bluuebunny/crossref_metadata_2025 huggingface dataset:
A calculation method of field current of synchronous machines at sudden short‐circuit
Authors: Kano Takashi , Yamamoto Shu , Ara Takahiro
Published: March 2005

The mutual leakage reactance between D‐axis damper and field windings is ignored in conventional D‐axis equivalent circuits. It has been pointed out, however, that the calculated value of the field current differs considerably from the measured value if this reactance is not taken into account. This is due to the difficulty of determining the physically correct damper winding impedance value. A method of determining the equivalent circuit constants using the mutual leakage reactance has been reported previously, where the D‐axis damper winding time constant is measured from the upper and lower envelopes of field current at sudden three‐phase short‐circuit. Yet there are machines for which the upper and lower envelopes of field current are not readily established, and in this case the method is unsatisfactory. The authors describe a method to accurately identify the equivalent circuit constants taking into account the mutual leakage reactance, using a standstill test with a small‐capacity DC power supply (DC decay testing method). The field current at sudden short‐circuit can be simulated accurately using these equivalent circuit constants. The validity of the proposed method is demonstrated by implementation results on two salient‐pole synchronous machines at the same specifications (one with damper winding, the other without). Furthermore, the dependent relation between the armature leakage reactance and mutual leakage reactance, as well as its influence on the calculation of field transient currents, are made clear. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(3): 61–70, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20113
The non‐receptor tyrosine kinase Syk regulates lamellipodium formation and site‐directed migration of human leukocytes
Authors: Schymeinsky Jürgen , Then Cornelia , Walzog Barbara
Published: March 2005

The tyrosine kinase Syk is associated with CD18, the β‐subunit of the leukocyte adhesion molecules of the β2 integrin family (CD11/CD18), and becomes activated upon β2 integrin‐mediated adhesion. In this study, we elucidated the role of Syk in polarization and site‐directed migration of neutrophil‐like differentiated HL‐60 cells and monocytic THP‐1 cells. By means of confocal microscopy, we detected a homogenous distribution of Syk in unstimulated cells in suspension. The stimulation of HL‐60 cells by formyl‐methionyl‐leucyl‐phenylalanine (fMLP, 100 nM) or the activation of THP‐1 cells by monocyte chemoattractant protein‐1 (10 ng/ml) induced β2 integrin‐mediated cell adhesion and polarization on immobilized fibrinogen which was associated with an enrichment of Syk at the lamellipodium forming site. This effect was abolished by function blocking anti‐CD18 antibody or by treatment of the cells with the Syk inhibitor piceatannol (30 μM) suggesting that the redistribution of Syk required both, β2 integrin‐mediated adhesion and Syk activation. Moreover, the inhibition of Syk by piceatannol or the downregulation of Syk by antisense technique resulted in an excessive formation of lamellipodia indicating that Syk may act as a negative regulator that limits lamellipodium formation. The analysis of chemotaxis revealed that the inhibition of Syk impaired the ability of the cells to follow a chemotactic gradient whereas random migration was intact. Taken together, our data suggest a novel role for Syk in the maintenance of a bipolar phenotype by regulating lamellipodium formation, which is a critical prerequisite for site‐directed migration of leukocytes. © 2005 Wiley‐Liss, Inc.
Functional analysis of TMLH variants and definition of domains required for catalytic activity and mitochondrial targeting
Authors: Monfregola Jlenia , Cevenini Armando , Terracciano Antonio , Vlies Naomi van , Arbucci Salvatore , Wanders Ronald J.A. , D'Urso Michele , Vaz Frédéric M. , Ursini Matilde Valeria
Published: March 2005

ε‐N‐Trimethyllysine hydroxylase (TMLH) (EC 1.14.11.8) is a non‐heme‐ferrous iron hydroxylase, Fe++ and 2‐oxoglutarate (2OG) dependent, catalyzing the first of four enzymatic reactions of the highly conserved carnitine biosynthetic pathway. Otherwise from all the other enzymes of carnitine biosynthesis, TMLH was found to be associated to the mitochondrial fraction. We here report molecular cloning of two alternative spliced forms of TMLH, which appear ubiquitously expressed in human adult and fetal tissues. The deduced proteins are designated TMLH‐a and TMLH‐b, and contain 421 and 399 amino acids, respectively. They share the first N‐terminal 332 amino acids, including a mitochondrial targeting signal, but diverge at the C‐terminal end. TMLH‐a and TMLH‐b exogenous expression in COS‐1 cells shows that the first 15 amino acids are necessary and sufficient for mitochondrial import. Furthermore, comparative evolutionary analysis of the C‐terminal portion of TMLH‐a identifies a conserved domain characterized by a key triad of residues, His242‐Glu244‐His389 predicted to bind 2OG end. This sequence is conserved in the TMLH enzyme from all species but is partially substituted by a unique sequence in the TMLH‐b variant. Indeed, TMLH‐b is not functional by itself as well as a TMLH‐H389L mutant produced by site directed mutagenesis. As great interest, we found that TMLH‐b and TMLH‐H389L, individually co‐expressed with TMLH‐a in COS‐1 cells, negatively affect TMLH activity. Therefore, our studies on the TMLH alternative form provide relevant novel information, first that the C‐terminal region of TMLH contains the main determinants for its enzymatic activity including a key H389 residue, and second that TMLH‐b could act as a crucial physiological negative regulator of TMLH. © 2005 Wiley‐Liss, Inc.
Development and resolution of experimental colitis in mice with targeted deletion of dipeptidyl peptidase IV
Authors: Geier Mark S. , Tenikoff Danik , Yazbeck Roger , McCaughan Geoffrey W. , Abbott Catherine A. , Howarth Gordon S.
Published: March 2005

Glucagon‐like peptide‐2 (GLP‐2) is a potent intestinotrophic growth factor that enhances repair of damaged intestinal tissue. However, its bioactivity is limited by dipeptidyl peptidase IV (DPIV)‐mediated degradation. We hypothesized that DPIV−/− mice would display an increased resistance to, and an enhanced recovery from, dextran sulfate sodium (DSS)‐induced colitis compared to DPIV+/+ mice. DPIV+/+ and DPIV−/− mice consumed 2% DSS for 6 days, followed by a 15 day recovery period. Mice were killed at days 0, 3, 6, 9, 14, and 21 (n = 6–8) and the small intestine and colon removed for histological assessment of villus height, crypt depth, and crypt area. The epithelial cell proliferative labeling index was determined by proliferating cell nuclear antigen (PCNA) immunostaining. Small intestine, colon, and total body weight did not differ between DPIV+/+ and DPIV−/− mice. Distal colon crypt depth did not differ significantly between DPIV+/+ and DPIV−/− mice during the development of DSS‐colitis or during the recovery phase. Similarly no significant effects were apparent on distal colon crypt area or PCNA labeling index between DPIV+/+ and DPIV−/− during the development of and recovery from DSS‐colitis. However, DPIV−/− mice still possessed significant levels of plasma DPIV‐like activity. We conclude that loss of DPIV activity does not increase resistance to experimental colitis and hypothesize that other DPIV family members may also be involved in the cleavage of GLP‐2. © 2005 Wiley‐Liss, Inc.
Investigation of adsorption of lead, mercury and nickel from aqueous solutions onto carbon aerogel
Authors: Goel Jyotsna , Kadirvelu K , Rajagopal Chitra , Garg Vinod Kumar
Published: March 2005

Recently a new form of activated carbon has appeared: carbon aerogel (CA). Its use for the removal of inorganic (and especially metal ions) has not been studied. In the present study, the adsorption of three metal ions, Hg(II), Pb(II) and Ni(II), onto carbon aerogel has been investigated. Batch experiments were carried out to assess adsorption equilibria and kinetic behaviour of heavy metal ions by varying parameters such as agitation time, metal ions' concentration, adsorbent dose and pH. They facilitated the computation of kinetic parameters and maximum metal ion adsorption capacities. Increasing the initial solution pH (2–10) and carbon concentration (50–500 mg per 50 cm3) increases the removal of all three metal ions. A decrease of equilibrium pH with an increase of metal ion concentration led us to propose an adsorption mechanism by ion exchange between metal cations and H+ at the carbon aerogel surface. Carboxylic groups are especially involved in this adsorption mechanism. Langmuir and Freundlich isotherm models were used to analyse the experimental data of carbon aerogel. The thermodynamics of the metal adsorption was also investigated for the practical implementation of the adsorbent. The sorption showed significant increase with increase of temperature. Kinetics models describing the adsorption of Hg(II), Pb(II) and Ni(II) ions onto carbon aerogel have been compared. Kinetics models evaluated include the pseudo‐first order and second order model. The parameters of the adsorption rate constants have been determined and the effectiveness of each model assessed. The result obtained showed that the pseudo‐second order kinetic model correlated well with the experimental data and better than the pseudo‐first order model examined in the study. Mass transfer coefficients obtained can be useful in designing wastewater treatment systems or in the development of environmental technologies. Copyright © 2005 Society of Chemical Industry
Analysis and simulation of the sludge profile dynamics in a full‐scale clarifier
Authors: De Clercq Jeriffa , Devisscher Martijn , Boonen Ivo , Defrancq Jacques , Vanrolleghem Peter A
Published: March 2005

A one‐dimensional clarifier model was assessed for its capability to describe dynamic full‐scale sludge concentration profiles by using the settling properties calibrated with batch settling curve data collected by a SettloMeter®. These sludge concentration profiles and batch settling tests formed part of a detailed one‐month measuring campaign on a full‐scale wastewater treatment plant; the measurements showed a daily variation in settling properties. Using the settling properties obtained from batch settling tests and a one‐dimensional model without dispersion, the dynamics of the full‐scale clarifier were analysed and the need for dispersion clearly shown. The parameters of the dispersion model were estimated from the full‐scale sludge concentration profiles. The settling properties of activated sludge can be automatically determined by fitting the model to the on‐line batch settling curve measurements and are needed as input to the one‐dimensional model. This model can therefore be used for operation and control. The dispersion model parameters have to be determined from dynamic sludge concentration profiles but are assumed to be constant for a specific clarifier. Copyright © 2005 Society of Chemical Industry
Enhancement of enantioselectivity and reaction rate on the synthesis of (S)‐ketoprofen hydroxyalkyl ester in organic solvents via isopropanol‐dried immobilized lipase
Authors: Chang Chun‐Sheng , Hsu Chin‐Shuo
Published: March 2005

Lipase‐catalyzed enantioselective esterification between (R,S)‐ketoprofen and alkanediol in organic solvents was developed to produce (S)‐ketoprofen hydroxyalkyl esters. The acyl acceptor of 1,6‐hexanediol for the resolution of (R,S)‐ketoprofen yielded only the enantioselectivity (the enantiomeric ratio of initial rate for (S)‐ketoprofen to that of (R)‐ketoprofen) VS/VR = 8, when crude Lipase MY originating from Candida rugosa was used. However, isopropanol‐dried immobilized lipases (IPA‐dried IM‐lipase) effectively enhanced the enantioselectivity to greater than 20 in the esterification of (R,S)‐ketoprofen when 1,4‐butanediol, 1,5‐pentanediol or 1,6‐hexanediol was employed. IPA‐dried IM‐lipase and isooctane were selected to use for optimally immobilized lipase and reaction medium, respectively. The IPA‐dried IM‐lipase exhibited the highest enantioselectivity, E = 26.7, to the (S)‐enantiomer with 1,5‐pentanediol and the best enzyme activity to the (S)‐enantiomer with 1,4‐butanediol. The finding indicates that the carbon chain length of the alkanediol strongly affected the enzyme activity and enantioselectivity of lipase‐catalyzed esterification. A maximum enantioselectivity of 37 at 27 °C was generated by IPA‐dried IM‐lipase for the enantioselective esterification of racemic ketoprofen with 1,4‐butanediol. IPA‐dried IM‐lipase can effectively increase the enantioselectivity of lipase. Copyright © 2005 Society of Chemical Industry
Lipase‐catalyzed esterification of cinnamic acid and oleyl alcohol in organic solvent media
Authors: Lue Bena‐Marie , Karboune Salwa , Yeboah Faustinus K , Kermasha Selim
Published: March 2005

The esterification of cinnamic acid (CA) and oleyl alcohol (OA) in organic solvent media by immobilized lipase Novozym 435 was optimized in terms of selected parameters, including the logarithm of the 1‐octanol/water partition coefficient of the organic solvent (log P, 0.29–4.5), initial water activity (aw, 0.05–0.75), agitation speed (0–200 rpm), temperature (35–65 °C) and ratio of substrates (CA/OA, 1.0:0.5–1.0:6.0). The results showed that the more hydrophobic solvent mixtures and lower initial aw values resulted in a higher enzymatic activity and bioconversion yield. The most appropriate solvent medium and initial aw value was the mixture of iso‐octane/2‐butanone (85:15, v/v) and 0.05, respectively. The results also showed that an agitation speed of 150 rpm and a reaction temperature of 55 °C were optimal for the reaction system. The activation energy (Ea) of the esterification reaction was calculated as 43.6 kJ mol−1. The optimal ratio of CA to OA was 1.0:6.0, with the absence of any inhibition by OA. Using the optimized conditions, the maximum enzymatic activity was 390.3 nmol g−1 min−1, with a bioconversion yield of 100% after 12 days of reaction. In addition, the electrospray ionization‐mass spectroscopy analysis confirmed that the major end product of the esterification reaction was oleyl cinnamate. Copyright © 2005 Society of Chemical Industry
A preliminary approach to predictive modelling of extra virgin olive oil stability
Authors: Zanoni Bruno , Bertuccioli Mario , Rovellini Pierangela , Marotta Federico , Mattei Alissa
Published: March 2005

The aim of this work was to set up a phenomenological model to predict the stability of extra virgin olive oil based on combined stability/instability indices. A screening of stability/instability indices was carried out by multivariate statistical analyses on company data for virgin olive oil. Screened indices were acidity, oleic acid content and bitter taste. The ability of these indices to predict stability was checked by measuring the following degradation parameters on 11 oil samples of different compositions planned by a fractional factorial design (FFD): peroxide value, UV spectroscopic indices, minor polar component content, oxidative status of fatty acids, antioxidant activity and sensory descriptors of aroma, taste and flavour. Experimental data were processed by multivariate statistical analyses. A combination of acidity, oleic acid content and bitter taste values was significantly able to predict oil stability expressed by the peroxide value, the K232 UV index and the oxidative status of fatty acids. Copyright © 2005 Society of Chemical Industry
Physicochemical properties of the starchy flour extracted from sweet potato tubers through lactic acid fermentation
Authors: Jyothi Alummoottil N , Wilson Barnabas , Moorthy Subramoney N , George Mathew
Published: March 2005

The efficiency of starch extraction from sweet potato tubers was improved by lactic acid fermentation using a mixed culture inoculum. Study of the properties of the starchy flour showed that there was a significant reduction in the starch content and consequently the soluble and apparent amylose contents of fermented samples from all six varieties used. A fall in peak viscosity and viscosity breakdown was observed for fermented samples, while the pasting temperature was enhanced significantly. The fermented flour showed greater solubility and reduced swelling. Differential scanning calorimetry studies indicated a delay in gelatinisation and a fall in enthalpy of gelatinisation of the starch on fermentation. Unlike cassava, all the properties of the starch from sweet potato tubers, ie viscosity, swelling, solubility, gelatinisation temperature, amylose content and starch content, were affected by fermentation, and variation was also observed among cultivars. Copyright © 2005 Society of Chemical Industry
Nutritive evaluation of herbage from permanent meadows by near‐infrared reflectance spectroscopy: 1. Prediction of chemical composition and in vitro digestibility
Authors: Andrés Sonia , Giráldez F Javier , López Secundino , Mantecón Ángel R , Calleja Alfredo
Published: March 2005

This study was implemented to evaluate the potential of near‐infrared reflectance spectroscopy (NIRS) technology to estimate the chemical composition and in vitro digestibility of botanically complex herbage mixtures characterised, moreover, by a noteworthy variation among samples in the maturity of the forage plants. A total of 107 herbage samples harvested from permanent meadows located in the uplands of León (northwestern Spain) were analysed to determine their chemical composition. In addition, the in vitro digestibility of each herbage sample was measured by two different in vitro procedures using buffered rumen fluid. A Bran + Luebbe InfraAlyzer 500 spectrophotometer was used to obtain the near‐infrared spectra corresponding to each herbage sample. Prediction equations developed for the estimation of the chemical components showed that NIRS technology could predict these parameters accurately, especially the crude protein and neutral detergent fibre contents ($R_{\rm adj}^{2} > 0.95$ in both cases). In vitro digestibility parameters could also be predicted with an acceptable degree of accuracy using NIRS technology, particularly the in vitro Tilley and Terry organic matter digestibility ($R_{\rm adj}^{2} = 0.925$, standard error of prediction (SEP) = 2.165% organic matter) and the in vitro dry matter true digestibility measured according to the Goering and Van Soest procedure ($R_{\rm adj}^{2} = 0.891$, SEP = 2.208% dry matter). Copyright © 2005 Society of Chemical Industry
Nutritive evaluation of herbage from permanent meadows by near‐infrared reflectance spectroscopy: 2. Prediction of crude protein and dry matter degradability
Authors: Andrés Sonia , Calleja Alfredo , López Secundino , Mantecón Ángel R , Giráldez F Javier
Published: March 2005

A total of 62 herbage samples, harvested in natural meadows located in the uplands of León (northwestern Spain) and characterised by a diverse botanical composition and different stages of maturity of the plants, were used to evaluate the ability of chemical composition and near‐infrared reflectance spectroscopy to predict dry matter (DM) and crude protein (CP) ruminal degradability. Three non‐productive Holstein‐Friesian cows fitted with rumen cannulae were used to incubate the herbage samples. Once the DM and CP disappearance rates had been calculated, the exponential model of McDonald was fitted to estimate the kinetic parameters, which were used to calculate the potential and effective ruminal degradability at different passage rates. A Bran + Luebbe InfraAlyzer 500 spectrophotometer was used to obtain the near‐infrared (NIR) spectra corresponding to the 62 original herbage samples. Prediction equations for the estimation of the DM and CP degradability parameters were generated using the chemical composition data and the NIR spectra as independent variables. The results showed that the kinetic parameters were predicted with less accuracy than the potential or effective degradability of the chemical fractions. When NIR spectra were used as independent variables, the accuracy of the predictions of the potential or effective degradability of DM and CP was higher. Overall, the degradability of CP was predicted less successfully than the degradability of DM, probably owing to errors in the reference method, such as the microbial contamination of the incubation residues. Copyright © 2005 Society of Chemical Industry
Effects of storage conditions on oxidative stability of soybean oil
Authors: Yang Tsung‐Shi , Chu Yan‐Hwa , Liu Tai‐Ti
Published: March 2005

Soybean oil in the presence or absence of 200 µg g−1 tert‐butyl hydroquinone (TBHQ) was subjected to accelerated oxidative storage at 60 °C for 10 days or stored at room temperature for 12 months. Tocopherol contents of the oil decreased, whereas the headspace volatiles and peroxide values (PV) increased as the storage time increased. During accelerated storage, TBHQ was effective in retarding the formation of hydroperoxides and headspace volatiles in the oil. TBHQ also protected tocopherols, especially α‐tocopherol, from oxidation. During long‐term room‐temperature (LTRT) storage, the changes in PV between the oils with and without TBHQ were similar, but the oil with TBHQ had lower headspace volatile contents than that without TBHQ. Headspace volatile analysis was more suitable than PV measurement for predicting the oxidative stability of soybean oil during LTRT storage. The contents of hexanal or (E)‐2‐heptenal in the oil at 1–5 days of accelerated storage could be used to predict those of the corresponding compound in the oil at 0–4 weeks of LTRT storage. Copyright © 2005 Society of Chemical Industry
A decomposition algorithm applied to planning the interdiction of stochastic networks
Authors: Held Harald , Hemmecke Raymond , Woodruff David L.
Published: March 2005

We describe the application of a decomposition based solution method to a class of network interdiction problems. The problem of maximizing the probability of sufficient disruption of the flow of information or goods in a network whose characteristics are not certain is shown to be solved effectively by applying a scenario decomposition method developed by Riis and Schultz [Comput Optim Appl 24 (2003), 267–287]. Computational results demonstrate the effectiveness of the algorithm and design decisions that result in speed improvements. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005.
An implicit QR algorithm for symmetric semiseparable matrices
Authors: Vandebril Raf , Van Barel Marc , Mastronardi Nicola
Published: March 2005

The QR algorithm is one of the classical methods to compute the eigendecomposition of a matrix. If it is applied on a dense n × n matrix, this algorithm requires O(n3) operations per iteration step. To reduce this complexity for a symmetric matrix to O(n), the original matrix is first reduced to tridiagonal form using orthogonal similarity transformations.

In the report (Report TW360, May 2003) a reduction from a symmetric matrix into a similar semiseparable one is described. In this paper a QR algorithm to compute the eigenvalues of semiseparable matrices is designed where each iteration step requires O(n) operations. Hence, combined with the reduction to semiseparable form, the eigenvalues of symmetric matrices can be computed via intermediate semiseparable matrices, instead of tridiagonal ones.

The eigenvectors of the intermediate semiseparable matrix will be computed by applying inverse iteration to this matrix. This will be achieved by using an O(n) system solver, for semiseparable matrices.

A combination of the previous steps leads to an algorithm for computing the eigenvalue decompositions of semiseparable matrices. Combined with the reduction of a symmetric matrix towards semiseparable form, this algorithm can also be used to calculate the eigenvalue decomposition of symmetric matrices. The presented algorithm has the same order of complexity as the tridiagonal approach, but has larger lower order terms. Numerical experiments illustrate the complexity and the numerical accuracy of the proposed method. Copyright © 2005 John Wiley & Sons, Ltd.
A kernel free particle‐finite element method for hypervelocity impact simulation
Authors: Park Young‐Keun , Fahrenthold Eric P.
Published: March 2005

An improved hybrid particle‐finite element method has been developed for the simulation of hypervelocity impact problems. Unlike alternative methods, the revised formulation computes the density without reference to any kernel or interpolation functions, for either the density or the rate of dilatation. This simplifies the state space model and leads to a significant reduction in computational cost. The improved method introduces internal energy variables as generalized co‐ordinates in a new formulation of the thermomechanical Lagrange equations. Example problems show good agreement with exact solutions in one dimension and good agreement with experimental data in a three‐dimensional simulation. Copyright © 2005 John Wiley & Sons, Ltd.
Nitrogen transport in float‐zone and Czochralski silicon investigated by dislocation locking experiments
Authors: Murphy J. D. , Giannattasio A. , Senkader S. , Falster R. J. , Wilshaw P. R.
Published: March 2005

Dislocation locking experiments have been used to investigate nitrogen‐doped float‐zone silicon (NFZ‐Si). Experiments on NFZ‐Si with a nitrogen concentration of 2.2 × 1015 cm–3 were carried out at different annealing temperatures (550–830 °C) for different annealing times (0–1500 hours) and experiments on NFZ‐Si with a nitrogen concentration of 3 × 1014 cm–3 were carried out at 600 °C for 0–1200 hours. After an initial rise, the unlocking stress was found to saturate for all combinations of conditions investigated. The rate of the initial rise was found to be consistent with diffusion by a dimeric nitrogen species. The saturation value of the unlocking stress was found to be dependent on the nitrogen concentration. Experiments were also carried out on nitrogen‐doped Czochralski silicon (NCz‐Si) with an oxygen concentration of 5.74 × 1017 cm–3 and a nitrogen concentration of 2.10 × 1015 cm–3 at 600 °C from 0–5 hours. The dislocation locking due to oxygen appeared to be unaffected by the presence of nitrogen for the conditions investigated. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Scaling factors for the prediction of vibrational spectra. II. The aniline molecule and several derivatives
Authors: Palafox M. Alcolea , Gill M. , Nunez N. J. , Rastogi V. K. , Mittal Lalit , Sharma Rekha
Published: March 2005

The structure of aniline was studied by semiempirical, ab initio, and density functional methods. Complete geometry optimization of the minimum energy structure and of the transition states for internal rotation and inversion of the amino group was carried out using several levels. The performance of the different methods in calculating and describing the vibrational frequencies of aniline was determined. The normal modes were characterized by the magnitudes and direction of the displacement vectors. Three procedures were used to obtain the scaled frequencies, two of them new, using specific scale factors and scaling equations from the benzene molecule. The errors obtained were compared with those calculated through other standard procedures. A reassignment of several bands was made. A comparison of the cost‐effective method and procedure of scaling was carried out. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Luminescent compounds diphenylboron analogs of Alq3 and its methyl substituents: A theoretical investigation of their electronic and spectroscopic properties
Authors: Teng Y. L. , Kan Y. H. , Su Z. M. , Liao Y. , Yan L. K. , Yang Y. J. , Wang R. S.
Published: March 2005

The absorption and emission energies for diphenylboron analogs of Alq3 (Ph2Bq) and its methyl substituents (Ph2Bmq) were systematically investigated at the Zerner's intermediate neglect of differential overlap (ZINDO), configuration interaction singles (CIS), and time‐dependent density functional theory (TD‐DFT) levels of theory. The lowest excited‐state geometries were optimized at the ab initio CIS level. The TD‐DFT method provides the most reliable results for the absorption and emission transition energies, compared with other methods. Moreover, the TD‐DFT calculations reliably estimate the changes of absorption and emission λmax values upon methyl substitution, with errors of 1.2% and 1.8%, respectively. The Stokes shifts are well reproduced by TD‐DFT calculations. Various density functional theory methods have been tested and the B3LYP functional clearly seems to be the best choice for this class of compounds. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Summary of ISO/TC 201 standard: XVIII, ISO 19318:2004—surface chemical analysis—X‐ray photoelectron spectroscopy—Reporting of methods used for charge control and charge correction
Authors: Baer D. R.
Published: March 2005

International Standard ISO 19318 specifies the minimum amount of information describing the methods of charge control and charge correction in measurements of core‐level binding energies for insulating specimens by x‐ray photoelectron spectroscopy, which is to be reported with the analytical results. Information is also provided on methods that have been found useful for charge control and charge correction in the measurement of binding energies. Copyright © 2005 John Wiley & Sons, Ltd.
Monochromatized x‐ray photoelectron spectroscopy of the AM60 magnesium alloy surface after treatments in fluoride‐based Ti and Zr solutions
Authors: Verdier S. , Delalande S. , van der Laak N. , Metson J. , Dalard F.
Published: March 2005

The behaviour of the 6% aluminium–magnesium alloy (AM60) surface in zirconium or titanium fluoride aqueous acid solutions was studied. X‐ray photoelectron spectroscopy was used to investigate modifications in the surface chemistry with respect to the composition of the surface treatment solution. The surface film is composed of magnesium hydroxide and hydroxyfluoride, zirconium oxide, oxyhydroxide or oxyfluoride, titanium oxide and structural and adsorbed water. Optimal parameters leading to the formation of a zirconium‐ or titanium‐rich film were determined. A mechanism is proposed for the formation of zirconium‐ or titanium‐based films. Copyright © 2005 John Wiley & Sons, Ltd.
Diachronous supracrustal extension in an intraplate setting and the origin of the Connecticut Valley–Gaspé and Merrimack troughs, northern Appalachians
Authors: TREMBLAY ALAIN , PINET NICOLAS
Published: March 2005

In the Appalachians of mainland Canada and New England, Silurian/Early Devonian rocks are preserved in the Connecticut Valley–Gaspé and Merrimack troughs, and rest unconformably or in fault contact with older rocks belonging to Laurentia and to Gander/Avalon, respectively. The Silurian/Early Devonian rocks consist of marine clastic deposits with subordinate carbonates, lava flows and terrestrial deposits. The origin of these sedimentary basins is still poorly understood. Metamorphic ages and structures in the Laurentian margin, major unconformities and syn-sedimentary normal faulting in both troughs argue for significant crustal extension during deposition. The Connecticut Valley–Gaspé and Merrimack troughs are separated by inliers of pre-Ordovician to Ordovician rocks which we interpret as Silurian basement highs that would have been buried in Devonian times to form a composite sedimentary basin. Volcanic rocks are widely distributed in time and space in both basins, and are mostly subalkaline within-plate tholeiites, which is consistent with a tectonic setting involving crustal extension rather than with subduction. Granitic plutons are abundant in the Merrimack trough and attest to high temperatures at mid-crustal levels. It is suggested that crustal extension was responsible for the formation of both basins and that heating of the lower crust in the Merrimack trough during the Silurian was the result of synorogenic collapse likely triggered by delamination at the Laurentia–Medial New England boundary. Delamination of the subducted slab and the upwelling of the asthenosphere would have caused (1) isostatic uplift and formation of basement highs, (2) magmatism in the lower crust and regional-scale contact metamorphism in the upper crust, and (3) collapse of metamorphic terranes and the formation of subsiding sedimentary basins.
Petrology and geochronology of Mesoproterozoic mafic–intermediate plutonic rocks from Mitwaba (D. R. Congo): implications for the evolution of the Kibaran belt in central Africa
Authors: KOKONYANGI J. , KAMPUNZU A. B. , POUJOL M. , OKUDAIRA T. , YOSHIDA M. , SHABEER K. P.
Published: March 2005

Mesoproterozoic supracrustal rocks in the Kibaride belt (southeast Congo) were intruded by mafic–intermediate plutonic rocks. These igneous rocks were affected by greenschist- to amphibolite-facies metamorphism during the Mesoproterozoic Kibaran orogenesis. U–Pb single zircon dating of the Mitwaba mafic–intermediate plutonic rocks yields an emplacement age of 1.38 Ga. The compositions of the Mitwaba mafic–intermediate plutonic rocks range from gabbro to diorite and show the following elemental concentrations: SiO2: 49–58 wt%, TiO2: 0.53–0.92 wt%, A2O3: 13.1–18.68 wt%, Zr: 45–142 ppm, Y: 13–43 ppm. Mg no. 40–66 indicates variable degrees of fractionation of the magmas. The rocks are marked by high and variable Th/Ta (3–14), La/Nb (2–5) and low Ce/Pb (0.3–12.8) and Ti/V (10–19). Chondrite-normalized REE patterns exhibit enrichment in LREE relative to HREE ((La/Yb)N=2.9–5.8). Primordial mantle-normalized spider diagrams show negative slopes with gradual decrease from LIL to HFS elements and are marked by Nb and Ti negative anomalies. Immobile trace-element contents indicate a continental arc setting for these mafic–intermediate igneous rocks. They are inferred to have originated from a mantle wedge enriched by fluid from a subducting slab, with possibly an additional contribution from subducted sediments. Low, sub-chondritic Nb/Ta ratios in these mafic rocks support this interpretation. A model involving underplating of mafic–intermediate arc magma into the crust, triggering partial melting of Mitwaba group metasedimentary rocks during the accretionary stage of the Kibaran orogeny, is proposed to explain the coeval emplacement of mafic–intermediate arc magmas and peraluminous S-type granitoids in the Kibaride belt of central Africa.
Characterization of proteinases in different isolates of adult Haemonchus contortus
Authors: REDMOND D. L. , WINDHAM R.
Published: March 2005

A high degree of intra- and inter-geographical variation has been demonstrated previously in the excretory/secretory proteinases released by adult Haemonchus contortus. Proteinase activity has also been associated with host-protective ‘hidden’ antigens isolated from the gut of adult H. contortus. If similar geographical strain variation also exists within the gut-associated proteinases, this will have important implications for the development of a globally effective vaccine. The proteinases active in integral-membrane protein extracts from 3 different strains of adult H. contortus were characterized on the basis of their pH optima and molecular size. Although enzyme activity was detected over a wide pH range, the majority of proteinase activity was detected at acidic pH. Differences in specific activity and size of enzymes were observed between the 3 different parasite strains at different pH values. A high degree of conservation in reactive peptides was observed when protein extracts were probed with antisera raised to the protective hidden gut-antigen complexes isolated from the Moredun strain of H. contortus, or to bacterially expressed subcomponents thereof. Therefore, despite the observed differences in membrane-bound proteinase profiles, the similarity of the immunogenic response against these hidden antigens may be sufficient to prove protective against different geographical isolates of H. contortus.
Quantitative assessment of sense and antisense transcripts from genes involved in antigenic variation (vsp genes) and encystation (cwp 1 gene) of Giardia lamblia clone GS/M-83-H7
Authors: von ALLMEN N. , BIENZ M. , HEMPHILL A. , MÜLLER N.
Published: March 2005

Antigenic variation of the intestinal protozoan parasite Giardia lamblia is caused by an exchange of the parasite's variant surface protein (VSP) coat. Many investigations on antigenic variation were performed with G. lamblia clone GS/M-83-H7 which produces surface antigen VSP H7. To generate novel information on giardial vsp gene transcription, vsp RNA levels were assessed by quantitative reverse transcription-(RT)-PCR in both axenic VSP H7-type trophozoites and subvariants obtained after negative selection of GS/M-83-H7 trophozoites by treatment with a cytotoxic, VSP H7-specific monoclonal antibody. Our investigation was not restricted to the assessment of the sense vsp transcript levels but also included an approach aimed at the detection of complementary antisense vsp transcripts within the two trophozoite populations. We found that sense vsp H7 RNA predominated in VSP H7-type trophozoites while sense RNA from only one (vsp IVg) of 8 subvariant vsp genes totally analysed predominated in subvariant-type trophozoites. Interestingly, the two trophozoite populations exhibited a similar relative distribution regarding the vsp H7 and vsp IVg antisense RNA molecules. An analogous sense versus antisense RNA pattern was also observed when the transcripts of gene cwp 1 (encoding cyst wall protein 1) were investigated. Here, both types of RNA molecules only appeared after cwp 1 had been induced through in vitro encystation of the parasite. These findings for the first time demonstrated that giardial antisense RNA production did not occur in a constitutive manner but was directly linked to complementary sense RNA production after activation of the respective gene systems.
Evidence for macrofilaricidal activity of ivermectin against female Onchocerca volvulus: further analysis of a clinical trial in the Republic of Cameroon indicating two distinct killing mechanisms
Authors: DUKE B. O. L.
Published: March 2005

During a 3-year trial of the effects of ivermectin (MectizanR) on adult worms and microfilariae of Onchocerca volvulus in the Republic of Cameroon, comparison was made between the percentages of calcified and uncalcified moribund (M) and dead (D) adult female worms dying following (a) the standard dose (150 μg/kg) given annually; (b) high doses (400, then 800 μg/kg) given annually; and (c and d) these same doses given at 3-monthly intervals. In the killing of adult female O. volvulus worms, the relative rôles of (a) natural causes; (b) a presumed, direct, anthelminthic, macrofilaricidal action of ivermectin; and (c) a potentially fatal pleomorphic ovarian neoplasm (PN), of which the incidence is increased by ivermectin treatment, are herein further investigated and discussed. It is concluded that ivermectin per se has a considerable direct macrofilaricidal action against female worms and that this lethal effect is supplemented by the drug's ability in some worms to increase the incidence, and the spread throughout the body of the worm, of the potentially fatal PN ovarian tumour. In moribund and dead ivermectin-treated female worms that were heavily invaded by PN, it is probable that the neoplasm was chiefly responsible for their death, but the additional direct anthelminthic action of the drug, which by itself has been responsible for the death of many other female worms, cannot be excluded as having played a supplementary lethal rôle. Similar problems as to the exact means by which adult female worms are killed may arise now that ivermectin is used in Africa for the mass treatment of lymphatic filariasis; or if and when the macrofilaricidal actions on O. volvulus of other drugs, which are closely related to ivermectin, come to be investigated.
Phylogenetic analysis of freshwater fish trypanosomes from Europe using ssu rRNA gene sequences and random amplification of polymorphic DNA
Authors: GIBSON W. C. , LOM J. , PECKOVÁ H. , FERRIS V. R. , HAMILTON P. B.
Published: March 2005

The taxonomy and phylogenetic relationships of fish trypanosomes are uncertain. A collection of 22 cloned trypanosome isolates from 14 species of European freshwater fish and 1 species of African freshwater fish were examined by molecular phylogenetic analysis. The small subunit ribosomal RNA (ssu rRNA) genes of 8 clones were sequenced and compared with ssu rRNA gene sequences from a wider selection of vertebrate trypanosome isolates by phylogenetic analysis. All trypanosomes from freshwater fish fell in a single clade, subdivided into 3 groups. This clade sits within a larger, robust clade containing trypanosomes from marine fish and various amphibious vertebrates. All 22 trypanosome clones were analysed by random amplification of polymorphic DNA. The resulting dendrogram shows 3 groups, which are congruent with the groups identified in the ssu rRNA gene phylogeny. Two of the groups contain the majority of trypanosome isolates and within-group variation is slight. These groups do not separate purported trypanosome species distinguished by morphology or host origin, and thus these criteria do not appear to be reliable guides to genetic relationships among fish trypanosomes. However, we suggest that the 2 groups themselves may represent different species of fish trypanosomes. The polymorphic DNA markers we have identified will facilitate future comparisons of the biology of these 2 groups of fish trypanosomes.
Chlorin Index: A new parameter for organic matter freshness in sediments
Authors: Schubert Carsten J. , Niggemann Jutta , Klockgether Gabriele , Ferdelman Timothy G.
Published: March 2005

Total chlorins, comprising degradation products of chlorophyll, have been used recently to reconstruct paleoproductivity from marine sediment cores. Here, we report on a new index, the Chlorin Index (CI), that proves to be a helpful tool for rapidly estimating organic matter freshness in marine sediments. The CI is a ratio between the fluorescence intensity of a sediment extracted with acetone and treated with hydrochloric acid and the original sediment extract. It represents the ratio of chlorophyll and its degradation products deposited in the sediments that could still be chemically transformed and those that are inert to chemical attack. The ratio is lower in sediments that include freshly deposited phytoplankton material and higher in older, more degraded sediments. We measured this new parameter on surface sediments, and sediments from several short and a long sediment core from different oceanic settings. CI values range from 0.2 for chlorophyll a to 0.36–0.56 for fresh material deposited on the shelf off Namibia to values around 0.67 in sediments off Chile and Peru to values up to 0.97 for sediments in a deep core from the northeastern slope of the Arabian Sea. We have compared the CI to rates of bacterial sulfate reduction, as a direct measure of organic matter reactivity and to other degradation indices based on amino acid composition. We conclude that the CI is a reliable and simple tool for the characterization of organic material freshness in sediments in respect to its degradation state.
Sensitivity analysis of sediment resuspension parameters in coastal area of southern Lake Michigan
Authors: Lee Cheegwan , Schwab David J. , Hawley Nathan
Published: March 2005

Model sensitivity analysis was performed to identify and compare quantitatively the important resuspension parameters in the coastal area of southern Lake Michigan. A one‐dimensional resuspension and bed model capable of dealing with the type of mixed sediments (fine‐grained+sand) common in the coastal area was developed and utilized to compare with measured suspended sediment concentrations. The results show that the most sensitive parameters in the model are the fraction of fine‐grained materials and sediment availability. Other resuspension parameters such as settling velocity, critical shear stress, and erosion rate constant are also found to be important and may cause up to a 40% difference in suspended sediment concentration. Among those, the absolute magnitude of settling velocity is most crucial in controlling the first order prediction.
Wave spectral energy variability in the northeast Pacific
Authors: Bromirski Peter D. , Cayan Daniel R. , Flick Reinhard E.
Published: March 2005

The dominant characteristics of wave energy variability in the eastern North Pacific are described from NOAA National Data Buoy Center (NDBC) buoy data collected from 1981 to 2003. Ten buoys at distributed locations were selected for comparison based on record duration and data continuity. Long‐period (LP) [T > 12] s, intermediate‐period [6 ≤ T ≤ 12] s, and short‐period [T < 6] s wave spectral energy components are considered separately. Empirical orthogonal function (EOF) analyses of monthly wave energy anomalies reveal that all three wave energy components exhibit similar patterns of spatial variability. The dominant mode represents coherent heightened (or diminished) wave energy along the West Coast from Alaska to southern California, as indicated by composites of the 700 hPa height field. The second EOF mode reveals a distinct El Niño‐Southern Oscillation (ENSO)‐associated spatial distribution of wave energy, which occurs when the North Pacific storm track is extended unusually far south or has receded to the north. Monthly means and principal components (PCs) of wave energy levels indicate that the 1997–1998 El Niño winter had the highest basin‐wide wave energy within this record, substantially higher than the 1982–1983 El Niño. An increasing trend in the dominant PC of LP wave energy suggests that storminess has increased in the northeast Pacific since 1980. This trend is emphasized at central eastern North Pacific locations. Patterns of storminess variability are consistent with increasing activity in the central North Pacific as well as the tendency for more extreme waves in the south during El Niño episodes and in the north during La Niña.
The effect of sediment stratification on tidal dynamics and sediment transport patterns
Authors: Byun Do‐Seong , Wang Xiao Hua
Published: March 2005

The western tip of southwest Korea is characterized by a tidally dominated, turbid, coastal environment. There are well‐developed tidal flats along the coast and around islands, together with offshore sand ridges several tens of kilometers long in the west. The effects of bottom boundary layer (BBL) sediment stratification on sediment‐transport and tidal dynamics in this environment were examined using a sediment transport model coupled with a three‐dimensional tidal hydrodynamic model. Model experiments using two scenarios, with and without the effect of sediment‐induced stratification, showed that BBL sediment‐stratification influenced the spatial distribution and reduced the magnitude of net sedimentation. The presence of a sediment‐stratified BBL also led to a reduction in suspended sediment fluxes and an increase in the vertical gradient of sediment concentrations in the water column. These variations occurred because sediment‐induced BBL stratification leads to not only a reduction in bottom shear stress but also a decrease in buoyancy production of turbulent kinetic energy and an associated dampening of turbulence. The significant reductions in turbulence and bottom shear stress result in changes to the vertical‐current structure of the M2 tide, including alteration of the tidal ellipse configuration and an increase in vertical shears of the tidal current amplitude and phase. These reductions also lead to a slight increase in tidal amplitudes due to the decreased tidal‐energy dissipation. The model results indicate that feedback between the sediment‐transport dynamics and hydrodynamics is an important factor in modeling sediment transport dynamics in tidally dominated, turbid, coastal environments. Such environments include the west coast of Korea and the Yellow Sea. A suitable approach to simulating the effects of this feedback may be the use of a modified bottom‐drag coefficient as a stability function, together with the inclusion of the effect of sediment stratification on the hydrodynamics.