bluuebunny/crossref_metadata_2025 huggingface dataset:
Constituent Particle Break‐Up During Hot Rolling of AA 5182
Authors: Moulin Nicolas , Parra‐Denis Estelle , Jeulin Dominique , Ducottet Christophe , Bigot Annabelle , Boller Elodie , Maire Eric , Barat Cécile , Klöcker Helmut
Published: December 2009

Aluminum sheet is currently used for body panels on a number of mass‐produced vehicles, in particular for closure panels. AA5xxxalloys always contain coarse inter‐metallic particles (Alx(Fe,Mn)ySi, Mg2Si) after casting. In the present work inter‐metallic particle break‐up during hot reversible rolling of AA5182 alloy sheets has been analyzed. The sizes and shapes of inter‐metallic particles in as‐cast and industrially hot rolled AA5182 alloys sheets were characterized by 3D X‐ray tomography observations. The relation between particle break‐up and particle morphology was then analyzed statistically and by a micromechanical finite element (FE)‐based model. The essential outcomes of the statistical approach may be summarized as follows. The inter‐metallic particle population may be described by five morphological parameters. Secondly the comparison of the particle morphology in as cast and industrially rolled sheets leads to the definition of five classes. The evolution of each particle class as function of the rolling strain is provided. The statistical analysis showswhichparticles break‐up. The stresses and strains in inter‐metallic particles, embedded in an elasto‐viscoplastic aluminum matrix submitted to plane strain compression, were analyzed by an FE model. A new failure criterion was proposed. The essential outcomes of the mechanical approach are as follows: a precise description of stress concentration mechanisms in nonconvex particles, a close description of the parameters controlling particle break‐up, and finally a simplified classification of the failure behavior.
Binuclear Ru(III) Schiff base complexes: synthesis, spectral characterization, oxidation, CC coupling reactions and antibacterial activities
Authors: Manimaran Arumugam , Jayabalakrishnan Chinnasamy
Published: December 2009

New hexa‐coordinated binuclear Ru(III) Schiff base complexes of the type {[(B)2X2Ru]2L} (where B = PPh3 or AsPh3; X = Cl or Br; L = binucleating N2O2 Schiff bases) were synthesized and characterized by elemental analysis, magnetic susceptibility measurement, FT‐IR, UV–vis, 13C{1H}‐NMR, ESR at 300 and 77 K, cyclic voltammetric technique, powder X‐ray diffraction pattern and SEM. The new complexes were used as catalysts in phenyl–phenyl coupling reaction and the oxidation of alcohols to their corresponding carbonyl compounds using molecular oxygen atmosphere at room temperature. Further, the new Schiff base ligands and their Ru(III) complexes were also screened for their antibacterial activity against K. pneumoniae, Shigella sp., M. luteus, E. coli and S. typhi. From this study, it was found that the activity of the ruthenium(III) Schiff base complexes almost reaches the effectiveness of the conventional bacteriocide standards. Copyright © 2009 John Wiley & Sons, Ltd.
Cyclodextrin inclusion complexes as novel MOCVD precursors for potential cobalt oxide deposition
Authors: Papadopoulos N. D. , Karayianni H.S. , Tsakiridis P.E. , Perraki M. , Hristoforou E.
Published: December 2009

The potential use of the inclusion complexes of β‐cyclodextrins with metal halides as novel precursors in MOCVD applications was examined in terms of microstructure, thermal stability and chemical modifications during heating. The investigation was especially focused on the inclusion complex of β‐cyclodextrin with cobalt iodide for cobalt oxide thin film deposition. The general composition assigned to the dextrin's inclusion complex was: (β‐CD)2•CoI7•11H2O. It was found that the inclusion complex of β‐cyclodextrin with CoI2 may prove a promising alternative to traditional metalorganic or organometallic Co‐precursors for precise CVD applications. The sublimation temperature must be preferably in the range 70–125 °C, and the decomposition temperature (substrate temperature) in the range of 350–400 °C. Three distinct regions can be recognized by heating: transformation of tightly bound water molecules into easily movable ones, sublimation of iodine ions and Co atoms oscillation and thermal decomposition of the glycositic ring into volatile by‐products. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis, characterization and biological studies of oxovanadium(IV) complexes with triazole‐derived Schiff bases
Authors: Chohan Zahid H. , Sumrra Sajjad H.
Published: December 2009

A series of triazole‐derived Schiff bases (L1–L5) and their oxovanadium(IV) complexes have been synthesized. The chemical structures of Schiff bases were characterized by their analytical (CHN analysis) and spectral (IR, 1H and 13C NMR and mass spectrometry) data, and oxovanadium(IV) complexes were elucidated by their physical (magnetic susceptibility and conductivity), analytical (CHN analysis), conductance measurements and electronic spectral data. The molar conductivity data indicate the oxovanadium(IV) complexes to be non‐electrolyte. The Schiff bases act as bidentate and coordinate with the oxovanadium(IV)‐forming stoichiometry of a complex as [M (L‐H)2] where M = VO and L = L1–L5 in a square‐pyramidal geometry. The agar well diffusion method was used for in vitro antibacterial screening against E. coli, S. flexenari, P. aeruginosa, S. typhi, S. aureus and B. subtilis and for antifungal activity against T. longifucus, C. albican, A. flavus, M. canis, F. solani and C. glaberata. The biological activity data show the oxovanadium(IV) complexes to be more antibacterial and antifungal than the parent Schiff bases against one or more bacterial and fungal strains. Copyright © 2009 John Wiley & Sons, Ltd.
Novel methodologies for the synthesis of functionalized lipophilic carboranes
Authors: Jonnalagadda Subash C. , Verga Steven R. , Patel Parth D. , Reddy A. V. , Srinivas T. , Scott Patricia M. , Mereddy Venkatram R.
Published: December 2009

Novel synthetic protocols for the synthesis of lipophilic carboranes were developed utilizing two CC bond forming reactions, namely Baylis–Hillman and enynedioate cycloaddition reactions. Some of these carboranes were converted into further functionalized carboranes via nucleophilic allylic isomerization. Copyright © 2009 John Wiley & Sons, Ltd.
Separation and isomerization of xylenes using zeolite membranes: a short overview
Authors: Daramola M. O. , Burger A. J. , Pera‐Titus M. , Giroir‐Fendler A. , Miachon S. , Dalmon J.‐A. , Lorenzen L.
Published: December 2009

During the last 30 years, there has been a great evolution in p‐xylene production technology, with many equipment improvements being instituted in the industry. Typically, these improvements bring economic as well as processing advantages to the producers. Such developments are vital, as the capital costs for process equipment to separate xylene isomers, especially into highly purified p‐xylene, still remain very high. In view of this, research efforts have recently focused on the development of zeolite membranes for the separation and production of p‐xylene, the precursor for the production of terephthalic acid, for which the current p‐xylene world demand stands at about 86% of the production. Over a list of about 200 references, this review reports on the present state‐of‐the‐art in p‐xylene separation from lesser used isomers (o‐ and m‐xylene) by means of MFI‐type zeolite membranes, and on the most recent achievements in o/m‐xylene isomerization to p‐xylene using extractor‐type catalytic membrane reactors. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Medium development for enhanced production of alkaline protease from a newly isolated Bacillus pseudofirmus SVB1
Authors: Sen S. , Venkata Dasu V. , Mandal B.
Published: December 2009

The most significantly influencing medium components viz., casein, MgSO4, CaCl2, and NH4NO3 were selected to maximize the production of alkaline protease (specific activity) from a newly isolated Bacillus pseudofirmus SVB1 using Plackett–Burman experimental design. Central composite design was used to determine the optimal levels of these screened medium components. The optimal levels of casein, MgSO4, CaCl2, and NH4NO3 were found to be 7.636, 0.811, 0.086, and 0.576 g/l, respectively. An overall 4.89‐fold increase in alkaline protease production (specific activity) was achieved in the optimized medium. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Constitutive relations for the extrusion of siloxane gum and silicone rubber
Authors: Crawford B. , Doherty A. P. , Spedding P. L. , Herron W. , Proctor M.
Published: December 2009

Silicones are widely used in many industries and in many forms, and extrusion is the most common fabrication method used to produce a range of products. However, the material properties and the extrusion process are not well understood and a generalised model including prediction of material properties and process simulations is not available. It is envisioned that computational fluid dynamic (CFD) modelling will be applicable to providing a better description of the extrusion process. Constitutive relations required for a CFD model were developed from viscosity data for silicone gum and rubber compounds. For the generalised Newtonian fluid (GNF) relations, the Yasuda model gave good prediction of the shear viscosity for all materials. Only the non‐linear differential models were capable of describing the viscoelastic behaviour. The Phan Thien–Tanner (PTT) model correctly modelled the viscosity and dynamic moduli for silicone gum, but for the rubber compounds only the viscosities could be adequately predicted. Underprediction was in evidence at low shear rates. The irreversible Papanastasiou–Scriven–Macosko (PSM) form of the Kaye–Bernstein–Kearsley–Zapas (KBKZ) was the most successful of the integral viscoelastic models. Good prediction of shear viscosity and dynamic moduli was achieved for all silicone materials. The first normal stress and extensional behaviour were predicted at high to medium shear rates. The constitutive equations presented here will enable a detailed CFD modelling study to be undertaken of the extrusion process, and this will be presented in a subsequent paper. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Synthesis and solution properties of temperature‐sensitive copolymers based on NIPAM
Authors: Zhang Xiaofei , Zhou Li , Zhang Xi , Dai Hua
Published: December 2009

A kind of temperature‐sensitive water‐soluble polymers P(NIPAM‐HEMA‐AM) of N‐isopropylacrylamide (NIPAM), hydroxyethyl methacrylate (HEMA) and acrylamide (AM) were synthesized by free radical aqueous solution copolymerization. The polymers were characterized by Fourier transform infrared spectrum (FTIR) method. Solution properties, such as the influences of monomer ratios and additives on the low critical soluble temperature (LCST) of the polymer solutions as well as the viscosity‐temperature properties were studied. The results show that the polymer concentrations have no significant influence on the LCST of polymer solutions. The incorporation of HEMA units leads to a lower LCST, while AM units to a higher LCST. The additions of small molecules such as salt and surfactant also have significant effect on the LCST, the addition of NaCl decreases the LCST, while the addition of sodium dodecylbenzenesulfonate (SDBS) increases the LCST. The apparent viscosity of polymer solutions depends on temperature. The 1.5 wt % aqueous solutions of P(NIPAM‐HEMA‐AM) exhibits good thermo‐thickening behavior over 55°C, whereas the 0.8 wt % aqueous solutions do not show this behavior during the heating process. The aqueous solutions of P(NIPAM‐HEMA‐AM) are viscoelastic fluids, and the viscoelasticities mainly depend on temperature. Both the storage modulus (G') and loss modulus (G'') of 1.5 wt % polymer solutions increase with temperature. Over 55°C, G' exceeds G'', and the polymer solutions are elasticity‐dominated. In contrast, below 55°C, G'' is larger than G', and the polymer solutions are viscosity‐dominated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Mechanical and acoustic performance of compression‐molded open‐cell polypropylene foams
Authors: McRae Joe D. , Naguib Hani E. , Atalla Noureddine
Published: December 2009

Open‐cell materials are lightweight and multifunctional capable of absorbing acoustic energy and supporting mechanical load. The acoustic and mechanical performance of open‐cell materials can be optimized through processing. In this article, the relationships between processing parameters and acoustic and mechanical performance are shown for polypropylene (PP) foams. PP foam samples are fabricated using a combined compression molding and particulate leaching process. The results from a parametric study showed that both salt size and salt to polymer ratio affect the acoustic and mechanical performance of open‐cell PP foams. As salt size increases, cell size increased and cell density decreased. The salt to polymer ratio had opposite affect on cell density, and increasing the salt to polymer mass ratio increased the open‐cell content. The airflow resistivity decreased significantly by increasing the cell size, which means that foam samples with smaller cell size have better sound absorption. When foam samples were thin, smaller cell sizes produced better sound absorption; however, as thickness of the sample increases, medium cell size offered the best acoustic performance. The compressive strength of the foams was increased by increasing the relative density. Acoustic performance results from the parametric study were compared to the Johnson‐Allard model with good agreement. Finally, optimal cellular morphologies for acoustic absorption and mechanical performance were identified. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
A study on the nonuniform deformation of PTFE membrane during its tentering transverse stretching
Authors: Guo Yu‐Hai , Chen Jian‐Yong , Gao Jing‐Xin , Zhang Hua‐Peng , Feng Xin‐Xing
Published: December 2009

To understand the deformation of biaxially stretched polytetrafluoroethylene (PTFE) membrane during the tenter frame transverse stretching process, a finite element analysis (FEA) model was established to study the stress and displacement distribution during the transverse stretching. The morphology, pore size, and mechanical properties of the membrane were also characterized. It has been found from the experimental and FEA simulation results that the tentering transverse stretching of PTFE membrane is a nonuniform stretching, the stress and displacement distribution of the PTFE membrane during tentering is nonuniform because of the nonuniform deformation and the ease of yield and plastic deformation originated from the specific structure of the virgin PTFE particles. The nonuniform thickness and pore size distribution across the membrane width resulted from this nonuniform deformation was also characterized and discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Non‐isothermal cold crystallization kinetics and morphology of PET + SAN blends
Authors: Wellen Renate M. R. , Rabello Marcelo S.
Published: December 2009

The influence of small amounts of poly(styrene‐co‐acrylonitrile) (SAN) on the non‐isothermal cold crystallization behavior and morphology of poly(ethylene terephthalate) (PET) was investigated by dynamic‐mechanical thermal analysis, differential scanning calorimetry (DSC), optical microscopy, and scanning electron microscopy. The results indicated that SAN had a limited solubility in the amorphous phase of PET although in a larger scale a phase separation occurred. The addition of 1 wt % of SAN promoted a significant reduction in the crystallization rate of PET, acting as an antinucleating agent. The kinetics parameters were determined applying both the Ozawa and Mo approaches. Mo's model described the crystallization evolution better than the Ozawa one because it is possible to analyze the kinetic parameters in similar range of crystallinity degrees. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Role of internal additives in the friction and wear of carbon‐fiber‐reinforced polyimide
Authors: Samyn Pieter , De Baets Patrick , Schoukens Gustaaf
Published: December 2009

Polyimide composites should function in sliding contacts under high temperatures, but the interference of carbon fibers with sliding mechanisms is difficult to predict: they often increase the coefficients of friction and act abrasively but show lubricating properties under other conditions. The friction and wear behavior of thermoplastic polyimides reinforced with short carbon fibers and filled with solid internal lubricant (polytetrafluoroethylene) or silicon oil was investigated in this study with a reciprocating cylinder‐on‐plate tester under 50 N at 0.3 m/s with steel counterfaces that were heated at 23–260°C. We concluded that polytetrafluoroethylene additives effectively reduced the coefficients of friction over the entire temperature range, especially under thermally controlled sliding conditions at 120°C, whereas the internal silicon oil increased the coefficients of friction. The wear rates of the fiber‐reinforced polyimide significantly decreased with respect to those of the thermoplastic polyimide, whereas additional fillers slightly increased the wear rates. We further analyzed the role of internal additives by considering the deformation and maximum polymer surface temperature during sliding. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Mechanical and thermal properties of EVA blended with biodegradable ethyl cellulose
Authors: Girija B. G. , Sailaja R. R. N. , Biswas Sharmistha , Deepthi M. V.
Published: December 2009

In this study, biodegradable blend of Poly (Ethylene‐co‐Vinyl Acetate) (EVA) and Ethyl Cellulose (EC) were prepared. Ethylene vinyl alcohol (EVOH) copolymer was used as an interfacial compatibilizer to enhance adhesion between EVA and EC. The melt blended compatibilized biocomposites were examined for mechanical and thermal properties as per the ASTM standards. It has been found that the EC has a reinforcing effect on EVA leading to enhanced tensile strength and also impart biodegradability. Thus, a high loading of 50% EC could be added without compromising much on the mechanical properties. Analysis of the tensile data using predictive theories showed an enhanced interaction of the dispersed phase (EC) and the matrix (EVA). The compatibilizing effects of EVOH on these blends were confirmed by the significant improvement in the mechanical properties comparable with neat EVA as also observed by SEM microscopy. The TGA thermograms exhibits two‐stage degradation and as EC content increases, the onset temperature for thermal degradation reduces. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Accelerated crystallization of poly(L‐lactide) by physical aging
Authors: Tsuji Hideto , Sawada Mariko
Published: December 2009

The low‐temperature physical aging of amorphous poly(L‐lactide) (PLLA) at 25–50°C below glass transition temperature (Tg) was carried out for 90 days. The physical aging significantly increased the Tg and glass transition enthalpy, but did not cause crystallization, regardless of aging temperature. The nonisothermal crystallization of PLLA during heating was accelerated only by physical aging at 50°C. These results indicate that the structure formed by physical aging only at 50°C induced the accelerated crystallization of PLLA during heating, whereas the structure formed by physical aging at 25 and 37°C had a negligible effect on the crystallization of PLLA during heating, except when the physical aging at 37°C was continued for the period as long as 90 days. The mechanism for the accelerated crystallization of PLLA by physical aging is discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Investigations on the electrical and structural properties of PVA doped with (NH4)2SO4
Authors: Hassan M. A. , Gouda M. E. , Sheha E.
Published: December 2009

Solid polymer electrolytes based on poly(vinyl alcohol) (PVA) complexed with ammonium sulfate (NH4)2SO4 at different weight percent ratios were prepared using solution cast technique. The structural properties of these electrolyte films were examined by X‐ray diffraction (XRD) studies. The XRD data revealed that the amorphous domains of PVA polymer matrix increased with the increase of ammonium sulfate added up to 5 wt %, after which the degree of crystallinity increases. The complexation of the salt with the polymer was confirmed by Fourier transform infrared (FTIR) spectroscopy. Electrical conductivity was measured in the temperature range of 303–373 K. The conductivity was found to obey Arrhenius formula. The dielectric permittivity ε′ was studied as function of temperature and frequency, respectively.The data showed increasing in ε′ values with the increase in temperature while decreased with increase in frequency for polymer electrolyte system up to 10% of ammonium sulfate added. For values of addition greater than 10%, ε′ is independent of both temperature and frequency. The ac conductivity is found to obey the power relation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Optimal investment and consumption with stochastic dividends
Authors: Wang Xikui , Wang Yan
Published: December 2009

We use the statistical model of bandit processes to formulate and solve two kinds of optimal investment and consumption problems. The payoffs from the investment are dividend payments with fixed return rates, but the payment frequency is stochastic following a Poisson distribution. The financial market consists of assets which follow Poisson distributions with known or unknown intensity rates. Two kinds of consumption patterns are defined and the optimality of the myopic strategy, the Gittins index strategy, and the play‐the‐winner strategy are discussed. Copyright © 2009 John Wiley & Sons, Ltd.
Does CTCF mediate between nuclear organization and gene expression?
Authors: Ohlsson Rolf , Lobanenkov Victor , Klenova Elena
Published: December 2009

The multifunctional zinc‐finger protein CCCTC‐binding factor (CTCF) is a very strong candidate for the role of coordinating the expression level of coding sequences with their three‐dimensional position in the nucleus, apparently responding to a “code” in the DNA itself. Dynamic interactions between chromatin fibers in the context of nuclear architecture have been implicated in various aspects of genome functions. However, the molecular basis of these interactions still remains elusive and is a subject of intense debate. Here we discuss the nature of CTCF‐DNA interactions, the CTCF‐binding specificity to its binding sites and the relationship between CTCF and chromatin, and we examine data linking CTCF with gene regulation in the three‐dimensional nuclear space. We discuss why these features render CTCF a very strong candidate for the role and propose a unifying model, the “CTCF code,” explaining the mechanistic basis of how the information encrypted in DNA may be interpreted by CTCF into diverse nuclear functions.
Proteomics enhances evolutionary and functional analysis of reproductive proteins
Authors: Findlay Geoffrey D. , Swanson Willie J.
Published: December 2009

Reproductive proteins maintain species‐specific barriers to fertilization, affect the outcome of sperm competition, mediate reproductive conflicts between the sexes, and potentially contribute to the formation of new species. However, the specific proteins and molecular mechanisms that underlie these processes are understood in only a handful of cases. Advances in genomic and proteomic technologies enable the identification of large suites of reproductive proteins, making it possible to dissect reproductive phenotypes at the molecular level. We first review these technological advances and describe how reproductive proteins are identified in diverse animal taxa. We then discuss the dynamic evolution of reproductive proteins and the potential selective forces that act on them. Finally, we describe molecular and genomic tools for functional analysis and detail how evolutionary data may be used to make predictions about interactions among reproductive proteins.
Parallel evolution of segmentation by co‐option of ancestral gene regulatory networks
Authors: Chipman Ariel D.
Published: December 2009

Different sources of data on the evolution of segmentation lead to very different conclusions. Molecular similarities in the developmental pathways generating a segmented body plan tend to suggest a segmented common ancestor for all bilaterally symmetrical animals. Data from paleontology and comparative morphology suggest that this is unlikely. A possible solution to this conundrum is that throughout evolution there was a parallel co‐option of gene regulatory networks that had conserved ancestral roles in determining body axes and in elongating the anterior‐posterior axis. Inherent properties in some of these networks made them easily recruitable for generating repeated patterns and for determining segmental boundaries. Phyla where this process happened are among the most successful in the animal kingdom, as the modular nature of the segmental body organization allowed them to diverge and radiate into a bewildering array of variations on a common theme.
Determination of eflornithine enantiomers in plasma by precolumn derivatization with o‐phthalaldehyde‐N‐acetyl‐l‐cysteine and liquid chromatography with UV detection
Authors: Jansson‐Löfmark R. , Römsing S. , Albers E. , Ashton M.
Published: December 2009

A bioanalytical method for indirect determination of eflornithine enantiomers in 75 μL human plasma has been developed and validated. l‐ and d‐eflornithine were derivatized with o‐phthalaldehyde and N‐acetyl‐L‐cysteine to generate diastereomers which were separated on two serially connected Chromolith Performance columns (RP‐18e 100 × 4.6 mm i.d.) by a isocratic flow followed by a gradient flow for elution of endogenous compounds. The diastereomers were detected with UV (340 nm). The between‐day precisions for L‐ and D‐eflornithine in plasma were 8.4 and 2.3% at 3 μm, 4.0 and 5.1% at 400 μm, and 2.0 and 3.7% at 1000 μm. The lower limit of quantification was determined to be 1.5 μm, at which precision was 14.9 and 9.9% for L‐ and D‐eflornithine, respectively. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis and Anti‐HIV Activity of [ddN]‐[ddN] Dimers and Benzimidazole Nucleoside Dimers
Authors: Li Guo‐Rui , Liu Jun , Pan Qin , Song Zhi‐Bin , Luo Feng‐Ling , Wang Shao‐Ru , Zhang Xiao‐Lian , Zhou Xiang
Published: December 2009

In an attempt to combine the HIV‐inhibitory capacity of different 2′,3′‐dideoxynucleoside (ddN) analogs, we have designed and synthesized several dimers of [AZT]‐[AZT] and [AZT]‐[d4T]. In addition, we also synthesized the dimers of 1‐(1H‐benzimidazol‐1‐yl)‐1‐deoxy‐β‐D‐ribofuranose. The in vitro anti‐HIV activity of these compounds on a pseudotype virus, pNL4‐3.Luc.R‐E‐, in the 293T cells has been determined. Among these compounds, 2,2′‐(propane‐1,3‐diyl)bis[1‐(β‐D‐ribofuranosyl)‐1H‐benzimidazole] (3) showed the highest anti‐HIV activity with similar effect as AZT.
Sinuladiterpenes A–F, New Cembrane Diterpenes from Sinularia flexibilis
Authors: Lo Kuang‐Liang , Khalil Ashraf Taha , Kuo Yao‐Haur , Shen Ya‐Ching
Published: December 2009

Chromatographic investigation of the octocoral Sinularia flexibilis afforded six new cembrane diterpenes, sinuladiterpenes A–F (1–6, resp.), in addition to four known cembranolides, 11‐episinulariolide acetate, 11‐dehydrosinulariolide, 11‐episinulariolide, and sinulariolide. Their structures were elucidated by spectroscopic analysis, especially 2D‐NMR and HR‐ESI‐MS. Compound 2 exhibited significant in vitro cytotoxic activity against human colon adenocarcinoma (WiDr) cell line.
Synthesis and DNA‐Cleavage Activities of Dinuclear Copper(II) Complexes of Urea‐Bridged Macrocyclic Polyamines
Authors: Yue Yang , Li Jing , Zhang Ji , Zhang Zhong‐Wei , Lin Hong‐Hui , Chen Shan‐Yong , Yu Xiao‐Qi
Published: December 2009

Two dinuclear macrocyclic polyamine copper(II) (CuII) complexes, which have two cyclen units linked by urea, were synthesized as DNA‐cleavage agents. The structures of these new dinuclear complexes were identified by HR‐ESI‐MS and IR analyses. The catalytic activities of DNA cleavage of these dinuclear CuII complexes were subsequently studied. The results show that 6a was the better catalyst in the DNA‐cleavage process than 6b. The effects of reaction time and concentration of complexes were also investigated. The results indicate, that the CuII complexes could catalyze the cleavage of supercoiled DNA (pUC 19 plasmid DNA; Form I) under physiological conditions to produce selectively nicked DNA (Form II; no Form III was produced) with high yields (nearly 100%) in short time in the absence of reductant or oxidant.
In silicoStructural Study of Random Amino Acid Sequence Proteins Not Present in Nature
Authors: Prymula Katarzyna , Piwowar Monika , Kochanczyk Marek , Flis Lukasz , Malawski Maciej , Szepieniec Tomasz , Evangelista Giovanni , Minervini Giuseppe , Polticelli Fabio , Wiśniowski Zdzisław , Sałapa Kinga , Matczyńska Ewa , Roterman Irena
Published: December 2009

The three‐dimensional structures of a set of ‘never born proteins’ (NBP, random amino acid sequence proteins with no significant homology with known proteins) were predicted using two methods: Rosetta and the one based on the ‘fuzzy‐oil‐drop’ (FOD) model. More than 3000 different random amino acid sequences have been generated, filtered against the non redundant protein sequence data base, to remove sequences with significant homology with known proteins, and subjected to three‐dimensional structure prediction. Comparison between Rosetta and FOD predictions allowed to select the ten top (highest structural similarity) and the ten bottom (the lowest structural similarity) structures from the ranking list organized according to the RMS‐D value. The selected structures were taken for detailed analysis to define the scale of structural accordance and discrepancy between the two methods. The structural similarity measurements revealed discrepancies between structures generated on the basis of the two methods. Their potential biological function appeared to be quite different as well. The ten bottom structures appeared to be ‘unfoldable’ for the FOD model. Some aspects of the general characteristics of the NBPs are also discussed. The calculations were performed on the EUChinaGRID grid platform to test the performance of this infrastructure for massive protein structure predictions.
Chemical and Genetic Differentiation of Ligularia hodgsonii in Japan and China
Authors: Torihata Atsushi , Chao Xun , Kuroda Chiaki , Hanai Ryo , Hirota Hiroshi , Gong Xun
Published: December 2009

The chemical composition of the root extract and neutral base sequences of L. hodgsonii samples collected in Japan and China were examined. From the Japanese and the Chinese samples, 6β‐(angeloyloxy)furanoeremophilan‐15‐oic acid (2) and 3β‐acetoxy‐6β‐[(2‐methylbutanoyl)oxy]furanoeremophilan‐10β‐ol (3) were isolated as the major component, respectively. The sequence of the internal transcribed spacers (ITSs) of the ribosomal RNA gene was different in the Japanese and the Chinese samples. In contrast to the significant genetic difference, chemical diversity was limited to the positions of O‐functionalities on the furanoeremophilane skeleton, supporting our hypothesis that the production of furanoeremophilanes is ecologically advantageous.
abeo‐Taxane Diterpenoids from the Taiwanese Yew Taxus sumatrana
Authors: Wang Shih‐Sheng , Abd El‐Razek Mohamed H. , Chen Yi‐Cheng , Chien Ching‐Te , Guh Jih‐Hwa , Kuo Yao‐Haur , Shen Ya‐Ching
Published: December 2009

Chemical investigation of the acetonic extract of the leaves and twigs of Taxus sumatrana (Taxaceae) led to the isolation of four new taxane diterpene esters, taiwantaxins A–D (1–4, resp.). Their structures were determined primarily on the basis of 1D‐ and 2D‐NMR techniques as well as MS. Compound 1 is a rearranged taxane diterpenoid possessing an opened oxetane ring moiety containing C(4), C(5), and C(20). The metabolites 2 and 3 belong to a 5/6/6 taxene system having a rare five‐membered γ‐lactone ring comprising C(8), C(9), C(10), and C(19). Compound 4 is an example of a taxane diterpene containing a 6/8/6 ring system with a tetrahydrofuran ring comprising C(2), C(3), C(4), and C(20). The 11(15→1)abeo‐taxane diterpenoids, taiwantaxins A–C (1–3, resp.) are lacking an O‐bearing functionality at either C(13) or C(14). Compound 2 showed significant cytotoxic activity against human PC‐3 tumor cells.
A Novel Cytotoxic Cerium Complex: Aquatrichloridobis(1,10‐phenanthroline)cerium(III) (KP776). Synthesis, Characterization, Behavior in H2O, Binding towards Biomolecules, and Antiproliferative Activity
Authors: Biba Florian , Groessl Michael , Egger Alexander , Jakupec Michael A. , Keppler Bernhard K.
Published: December 2009

The lanthanide complex aquatrichloridobis(1,10‐phenanthroline)cerium(III) [Ce(phen)2(H2O)Cl3] (KP776) was fully characterized by elemental analysis, IR‐, and 1H‐ and 13C‐NMR spectroscopy, as well as TG/DTA measurements, and its behavior in H2O, important for the application as a chemotherapeutic, was studied. In addition, the binding of KP776 to nucleotides and single serum proteins was investigated by capillary electrophoresis, whereas binding to proteins in human plasma was observed by ICP‐MS. The compound shows promising anticancer properties in vitro: proliferation of human cancer cell lines is strongly inhibited with IC50 values in the very low micromolar range.
HS‐SPME/GC Analysis Reveals the Population Variability of Terpene Contents in Juniperus communis Needles
Authors: Filipowicz Natalia , Madanecki Piotr , Gołębiowski Marek , Stepnowski Piotr , Ochocka J. Renata
Published: December 2009

Juniperus communis var. communis L. is an aromatic plant – typical boreal element of flora. In the extensive literature concerning J. communis, there is much data on the composition and the content of essential oil of needles and coneberries, but a detailed analysis of terpene distribution within and between populations is missing. A representative pool of 74 J. communis individuals originating from ten populations of Northern Poland was investigated in order to evaluate the intra‐ and interpopulational variability of the terpene pattern. Headspace solid‐phase microextraction (HS‐SPME) coupled with GC/MS and GC/FID was applied in achiral and enantioselective analysis. The majority of the samples (85%), despite different origin, were similar in the terpene pattern. High diversity of terpenes was observed within the populations and low diversity between them. High variation of enantiomeric composition was in accordance with large variation of individual compounds in general (achiral analysis). J. communis samples from Northern Poland could be distinguished by the α‐pinene/sabinene ratio, and they were divided into three chemical races.
New Isoprenylated 2‐Arylbenzofurans and Pancreatic Lipase Inhibitory Constituents from Artocarpus nitidus
Authors: Zhao Ting , Yan Gui‐Rui , Pan Sheng‐Li , Wang He‐Yao , Hou Ai‐Jun
Published: December 2009

Two new isoprenylated 2‐arylbenzofurans, artonitidin A (=(2′R)‐2′,3′‐dihydro‐2′‐(1‐hydroxy‐1‐methylethyl)‐5′,7‐bis(3‐methylbut‐2‐en‐1‐yl)‐2,4′‐bi‐1‐benzofuran‐6,6′‐diol; 1) and artonitidin B (=5‐[6‐hydroxy‐7‐(3‐methylbut‐2‐en‐1‐yl)‐1‐benzofuran‐2‐yl]‐4‐(3‐methylbut‐2‐en‐1‐yl)benzene‐1,3‐diol; 2), together with 14 known compounds, 3–16, were isolated from the stems of Artocarpus nitidus Trec. The structures were elucidated by spectroscopic methods. Norartocarpin (3), cudraflavone C (5), brosimone I (8), artotonkin (11), albanin A (13), and artopetelin M (14) showed inhibitory effects on pancreatic lipase with IC50 values ranging from 1.8±0.1 to 63.8±3.6 μM.
Highly Sensitive Indicator‐Free Impedance Sensing of DNA Hybridization Based on Poly(m‐aminobenzenesulfonic acid)/TiO2 Nanosheet Membranes with Pulse Potentiostatic Method Preparation
Authors: Hu Yu‐Wei , Yang Tao , Wang Xin‐Xing , Jiao Kui
Published: December 2009

A direct electrochemical detection procedure for DNA hybridization by using the electrochemical signal changes of conductive poly(m‐aminobenzenesulfonic) acid (PABSA)/TiO2 nanosheet membranes, which were electropolymerized by using the pulse potentiostatic method, is reported. Due to the unique properties of TiO2 nanoparticles, m‐aminobenzenesulfonic acid monomers tend to be adsorbed around the particles, and the electropolymerization efficiency is greatly improved. The combination of TiO2 nanoparticles and PABSA resulted in a nanocomposite membrane with unique and novel nanosheet morphology that provides more activation sites and enhances the surface electron‐transfer rate. These characteristics were propitious for the magnification of PABSA electrochemical signals and the direct detection of DNA hybridization. Owing to the presence of abundant sulfonic acid groups, PABSA could overcome the drawbacks of polyaniline and be used to detect bioanalytes at physiological pH. DNA probes could be covalently attached to the sulfonic groups through the amines of DNA sequences by using an acyl chloride cross‐linking reaction. After immobilization of probe DNA, the electrochemical impedance value increased significantly compared to that of PABSA/TiO2 nanosheet membranes, and then decreased dramatically after the hybridization reaction of the probe DNA with the complementary DNA sequence compared to that of the probe‐immobilized electrode. Electrochemical impedance spectroscopy was adopted for indicator‐free DNA biosensing, which had an eminent ability for the recognition between double‐base mismatched sequences or non‐complementary DNA sequences and complementary DNA sequences. A gene fragment, which is related to one of the screening genes for the transgenically modified plants, the cauliflower mosaic virus 35S gene was satisfactorily detected. This is the first report for the indicator‐free impedance DNA hybridization detection by using PABSA/TiO2 membranes under neutral conditions.
Glomerular activity patterns evoked by natural odor objects in the rat olfactory bulb are related to patterns evoked by major odorant components
Authors: Johnson Brett A. , Ong Joan , Leon Michael
Published: December 2009

To determine how responses evoked by natural odorant mixtures compare to responses evoked by individual odorant chemicals, we mapped 2‐deoxyglucose uptake during exposures to vapors arising from a variety of odor objects that may be important to rodents in the wild. We studied 21 distinct natural odor stimuli ranging from possible food sources such as fruits, vegetables, and meats to environmental odor objects such as grass, herbs, and tree leaves. The natural odor objects evoked robust and surprisingly focal patterns of 2‐deoxyglucose uptake involving clusters of neighboring glomeruli, thereby resembling patterns evoked by pure chemicals. Overall, the patterns were significantly related to patterns evoked by monomolecular odorant components that had been studied previously. Object patterns also were significantly related to the molecular features present in the mixture components. Despite these overall relationships, there were individual examples of object patterns that were simpler than might have been predicted given the multiplicity of components present in the vapors. In these cases, the object patterns lacked certain responses evoked by their major odorant mixture components. These data suggest the possibility of mixture response interactions and provide a foundation for understanding the neural coding of natural odor stimuli. J. Comp. Neurol. 518:1542–1555, 2010. © 2009 Wiley‐Liss, Inc.
Neuroglobin expression in the rat suprachiasmatic nucleus: Colocalization, innervation, and response to light
Authors: Hundahl C.A. , Hannibal J. , Fahrenkrug J. , Dewilde S. , Hay‐Schmidt A.
Published: December 2009

Neuroglobin (Ngb) is a myoglobin‐like (Mb) heme‐globin, belonging the globin family located only in neuronal tissue of the central nervous system. Ngb has been shown to be upregulated in and to protect neurons from hypoxic and ischemic injury, but the function of Ngb—in particular how Ngb may protect neurons—remains largely elusive. We have previously described the localization of Ngb in the rat brain and found it to be expressed in areas primarily involved in sleep/wake, circadian, and food regulation. The present study was undertaken, using immunohistochemistry, to characterize the localization, colocalization, innervation, and response to light of Ngb‐immunoreactive (IR) cells in the rat suprachiasmatic nucleus (SCN). Our results demonstrate that the majority of Ngb‐expressing neurons in the SCN belong to a cell group not previously characterized by neurotransmitter content; only a small portion was found to co‐store GRP in the ventral SCN. Furthermore, some Ngb‐containing neurons were responsive to light stimulation at late night evaluated by the induction of cFOS and only a few cells were found to express the core clock gene PER1 during the 24‐hour light/dark cycle. The Ngb‐containing cells received input from neuropeptide Y (NPY)‐containing nerve fibers of the geniticulo‐hypothalamic tract (GHT), whereas no direct input from the eye or the midbrain raphe system was demonstrated. The results indicate that the Ngb could be involved in both photic and nonphotic entrainment via input from the GHT. J. Comp. Neurol. 518:1556–1569, 2010. © 2009 Wiley‐Liss, Inc.
Guinea pig horizontal cells express GABA, the GABA‐synthesizing enzyme GAD65, and the GABA vesicular transporter
Authors: Guo Chenying , Hirano Arlene A. , Stella Salvatore L. , Bitzer Michaela , Brecha Nicholas C.
Published: December 2009

γ‐Aminobutyric acid (GABA) is likely expressed in horizontal cells of all species, although conflicting physiological findings have led to considerable controversy regarding its role as a transmitter in the outer retina. This study has evaluated key components of the GABA system in the outer retina of guinea pig, an emerging retinal model system. The presence of GABA, its rate‐limiting synthetic enzyme glutamic acid decarboxylase (GAD65 and GAD67 isoforms), the plasma membrane GABA transporters (GAT‐1 and GAT‐3), and the vesicular GABA transporter (VGAT) was evaluated by using immunohistochemistry with well‐characterized antibodies. The presence of GAD65 mRNA was also evaluated by using laser capture microdissection and reverse transcriptase‐polymerase chain reaction. Specific GABA, GAD65, and VGAT immunostaining was localized to horizontal cell bodies, as well as to their processes and tips in the outer plexiform layer. Furthermore, immunostaining of retinal whole mounts and acutely dissociated retinas showed GAD65 and VGAT immunoreactivity in both A‐type and B‐type horizontal cells. However, these cells did not contain GAD67, GAT‐1, or GAT‐3 immunoreactivity. GAD65 mRNA was detected in horizontal cells, and sequencing of the amplified GAD65 fragment showed approximately 85% identity with other mammalian GAD65 mRNAs. These studies demonstrate the presence of GABA, GAD65, and VGAT in horizontal cells of the guinea pig retina, and support the idea that GABA is synthesized from GAD65, taken up into synaptic vesicles by VGAT, and likely released by a vesicular mechanism from horizontal cells. J. Comp. Neurol. 518:1647–1669, 2010. © 2009 Wiley‐Liss, Inc.
D‐serine is distributed in neurons in the brain of the sea lamprey
Authors: Villar‐Cerviño Verona , Barreiro‐Iglesias Antón , Rodicio María Celina , Anadón Ramón
Published: December 2009

The amino acid D‐serine is an endogenous coagonist of N‐methyl‐D‐aspartate (NMDA) receptors in mammals that has been shown to play an important role in synaptic function, behavior, learning, and memory. The distribution and cellular location of D‐serine in the brain of the sea lamprey was investigated by using immunofluorescence methods. One major finding of our study, unlike early studies of mammals, was the localization of D‐serine immunoreactivity in perikarya and dendrites of neurons, whereas D‐serine immunoreactivity was not generally observed in the lamprey glia. D‐serine‐immunoreactive neurons were observed in different brain regions, including the olfactory bulb, medial pallium, thalamus, torus semicircularis, isthmus, and reticular formation. The colocalization of D‐serine with γ‐aminobutyric acid (GABA) was also studied with a double‐immunofluorescence technique. The relationship between D‐serine and glycine immunoreactivities was studied in alternate parallel series of sections stained for either D‐serine/GABA or glycine/GABA. Colocalization with GABA was observed in various D‐serine‐immunoreactive populations, and codistribution and possible colocalization with glycine was also observed in some populations, mainly in the dorsal isthmic gray, medial octavolateral nucleus, dorsal column nucleus, interpeduncular nucleus, and reticular formation. Although numerous fibers were strongly GABA‐ and glycine‐immunoreactive, D‐serine immunoreactivity was observed mostly in cell perikarya and dendrites. The present results indicate that the D‐serine immunoreactive cells are small to medium‐sized neurons, some exhibiting classical inhibitory neurotransmitters, in which D‐serine might be acting as a modulator. The neuronal distribution of D‐serine and its frequent colocalization and/or codistribution with the two main inhibitory neurotransmitters appeared early in vertebrates. J. Comp. Neurol. 518:1688–1710, 2010. © 2009 Wiley‐Liss, Inc.
Projections of preBötzinger Complex neurons in adult rats
Authors: Tan Wenbin , Pagliardini Silvia , Yang Paul , Janczewski Wiktor A. , Feldman Jack L.
Published: December 2009

The preBötzinger Complex (preBötC) contains neural microcircuitry essential for normal respiratory rhythm generation in rodents. A subpopulation of preBötC neurons expresses somatostatin, a neuropeptide with a modulatory action on breathing. Acute silencing of a subpopulation of preBötC neurons transfected by a virus driving protein expression under the somatostatin promoter results in persistent apnea in awake adult rats. Given the profound effect of silencing these neurons, their projections are of interest. We used an adeno‐associated virus to overexpress enhanced green fluorescent protein driven by the somatostatin promoter in preBötC neurons to label their axons and terminal fields. These neurons send brainstem projections to: 1) contralateral preBötC; 2) ipsi‐ and contralateral Bötzinger Complex; 3) ventral respiratory column caudal to preBötC; 4) parafacial respiratory group / retrotrapezoid nucleus; 5) parahypoglossal nucleus/nucleus of the solitary tract; 6) parabrachial/Kölliker‐Fuse nuclei; and 7) periaqueductal gray. We did not find major projections to either cerebellum or spinal cord. We conclude that there are widespread projections from preBötC somatostatin‐expressing neurons specifically targeted to brainstem regions implicated in control of breathing, and provide a network basis for the profound effects and the essential role of the preBötC in breathing. J. Comp. Neurol. 518:1862–1878, 2010. © 2009 Wiley‐Liss, Inc.