bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoelectron Spectra and Electronic Structures of Some Acceptor‐Substituted Cyclopropanes: Linear Correlation of Substituent Effects on MO Energies with Molecular Structures
Authors: Rademacher Paul , Coskun Timur , Kowski Klaus , Larionov Oleg , de Meijere Armin
Published: June 2003

The relationship between electronic and geometrical structures in acceptor‐substituted cyclopropanes has been investigated by B3LYP DFT calculations and photoelectron (PE) spectroscopy. The spectra of cyclopropanecarbaldehyde (2), cyclopropanecarboxylic acid (3), cyclopropanecarboxylic acid methyl ester (4), nitrocyclopropane (5), isothiocyanatocyclopropane (6), cyanocyclopropane (7), and 1,1‐dicyanocyclopropane (8) have been analyzed. The first ionization potential (IP1) of compounds 2–5 was found to be 0.1–0.4 eV higher than that of the analogous isopropyl derivatives indicating—contrary to expectation—that in these compounds the cyclopropyl group acts as a weaker electron donor than an isopropyl group. In the other compounds, IP1 values are 0.4–1.1 eV lower than in the open‐chain congeners. The Walsh orbitals ωS and ωA of the three‐membered ring are substantially stabilized to different extents by interactions with substituent orbitals, and this is reflected in shortened distal and elongated vicinal CC bonds. Although the nitro group in compound 5 causes large stabilizations of both ωS and ωA, their energy difference Δω remains rather small; this is in agreement with a relatively small difference Δr of the CC bond lengths. For the investigated monosubstituted cyclopropanes 2–7, the largest effects with respect to Δω and Δr are caused by the formyl group in carboxaldehyde 2. Comparison of the results for nitriles 7 and 8 indicates that the effects of the cyano groups are additive. A linear relationship between Δω and Δr was established by B3LYP DFT calculations on geometrically distorted cyclopropane (1) and from the PE data of 2–8.
Synthesis and Microstructural Characterisation of Two New One‐Dimensional Members of the (A3NiMnO6)α(A3Mn3O9)β Homologous Series (A = Ba, Sr)
Authors: Hernando María , Boulahya Khalid , Parras Marina , González‐Calbet Jose M. , Amador Ulises
Published: June 2003

Two new members of the one‐dimensional (A3NiMnO6)α(A3Mn3O9)β homologous series, with the compositions (Sr0.75Ba0.25)5NiMn3O12 and Sr9Ni2Mn5O21, have been synthesised. Their structures can each be described as a hexagonal array of infinite one‐dimensional chains of face‐sharing polyhedra, running parallel to the c axis and separated by the Sr/Ba cations. The structure of (Sr0.75Ba0.25)5NiMn3O12, which constitutes the (α = 3, β = 2) member of the series, is made up of three face‐sharing octahedra linked by one trigonal prism. For Sr9Ni2Mn5O21 (α = 2, β = 1) the sequence of polyhedra along the chains corresponds to a motif consisting of two octahedra−one trigonal prism−three octahedra−one trigonal prism. The manganese atoms occupy the octahedral sites in both phases, while the Ni2+ cations are distributed in the trigonal‐prismatic sites in a disordered way. Only a small fraction of these (close to 20%) is located at the centres of the trigonal prisms, 80% being displaced towards the rectangular faces of the polyhedra and giving rise to a square‐planar‐like coordination. Both oxides present twinned microstructures, as evidenced by SAED and HREM. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Discrete Supramolecular Assemblies of Porphyrins Mediated by Coordination Compounds
Authors: Iengo Elisabetta , Zangrando Ennio , Alessio Enzo
Published: June 2003

Metal‐driven self‐assembly has emerged as a viable alternative to covalent synthesis in the construction of large and sophisticated multi‐porphyrin architectures, whose complexity and function begin to approach the properties of naturally occurring systems. The design and preparation of robust and shape‐persistent discrete assemblies, obtained by coordination of meso‐pyridylporphyrins to ruthenium, palladium and zinc centers, is comprehensively discussed in this microreview, that covers research in this field carried out by the authors at the University of Trieste in the last few years. NMR spectroscopy and X‐ray crystallography were used jointly for the unambiguous characterization of the new species in solution and solid state, respectively. Very often the adducts of nanoscopic dimensions, in which the number, position, relative distance and orientation of the chromophores is well defined, were obtained through hierarchical supramolecular self‐assembly: multi‐porphyrin components were used as building blocks for the metal‐mediated assembly of more elaborate architectures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Fatty acid esters with short‐chain alcohols in two‐phase olive pomace oils
Authors: Ruiz‐Méndez M. Victoria , Ramos‐Hinojosa Álvaro E.
Published: June 2003

Two‐phase decanter olive pomace (TPOP) is the by‐product of a centrifugation system, used to produce olive oil, that separates olive oil and moist pomace. The water content in these olive pomaces is about 70%, while it was 45‐50% in the olive pomace stemming from three‐phase systems (oil, water, and pomace) and 30% in the old press system. The aim of this work is focused on quantification and changes undergone during olive pomace storage in ponds of esters of fatty acids with short‐chain linear alcohols, which can be considered as a refining loss. The results indicate that oil deterioration increases very rapidly, in particular when oil is extracted from the TPOP surface. Special attention should be paid to the storage of TPOP, establishing a maximum of 2 months in all cases.
Electrochemical Oxidation of Hyperforin on Glassy Carbon Electrode and Determination in Herbal Medicinal Products
Authors: Michelitsch Astrid , Wurglics Mario
Published: June 2003

Hyperforin, one of the active components of St. John's Wort and St. John's Wort extracts is oxidized on the glassy carbon electrode. Electrode process, type and reversibility were examined by means of cyclic voltammetry in various buffer systems (NaAc/HAc, Sörensen‐phosphate buffer, borate buffer). A differential pulse voltammetric method was developed for the determination of hyperforin. In the concentration range from 1.0 μg/mL to 40.0 μg/mL there is a strong linearity between the concentration of hyperforin and peak height. The detection limit is 200 ng /mL. The differential pulse voltammetric method developed is used to determine hyperforin in herbal medicinal products.
Using Ferrocenes to Assist in Voltammetric Characterization of Carbon Fiber Microelectrodes after Electrochemical and Laser Activation
Authors: Farrell Patrick C. , Kinley Patrick R. , Weiss David J. , Strein Timothy G.
Published: June 2003

In this report the voltammetry of water‐soluble ferrocene derivatives is used to characterize the surface of carbon fiber microelectrodes before and after both electrochemical and laser activation procedures. Activation of carbon electrodes is necessary to produce a reproducible surface that will allow fast electron transfer. However, the activation method that is best suited for a given analysis can differ with analyte. In order to directly compare activation methods and characterize the resulting electrode performance, the voltammetry of a set of ferrocenes which have fast and well‐known electrochemistry has been used. As expected, electrochemical activation (0.000 to 2.000 V (vs. SSCE) at 500 V/s for 15 seconds) resulted in a hydrophilic surface with increased surface area. Laser pretreatment (20 Hz pulsed nitrogen laser irradiation for 15 seconds) appeared to remove surface oxides thereby producing a more hydrophobic surface that facilitates the adsorption of neutral analytes. In general, anionic ferrocene derivatives exhibited more quasi‐reversible voltammetry and were not as strongly adsorbed as the neutral analyte, particularly with electrochemically activated probes. In addition, neutral analytes show considerable adsorption, particularly at laser‐activated electrodes, while the cationic analyte shows significant adsorption at only the electrochemically‐pretreated electrodes, indicating surface‐specific interactions.
Renewable Drops Electrochemical Sensor for Sulfide Ions Detection
Authors: Milani M. R. , Stradiotto N. R. , Cardoso A. A.
Published: June 2003

The design and characteristics of a novel electrochemical system, which uses a drop as a renewable electroanalytical sensor, are described. This article describes the performance of the electrochemical system, the coupling of the experimental arrangement with flow injection technique and a demonstration of its applicability for the measurement of sulfide. The method is based on renewable drops of ferricyanide ions, buffered by borate. The ferrocyanide ions, product of the reaction between ferricyanide and sulfide ions, are oxidized on a platinum microelectrode and the current measured is related to sulfide concentration. The measurements can be done in continuous or static flow mode. In continuous mode, the detection limit is 5.0×10−5 mol L−1.
Disposable Glucose Sensors for Flow Injection Analysis Using Substituted 1,4‐Benzoquinone Mediators
Authors: Lau King‐Tong , de Fortescu Stephane A. L. , Murphy Lindy J. , Slater Jonathan M.
Published: July 2003

The redox chemistry of several substituted benzoquinones was investigated by cyclic voltammetry at a glassy carbon electrode and candidates for inclusion in a mediated biosensor for use in flow analysis were selected on the basis of oxidation potential, electrochemical reversibility and solubility. Glucose sensors constructed by sequential deposition onto a carbon pellet of 2,6‐dimethyl‐1,4‐benzoquinone, 2,3,5,6‐tetramethyl‐1,4‐benzoquinone or phenyl‐1,4‐benzoquinone mediator solution, followed by glucose oxidase in polyvinylalcohol‐Nafion solution, were tested for response to glucose using flow injection analysis. Sensors prepared from 2,6‐dimethyl‐1,4‐benzoquinone gave highest sensitivity, with a linear range of response to glucose of 2.5–40 mM. The use of an enzyme‐free comparative electrode to eliminate the response from interferents was investigated.
Chiral separation of methadone, 2‐ethylidene‐ 1,5‐dimethyl‐3,3‐diphenylpyrrolidine (EDDP) and 2‐ethyl‐5‐methyl‐3,3‐diphenyl‐1‐pyrroline (EMDP) by capillary electrophoresis using cyclodextrin derivatives
Authors: Kelly Tamsin , Doble Philip , Dawson Michael
Published: July 2003

A stereoselective method was developed for the simultaneous determination of methadone and its two major metabolites, 2‐ethylidene‐1,5‐dimethyl‐3,3‐diphenylpyrrolidine (EDDP) and 2‐ethyl‐5‐methyl‐3,3‐diphenyl‐1‐pyrroline (EMDP) by capillary electrophoresis. Five β‐cyclodextrin (βCD) background electrolyte (BGE) additives were evaluated for resolution efficiency. The conditions for baseline resolution of each of the three enantiomer pairs was determined to be 1 mM heptakis‐(2,6‐di‐O‐methyl)‐β‐cyclodextrin (DMβCD) in 100 mM phosphate at pH 2.6. This method represents the first successful method for the resolution of the six enantiomers associated with the metabolism of methadone. The utilisation of doubly coated capillaries in conjunction with βCD derivatives for a faster separation of the methadone‐related enantiomers is also reported. The coated capillaries were prepared using a polycation of poly(diallyldimethylammonium chloride) (PDDAC) and a polyanion of dextran sulfate. Baseline resolution of the methadone enantiomers was achieved with a BGE of 8 mM (2‐hydroxy)propyl‐β‐cyclodextrin (HPβCD) in 100 mM phosphate at pH 2.6. The migration times for the stereoselective methadone separation were approximately 4 min, which represented a reduction by a factor of approximately three, compared to that attained using analogous conditions with the uncoated capillary.
Capacitively coupled contactless conductivity detection in capillary electrophoresis
Authors: Zemann Andreas J.
Published: July 2003

Capacitively coupled contactless conductivity detection (C4D) has become an accepted detection method in capillary electrophoresis (CE) for a variety of analytes. Advantages of this technique over optical detection modes and galvanic contact conductivity detection include great flexibility in capillary handling and rather simple mechanical parts and electronics, as it can be performed in an on‐capillary mode. Furthermore, the detection principle can be used with capillaries made of other materials than fused silica (PEEK®, Teflon®), with chip‐based separation technologies, or with capillaries having very small inner diameters. This review presents a discussion of the published literature on C4D for CE and capillary electrochromatography.
Fed‐Batch Process for Pyruvate Production by Recombinant Escherichia coli YYC202 Strain
Authors: Zelić B. , Gerharz T. , Bott M. , Vasić‐Rački Đ. , Wandrey C. , Takors R.
Published: July 2003

Fed‐batch fermentation was applied to the production of pyruvate by using a recombinant Escherichia coli YYC202 strain. This strain is completely blocked in its ability to convert pyruvate into acetyl‐CoA or acetate, resulting in acetate auxotrophy during growth in glucose minimal medium. By controlling acetate and glucose feed rate, a series of lab‐scale fed‐batch experiments were performed at pH 7 and 37 °C. CO2 production rate (CTR) was used for on‐line regulation of the acetate feed rate. The correlation between CTR and acetate consumption rate (ACR) was determined experimentally. At optimal process conditions a final pyruvate concentration higher than 62 g/L, a space‐time yield of up to 42 g/L/d and pyruvate/glucose molar yield of 1.11 mol/mol were achieved. Experimental evidence was gathered that pyruvate export is active.
On detrending and cyclical asymmetry
Authors: Psaradakis Zacharias , Sola Martin
Published: June 2003

This paper considers the issue of testing for symmetry of the business cycle. It is demonstrated that findings of symmetry should be interpreted with caution since tests tend to have low power to detect asymmetries when applied to data that have been filtered to isolate their stationary business‐cycle component. This implies that asymmetries are likely to be detected in practice only when they are particularly prominent. An empirical application examines the properties of the cyclical component of real GDP for the G7 countries. Copyright © 2002 John Wiley & Sons, Ltd.
Effect of water‐miscible solvents on the organic solvent‐resistant tyrosinase from Streptomyces sp. REN‐21
Authors: Rodakiewicz‐Nowak Janina , Ito Masaaki
Published: June 2003

The effect of various water‐miscible organic solvents (ethanol, methanol, acetone, acetonitrile, N,N‐dimethylformamide (DMF) and dimethylsulfoxide (DMSO)) on the kinetics of 4‐tert‐butylcatechol (tBC) oxidation in the presence of different samples of organic solvent‐resistant tyrosinase (OSRT) has been studied. In contrast to mushroom tyrosinase the enzyme shows a high relative stability in solutions of organic solvents and increased activity toward the bulky and hydrophobic substrate, tBC, in respect to catechol. Rates of the studied OSRT‐catalyzed reactions are however reduced by the presence of organic solvents and for all studied samples of OSRT decrease exponentially with the content of an organic solvent. The effect has been satisfactorily described by the effect of organic solvents on the thermodynamic activity of tBC. The correlation of the inhibition parameters with the hydrophobicity of a particular solvent (log P), its intrinsic molar volume, Vi, and the Dimroth–Reichardt parameter, ET(30), are shown. The results allow also the prediction of OSRT activity in aqueous solutions of water‐miscible organic solvents. Copyright © 2003 Society of Chemical Industry
Process kinetics of UASB reactors treating non‐inhibitory substrate
Authors: Huang Ju‐Sheng , Jih Charng‐Gwo , Lin Shin‐Dow , Ting Wen‐Huei
Published: June 2003

The degradation of a non‐inhibitory substrate (sucrose) in upflow anaerobic sludge bed (UASB) reactors with different superficial flow velocites (us) was performed to generate experimental data. Additionally, a kinetic model accounting for the mass fraction of methanogens (f) and granule size distribution in UASB reactors is also proposed. At the volumetric loadings of 2.65–21.16 g COD dm−3 day−1, both the COD removal efficiency and granule size of the UASB reactors increase with increasing us. The f values determined experimentally increase from 0.13–0.24 to 0.27–0.43 if the volumetric loading is increased from 2.65 to 5.29 g COD dm−3 day−1. With a further increase in volumetric loading, the f values decline because of the accumulation of volatile fatty acids (VFAs). The predicted residual concentrations of VFAs and COD are in fairly good agreement with the experimental data. From the calculated effectiveness‐factor values, the influence of mass transfer resistance of the substrate sucrose on the overall substrate removal rate should not be neglected. From parametric sensitivity analyses together with the simulated concentration profiles, methanogenesis is the rate‐limiting step. Copyright © 2003 Society of Chemical Industry
Conformational restrictions in the active site of unliganded human caspase‐3
Authors: Ni Chao‐Zhou , Li Chenglong , Wu Joe C. , Spada Alfred P. , Ely Kathryn R.
Published: June 2003

Caspases are cysteine proteases that play a critical role in the initiation and regulation of apoptosis. These enzymes act in a cascade to promote cell death through proteolytic cleavage of intracellular proteins. Since activation of apoptosis is implicated in human diseases such as cancer and neurodegenerative disorders, caspases are targets for drugs designed to modulate their action. Active caspases are heterodimeric enzymes with two symmetrically arranged active sites at opposite ends of the molecule. A number of crystal structures of caspases with peptides or proteins bound at the active sites have defined the mechanism of action of these enzymes, but molecular information about the active sites before substrate engagement has been lacking. As part of a study of peptidyl inhibitors of caspase‐3, we crystallized a complex where the inhibitor did not bind in the active site. Here we present the crystal structure of the unoccupied substrate‐binding site of caspase‐3. No large conformational differences were apparent when this site was compared with that in enzyme‐inhibitor complexes. Instead, the 1.9 Å structure reveals critical side chain movements in a hydrophobic pocket in the active site. Notably, the side chain of tyrosine204 is rotated by ∼90° so that the phenol group occupies the S2 subsite in the active site. Thus, binding of substrate or inhibitors is impeded unless rotation of this side chain opens the area. The positions of these side chains may have important implications for the directed design of inhibitors of caspase‐3 or caspase‐7. Copyright © 2003 John Wiley & Sons, Ltd.
Reexamination of the recognition preference of the specificity pocket of the Abl SH3 domain
Authors: Santamaria Fanny , Wu Zhibin , Boulègue Cyril , Pál Gábor , Lu Wuyuan
Published: June 2003

Src homology‐3 (SH3) domains mediate important protein–protein interactions in a variety of normal and pathological cellular processes, thus providing an attractive target for the selective interference of SH3‐dependent signaling events that govern these processes. Most SH3 domains recognize proline‐rich peptides with low affinity and poor selectivity, and the goal to design potent and specific ligands for various SH3 domains remains elusive. Better understanding of the molecular basis for SH3 domain recognition is needed in order to design such ligands with potency and specificity. In this report, we seek to define a clear recognition preference of the specificity pocket of the Abl SH3 domain using targeted synthetic peptide libraries. High‐resolution affinity panning coupled with mass spectrometric readout allows for quick identification of Trp as the preferred fourth residue in the decapeptide ligand APTWSPPPPP, which binds to Abl SH3 four times stronger than does the decapeptide containing Tyr or Phe in the fourth position. This finding is in contrast to several reports that Tyr is the only residue selected from phage displayed peptide libraries that interacts with the specificity pocket of Abl SH3. This simple, unbiased approach can fine‐tune the affinity and selectivity of both natural and unnatural SH3 ligands whose consensus binding sequence has been pre‐defined by combinatorial library methods. Copyright © 2003 John Wiley & Sons, Ltd.
Influence of microbial activity and soil moisture on herbicide immobilization in soils
Authors: Pätzold Stefan , Brümmer Gerhard W.
Published: June 2003

Mobility, extractability, and disappearance of the herbicides diuron, terbuthylazine, metolachlor, and pendimethalin were examined in incubation experiments with two topsoil samples of different natural microbial activity and after sterilization. Soil moisture was held constant at 10, 40, and 60 % WHC. In other variants, the soil water content was changed during the incubation.

The four herbicides reveal a fairly different extent of microbial and chemical degradation and immobilization. The herbicide mobility – expressed by coefficients of partition between adsorbed and dissolved herbicide amounts – decreases at a lower rate and extent, when the microbial activity is low or the soil is sterile. With increasing initial soil moisture, also herbicide mobility and extractability increase; but in the course of time, abiotic immobilization occurs to a higher extent. When soil moisture changes during the incubation, formerly non‐extractable herbicide fractions (up to 40 % of the applied amounts) become extractable.

Kinetics of herbicide immobilization follow an empirical sigmoidal function, which describes three periods of immobilization. The three‐period shape of the curve and its possible reasons are discussed for the data of the incubation experiments as well as for the results of a long‐term field trial with diuron.
Erfassung der Variabilität von Bodenmerkmalen in einem Blindversuch auf Fahlerde mittels Methoden der räumlichen Statistik
Authors: Kuzyakova Irina , Richter Christel
Published: June 2003

Mittels Kopplung der Methoden der klassischen Statistik und der Geostatistik wurden für einen Blindversuch auf Fahlerde die Zusammenhänge zwischen den Bodenmerkmalen Gesamtkohlenstoffgehalt (Ct), Gehalt an Feinerde (FAT = Ton+Feinschluff [%]), pflanzenverfügbarem K und P (mg (100g Boden)–1), pHKCl‐Werten im Ober‐ (0 – 30 cm) und Unterboden (31 – 40 cm) und bodenbildenden Faktoren (Tiefe der Lehmunterlagerung und Mikrorelief) untersucht.

Die Glättung der Rohdaten mittels Block‐Kriging führte zur Eliminierung der kleinräumigen Komponente der Variabilität. Dadurch stiegen die Rangkorrelationskoeffizienten zwischen den Bodenmerkmalen bis auf das 2‐fache an und erreichten im Oberboden –0, 52 für Ct–FAT; 0, 69 für Ct–K und 0, 55 für Ct–P. Signifikante Korrelationen, Ähnlichkeit der Karten und der Variogramme ließen schlussfolgern, dass die räumliche Verteilung von FAT, Ct, K und P im Oberboden durch gemeinsame Faktoren bedingt ist. Als wichtigste variabilitätsverursachende Faktoren der Bodeneigenschaften ergaben sich die Tiefe der Lehmunterlagerung und das Relief. Die Rangkorrelationskoeffizienten der geglätteten trendbereinigten Nivellementwerte mit den Merkmalen FAT, Ct, K und P im Oberboden betrugen –0, 63; –0, 77; –0, 71 und –0, 57.
Soil properties, but not plant nutrients (N, P, K) interact with chemically induced resistance against powdery mildew in barley
Authors: Wiese Joachim , Bagy Magdy M. K. , Schubert Sven
Published: June 2003

Chemically induced resistance is a promising method of plant protection against diseases, which can be triggered by systemically acting chemical inducers such as BTH (benzo(1, 2, 3)thiadiazole‐carbothioic‐acid‐S‐methylester). BTH is commercially distributed as a 50 % formulation, called Bion®. The uncertain success of Bion® application in controlling infection by powdery mildew is a major obstacle in using induced resistance for plant protection in agriculture. This study aimed to investigate the effect of soil properties, selected macronutrients (N, P, and K), and addition of organic matter on induced resistance and to identify possible factors responsible for the high variability of BTH effect under field conditions. A pot experiment under open‐air conditions was set up using the pathosystem Hordeum vulgare cv. Ingrid / Blumeria graminis f. sp. hordei race A6. The different soils strongly affected the resistance of barley plants against powdery mildew after BTH treatment. The infection of barley by powdery mildew was lower than on all other soils when grown on an acid forest soil which was limed up to pH 4.9, even after BTH treatment. A reproducible induction of pathogen resistance by BTH was shown only on a mineral soil (Kleinlinden) with a negligible C content. Application of N, P, and K did not consistently affect the induction of resistance by BTH. The addition of green manure and compost led to an enhanced variability of resistance induction on the soil “Kleinlinden”. Possible effects of soil microflora on resistance induction are discussed.
Modulating effects of L‐arginine on cytokine‐stimulated lymphocyte migration in vitro
Authors: Scott Isenberg J.
Published: June 2003

Elective microsurgical transplants have become routine. Yet there remains a 1–5% rate of complete flap necrosis among these surgical reconstructions. This rate is much higher in emergent replantations. Despite technically accurate surgery, perfusion fails in this group. This lack of perfusion, or no‐reflow, has been attributed to ischemic‐reperfusion injury. The exact nature of this phenomenon remains poorly characterized, though it is clear that significant changes occur in such situations at the endothelial vascular interface. In an effort to understand the biomolecular events involved in ischemic‐reperfusion injury we investigated the modulation of leukocyte transendothelial migration. Using a chemotactic chamber model with a cytokine stimulate mono‐layer of umbilical vein endothelium, we evaluated the migration rate of peripheral blood mononuclear cells in the presence of exogenous L‐arginine and/or the nitric oxide synthase inhibitor L‐NAME. Levels of INF‐γ and TNF‐α production were also determined. It was found that in the face of cytokine pre‐stimulation and L‐arginine, mononuclear cell trans‐endothelial migration increased dramatically. There were also parallel increases in inflammatory cytokine output. These responses were sharply decreased by L‐NAME. The results of this study suggest that in vitro nitric oxide augments transendothelial migration of inflammatory cells. Modulation of this response may provide a clinically useful method of minimizing ischemic‐reperfusion injury. © 2003 Wiley‐Liss, Inc. MICROSURGERY 23:262–267 2003
Free flaps for type III complex pharyngoesophageal defects after enlarged ablative surgery for advanced cancer of larynx and hypopharynx
Authors: Antohi Nicolae , Tibirna Gheorghe , Suharski Ilie , Bejan Anatol , Marina Sergiu , Pogonet Vadim , Stan Vitalie
Published: June 2003

Free tissue transfer has become a useful technique for reconstruction of type III complex pharyngoesophageal defects after enlarged laryngectomy and partial or total pharyngoesophageal resection. We present a retrospective analysis of our experience with 36 patients who received free flaps for reconstruction of complex pharyngoesophageal defects associated with skin and soft‐tissue defects. Free fasciocutaneous flaps and jejunum combined with a deltopectoral flap and musculocutaneous pectoralis major flap, gastro‐omental flap, and combined latissimus dorsi musculocutaneous and cutaneous scapular flaps were used for reconstruction. Adjuvant therapy included preoperative or postoperative radiotherapy. Free flap failure occurred in 2 of 36 patients. Twenty‐eight patients had good swallowing function. Better results with fewer complications in reconstruction of type III complex pharyngoesophageal defects were obtained with the use of a combined latissimus dorsi and scapular flap. © 2003 Wiley‐Liss, Inc. MICROSURGERY 23:189–193 2003
New polysaccharide‐g‐polyacrylonitrile copolymers: synthesis and thermal characterization
Authors: Zohuriaan‐Mehr M. J. , Pourjavadi A.
Published: June 2003

Various natural and modified polysaccharides (i.e. arabic gum, tragacanth gum, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) were modified using ceric‐initiated graft polymerization of acrylonitrile under inert atmosphere. Grafting was confirmed using spectral (FT‐IR) proofs. The grafting parameters were determined by conventional methods. Thermal characteristics of the homopolymer‐free copolymers were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) under nitrogen atmosphere. The major thermal transitions as well as the activation energy of the major decomposition stages were investigated. The polyacrylonitrile (PAN)‐grafted polysaccharides were recognized to be thermally stable more than the corresponding non‐grafted substrates, although they begin to decompose at relatively lower temperatures than the non‐grafted counterparts. Copyright © 2003 John Wiley & Sons, Ltd.
Unusual rheology behaviour of ultra high molecular weight polyethylene/kaolin composites prepared via polymerization‐filling
Authors: Wang Xin , Wu Qiye , Qi Zongneng
Published: June 2003

The rheological behaviour of ultra high molecular weight polyethylene (UHMWPE)/Kaolin composites prepared by a polymerization‐filling process was investigated by conducting capillary and dynamic rheology tests. The results showed that the addition of Kaolin could significantly improve the processability of UHMWPE composites. The common viscoelastic flow was discovered for UHMWPE composites in capillary extrusion testing. The further discussion showed that the unique microstructure provided by polymerization‐filling of UHMWPE/Kaolin composites led to this unusual rheology behaviour. Copyright © 2003 Society of Chemical Industry
The effect of initiator‐to‐monomer ratio on the properties of the polybutadiene‐ol synthesized by free radical solution polymerization of 1,3‐butadiene
Authors: Mohamad Sadeghi Gity Mir , Morshedian Jalil , Barikani Mehdi
Published: June 2003

Polybutadiene‐ol was synthesized by solution radical polymerization of 1,3‐butadiene in the presence of hydrogen peroxide as initiator and 2‐propanol as solvent. The ratio of initiator to monomer molar concentration, [I0]/[M0], was varied while temperature, reaction time and the type and amount of solvent were kept constant. The effects on the Mn; Mw; Mv; PDI, OH‐number and functionality of the synthesized polyols were studied. By taking several samples during a polymerization batch and analyzing them, the time of reaction was chosen as 100 min, after which the PDI changed dramatically. Mn decreased exponentially with increasing [I0]/[M0] according to the relationship Mn = 565.55 ([I0]/[M0])−0.7553. The decrease observed in Mw gradually levelled off with increasing [I0]/[M0] and molecular weight distribution broadened at larger values of [I0]/[M0]. The OH‐number increases with [I0]/[M0]. In addition to the number‐average molecular weight, functionality is dependent on the number of hydroxyl‐terminated chain radicals in the reaction medium. Copyright © 2003 Society of Chemical Industry
Electrical properties of macromolecular complexes of coordinated polymers with mixed valence of Co(II), Co(III) and Co(II–III)
Authors: Elghanem HM , Jawad S Abdul , Aljundi J , Afaneh F , Arafa I
Published: June 2003

Electrical properties of bis‐ethylenediamine Co(II), Co(III) and Co(II–III) mixed valence complexes and polyethylenediaminecarbosilazane (PEDCSZ) [Co(II), Co(III) and Co(II–III)] macromolecules were measured at room temperature in a frequency range between 1 Hz and 106 Hz. Electrical modulus, permittivity and ac conductivity were calculated using ac impedance and phase‐angle measurements. It was found that the overall conductivity of PEDCSZ macromolecules with Co is much higher than that for Co monomers. In addition, the conductivity of PEDCSZ Co(III) and Co(II–III) mixed valence compounds are higher than those containing Co(II) where the electronic conduction is dominant. The relaxation time increases from about 2.7 × 10−6 s for Co(II) chloride to a value of 2.9 × 10−4 s for Co(II–III) chloride monomers. Copyright © 2003 Society of Chemical Industry
Synthesis and characterization of novel aromatic poly(amide‐imide)s derived from 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl or 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl and various aromatic diamines
Authors: Banihashemi Ahmad , Behniafar Hossein
Published: June 2003

New aromatic diimide‐dicarboxylic acids having kinked and cranked structures, 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl (2a) and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl (2b), were synthesized by the reaction of trimellitic anhydride with 2,2′‐bis(4‐aminophenoxy)biphenyl (1a) and 2,2′‐bis(4‐aminophenoxy)‐1,1′‐binaphthyl (1b), respectively. Compounds 2a and 2b were characterized by FT‐IR and NMR spectroscopy and elemental analyses. Then, a series of novel aromatic poly(amide‐imide)s were prepared by the phosphorylation polycondensation of the synthesized monomers with various aromatic diamines. Owing to structural similarity, and a comparison of the characterization data, a model compound was synthesized by the reaction of 2b with aniline. The resulting polymers with inherent viscosities of 0.58–0.97 dl g−1 were obtained in high yield. The polymers were fully characterized by FT‐IR and NMR spectroscopy. The ultraviolet λmax values of the poly(amide‐imide)s were also determined. The polymers were readily soluble in polar aprotic solvents. They exhibited excellent thermal stabilities and had 10% weight loss at temperatures above 500 °C under a nitrogen atmosphere. Copyright © 2003 Society of Chemical Industry
DNA adsorption on a poly‐L‐lysine‐immobilized poly(2‐hydroxyethyl methacrylate) membrane
Authors: Şenel Serap , Bayramoǧlu Gülay , Arıca M Yakup
Published: June 2003

The DNA adsorption properties of poly‐L‐lysine‐immobilized poly(2‐hydroxyethyl methacrylate) (pHEMA) membrane were investigated. The pHEMA membrane was prepared by UV‐initiated photopolymerization and activated with epichlorohydrin. Poly‐L‐lysine was then immobilized on the activated pHEMA membrane by covalent bonding, via a direct chemical reaction between the amino group of poly‐L‐lysine and the epoxy group of pHEMA. The poly‐L‐lysine content of the membrane was determined as 1537 mg m−2. The poly‐L‐lysine‐immobilized membrane was utilized as an adsorbent in DNA adsorption experiments. The maximum adsorption of DNA on the poly‐L‐lysine‐immobilized pHEMA membrane was observed at 4 °C from phosphate‐buffered salt solution (pH 7.4, 0.1 M; NaCl 0.5 M) containing different amounts of DNA. The non‐specific adsorption of DNA on the plain pHEMA membrane was low (about 263 mg m−2). Higher DNA adsorption values (up to 5849 mg m−2) were obtained in which the poly‐L‐lysine‐immobilized pHEMA membrane was used. Copyright © 2003 Society of Chemical Industry
Factors influencing the small‐scale melt spinning of poly(ε‐caprolactone) monofilament fibres
Authors: Charuchinda Anodar , Molloy Robert , Siripitayananon Jintana , Molloy Nipapan , Sriyai Montira
Published: June 2003

Some of the main factors affecting the small‐scale melt spinning of poly(ε‐caprolactone), PCL, monofilament fibres have been studied. These factors included spinning temperature, extrusion rate, take‐up rate and draw ratio. The underlying influence of the polymer's own characteristic properties, in particular its chemical structure, transition temperatures (Tg, Tm) and crystallizability, were also interpreted within the context of the melt spinning process. Physically, the as‐spun fibres obtained were uniform in diameter and smooth in surface appearance. They were also semi‐crystalline (>50%) in morphology. Mechanically, however, they were still very weak and highly extensible. Subsequent off‐line cold‐drawing at room temperature introduced the required degree of molecular orientation to reinforce the fibres, yielding tensile strengths of approaching 300 MPa. PCL fibres of precisely controlled physical dimensions and matrix morphology are attracting increasing interest for use in biomedical applications. This paper describes how this control can be achieved through the processing operation. Copyright © 2003 Society of Chemical Industry
Morphology and rheological properties of nanocomposites based on nitrile rubber and organophilic layered silicates
Authors: Kim Jin‐tae , Oh Taeg‐su , Lee Dong‐ho
Published: June 2003

Organo‐montmorillonite/nitrile rubber (NBR) nanocomposites were prepared by a melt intercalation process. The characteristics of NBR nanocomposites were determined by an oscillating disk rheometer and transmission electron microscopy. The cure characteristics were investigated according to the change in clay content and clay types. This study confirmed that organo‐montmorillonite/NBR nanocomposites have various cure characteristics, namely minimum torque, maximum torque, scorch time and curing time, according to the change in clay content and clay types. In particular, as the chain length of the modifier used for the treatment of Na+‐MMT following vulcanization increases, scorch time and optimum curing time are reduced. This is because, as the chain length of the modifier increases, organo‐MMT is distributed more equally during the formation of the nanocomposites. As swelling increases, the chain length of the clay modifier expands and then constitutes a better barrier. Copyright © 2003 Society of Chemical Industry
Synthesis and characterisation of branched and partially crosslinked poly(ethylene terephthalate)
Authors: Bikiaris DN , Karayannidis GP
Published: June 2003

In the present study, a series of branched and partially crosslinked poly(ethylene terephthalate) (PET) samples were prepared by the two‐stage melt polycondensation method, using different amounts of trimethyl trimellitate (TMT) as polyfunctional monomer. The samples were characterised with respect to intrinsic viscosity, density and gel content as well as thermal and mechanical properties. The intrinsic viscosity of the polymers ranged between 0.7 and 1.6 dl g−1 depending on the concentration of the TMT comonomer. When TMT was used at a concentration 0.625 wt% or higher, gel formation was observed. For the sample containing 1.25 wt% TMT, almost half of the polymer was insoluble in phenol–tetrachloroethane mixture, due to extensive crosslinking. The increase of TMT content resulted in a small decrease of crystallinity attributed to branching and crosslinking, both of which restrict the organisation of the polymer chains in the crystal structure. This was reflected directly in the thermal properties of the polymers prepared. Increasing the TMT content decreased the melting point and the heat of fusion. In contrast, cold crystallization and glass transition temperatures were shifted to higher temperatures. Mechanical properties like tensile strength and elongation at break increased with increasing the content in branching agent. However, crosslinking had a negative effect on elongation at break. Copyright © 2003 Society of Chemical Industry
Analysis of rat testicular protein expression following 91‐day exposure to JP‐8 jet fuel vapor
Authors: Witzmann Frank A. , Bobb Andrew , Briggs G. Bruce , Coppage Heather N. , Hess Rex A. , Li Junyu , Pedrick Nathan M. , Ritchie Glenn D. , III John Rossi , Still Kenneth R.
Published: June 2003

We analyzed protein expression in preparations from whole testis in adult male Sprague‐Dawley rats exposed for 6 h/d for 91 consecutive days to jet propulsion fuel‐8 (JP‐8) in the vapor phase (0, 250, 500, or 1000 mg/m3 ± 10%), simulating a range of possible human occupational exposures. Whole body inhalation exposures were carefully controlled to eliminate aerosol phase, and subjects were sacrificed within 48 h postexposure. Organ fractions were solubilized and separated via large‐scale, high resolution two‐dimensional electrophoresis, and gel patterns scanned, digitized and processed for statistical analysis. Seventy‐six different testis proteins were significantly increased or decreased in abundance in vapor‐exposed groups, compared to controls, and dose‐response profiles were often nonlinear. A number of the proteins were identified by peptide mass fingerprinting and related to histopathological or physiological deficits shown in previously published studies to occur with repeated exposure to hydrocarbon fuels or solvents. These results demonstrate a significant effect of JP‐8 exposure on protein expression, particularly in protein expression in the rodent testis, and suggest that a 91 d exposure to jet fuel vapor induces changes of equal or greater magnitude to those reported previously for shorter duration JP‐8 aerosol exposures.
Proteome analysis of dermal fibroblasts cultured in vitro from human healthy subjects of different ages
Authors: Boraldi Frederica , Bini Luca , Liberatori Sabrina , Armini Allessandro , Pallini Vitaliano , Tiozzo Roberta , Pasquali‐Ronchetti Ivonne , Quaglino Daniela
Published: June 2003

Aging is a complex multifactorial process still far from being completely understood. The aim of the present study was to compare the proteome of in vitro cultured dermal fibroblasts from healthy subjects of different ages (i.e. 15 ± 2, 41 ± 4 and 82 ± 3 years old). Proteins of the cell layer were separated by two‐dimensional electrophoresis and protein identification was performed by matrix‐assisted laser desorption/ionization‐time of flight mass spectrometry; moreover, synthetic gels were qualitatively and quantitatively analyzed by Melanie 3 software. Our study did not reveal any protein typical of any one age group. On the other hand, we observed 38 proteins exhibiting more than three‐fold reproducible variations with aging, some (45%) being reduced such as F‐actin capping protein α1, proteasome subunit alpha type 3, heat shock protein 27, ubiquitin carboxyl‐terminal hydrolase isozyme L1, mitochondrial thioredoxin‐dependent peroxide reductase, cathepsin B, glutathione S‐transferase P, cyclophilin A and calgizzarin. In contrast, T‐complex protein 1, probable protein disulfide isomerase ER60, phosphoglycerate kinase 1, Ran‐specific GTPase‐activating protein, proteasome subunit alpha type 5, triosephosphate isomerase and superoxide dismutase (Mn) increased with age. Furthermore, annexin 1, elongation factor 1β, proteasome activator complex subunit 1, phosphoglycerate mutase, superoxide dismutase (Cu‐Zn) and cofilin, exhibited the highest levels in adult cells; whereas, septin 2 homolog, RNA‐binding protein regulatory subunit and ATP synthase D chain revealed the lowest values in adults. The present investigation, underlining the complexity of the aging process, highlights the role of synthetic and degradative pathways in modulating the whole cell machinery and emphasizes that metabolic impairment with age could depend partly on different expression of a number of genes and leading to an imbalance among functional proteins.
Proteomic analysis of human vessels: Application to atherosclerotic plaques
Authors: Duran Mari Carmen , Mas Sebastian , Martin‐Ventura Jose Luis , Meilhac Olivier , Michel Jean Baptiste , Gallego‐Delgado Julio , Lázaro Alberto , Tuñon José , Egido Jesus , Vivanco Fernando
Published: June 2003

Atherosclerosis is a chronic disease that affects medium and large arteries. This process originates from the interaction between cells of the arterial wall, lipoproteins and inflammatory cells, leading to the development of complex lesions or plaques that protrude into the arterial lumen. Plaque rupture and thrombosis result in acute clinical complications such as myocardial infarction and stroke. Owing to the heterogeneous cellular composition of the plaques, a proteomic analysis of the whole lesion is not appropriate. Therefore, we have studied the proteins secreted by human carotid atherosclerotic plaques, obtained by endarterectomy. Normal artery segments and different regions of the surgical pieces (noncomplicated plaque, complicated plaque with thrombus) were cultured in protein‐free medium and the secreted proteins (supernatants) analyzed by two‐dimensional gel electrophoresis. Normal artery segments secreted a moderate number of proteins (42 spots). However in the two‐dimensional (2‐D) gels (pH 3–10) of segments bearing a plaque, the number of spots increased markedly (154). The number of spots also increased (202) in the 2‐D gels of artery segments with a ruptured plaque and thrombus. Thus, the more complicated the lesion, the higher the number of secreted proteins, suggesting the production of specific proteins relating to the complexity of the atherosclerotic lesion.
Detection of protein‐protein interactions and a group of immunoglobulin G‐associated minor proteins in human plasma by nondenaturing and denaturing two‐dimensional gel electrophoresis
Authors: Manabe Takashi , Yamaguchi Nao , Mukai Jun , Hamada Osamu , Tani Osamu
Published: June 2003

The dissociation of noncovalently associated protein‐protein complexes in human plasma was examined by comparing two‐dimensional gel electrophoresis (2‐DE) patterns obtained in two different electrophoretic conditions. A type I 2‐DE pattern was obtained running nondenaturing isoelectric focusing (IEF) followed by nondenaturing gel electrophoresis and a type II 2‐DE pattern was nondenaturing IEF followed by sodium dodecyl sulfate gel electrophoresis. Micro‐sized gels (internal diameter(id) 1.3×35 mm polyacrylamide IEF gels and 38×38×1 mm polyacryamide slab gels) were used to follow the dissociation processes of major plasma proteins. Larger gel sizes (id 3.4×160 mm agarose IEF gels and 160×120×2.8 mm polyacrylamide slab gels) were used to detect minor plasma proteins dissociated from major proteins. About 110 spots, which have not been detected on type I (nondenaturing) 2‐D gels, newly appeared on type II large‐sized 2‐D gels at molecular masses smaller than 67 kDa. Some of these spots had been analyzed and identified, but about 70 minor spots (isoelectric point 5.5–7.5 and relative molecular mass 8–45 kDa) were detected for the first time by applying large volumes of human plasma samples to the large type II 2‐D gels. These minor spots could be concentrated on type II 2‐D gels by enriching the immunoglobulin G (IgG) fraction under nondenaturing conditions, and they disappeared when IgG was removed from the fraction. These results strongly suggest that many of the minor spots newly detected were bound to IgG in physiological conditions.