bluuebunny/crossref_metadata_2025 huggingface dataset:
Lackarbeiten aus Myanmar: Vom Baumsaft zum Kunsthandwerk
Authors: Golloch Alfred , Sein Myint Myint
Published: June 2004

Dekorative Lackwaren sind ein wichtiges Produkt des Kunsthandwerks in Myanmar (Birma). Ihre Herstellung basiert auf dem von Lackbäumen gebildeten Saft, der nach alten Verfahren manuell verarbeitet wird. Der Lack enthält als Hauptkomponenten Brenzcatechine mit langkettigen Substituenten, die eine oder mehrere Doppelbindungen enthalten. Unter Mitwirkung des Enzyms Laccase verläuft die oxidative Polymerisation der Brenzcatechine. Die Bildung des Lackfilms kann aber nach verschiedenen Mechanismen erfolgen.
Ionen an der Luft/Wasser‐Grenzfläche
Authors: Jaenicke Lothar
Published: June 2004

Die gefühlsmäßige und auch von schlichten Gibbsschen Phasenregel‐ Thermodynamikern ohne „computerhinterfragte”︁ Experimentalkritik gestützte Vorstellung ist, dass im Luftraum über einer wässrigen Lösung stark dissoziierter Salze, wie NaCl etc., keine Ionen zu finden sind, sondern nur in der Wasserphase, denn die Änderung der Oberflächenspannung geht der Salzkonzentration proportional.
Die Lakritzschnecke
Authors: Roth Klaus
Published: June 2004

Das genüssliche Abrollen und stückweise Vernaschen einer Lakritzschnecke ist der schmackhafteste Weg, die eigene Zunge tiefschwarz zu färben. Aber Lakritze kann noch mehr: „Ein schwarzer Mund ist dem Magen gesund”︁, mit diesem Motto warb die Firma Haribo Ende der Fünfziger Jahre um die Gunst der Käufer, und tatsächlich sind die Wurzeln des Süßholzes, aus der Lakritze gewonnen wird, eine der ältesten Drogen. Im Folgenden wollen wir die Chemie dieser gesunden Köstlichkeit näher ergründen.
Entschwefelung von Dieselkraftstoff
Authors: Uerdingen Mark
Published: June 2004

Die Entschwefelung von Dieselöl erfährt derzeit eine hohe Aufmerksamkeit: Aufgrund von Umweltschutzbestimmungen müssen Kraftstoffe praktisch vollständig entschwefelt werden, da beim Verbrennen schwefelhaltiger Kraftstoffe unerwünschtes Schwefeldioxid entsteht (Stichwort „Saurer Regen”︁). Darüber hinaus sollen Kraftstoffe zukünftig aber vor allem deshalb bis auf wenige ppm Schwefel tiefenentschwefelt werden, um neue Motor‐ und Katalysatorkonzepte zu realisieren, die die CO‐, NOx‐ und Partikelemissionen und den Kraftstoffverbrauch noch weiter vermindern.
A study of transfer switching for the purpose of fault detection in FRIENDS
Authors: Suzuki Toshihiro , Hara Ryoichi , Kita Hiroyuki , Tanaka Eiichi , Hasegawa Jun , Iyoda Isao
Published: June 2004

The authors have proposed a new concept of a distribution system “Flexible, Reliable and Intelligent ENergy Delivery System (FRIENDS)” with intent to solve imminent operating problems faced by utilities in providing their customers with reliable supply of power at several levels of quality. The main idea of FRIENDS is to introduce new facilities, so‐called Quality Control Centers (QCCs), which are installed very close to the customers for the purpose of implementing multiple functions, such as Customized Power Quality Service. In addition, these QCCs form a network for energy and information transmission at a level below distribution substations. QCCs make it possible to frequently change configuration of the network depending on the system and load conditions. These frequent reconfigurations of the network require fast and reliable Transfer Switching in the QCCs to ease an effect on customers. The reconfiguration for the purpose of fault area isolation also requires a fast Fault Detection feature.

This paper presents a new method for controlling Transfer Switching and a method of Fault Detection in order to realize a fast and reliable reconfiguration of QCC network in a normal state, as well as under fault conditions. This paper also analyzes the methods in terms of instantaneous values calculated by PSCAD/EMTDC. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(3): 25–35, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10298
Application of the wavelet transform to the low‐bit‐rate speech coding system
Authors: Moriai Shogo , Hanazaki Izumi
Published: June 2004

In the analysis‐synthesis coding of speech signals, realization of high quality in the low‐bit‐rate coding depends on the extraction of its characteristic parameters in the preprocessing. The precise extraction of the fundamental frequency, one of the parameters of the source information, guarantees quality in speech synthesis. But its extraction is difficult because of the influence of the consonant, nonperiodicity of vocal cord vibrations, the wide range of the fundamental frequency, and so on. In this paper we propose a new fundamental frequency extraction with the criterion based on its harmonics structure and low‐bit‐rate speech coding system using the wavelet transform. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(3): 62–71, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10309
A method of coding LSP residual signals using wavelets for speech synthesis
Authors: Shimizu Tadaaki , Kimoto Masaya , Yoshimura Hiroki , Isu Naoki , Sugata Kazuhiro
Published: June 2004

This paper presents a method of using wavelet analysis for speech coding and synthesis by rule. It is a coding system where LSP residual signal is transformed into wave‐let coefficients. As wavelet analysis is implemented effectively by filter banks, our method requires less computation than multipulse coding and others where complicated prediction procedures are essential. To achieve good‐quality speech at low bit rates, we verified allocation of different bits onto the wavelet coefficients, with more bits in lower frequencies, and less in higher. The synthesized speech by Haar wavelet with 16.538 kbit/s has nearly the same perceptual quality with 6 bits µlog PCM (66.15 kbit/s). We are convinced that the coding method of LSP residual signals using wavelet analysis is an effective approach to synthesize speech. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(3): 54–61, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10326
Proof‐of‐principle experiment on control of ion flow and ion heating during magnetic reconnection
Authors: Murata Yukihiro , Ono Yasushi
Published: June 2004

Magnetic reconnection of two merging toroids was used to accelerate and heat plasma particles in a TS‐3 device. External application of an electric field by an ohmic heating coil, which was located along the center axis of the device, to the reconnection area was found to be useful for varying the ion speed from zero to 20 km/s and the ion heating from 10 to 90 eV. The preferential ion acceleration/heating of reconnection enables us to produce new processing plasma with an arbitrary ion temperature. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(3): 1–6, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10336
Influence of output power out of a synchronous generator installed in a customer system on current limiting effects due to a fault current limiter
Authors: Iioka Daisuke , Shimizu Hirotaka , Yokomizu Yasunobu , Goto Masuo , Matsumura Toshiro
Published: June 2004

In this paper, it was assumed that a synchronous generator in a customer system was connected to a distribution system via the fault current limiter (FCL). We theoretically investigated the influence of the output power of the generator on the limiting effect of the fault current when a three‐phase short‐circuit fault occurs. It was shown that the fault current out of the customer system, limited by the FCL, rises with the output power of the generator. It was found that the larger the output, the higher the fault current at the fault point is when the limiting resistance is less than 15 Ω in the case of the resistive‐type FCL. On the other hand, the fault current at the fault point decreases with an increase in the output power for a limiting resistance more than 15 Ω. In contrast, it was found that the suppressing effect on the fault current at the fault point due to the inductive‐type FCL hardly depends on the output power. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(3): 15–24, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10357
Pre‐exposure to sub‐saturating concentrations of HLA class I antibodies confers resistance to endothelial cells against antibody complement‐mediated lysis by regulating Bad through the phosphatidylinositol 3‐kinase/Akt pathway
Authors: Narayanan Kishore , Jaramillo Andrés , Phelan Donna L. , Mohanakumar T.
Published: June 2004

Allografts transplanted across HLA‐sensitization results in an antibody‐mediated rejection known as hyperacute rejection. Depleting anti‐graft antibodies from the recipient by plasmapheresis prior to transplantation can prevent this rejection. We developed an in vitro model using polyclonal HLA class I antibodies obtained from highly sensitized patients awaiting transplantation,and analyzed their ability to provide signals following binding to human aortic endothelial cells (EC). Using this model, we show that EC undergo caspase 3‐dependent cell death by apoptosis upon exposure to saturating concentrations of HLA class I antibodies and complement accompanied by loss of Akt activation and phosphorylation of Bad. In contrast, exposure of EC to sub‐saturating concentrations of HLA class I antibodies conferred resistance towards antibody/complement‐mediated lysis termed accommodation. Accommodated EC exhibited reduction in the expression of the adhesion molecules ICAM‐1 and VCAM‐1 and a significant increase in the expression of anti‐apoptotic genes Bcl‐xL, Bcl‐2 and heme oxygenase‐1. Further, induction of phosphatidylinositol 3‐kinase (PI3K) and Akt activities thatfacilitate the phosphorylation of Bad were also noted. In conclusion, exposure of sub‐saturating concentrations of HLA class I antibodies results in the induction of PI3K/Akt pathway that confers resistance to endothelial cells against antibody/complement‐mediated cell death.
Functional expression of CD134 by neutrophils
Authors: Baumann Ralf , Yousefi Shida , Simon Dagmar , Russmann Stefan , Mueller Christoph , Simon Hans‐Uwe
Published: June 2004

CD134 (OX40) is a member of the tumor necrosis factor (TNF) receptor superfamily expressed on activated T cells. Here, we show that human peripheral blood neutrophils express CD134. Activationof CD134 by soluble CD134 ligand (OX40 ligand/gp34) resulted in delayed caspase‐3 activation and consequently in delayed neutrophil apoptosis in vitro. Moreover, CD134 ligand, like G‐CSF, maintained anti‐apoptotic Mcl‐1 levels and inhibited cleavage of the pro‐apoptotic Bcl‐2 family members Bid and Bax in these cells, suggesting that CD134‐mediated signals block apoptosis pathways proximal to mitochondria activation. In conclusion, CD134 regulates neutrophil survival, suggesting that this molecule does not only contribute to adaptive but also to innate immune responses.
A peptide inhibitor of vascular adhesion protein‐1 (VAP‐1) blocks leukocyte–endothelium interactions under shear stress
Authors: Yegutkin Gennady G. , Salminen Tiina , Koskinen Kaisa , Kurtis Christian , McPherson Michael J. , Jalkanen Sirpa , Salmi Marko
Published: June 2004

Vascular adhesion protein‐1 (VAP‐1) is an endothelial adhesion molecule mediating leukocyte interactions with blood vessels during leukocyte extravasation. Molecularly VAP‐1 is a cell‐surface‐expressed ecto‐enzyme belonging to the group of semicarbazide‐sensitive amine oxidases (SSAO; EC 2.4.6.3), which deaminate primary amines. Here we asked whether peptides displaying a suitable free amine group could be a substrate or inhibitor of SSAO and thus regulate VAP‐1‐mediated leukocyte adhesion. On the basis of a molecular model of VAP‐1, we designed synthetic peptides that fit to the substrate channel of VAP‐1. One of these lysine‐containing peptides effectively inhibits VAP‐1‐dependent lymphocyte rolling and firm adhesion to primary endothelial cells under physiologically relevant shear conditions. The same peptide inhibits the SSAO activity of endothelial and recombinant VAP‐1 in a selective and long‐lasting manner. We also show that all enzymatically active VAP‐1 is displayed on the cell surface. Our results suggest that, in addition to soluble amines, specific cell‐surface‐bound molecules containing free NH2 groups in a suitable position may modulate the enzymaticactivity of SSAO. Moreover, the inhibitory peptide diminishes leukocyte interactions with endothelial cells under conditions of shear, and thus it may be useful to treat inflammatory conditions.
Knockdown of C‐terminal Src kinase by siRNA‐mediated RNA interference augments T cell receptor signaling in mature T cells
Authors: Vang Torkel , Abrahamsen Hilde , Myklebust Sondre , Enserink Jorrit , Prydz Hans , Mustelin Tomas , Amarzguioui Mohammed , Tasken Kjetil
Published: June 2004

C‐terminal Src kinase (Csk) controls the Src family kinase Lck, which is essential for T cell antigen receptor (TCR)‐mediated signaling. For the first time, we here report the effects of acuteelimination of Csk in Jurkat T cells and primary T cells using short interfering (si) RNA. In both cell types, 70–85% knockdown of Csk was achieved within 48 h. No alterations in surface expressionof CD3, CD4 or CD8, or in Lck protein level were observed. Phosphorylation of Y505 in Lck was markedly reduced and a concomitant 4–5‐fold increase in Lck Y394 phosphorylation was observed both in normal and Jurkat T cells. Kinase assays revealed 2–3‐fold higher Lck activity. In Jurkat cells, basal levels of ζ chain phosphorylation were elevated, and spontaneous NFAT‐AP‐1 activation occurred, indicating aberrant Lck kinase activity. After TCR triggering, Csk knockdown cells revealed faster and stronger, but not sustained, phosphorylation of Lck Y394 and ζ chains compared to control. TCR‐induced activation of NFAT‐AP‐1 and TCR/CD28‐stimulated IL‐2 secretion occurred at weaker stimuli and with augmented responses in Csk knockdown Jurkat and primary T cells, respectively. Altogether, these data suggest that acute elimination of Csk in T cells without evolution of compensatory mechanisms results in aberrant Lck activity and augmented TCR‐stimulated responses.
Macrophage colony‐stimulating factor‐, granulocyte‐macrophage colony‐stimulating factor‐, or IL‐3‐dependent survival of macrophages, but not proliferation, requires the expression of p21Waf1 through the phosphatidylinositol 3‐kinase/Akt pathway
Authors: Comalada Mònica , Xaus Jordi , Sánchez Ester , Valledor Annabel F. , Celada Antonio
Published: June 2004

Mouse bone marrow‐derived macrophages proliferate in the presence of macrophage colony‐stimulating factor (M‐CSF), granulocyte‐macrophage colony‐stimulating factor, or IL‐3, but undergo apoptosis in their absence. Inhibition of extracellular signal‐regulated kinases (ERK)‐1/2 blocks growth factor‐dependent proliferation but not survival, indicating that the two processes require independent signaling pathways. Although M‐CSF induces the activation of other kinase pathways, such as c‐Jun N‐terminal kinase, p38, and phosphatidylinositol 3‐kinase (PI‐3K), these pathways are not required for proliferation. However, PI‐3K is the only one necessary for the induction of survival, as demonstrated using the inhibitors LY294002 and Wortmannin. Growth factors also activate Akt kinase and a transient expression of the cdk inhibitor p21Waf1, which inhibits apoptosis but is not required for proliferation. PI‐3K inhibitors also block growth factor‐dependent expression of p21Waf1 and the activation of Akt. Moreover, the survival induced by cyclosporin A or decorin is also dependent on the PI‐3K/Akt kinases and p21Waf1. These findings demonstrate that the induction of p21Waf1 through the PI‐3K/Akt pathway is a general survival response of macrophages. Our results show that growth factors in macrophages use two pathways: one for proliferation, mediated by ERK, and the other for survival, which requires the PI‐3K/Akt kinases and p21Waf1.
Commentary: Sorting the wheat from the chaff: identifying demyelinating components of the myelin oligodendrocyte glycoprotein (MOG)‐specific autoantibody repertoire
Authors: Mathey Emily , Breithaupt Constanze , Schubart Anna S. , Linington Christopher
Published: June 2004

Myelin oligodendrocyte glycoprotein (MOG) is the only myelin protein known to initiate a demyelinating autoantibody response in EAE, an animal model for multiple sclerosis (MS). The pathophysiological significance of MOG‐specific autoantibodies in MS is, however, controversial, as high titer antibody responses to MOG are also found in many patients with non‐demyelinating neurological diseases. In this issue of the European Journal of Immunology, von Büdingen et al. demonstrate that demyelination in a primate model of MOG‐induced EAE is mediated by MOG‐specific antibodies directed against discontinuous, rather than linear, MOG epitopes. This functional segregation of pathogenic vs. non‐pathogenic autoantibodies in terms of epitope specificity may be crucial to understand the relevance of MOG‐specific responses in human disease. This commentary discusses these findings in the context of the structure and immunobiology of MOG, and their implications with respect to antibody‐mediated demyelination in MS.

See accompanying article http://dx.doi.org/10.1002/eji.200425050
Binary Neodymium Alkoxide/Dialkylmagnesium Polymerization Systems: Studies on the Nature of the Reaction Intermediates and Active Species
Authors: Gromada Jérôme , Mortreux André , Nowogrocki Guy , Leising Frédéric , Mathivet Thomas , Carpentier Jean‐François
Published: June 2004

Attempts to identify the intermediates and/or active species generated from binary combinations of a lanthanide alk(aryl)oxide with a dialkylmagnesium reagent, which behave as efficient olefin polymerization systems, are reported. The well‐defined trinuclear complex [Nd3(μ3‐OtBu)2(μ2‐OtBu)3(μ‐OtBu)4(THF)2] (1) and the monomeric precursor [Nd(OC6H2tBu2‐2,6‐Me‐4)3(THF)] (2) were used in association with [Mg(CH2SiMe3)2(Et2O)] (3). The new heterodimetallic complex [(THF)Nd(μ3‐OtBu)2(μ2‐OtBu)2(OtBu)Mg2(CH2TMS)2] (4) and the alkyllanthanide complex [Nd(OC6H2tBu2‐2,6‐Me‐4)2(CH2SiMe3)(THF)2] (5) have been isolated and characterized in the solid state and in solution. Complex 4 is proposed to be a reaction intermediate in the active species formation, while complex 5 is the first alkyllanthanide species isolated from an “Ln(OR)3”/MgR2 mixture, consistent with the observed behavior of these combinations in olefin polymerization. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Ruthenium Nitrosyl Complexes of Bis(3,5‐dimethylpyrazol‐1‐yl)methane Oxyanions
Authors: Ortiz Mayreli , Díaz Alicia , Cao Roberto , Suardíaz Reynier , Otero Antonio , Antiñolo Antonio , Fernández‐Baeza Juan
Published: June 2004

New ruthenium(II) mononitrosyl complexes of general composition [Ru(NO)LCl2], [Ru(NO)L(en)]Cl2 and [Ru(NO)L2]Cl have been obtained upon treating Ru(NO)Cl3 with potential κ3‐N,N,O ligands bis(3,5‐dimethylpyrazol‐1‐yl)methanesulfonate (bdmpzsa) and bis(3,5‐dimethylpyrazol‐1‐yl)acetate (bdmpza) in 1:1 and 1:2 molar ratios. These mononitrosyl complexes have a sharp, intense νNO band in the IR spectra within 1874−1851 cm−1, indicating a linear Ru−NO+ coordination. For both [Ru(NO)L2]Cl compounds, a dynamic switch on‐off process occurs between the oxyanionic moieties on the apical position trans to NO+ and the pyrazolic ligands on the equatorial plane. A dynamic 1H NMR experiment of this process gave ΔG#= 46−48 kJ·mol−1 at 218−228 K for the acetate derivative. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Determination of Cr(VI) by Catalytic Adsorptive Stripping Voltammetry with Application of Nitrilotriacetic Acid as a Masking Agent
Authors: Grabarczyk Malgorzata , Kaczmarek Lukasz , Korolczuk Mieczyslaw
Published: June 2004

A selective and sensitive method for determination of traces of Cr(VI) in the presence of a large excess of Cr(III) by differential pulse catalytic adsorptive stripping voltammetry is presented. For minimization of Cr(III) interference nitrilotriacetic acid was used as a masking agent. The determinations were performed in a flow system. The calibration plot was linear from 1×10−10 to 1×10−8 mol L−1 for accumulation time 60 s. The relative standard deviation for 3×10−9 mol L−1 Cr(VI) was 4.1% (n=5). The detection limit for an accumulation time of 60 s was 4×10−11 mol L−1. The influence of common foreign ions is also presented. The performance of the method was verified by analysis of certified reference material for Cr(VI) and comparing the results of analyses of natural water samples with those obtained by another accepted electrochemical method.
Novel Anion Exchangers for Electrodes with Improved Selectivity to Divalent Anions
Authors: Egorov Vladimir , Rakhman'ko Evgeni , Okaev Evgeni , Nazarov Valentin , Pomelyenok Ekaterina , Pavlova Tatyana
Published: June 2004

It has been found that replacing of several long‐chain alkyl substituents at the nitrogen atom of lipophilic quaternary ammonium salts (QAS) by methyls results in a dramatic increase of the potentiometric selectivity of ion‐selective electrodes (ISE) with QAS‐based plasticized PVC membranes to some divalent anions against the monovalent ones. The discussed effect of QAS cation nature on the potentiometric selectivity is also partly retained for ISE with neutral carrier‐based membranes doped with QAS to provide anion permselectivity. This opens up new possibilities to control the potentiometric selectivity of ISE for divalent anions by the appropriate selection of the anion exchanger.
Amperometric Nitrite Sensor Based on PVP‐Os Entrapped in Titania Sol‐Gel Matrix
Authors: Li Yancai , Zhang Suxia , Li Yazhuo , Sun Changqing
Published: June 2004

A novel nitrite sensor was developed based on the immobilization of a partially quaternized poly(4‐vinylpyridine) complexed with [Os(bpy)2Cl]+/2+ (PVP‐Os) in a porous TiO2 sol‐gel matrix by a vapor deposition method. The preparation process simplified the traditional sol‐gel process and prevented the cracking of conventional sol‐gel derived glasses. Electrochemical behavior of the sensor was characterized by cyclic voltammetry and shows excellent electrocatalytic response for the reduction of nitrite. Effect of operating potential on electrochemical responses of the sensor was explored for optimum analytical performance by using the amperometric method. The stability of the sensor was also evaluated.
Electrocatalytic Properties of Heme Proteins in Layer‐by‐Layer Films Assembled with SiO2 Nanoparticles
Authors: He Pingli , Hu Naifei
Published: June 2004

Electrochemical and electrocatalytic properties of heme proteins, including myoglobin (Mb), hemoglobin (Hb), and horseradish peroxidase (HRP), in layer‐by‐layer films assembled with SiO2 nanoparticles were investigated at pyrolytic graphite (PG) electrodes. The stable layer‐by‐layer {SiO2/protein}n films showed a pair of well‐defined, nearly reversible cyclic voltammetric peaks at about −0.25 V (vs. SCE) at pH 5.5, characteristic of the protein heme FeIII/FeII redox couples. The proteins in the films displayed good electrocatalytic activities toward various substrates such as oxygen, hydrogen peroxide, trichloroacetic acid, and nitrite, and showed a potential applicability in fabricating the new kind of biosensors without using mediators. Electrochemical parameters of the protein films such as apparent heterogeneous electron transfer rate constant (ks) and formal potential (E°′) were estimated by square‐wave voltammetry and nonlinear regression analysis. The influencing factors like the number of bilayer and the pH of external solution were also investigated.
Membrane Electrodes for Protein and Enzyme Electrochemistry
Authors: Lojou É. , Bianco P.
Published: June 2004

This review presents a new strategy for the electrochemical study of proteins and enzymes based on the use of membrane‐modified electrodes. In this approach, a thin layer of biological material is trapped between the electrode surface and a dialysis membrane. The advantages of such a procedure are underlined, including easiness, low cost, need of only small amounts of biological products, ability to study a large range of external parameters. The direct electrochemistry of various proteins is achieved via this technology. Applications of the membrane electrodes to the catalytic reduction of metals by bacterial cytochromes open an avenue to the use of sulfate‐reducing bacteria in the bioremediation of contaminated environmental. The membrane electrode technology has been used for determining the enzymatic activity of whole bacterial cells, allowing new insight in energetic metabolism of these bacteria to be achieved.
Electrocatalytic Reactions at Hydrogenase‐Modified Electrodes and Their Applications to Biosensors: From the Isolated Enzymes to the Whole Cells
Authors: Lojou É. , Bianco P.
Published: June 2004

Hydrogenases are involved in a series of key reactions which can have great potentiality in a large range of practical applications. In this review, the electrochemical behavior and the kinetic properties of hydrogenases from various sulfate‐reducing bacteria as enzymes involved in electron‐transfer chains are examined. Different approaches based on the modification of electrodes with either hydrogenases alone or whole cells are described, thus opening new avenues for further applications to biosensor area.
Telomerase activity measurement in magnetically captured epithelial cells: Comparison of slab‐gel and capillary electrophoresis
Authors: Hess Jennifer L. , Atha Donald H. , Xu Jing‐fan , Highsmith W. Edward
Published: June 2004

We have compared telomerase activity measurements by slab‐gel and capillary electrophoresis in cultured cells (A549 and H125 human cancer cell lines) and in cells isolated from clinical peripheral blood specimens epithelial cells of patients with lung and esophageal cancer. Telomerase activity was determined using the telomerase repeat amplification protocol (TRAP) assay with phosphoimager scanning of slab‐gels and by laser‐induced fluorescence capillary electrophoresis (LIF‐CE). Experiments using A549 and H125 cells were performed to determine the reproducibility of each method and to identify the contribution of each stage of the TRAP/polymerase chain reaction (PCR) assay to the variability. In these experiments, it was found that more than half of the overall variability (coefficient of variation, CV = 35%) of the slab‐gel method and almost all of the overall variability (CV = 20%) of the CE method was due to the PCR stage of the TRAP assay. In the clinical samples, classification as positive or negative was by visual inspection of the slab‐gel and CE electropherograms for the presence of the characteristic 6 base‐pair TRAP ladder and by GeneScan analysis of the CE. We examined several criteria including the use of 3, 4, or 5 TRAP bands as the definition of a positive test. Using the slab‐gel method, the 5‐band criterion gave 40% sensitivity with 100% specificity (no false positives in inactive controls). The CE method yielded a comparable 38% sensitivity and 100% specificity using this criterion. These data indicate that detection of telomerase activity in epithelial cells isolated from peripheral blood has a useful level of sensitivity and specificity and may be useful in the detection and monitoring of aerodigestive cancers. However, analysis by slab‐gel is cumbersome and the precision is poor (inter‐replicate CV = 20%) compared to LIF‐CE (CV = 5%). A high‐throughput CE‐LIF detection platform will be indispensable for validation studies of telomerase activity measurements.
Measurement of alkaline phosphatase isoenzymes in individual mouse bone marrow fibroblast cells based on capillary electrophoresis with on‐capillary enzyme‐catalyzed reaction and electrochemical detection
Authors: Sun Xuemei , Jin Wenrui , Li Dong , Bai Zengliang
Published: June 2004

A novel method for the determination of alkaline phosphatase (ALP) isoenzymes in individual fibroblast cells of mouse bone marrow was developed by combining capillary electrophoresis with an on‐capillary enzyme‐catalyzed reaction and electrochemical detection. In this method, a single an cell, followed by 5.0×10−2 mol/L Na2B4O7– 3.0×10−2 mol/L NaCl (pH 9.8) as cell lysis solution, was injected into the inlet of the separation capillary by electromigration. The cell was lysed by applying a voltage of 2 kV. The ALP isoenzymes in the cell were preseparated at 20 kV for 1 min, and then allowed to react for 30 min with disodium phenyl phosphate as enzyme substrate in the running buffer. ALP converted disodium phenyl phosphate into its product, phenol, at a relatively high reaction rate without consumption, with resultant amplification of the signal on prolonged reaction time, producing an adequate amount of product for final detection. A mass detection limit as low as 3.5×10−21 mol/L (corresponding to 1.5 nU) was achieved. Finally, the two zones of products generated by ALP isoenzymes were detected at the outlet of the capillary by using the end‐capillary amperometric detection at a carbon fiber microdisk bundle electrode with a constant potential.
Enzyme‐catalyzed amperometric oxidation of neurotransmitters in chip‐capillary electrophoresis
Authors: Schwarz Maria A.
Published: June 2004

The determination of biogenic monoamines by enzyme‐catalyzed oxidation after electrophoretical separation on a microfluidic chip decreases their detection limits significantly. An amperometric system with a chemically amplified response for neurotransmitters and their metabolites is presented. The principle is the rapid cyclic oxidation of the analyte on the amperometric detector in the presence of the redoxactive enzyme glucose oxidase in the capillary electrophoresis buffer. With this approach, detection limits in the range of 10−7–10−8 M could be reached. Because of the good linearity between the current response and the concentration of catecholamines and their metabolites at concentrations up to 300 μM, this method is attractive for the analytical detection at low concentration levels such as in biological fluids.
Multichannel homogeneous immunoassay for detection of 2,4,6‐trinitrotoluene (TNT) using a microfabricated capillary array electrophoresis chip
Authors: Bromberg Avraham , Mathies Richard A.
Published: June 2004

A high‐throughput homogeneous immunoassay for the sensitive detection of 2,4,6‐trinitrotoluene (TNT) has been developed using radial capillary array electrophoresis microdevices. Samples consisting of equilibrium mixtures of anti‐TNT antibody (Ab), fluorescein‐labeled TNT, and various concentrations of unlabeled TNT were electrokinetically injected into 48 channels of a radial capillary array electrophoresis microchannel plate. The rapid electrophoretic separation allows us to analyze the equilibrium ratio formed by the competition between the labeled and the unlabeled TNT for Ab binding. The simultaneous parallel TNT separations facilitate determination of a calibration curve for the TNT assay, which has high sensitivity (LOD, 1 ng/mL) and a wide dynamic range (1–300 ng/mL).
Preparative isoelectric focusing of proteins using binary buffers in a vortex‐stabilized, free‐flow apparatus
Authors: Tracy Noah I. , Ivory Cornelius F.
Published: June 2004

Recombinant proteins are often produced as isoforms with different kinds and amounts of post‐translational modifications that alter their function. Isoelectric focusing in shallow pH gradients, less than 0.5 pH/cm, might be capable of fractionating these isoforms. The synthetic carrier ampholyte mixtures typically used to generate these pH gradients are expensive and may adversely interact with proteins. Using defined buffers instead of synthetic carrier ampholytes reduces these problems. We tested two defined buffer systems in a vortex‐stabilized electrophoresis device to see if they could form shallow pH gradients useful for separating isoforms. These pH gradients were formed by pouring a two‐component concentration gradient. The poured gradients were smooth, reproducible, and stable for at least 1.5 h at 5 kV. One poured gradient focused 20 mg of cytochrome c. A second poured gradient separated glucose oxidase from amyloglucosidase. The breadth of the amyloglucosidase band indicates that the shallow, poured pH gradients can only partially separate protein isoforms at 10 kV. Proteins with pI < 0.2 pH units apart will have overlapping bands in these shallow, poured pH gradients.
A compactly integrated laser‐induced fluorescence detector for microchip electrophoresis
Authors: Li Hai‐Fang , Lin Jin‐Ming , Su Rong‐Guo , Uchiyama Katsumi , Hobo Toshiyuki
Published: June 2004

A simple and easy‐to‐use integrated laser‐induced fluorescence detector for microchip electrophoresis was constructed and evaluated. The fluid channels and optical fiber channels in the glass microchip were fabricated using standard photolithographic techniques and wet chemical etching. A 473 nm diode‐pumped laser was used as the excitation source, and the collimation and collection optics and mirrors were discarded by using a multimode optical fiber to couple the excitation light straight into the microchannel and placing the microchip directly on the top of the photomultiplier tube. A combination of filter systems was incorporated into a poly(dimethylsiloxane) layer, which was reversibly sealed to the bottom of the microchip to eliminate the scattering excitation light reaching to the photomultiplier tube. Fluorescein/calcein samples were taken as model analytes to evaluate the performance with respect to design factors. The detection limits were 0.05 μM for fluorescein and 0.18 μM for calcein, respectively. The suitability of this simple detector for fluorescence detection was demonstrated by baseline separation of fluorescein isothiocyanate (FITC)‐labeled arginine, phenylalanine, and glycine and FITC within 30 s at separation length of 3.8 cm and electrical field strength of 600 V/cm.
Dispersion control in microfluidic chips by localized zeta potential variation using the field effect
Authors: Lee Gwo‐Bin , Fu Lung‐Ming , Lin Che‐Hsin , Lee Chia‐Yen , Yang Ruey‐Jen
Published: June 2004

A new technique to minimize the effects of turn‐induced dispersion within U‐shaped separation channels by using the field effect within a capacitor to vary the zeta potential along the channel walls in the vicinity of the microchannel is described. The effects of the separation channel geometry, the fluid velocity profile, and the use of the field effect to control the zeta potential on the band distribution in the detection area are extensively discussed. The results for a U‐shaped separation channel indicate that varying the zeta potential by controlling the field effect significantly reduces the band dispersion induced by the 90° turns within the channel. Finally, it is shown that the application of the proposed localized zeta potential variation method also results in a correction of the band tilting phenomenon and a reduction in the racetrack effect.
Performance of throughout in‐capillary derivatization capillary electrophoresis employing an on‐line sample and run buffer loading device
Authors: Oguri Shigeyuki , Hibino Misako , Mizunuma Makiko
Published: June 2004

We report on the effect on performance of varying the length of the capillary during throughout in‐capillary derivatization (TICD) capillary electrophoresis (CE). Performance was evaluated by on‐line coupling with a sample and CE runbuffer loading device that was newly introduced for this study. The device was assembled with a low cost using two 5 mm inner diameter (ID) disposable polyethylene syringes. First, a sequence was manually formed consisting of a 200 μL run buffer solution plug, a 100 μL sample plug and another 200 μL run buffer solution plug. Each plug was separated from its neighbor by a 100 μL air plug. When each plug reached the injection point where both a platinum‐wire anode and the end of the separation capillary tube were located, 340 V/cm separation voltage (electrophoresis voltage) and 34 V/cm injection voltage were applied to the capillary for 3 s. Then the analytes were derivatized during migration in 50 μm ID capillaries filled with 2 mM o‐phthalaldehyde (OPA)/N‐acetylcysteine (NAC) in a 20 mM phosphate‐borate buffer (pH 10), followed by separating and detecting of OPA derivatives by absorbance of 340 nm. Derivatization, separation, and detection were performed systematically using capillaries which varied in length from 5 to 80 cm. In the case of TICD‐CE of a mixture containing 1 mM aspartic acid (Asp) and 20 mM m‐nitorophenol (MNP) as a test solution, it was determined that peak area and peak width ratios of Asp to MNP did not depend on capillary length. Enantiomeric separations of DL‐alanine (Ala) and Asp were examined using a run buffer consisting of a 45 μM β‐cyclodextrin (CD) – 2 mM OPA/NAC – 20 mM phosphate‐borate buffer (pH 10). Even though the resolution of these enantiomeric pairs decreased with decreasing capillary length, as expected, the peaks corresponding to both enantiomeric amino acids were identified even when a 5 cm capillary was used. An 8‐component amino acid mixture was also tested with 5 cm and 10 cm capillaries.
Repeatedly usable immobilized pH gradient in a monolithic capillary column
Authors: Yang Chun , Zhu Guijie , Zhang Lihua , Zhang Weibing , Zhang Yukui
Published: June 2004

Glycidyl methacrylate (GMA) and ethylene dimethacrylate (EDMA) were used to synthesize a monolithic capillary column containing reactive epoxy groups. Glutaraldehyde was introduced and linked to the monolith after a process of amination. An aqueous solution of commercial carrier ampholytes (CAs, Ampholine) was focused in such a polymer column. The primary amino groups of CAs reacted with glutaraldehyde along the capillary. CAs were immobilized at different positions in the column according to their isoelectric points (pI), resulting in a monolithic immobilized pH gradient (M‐IPG). Isoelectric focusing (IEF) was performed without CAs in such an M‐IPG column. Due to the covalent attachment of the CAs this M‐IPG can be repeatedly used after its preparation. Good stability, linearity, and reproducibility were obtained.
Editorial: A case of scientific fraud
Authors: Laurent Geoffrey J. , Radola Bertold J.
Published: June 2004

No abstracts.
An immersed boundary finite difference method for LES of flow around bluff shapes
Authors: Li C. W. , Wang L. L.
Published: June 2004

A three‐dimensional numerical model using large eddy simulation (LES) technique and incorporating the immersed boundary (IMB) concept has been developed to compute flow around bluff shapes. A fractional step finite differences method with rectilinear non‐uniform collocated grid is employed to solve the governing equations. Bluff shapes are treated in the IMB method by introducing artificial force terms into the momentum equations. Second‐order accurate interpolation schemes for all sorts of grid points adjacent to the immersed boundary have been developed to determine the velocities and pressure at these points. To enforce continuity, the methods of imposition of pressure boundary condition and addition of mass source/sink terms are tested. It has been found that imposing suitable pressure boundary condition (zero normal gradient) can effectively reproduce the correct pressure distribution and enforce mass conservation around a bluff shape. The present model has been verified and applied to simulate flow around bluff shapes: (1) a square cylinder and (2) the Tsing Ma suspension bridge deck section model. Complex flow phenomena such as flow separation and vortex shedding are reproduced and the drag coefficient, lift coefficient, and pressure coefficient are calculated and analyzed. Good agreement between the numerical results and the experimental data are obtained. The model is proven to be an efficient tool for flow simulation around bluff bodies in time varying flows. Copyright © 2004 John Wiley & Sons, Ltd.
Inhibitory effect of pollen and propolis extracts
Authors: Özcan Musa , Ünver Ahmet , Ceylan Durmus Ali , Yetisir Ramazan
Published: June 2004

Bee pollen and propolis were collected from Apis mellifera colonies in five regions of Turkey. The antifungal properties of methanol extracts of pollen and propolis (2% and 5% concentrations) were determined on Alternaria alternata and Fusarium oxysporium f. sp. melonis. The least active concentration towards the tested fungi was 2% concentration of both extracts. The inhibitory effect of all propolis extracts on growth of F. oxysporium and A. alternata were generally higher when compared with pollen extracts. The growth of A. alternata and F. oxysporium were not affected at both concentrations of pollens. However, F. oxysporium against propolis extracts was more sensitive than A. alternata (P < 0.01). None of the pollen extracts tested completely inhibited mycelial growth of fungi used in our experiment. Percent inhibition of both pollen concentrations against A. alternata and F. oxysporium was lower than 50%. However, both concentrations of Alanya and Beys?ehir propolis extracts were 100% effective on mycelial growth of F. oxysporium until the 7th day of incubation (P < 0.01). 2% Alanya and Beys?ehir pollen extracts completely stimulated mycelial growth of F. oxysporium on the 7th day of incubation. Both concentrations of propolis extract showed more than 50% inhibition against F. oxysporium. It is suggested that high concentrations of propolis extract could be used as an antifungal agent against tested fungi.
Change in glyceride composition of olive pomace oil during enzymatic esterification
Authors: Göǧüs Fahrettin , Fadıloǧlu Sibel , Çiftçi Ozan Nazım
Published: June 2004

Enzymatic esterification of free fatty acids of olive pomace oil with glycerol was investigated. The esterification reaction was carried out in the absence and presence of glycerol (glycerol to free fatty acids (FFA) molar ratio of 1/3 and 1/6). In the absence of glycerol, the FFA concentration decreased from 32 to 21% while the triglyceride concentration increased from 33 to 40% after of 8 h of reaction time. The most significant decrease in FFAs and increase in triglycerides was observed at the limiting concentration of glycerol (glycerol to FFA molar ratio of 1/3). The FFA concentration decreased to 2.5% and the triglyceride concentration increased up to 78%. The change in both FFA and triglyceride concentrations was found to be statistically significant (P < 0.05).
Metabolic activities of Lactobacillus spp. strains isolated from kefir
Authors: Yüksekdaǧ Zehra Nur , Beyath Yavuz , Aslım Belma
Published: June 2004

A total of 21 strains of Lactobacillus species were isolated from Turkish kefir samples, in order to select the most suitable strains according to their metabolic activities including probiotic properties. As a result of the identification tests, 21 Lactobacillus isolates were identified as L. acidophilus (4%), L. helveticus (9%), L. brevis (9%), L. bulgaricus (14%), L. plantarum (14%), L. casei (19%) and L. lactis (28%). The amount of produced lactic acid, hydrogen peroxide, proteolytic activity, and acetaldehyde productions of Lactobacillus spp. were determined. Different amounts of lactic acid were produced by strains studies; however, lactic acid levels were 1.7–11.4 mg/mL. All strains produced hydrogen peroxide. L. bulgaricus Z14L strain showed no proteolytic activity, L. casei Z6L strain produced the maximum amount (0.16 mg/mL) of proteolytic activity. Acetaldehyde concentration produced in Lactobacillus strains ranged between 0.88–3.52 μg/mL.
Composition and in vitro digestibility of raw versus cooked white‐ and colour‐flowered peas
Authors: Pastuszewska Barbara , Vitjazkova Maija , Swiech Ewa , Taciak Marcin
Published: June 2004

Ten pea cultivars (four white‐flowered, Pisum sativum ssp. hortense, and six colour‐flowered, Pisum sativum ssp. arvense) grown in Latvia were analyzed and tested in in vitro experiments, as raw and cooked seeds. The colour‐flowered (CF) had a greater proportion of hulls and a higher acid detergent fibre (ADF) content than white‐flowered (WF) pea seeds (10.7 vs. 8.2% and 92.2 vs. 84.5 g/kg dry matter (DM), respectively). Three out of six CF varieties had a significantly greater amount of protein bound to neutral detergent fibre (NDF) than WF peas. The tannin content was higher in CF than in WF peas (8.46 vs. 0.37 g/kg DM). In vitro protein and amino acid digestibility was about 8% higher in WF than in CF varieties. Cooking decreased the tannin content in CF peas (8.46 vs. 5.51 g/kg DM) but had no effect on in vitro protein digestibility. Heat treatment reduced significantly trypsin inhibitor activity and amount of protein bound to NDF in CF and WF varieties (from 6.50 to 0.52 and from 6.54 to 0.46 trypsin inhibitor units (TIU)/mg DM; from 1.250 to 0.831 and 0.761 to 0.209 g N/100 g NDF, respectively). However, the protein bound to NDF content in pea DM increased in CF and decreased in WF varieties (from 1.525 to 2.145 and from 0.913 to 0.502 g N/kg DM, respectively). Cooking resulted in an increased NDF content over two times in both CF and WF pea seeds (from 122 to 259 and from 120 to 262 g/kg DM, respectively). The results suggest that colour‐flowered pea may be considered as an interesting dietary alternative to white‐flowered pea since cooking removes trypsin inhibitor activity (TIA), decreases tannins, and increases dietary fibre contents.
Preparation and functional properties of extracts from bee bread
Authors: Nagai Takeshi , Nagashima Toshio , Myoda Takao , Inoue Reiji
Published: June 2004

Three extracts, namely hot‐water fraction (HWF), water‐soluble fraction (WSF), and ethanol‐soluble fraction (ESF), were prepared from fresh bee bread imported from Lithuania. The protein and total phenolic contents of these samples were very high. Among them, WSF at 100% concentration showed the highest antioxidative ability and scavenging ability. On the other hand, ESF at 10% concentration possessed the highest ability against 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and hydroxyl radicals. Bee bread will apply more and more as health food and medicine due to its functional properties such as antioxidative ability and scavenging activities of reactive oxygen species.
Influence of cooking and microwave heating on microstructure and mechanical properties of transgenic potatoes
Authors: Błaszczak Wioletta , Sadowska Jadwiga , Fornal Józef , Vacek Josef , Flis Bogdan , Zagórski‐Ostoja Włodzimierz
Published: June 2004

The transgenic potato clones of cultivar Irga with improved resistance to a necrotic strain of potato virus Y (PVYN) were subjected to heat treatment in order to determine their technological quality. The technological quality was determined on the basis of differences between mechanical properties of unmodified potato and transgenic clones during cooking and microwave heating. The compression test was applied in order to evaluate the mechanical resistance of raw, cooked and microwave‐treated potatoes. Compression resistance was expressed by fracture stress F (kPa), fracture strain D (mm/mm), and Young modulus E (kPa). The differences in microstructure of potato tubers (unmodified and modified) were investigated using scanning electron microscopy (SEM). The observed differentiation in the mechanical properties of heat‐treated potatoes was less connected with genetic modification but most of all with a kind of the process used. The heat processes caused a distinct decrease in mechanical resistance in all the examined tubers. However, the process of microwave heating resulted in more significant changes in mechanical properties of tubers than cooking. Deformation of parenchyma cells during cooking was directly connected with starch gelatinisation and gel formation. Microwave heating affected significantly cellular water evaporation which resulted in intercellular failure, collapsing of cells, and limitation of starch gelatinisation.