Functional and radiographic outcomes are different in patients depending on the disease activity category they attain, even if the same level of response (change from baseline) is achieved. Among patients who attain the same disease activity category, the degree of response they experience does not seem to matter. Assessing actual disease activity as well as disease activity states should constitute an integral part of clinical trial data reporting.
Metallodynamers: Neutral Double‐Dynamic Metallosupramolecular Polymers
Authors: Chow Cheuk‐Fai , Fujii Shunsuke , Lehn Jean‐Marie
Published: August 2008

Nine neutral dynamic metallosupramolecular polymers (metallodynamers) based on acyl hydrazone derived metal coordination centers (Co2+, Ni2+, Zn2+, and Cd2+) were generated through self‐assembly polymerization. These are linear coordination polymers with specific optical and mechanical properties. Monomer selection was found to take place in a mixture of subcomponents (carboxyaldehydes and bisacyl hydrazides) driven by hexacoordination to a specific metal ion. Most importantly, the metallodynamers were found to modify their constitution by exchanging and reshuffling their components with another metallodynamer through ligand exchange at the metal coordination site in solution as well as in the neat phase. As a result, the materials undergo remarkable changes in both their mechanical and optical properties.
Solvent‐Induced Aggregation and Cation‐Controlled Self‐Assembly of Tripodal Squaraine Dyes: Optical, Chiroptical and Morphological Properties
Authors: Chithra Parayalil , Varghese Reji , Divya Kizhmuri P. , Ajayaghosh Ayyappanpillai
Published: August 2008

The synthesis, characterisation, optical, chiroptical, aggregation, and alkaline earth metal cation assisted self‐assembly properties of tripodal squaraine dyes have been described. In the tripodal geometry, these dyes exhibit three absorption bands around 650, 620 and 580 nm in contrast to the single, sharp absorption of a simple dye (SQ) at 640 nm. The fluorescence quantum yield of the squaraine dyes are 25–30 times lower when compared to that of SQ, which indicates intramolecular exciton interaction as a result of the confinement of the dyes. The evaporation of an acetonitrile solution of the dye resulted in the formation of vesicular objects as confirmed by AFM and TEM analyses. However, evaporation of an acetonitrile solution containing 10–12 % water gave short fibrous aggregates. In the presence of Ca2+ or Mg2+ ions, the dyes exhibit an intense and sharp absorption band at 547 nm with a concomitant decrease of the native absorption. Interestingly, the dye with chiral groups failed to give a circular dichroic signal during aggregation in solvent mixtures, whereas strong signals were observed in the presence of Ca2+ and Mg2+ ions. AFM and TEM analyses of the corresponding cation complexes revealed the formation of worm like nanohelices. However, addition of EDTA to the Ca2+ or Mg2+ complex exhibited a reversal of the absorption, emission, and circular dichroic spectra to that of the native dye, indicating decomplexation. AFM analyses revealed the transformation of the helices to particles. These observations reveal the difference in the nature and properties of the simple aggregates formed in solvent mixtures and those formed in the presence of cations. In the present study, we were able to establish the importance of specific cation binding in controlling the size, shape, and properties of the hierarchical assemblies of tripodal squaraines.
A Non‐Cross‐Linked Soluble Polystyrene‐Supported Ruthenium Catalyst for Carbenoid Transfer Reactions
Authors: Choi Matthew Kwok‐Wai , Yu Wing‐Yiu , So Man‐Ho , Zhou Cong‐Ying , Deng Qing‐Hai , Che Chi‐Ming
Published: August 2008

Ruthenium nanoparticles supported on non‐cross‐linked soluble polystyrene were prepared by reacting [RuCl2(C6H5CO2Et)]2 with polystyrene in open air. They effectively catalyze intra‐ and intermolecular carbenoid insertion into CH and NH bonds, alkene cyclopropanation, and ammonium ylide/[2,3]‐sigmatropic rearrangement reactions. This supported ruthenium catalyst is much more reactive than [RuCl2(p‐cymene)]2 and [Ru(Por)CO] for catalytic intermolecular carbenoid CH bond insertion into saturated alkanes. By using α‐diazoacetamide as a substrate for intramolecular carbenoid CH insertion, the supported ruthenium catalyst can be recovered and reused for ten successive iterations without significant loss of activity.
Synthesis of Diamino Carboxylic Esters by Palladium‐Catalyzed Oxidative Intramolecular Diamination of Acrylates
Authors: Muñiz Kilian , Streuff Jan , Chávez Patricia , Hövelmann Claas H.
Published: August 2008

Unligated palladium(II) salts catalyze the oxidative diamination of acrylic esters to yield 2,3‐diamino carboxylic esters. The reaction employs copper(II) bromide as oxidant and proceeds with good to excellent stereoselectivities and complete chemoselectivity. Preliminary mechanistic studies provide evidence for the involvement of a direct amination of the CPd bond in the α position relative to the ester group. This protocol significantly broadens the overall scope of the palladium‐catalyzed diamination of alkenes and represents the first direct diamination of functionalized nonterminal substrates. The reaction yields readily protected 2,3‐diamino acid derivatives, which can be considered as highly functionalized building blocks for subsequent synthesis. The use of one of these new diamination products as a suitable starting material in a short synthesis of the alkaloid absouline is demonstrated as an example.
On the late twentieth century decrease in Australian east coast rainfall extremes
Authors: Speer Milton S.
Published: August 2008

A change from negative to positive circulation anomalies over New South Wales (NSW) during the 1970s resulted in a decrease in east coastal low‐pressure systems and accompanying rain. Negative pressure anomalies over eastern Australia, anomalous onshore low‐level winds and larger NSW rainfall totals since 1950, occur in the cool phase of the IPO rather than the warm phase (post‐1976). Larger NSW extreme annual rainfall totals occurred prior to 1977 and were characterized by negative mean sea level pressure (MSLP) anomalies over eastern Australia. In contrast, extreme annual rainfall totals from 1977 were smaller and characterized by positive MSLP anomalies. Copyright © 2008 Royal Meteorological Society
Quantile regression for binary performance indicators
Authors: Hewson Paul , Yu Keming
Published: August 2008

Quantile regression is an emerging modelling technique; we examine an approach allowing this technique to model binomial variables in a Bayesian framework and illustrate the value of this advanced technique on a set of local government performance indicators from England and Wales. In U.K. local government, there is currently particular interest in assessing performance relative to ‘top’ and ‘bottom’ quartiles; all authorities are expected to match the current best quartile performance within 5 years, any authority in the ‘bottom’ quartile is assumed to be significantly below par. By its very nature, quantile regression lets us to explore relationships between various covariates and these particular levels of performance. Additionally, by examining a number of other percentiles, we demonstrate how quantile regression gives a much fuller insight into the apparent behaviour of the system we are modelling. Rather than relying on asymptotic results, we use Bayesian methods that allow us to explore the uncertainty implicit in our model building and predictions. We suggest that this is most important when analysing data that are used to make managerial and administrative decisions. Copyright © 2008 John Wiley & Sons, Ltd.
Feuchtetransport in 15 cm dicken, liegend hergestellten wasserundurchlässigen Fertigteilen aus Stahlbeton bei drückendem Wasser
Authors: Mähner Dietmar , Becker Markus
Published: August 2008

In Versuchen konnte das Arbeitsmodell des Deutschen Ausschusses für Stahlbeton für Feuchtebedingungen in einem Betonbauteil unter einseitiger Beaufschlagung mit drückendem Wasser auf 15 cm dicke Betonfertigteilwände, die liegend hergestellt wurden, erweitert werden. Bei Wanddicken von 15 cm wurde trotz unterschiedlichen Beaufschlagungen mit drückendem Wasser über einen Zeitraum von einem Jahr kein signifikant unterschiedlicher Feuchtedurchtritt (weder qualitativ noch quantitativ) festgestellt. Der geringe Wasserzementwert der Fertigteile sowie die liegende Herstellung und Verdichtung lassen vermuten, dass in den Versuchen nur eine Feuchteabgabe aufgrund von Diffusion des anfänglich vorhandenen Überschusswassers festgestellt wurde.
Querbeanspruchung von Ankergruppen in Randnähe – Stochastische Studien
Authors: Spyridis Panagiotis , Unterweger Andreas , Mihala Ronald , Bergmeister Konrad
Published: August 2008

Ankergruppen in Beton kommen als Befestigungsmittel häufig in Randnähe zur Anwendung. Bei der Verbindung der Stahlanker mit einer Montageplatte kommt es aufgrund von Montagetoleranzen zu einer zufälligen Ankerstellung in den Durchgangslöchern der Montageplatte. Dadurch werden bei einer Querbeanspruchung der Gruppenbefestigung nicht alle Anker gleichzeitig aktiviert, was die Tragfähigkeit dieser in Randnähe besonders beeinflusst. Durch genauere Untersuchung dieses Sachverhalts sollten verbesserte Bemessungskonzepte entwickelt werden.

Im vorliegenden Beitrag wird auf eine stochastische Analyse eingegangen, welche durch zufällige Ankeranordnungen, verschiedene Geometrien und mechanische Parameter die gegenseitige Beeinflussung benachbarter Anker untersucht. Aufgrund dieser Untersuchungen wird im Abschluss eine Gleichung vorgeschlagen, welche den Zusammenhang zwischen Geometrie, Montagetoleranzen und der Bruchlast der Gruppenbefestigung unter Querlast beschreibt.
Ligand‐pKa Shifts through Metals: Potential Relevance to Ribozyme Chemistry
Authors: Lippert Bernhard
Published: August 2008

Functional and crystallographic analyses of catalytically active RNA molecules (‘ribozymes’) have revealed a multitude of different routes by which nature accomplishes cleavage reactions of the RNA sugar‐phosphate backbone. While there is agreement that these reactions involve general acid–base chemistry, the choice of ‘acid’ and of ‘base’ appears to be quite versatile. Among the numerous surprises that have emerged from these studies in recent years is the phenomenon of ‘shifted pKa values’ of nucleobases, hence, the fact that pKa values of isolated nucleobases in H2O can be shifted in either direction – upward or downward – into the physiological pH range, and that consequently allows these nucleobases to function as ‘acids’ or ‘bases’. Another change in paradigm in recent years relates to the role of divalent metal ions in these catalytic reactions, which points to the possibility of an indirect involvement in the catalytic cycle rather than necessarily to a direct participation, as in the case with the hepatitis delta virus ribozyme. In this review, basic features of nucleobases and/or aqua ligand pKa shifts caused by metal coordination and H‐bonding are discussed.
Characterization of Metal‐Responsive Transcription Factor (MTF‐1) from the Giant Rodent Capybara Reveals Features in Common with Human as Well as with Small Rodents (Mouse, Rat). Short Communication
Authors: Lindert Uschi , Leuzinger Lucas , Steiner Kurt , Georgiev Oleg , Schaffner Walter
Published: August 2008

From mammals to insects, metal‐responsive transcription factor 1 (MTF‐1) is essential for the activation of metallothionein genes upon heavy‐metal load. We have previously found that human MTF‐1 induces a stronger metal response than mouse MTF‐1. The latter differs from the human one in a number of amino acid positions and is also shorter by 78 aa at its C‐terminus. We reasoned that the weaker metal inducibility might be associated with a lesser demand for tight metal homeostasis in a low‐weight, short‐lived animal, and thus set out to determine the sequence of MTF‐1 from the largest living rodent, the Brazilian capybara that can reach 65 kg and also has a considerably longer life span than smaller rodents. An expression clone for capybara MTF‐1 was then tested for its activity in both mouse and human cells. Our analysis revealed three unexpected features: i) capybara MTF‐1 in terms of amino acid sequence is much more closely related to human than to mouse MTF‐1, suggesting an accelerated evolution of MTF‐1 in the evolutionary branch leading to small rodents; ii) capybara MTF‐1 is even 32 aa shorter at its C‐terminus than mouse MTF‐1, and iii) in an activity test, it is not more active than mouse MTF‐1. The latter two findings might indicate that capybara has evolved in an environment with low heavy‐metal load.
The Influence of Auranofin, a Clinically Established Antiarthritic Gold Drug, on Bone Metabolism: Analysis of Its Effects on Human Multipotent Adipose‐Derived Stem Cells, Taken as a Model
Authors: Chiellini Chiara , Casini Angela , Cochet Olivia , Gabbiani Chiara , Ailhaud Gérard , Dani Christian , Messori Luigi , Amri Ez‐Zoubir
Published: August 2008

Auranofin is a gold‐based antiarthritic drug in clinical use for more that 25 years. However, in spite of a long established use, its specific effects on bone metabolism are still greatly controversial. We have analyzed in vitro the actions of auranofin on human multipotent adipose‐derived stem (hMADS) cells, used as a model for bone metabolism, since these cells were reported to undergo osteogenesis both in vitro and in vivo. Cytotoxicity of auranofin on hMADS cells, differentiated into osteoblasts, was initially assessed. Thereafter, the consequences of exposure to nontoxic but clinically relevant auranofin concentrations were analyzed by monitoring the seleno‐protein glutathione peroxidase 3 or alkaline phosphatase, a characteristic biomarker of osteogenesis. Notably, we found that chronic treatment with auranofin alters only weakly the levels of alkaline phosphatase, thus implying an overall modest effect on osteogenesis. In contrast, auranofin turned out to greatly affect glutathione peroxidase 3 activity. The possible medical implications of these findings are discussed.
Influence of Carbonate on the Binding of Carboplatin to DNA
Authors: Sorokanich Robert S. , Di Pasqua Anthony J. , Geier Martina , Dabrowiak James C.
Published: August 2008

The reaction of aged carboplatin (reaction of carboplatin in 24 mM NaHCO3 for 45 h, 37°, pH 8.6) with pBR322 DNA at 0<r<2.8, where r=[drug]/[DNA‐bp], in 24 mM HEPES buffer, pH 7.4, for 24 h, followed by agarose gel electrophoresis showed DNA mobility changes consistent with unwinding closed circular DNA. However, identical experiments conducted in a two‐buffer system, 24 mM HEPES plus 24 mM carbonate, showed no DNA mobility changes, indicating that carbonate blocks formation of the 1,2 intrastrand cross‐link on DNA. Studies with aged carboplatin and with cisplatin carried out with ca. 4.0<r<10.0 in the two‐buffer system show that some DNA binding and unwinding occurs for both drugs. Since carbonate inhibits the binding of aged carboplatin and cisplatin to DNA, carbonate present in the body likely modulates the reactivity of these drugs with a variety of biological targets including DNA.
Effects of Vanadium‐Containing Compounds on Membrane Lipids and on Microdomains Used in Receptor‐Mediated Signaling
Authors: Roess Deborah A. , Smith Steven M. L. , Winter Peter , Zhou Jun , Dou Ping , Baruah Bharat , Trujillo Alejandro M. , Levinger Nancy E. , Yang Xioda , Barisas B. George , Crans Debbie C.
Published: August 2008

There is increasing evidence for the involvement of plasma membrane microdomains in insulin receptor function. Moreover, disruption of these structures, which are typically enriched in sphingomyelin and cholesterol, results in insulin resistance. Treatment strategies for insulin resistance include the use of vanadium (V) compounds which have been shown in animal models to enhance insulin responsiveness. One possible mechanism for insulin‐enhancing effects might involve direct effects of V compounds on membrane lipid organization. These changes in lipid organization promote the partitioning of insulin receptors and other receptors into membrane microdomains where receptors are optimally functional. To explore this possibility, we have used several strategies involving V complexes such as [VO2(dipic)]− (pyridin‐2,6‐dicarboxylatodioxovanadium(V)), decavanadate (V10O, V10), BMOV (bis(maltolato)oxovanadium(IV)), and [VO(saltris)]2 (2‐salicylideniminato‐2‐(hydroxymethyl)‐1,3‐dihydroxypropane‐oxovanadium(V)). Our strategies include an evaluation of interactions between V‐containing compounds and model lipid systems, an evaluation of the effects of V compounds on lipid fluidity in erythrocyte membranes, and studies of the effects of V‐containing compounds on signaling events initiated by receptors known to use membrane microdomains as signaling platforms.
Formation of {Cu(μ‐O)2}2+ Core Due to Dioxygen Reactivity of a Copper(I) Complex Supported by a New Hybrid Tridentate Ligand: Reaction with Exogenous Substrates
Authors: Mandal Sukanta , De Anindita , Mukherjee Rabindranath
Published: August 2008

Reaction of a CuI complex of a hybrid tridentate ligand, encompassing [2‐(pyridin‐2‐yl)ethyl]amine and dimethyl‐substituted ethylalkylamine with dioxygen, generates in acetone at −80° putative bis(μ‐oxo)dicopper(III) intermediate. Structural characterization of a PPh3‐adduct of a mononuclear CuI complex of this new ligand has been achieved. This ligand coordinates in a facial mode utilizing three N‐atoms (CH2CH2Py, CH2CH2NMe2, and NCH2Ph). Reactivity of bis(μ‐oxo)dicopper(III) intermediate toward exogenous substrates (2,4‐di(tert‐butyl)phenol and 2,4,6‐tri(tert‐butyl)phenol) has also been investigated.
Interaction of Flavin Adenine Dinucleotide (FAD) with a Glassy Carbon Electrode Surface
Authors: Wei Haizhen , Omanovic Sasha
Published: August 2008

The interaction of flavin adenine dinucleotide (FAD) with a glassy carbon electrode (GCE) surface was investigated in terms of the FAD adsorption thermodynamics and kinetics, the subsequent electroreduction mechanism, and the corresponding electron‐transfer rate. The kinetics of FAD electroreduction at the GCE was found to be an adsorption‐controlled process. A set of electroreduction kinetic parameters was calculated: the true number of electrons involved in the FAD reduction, n=1.76, the apparent transfer coefficient, αapp=0.41, and the apparent heterogeneous electron‐transfer rate constant, kapp=1.4 s−1. The deviation of the number of exchanged electrons from the theoretical value for the complete reduction of FAD to FADH2 (n=2) indicates that a small portion of FAD goes to a semiquinone state during the redox process. The FAD adsorption was well described by the Langmuir adsorption isotherm. The large negative apparent Gibbs energy of adsorption (ΔGads=−39.7 ±0.4 kJmol−1) indicated a highly spontaneous and strong adsorption of FAD on the GCE. The energetics of the adsorption process was found to be independent of the electrode surface charge in the electrochemical double‐layer region. The kinetics of FAD adsorption was modeled using a pseudo‐first‐order kinetic model.
Liposomal Forms of Rhenium Cluster Compounds: Enhancement of Biological Activity
Authors: Shtemenko Natalia I. , Zabitskaya Elena D. , Berzenina Oksana V. , Yegorova Dina E. , Shtemenko Alexander V.
Published: August 2008

Liposomal formulations of dinuclear cluster rhenium (Re) compounds were used in biochemical trials. Interaction of liposomal forms of some Re compounds with red blood cells in experiments in vitro showed strong cell‐stabilizing properties. In the models of tumor growth and hemolytic anemia in vivo, liposomal forms had better therapeutic effects in comparison with their solutions. The process of formation of liposomes of cluster Re compounds with different organic ligands was investigated by the method of electronic absorption spectra and mechanism of their interactions with lipids is proposed. Encapsulation of cluster Re compounds to lipid coating may have activation significance for the quadruple ReRe bond.
Cytochrome P450 2J2*7 polymorphisms in Japanese, Mongolians and Ovambos
Authors: Takeshita Haruo , Tsubota Etsuko , Takatsuka Hisakazu , Kunito Takashi , Fujihara Junko
Published: August 2008

Human cytochrome P450 2J2 (CYP2J2) is abundant in cardiovascular tissue and active in the metabolism of arachidonic acid to eicosanoids that have potent vasodilatory properties. Variability of the CYP2J2 gene is highly constrained except for its proximal promoter: there is a relatively common and functionally relevant single nucleotide polymorphism, indicated by −50G > T polymorphism (CYP2J2*7). Although genetic variation is known among ethnic groups, data for allele frequency are limited to a few Caucasian, Asian, and one African populations. In the present study, genotype distribution of CYP2J2*7 polymorphisms was investigated using polymerase chain reaction and restriction fragment length polymorphism assay in Japanese (n = 338), Mongolian (n = 118), and Ovambo (n = 186) populations and the findings compared with other populations. The mutant (CYP2J2*7) frequencies in the Japanese, Mongolians, and Ovambos were 0.0621, 0.0339, and 0.0672, respectively. Except for the Taiwanese, a general uniformity in the polymorphism in the Asian populations was observed. The mutation frequency of Ovambos was relatively lower than that of the African‐American population. This study is the first to investigate the distribution of the CYP2J2*7 gene polymorphisms in Japanese, Mongolians, and Ovambos. These data will be informative and facilitate genetic association studies, in Asian and African populations for CYP2J2‐related diseases such as cardiovascular disorders. Copyright © 2008 John Wiley & Sons, Ltd.
Metal‐Free and PdII‐Promoted [2+3] Cycloadditions of a Cyclic Nitrone to Phthalonitriles: Syntheses of Oxadiazolines as well as Phthalamide–PdII and Dihydropyrrolyl‐iminoisoindolinone–PdII Complexes with High Catalytic Activity in Suzuki–Miyaura Cross‐Coupling Reactions
Authors: Lasri Jamal , Kopylovich Maximilian N. , Guedes da Silva M. Fátima C. , Charmier M. Adília Januário , Pombeiro Armando J. L.
Published: August 2008

The previously unknown reactions between phthalonitriles, 1,2‐(CN)2(C6)R1R2R3R4 1 (1 a, R1=R2=R3=R4=H; 1 b, R1=R2=R4=H, R3=CH3; 1 c, R1=R4=H, R2=R3=Cl; 1 d, R1=R2=R3=R4=Cl; 1 e, R1=R2=R3=R4=F), and a cyclic nitrone, −O+NCHCH2CH2CMe2 2, proceed under heating in a sealed tube to give phthalimides 3, 2‐oxadiazolyl‐benzonitriles 4 or ortho‐bis(oxadiazolyl)tetrafluorobenzene 4 e′. In the presence of palladium(II) chloride, phthalonitriles 1 react with 2 at room temperature, to give bis(pyrrolidin‐2‐ylidene)phthalamide PdII complexes 5 via metal‐promoted rupture of the NO bond of the oxadiazoline ring. The ketoimine ligands thus generated can be liberated from the metal by displacement with a diphosphine. Although the first [2+3] cycloaddition of 2 to 1 can occur in the absence of the metal to give the mono‐cycloadducts 4, the second [2+3] coupling at the still‐unreacted cyano group requires its activation by coordination to PdII, affording complexes 6 containing two ligated oxadiazolyl‐benzonitriles. These ligands undergo either i) further cycloaddition with 2 to afford ultimately (upon rearrangement) the bis(pyrrolidinylidene)phthalamide complexes 5 or ii) NO bond cleavage in the oxadiazoline ring with intramolecular attack of the imine nitrogen on the cyano carbon and bridging to a second PdII center to afford dimeric palladium(II) complexes 7, with chloride bridges, that bear a dihydropyrrolyl‐iminoisoindolinone, a new type of ligand.

The compounds were characterized by IR, 1H, and 13C NMR spectroscopy, ESI MS or FAB+ MS, elemental analyses and, in the case of 4 c, 5 a, 5 c, and 7 c, also by X‐ray diffraction analysis. Complexes 5 a and 7 c show high catalytic activity for the Suzuki–Miyaura cross‐coupling reaction of bromobenzene and phenylboronic acid and give biphenyl in high yields with turnover frequencies (TOFs) of up to 9.0×105 h−1.