bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of the microenvironment‐pH and charge and size characteristics of amino acids through their electrophoretic mobilities determined by CZE
Authors: Piaggio Maria V. , Peirotti Marta B. , Deiber Julio A. 
Published: October 2007

AbstractEffective electrophoretic mobility data of 20 amino acids reported in the literature are analyzed and interpreted through simple physicochemical models, which are able to provide estimates of coupled quantities like hydrodynamic shape factor, equivalent hydrodynamic radius (size), net charge, actual pK values of ionizing groups, partial charges of ionizing groups, hydration number, and pH near molecule (microenvironment‐pH of the BGE). It is concluded that the modeling of the electrophoretic mobility of these analytes requires a careful consideration of hydrodynamic shape coupled to hydration. In the low range of pH studied here, distinctive hydrodynamic behaviors of amino acids are found. For instance, amino acids with basic polar and ionizing side chain remain with prolate shape for pH values varying from 1.99 to 3.2. It is evident that as the pH increases from low values, amino acids get higher hydrations as a consequence each analyte total charge also increases. This result is consistent with the monotonic increase of the hydrodynamic radius, which accounts for both the analyte and the quite immobilized water molecules defining the electrophoretic kinematical unit. It is also found that the actual or effective pK value of the α‐carboxylic ionizing group of amino acids increases when the pH is changed from 1.99 to 3.2. Several limitations concerning the simple modeling of the electrophoretic mobility of amino acids are presented for further research.
Temperature effects on the enantioselectivity of basic analytes in capillary EKC using sulfated β‐CDs as chiral selectors
Authors: Peng Zhen‐Lei , Yi Fei , Guo Baoyuan , Lin Jin‐Ming 
Published: October 2007

AbstractThe thermodynamic processes were investigated to reveal the temperature effects during chiral separation by capillary EKC with reversed polarity mode using sulfated β‐CD (S‐β‐CD) as chiral selectors. The temperature effects on enantioselectivities of basic analytes (ephedrine, norephedrine, synephrine, and epinephrine) were investigated in detail over a temperature range of 20–60°C. An increase of the capillary temperature produced the decrease of enantioselectivities for ephedrine and norephedrine, but increase of enantioselectivities for synephrine and epinephrine. The thermodynamic variations showed that the interactions between the basic analytes and chiral selectors were always enthalpy‐ driven. However, the difference in enthalpy and entropy showed that the enantioseparation was an enthalpy‐driven process for ephedrine and norephedrine, but an entropydriven process for synephrine and epinephrine. Just because of the different driving forces, there exist two kinds of temperature effects on enantioselectivities mentioned above.
Detection of microbial food contaminants and their products by capillary electromigration techniques
Authors: García‐Cañas Virginia , Cifuentes Alejandro 
Published: October 2007

AbstractThis work reviews the different analytical strategies based on capillary electromigration techniques developed for detecting microbial contaminants and their products in food matrices. Namely, this work presents an exhaustive and critical review, including works published till March 2007, on CE methods developed to detect and identify contaminants of microbial origin that represent a hazard to humans in foods. First, an overview on the strategies adopted for the analysis of intact microorganisms is presented. Next, CE methodologies based on the analysis of microbial constituents, including those based on genomics and proteomics approaches, are described. Finally, CE methods developed for detecting microbial toxins are discussed.
Rapid sample screening method for authenticity controlling vanilla flavors using a CE microchip approach with electrochemical detection
Authors: Ávila Mónica , González María Cristina , Zougagh Mohammed , Escarpa Alberto , Ríos Ángel 
Published: October 2007

AbstractFive vanilla‐related flavors of food significance, vanillic alcohol (VOH), ethyl maltol (EMA), maltol (MAL), ethyl vanillin (EVA) and vanillin (VAN), were separated using CE microchips with electrochemical detection (CE‐ED microchips). A +2 kV driving voltage for both injection and separation operation steps, using a borate buffer (pH 9.5, 20 mM) and 1 M nitric acid in the detection reservoir allowed the selective and sensitive detection of the target analytes in less than 200 s with reproducible control of EOF (RSDmigration times<3%). The analysis in selected real vanilla samples was focusing on VAN and EVA because VAN is a basic fragrance compound of the vanilla aroma, whereas EVA is an unequivocal proof of adulteration of vanilla flavors. Fast detection of all relevant flavors (200 s) with an acceptable resolution (Rs >1.5) and a high accuracy (recoveries higher than 90%) were obtained with independence of the matrices and samples examined. These results showed the reliability of the method and the potential use of CE microchips in the food control field for fraudulent purposes.
Determination of synthetic polypeptide conformations and molecular geometrical parameters by nonaqueous CE
Authors: Plasson Raphaël , Vayaboury Willy , Giani Olivia , Cottet Hervé 
Published: October 2007

AbstractThe aim of this work was to study changes in homopolypeptide chain conformation as a function of the number of residues by the modeling of the electrophoretic mobility. For this purpose, the frictional coefficients of poly(Nϵ‐trifluoroacetyl‐L‐lysine) with different number of residues (up to 11) were determined from the absolute ionic mobilities and modeled by the hydrodynamic frictional coefficient of an equivalent cylinder. This approach allowed determination of geometrical parameters of the polypeptide chain in a liquid phase (nonaqueous solution of the BGE). The fact that the BGE and analyte are dissolved in mixed (methanol–ACN) organic solvent implied to take into account different effects and corrections that are generally not considered in aqueous solvent: namely, the effect of ion‐pairs between constituents of the BGE for the calculation of the ionic strength, the effect of ion‐pairs between the solutes and the electrolyte counterions and the correction due to the dielectric friction (Hubbard‐Onsager equations). In addition, the influence of the ionic strength on the electrophoretic mobility was corrected using the Pitts equation, and the effect of lateral charges due to a slight deprotonation of the –NH– group in the lateral chain was also considered. From this modeling, molecular geometrical parameters relative to the linear and helicoïdal conformations were obtained with very good correlation coefficients. Interestingly, this work also points out that the use of ionic mobility modeling for extracting molecular geometrical parameters can also be applied to end‐charged polypeptides with slightly charged lateral chains (3% of elementary charge per residue).
Transform methods for frequency‐dependent complex stiffness to time domain using real or imaginary data only
Authors: Nakamura Naohiro 
Published: October 2007

AbstractThe author has studied the transform method of complex stiffness, which is strongly dependent on frequency, to the time domain. In this paper, new transform methods that use only the real part or the imaginary part data are proposed. By applying them to example problems, it is confirmed that the accuracy of the proposed methods is almost high in both causal and noncausal cases. These methods can also be thought as a standby for the Hilbert transform, because the undefined part is easily calculated by the recovering complex function from the obtained impulse response. Copyright © 2007 John Wiley & Sons, Ltd.
A genetic algorithm multi‐objective approach for efficient operational planning technique of distribution systems
Authors: Lakshminarayana C. , Mohan M. R. 
Published: October 2007

AbstractThis paper presents a genetic algorithm multi‐objective approach for efficient operational planning technique for electrical power distribution systems (EPDS). Service restoration is a non‐linear, combinatorial, non‐differential and multi‐objective optimization problem that often has a great number of candidate solutions to be evaluated by the operators. To tackle the problem of service restoration with multiple objectives, the weighted sum strategy is employed to convert these objectives into a single objective function by giving equal weighting values. The transformer/feeders capacity in the post‐fault distribution network creates a major problem for the electrical power distribution engineers and distribution system substation operators to satisfy the operational constraints at the consumer localities while restoring power supply. The feasibility of the developed algorithm for service restoration demonstrated on several distribution networks with fast and effective convergence of the results of this technique helps to find the efficient operational planning of the EPDS. Copyright © 2007 John Wiley & Sons, Ltd.
Transmission network optimal planning based on plant growth simulation algorithm
Authors: Wang Chun , Cheng Haozhong 
Published: October 2007

AbstractA new method, which employs a plant growth simulation algorithm (PGSA) as optimal means, is presented in this paper for solving the optimal planning problem of a transmission network in a single stage (horizon year). The transmission network planning is formulated as an integer programming problem subjected to the constraints such as overload, N − 1 security, and right‐of‐way, and an efficient solving approach based upon PGSA is developed. PGSA is a new and highly efficient random search algorithm, which characterizes the growth process of plant phototropism and can quickly find high quality solutions of the combinatorial optimization problems. The test results for two systems have verified the feasibility and efficiency of the developed PGSA based transmission network optimal planning method. Copyright © 2007 John Wiley & Sons, Ltd.
Antimicrobial activity of limonene enantiomers and 1,8‐cineole alone and in combination
Authors: Vuuren S. F. van , Viljoen A. M. 
Published: October 2007

AbstractTwo common essential oil constituents, 1,8‐cineole and limonene, were assessed for antimicrobial activity, using the minimum inhibitory concentration (MIC) microtitre plate method against eight organisms. The limonene enantiomers, i.e. (+), (−) and the racemate, singularly and in combination (1:1) with 1,8‐cineole, were investigated to establish possible interactions. The MIC values were in the ranges 3–27 mg/ml for (+)‐limonene; 2–27 mg/ml for (−)‐limonene and 23 mg/ml for 1,8‐cineole, depending on the pathogen studied. The combinations, when investigated in a 1:1 ratio, mostly indicated reduced activity. Using various ratios of limonene and 1,8‐cineole, the specific interaction was further investigated against Staphylococcus aureus (Gram‐positive), Pseudomonas aeruginosa (Gram‐negative) and a yeast, Cryptococcus neoformans. A figurative representation of the results using isobologram construction indicated that, depending on the ratio and specific enantiomer, an additive, synergistic or antagonistic interaction may be observed. Copyright © 2007 John Wiley & Sons, Ltd.
On the use of characteristic‐based split meshfree method for solving flow problems
Authors: Shamekhi Abazar , Sadeghy Kayvan 
Published: October 2007

AbstractThis study presents characteristic‐based split (CBS) algorithm in the meshfree context. This algorithm is the extension of general CBS method which was initially introduced in finite element framework. In this work, the general equations of flow have been represented in the meshfree context. A new finite element and MFree code is developed for solving flow problems. This computational code is capable of solving both time‐dependent and steady‐state flow problems. Numerical simulation of some known benchmark flow problems has been studied. Computational results of MFree method have been compared to those of finite element method. The results obtained have been verified by known numerical, analytical and experimental data in the literature. A number of shape functions are used for field variable interpolation. The performance of each interpolation method is discussed. It is concluded that the MFree method is more accurate than FEM if the same numbers of nodes are used for each solver. Meshfree CBS algorithm is completely stable even at high Reynolds numbers. Copyright © 2007 John Wiley & Sons, Ltd.
Numerical modeling of cohesive sediments dynamics in estuaries: Part I—Description of the model and simulations in the Po River Estuary
Authors: Leupi C. , Altinakar M. S. , Deville M. 
Published: October 2007

AbstractThe present work contributes to the numerical modeling of complex turbulent multiphasic fluid flows occurring in estuarine channels. This research finds its motivation in the increasing need for efficient management of estuaries by taking into account the complex turbulent stratified flows encountered in estuaries and costal zones. A time‐dependent, 3D finite element model of suspended sediment transport taking into account the effects of cohesiveness between sediments is presented. The model estuary is the forced time‐dependent winds, time elevation at open boundaries and river discharge. To cope with the stiffness problems a decoupling method is employed to solve the shallow‐water equations of mass conservation, momentum and suspended sediment transport with the conventional hydrostatic pressure. The decoupling method partitions a time step into three subcycles according to the physical phenomena. In the first sub‐cycle thepure hydrodynamicsincluding thek–ε turbulence model is solved, followed by the advection–diffusion equations for pollutants (salinity, temperature, suspended sediment concentration, (SSC)), and finally the bed evolution is solved. The model uses a mass‐preserving method based on the so‐called Raviart–Thomas finite element on the unstructured mesh in the horizontal plane, while the multi‐layers system is adopted in vertical with the conventional conforming finite element method, with the advantage that the lowermost and uppermost layers of variable height allow a faithful representation of the time‐varying bed and free surface, respectively. The model has been applied to investigate the SSC and seabed evolution in Po River Estuary (PRE) in Italy. The computed results mimic the field data well. Copyright © 2007 John Wiley & Sons, Ltd.
Was brauchen die Geisteswissenschaften?
Authors: Honemann Volker , Schlögl Rudolf 
Published: October 2007

Abstract„Selbstbewusst und exzellent”︁ – der Kommentar der Frankfurter Neuzeithistorikerin und DFG‐Vizepräsidentin Luise Schorn‐Schütte zur Lage und Zukunft der Geisteswissenschaften in „forschung 1/2007”︁ löste ein vielfältiges Echo aus. Im Folgenden dokumentieren wir zwei ausgewählte Zuschriften, die die wichtigsten Kritikpunkte bündeln. Die damit begonnene Debatte wird Luise Schorn‐Schütte in der nächsten „forschung”︁ fortführen.
Acquired genomic aberrations associated with methotrexate resistance vary with background genomic instability
Authors: Snijders Antoine M. , Hermsen Mario A. , Baughman Joshua , Buffart Tineke E. , Huey Bing , Gajduskova Pavla , Roydasgupta Ritu , Tokuyasu Taku , Meijer Gerrit A. , Fridlyand Jane , Albertson Donna G. 
Published: October 2007

AbstractTumors vary widely in chromosomal level genome instability. To gain a better understanding of the underlying defects which foster specific types of aberrations, we investigated the response of cells of related genetic backgrounds to challenge with methotrexate. We studied mismatch repair deficient HCT116 cells, two derivatives also deficient in XRCC5 (HCT116 Ku86+/−) or BLM (HCT116 BLM−/−), and mismatch repair competent HCT116+chr3 cells. We show that colony formation occurred at a significantly higher frequency in HCT116 cells and HCT116 Ku86+/− cells compared to HCT116 BLM−/− and HCT116+chr3 cells. Visible colonies arose most rapidly in HCT116 Ku86+/− cells, whereas they formed most slowly in HCT116+chr3 cells. Copy number changes acquired by the methotrexate resistant HCT116 and HCT116 BLM−/− cells most often included whole chromosome gains or losses or no acquired copy number changes, whereas resistance in HCT116+chr3 and HCT116 Ku86+/− cells was associated with amplification of DHFR and copy number transitions leading to increased copy number of DHFR, respectively. The additional copies of DHFR were present on unstable chromosomes and organized as inverted repeats in HCT116+chr3 cells, while they were most often present as direct repeats in HCT116 Ku86+/− cells. These observations suggest that different mutational mechanisms promote drug resistance in these genetic backgrounds; mismatch repair deficiency in HCT116, high rates of chromosomal instability in HCT116 Ku86+/−, and low rates of chromosomal instability in HCT116+chr3. On the other hand, it appears that loss of BLM function suppresses the mismatch repair mutator mechanism in mismatch repair and BLM deficient HCT116 BLM−/− cells. © 2007 Wiley‐Liss, Inc.
A study on thermal conductivity of a quasi‐ordered liquid layer on a solid substrate
Authors: Shi Xiao‐Yan , Zeng Dan‐Ling , Li You‐Rong 
Published: October 2007

AbstractIn the present paper, a study on thermal conductivity of a quasi‐ordered liquid layer on a solid surface was performed by molecular dynamic simulation. Results showed that the motion of the molecules and their radial distribution function in the quasi‐ordered liquid layer were similar to those of solid molecules. By using the Green–Kubo formula, the thermal conductivity of the layer was calculated. It was found that it increased with the increase of the parameters of ordering. The size effect and the influence of the boundary condition were also discussed. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(7): 429–434, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20171
A study on membrane distillation by a solar thermal‐driven system
Authors: Chen Tsung‐Ching , Ho Chii‐Dong , Guo Jia‐Jan , Tu Jr‐Wei 
Published: October 2007

AbstractMembrane distillation (MD) is a membrane separation process that has long been investigated in small scale laboratory studies and has the potential to become a viable tool for water desalination. MD is a separation process that combines simultaneous mass and heat transfer through a hydrophobic microporous membrane. A solar collector is used in direct contact membrane distillation (DCMD) to heat seawater as a temperature driving force in heat transfer to establish seawater desalting systems. The effect of the temperature difference makes the brine vaporize in the hot fluid side and condense in the cold fluid side. The optimal operating parameters on the pure water production rate will also be examined in this study. The purposes of this study are to develop the theoretical heat and mass transfer formulations, simulate heat transfer rate of solar collector with internal fins in membrane distillation, and investigate the mass‐transfer efficiency improvement in membrane distillation with the brine flow rate, solar collector efficiency, and temperature difference between both sides of membrane as parameters. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(7): 417–428, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20172
Experimental and numerical investigation of circularly lobed ejector with bend mixers
Authors: Liu You‐Hong , Liu Wei 
Published: October 2007

AbstractThe vent pipe for a turbo shaft engine may be required to have a lobed nozzle installed and to bend for the purpose of infrared stealth. The experimental setup was a circular 12‐lobed nozzle with bend mixers to study the effects on the pumping performance of the lobed bend mixer parameters. The experimental results show that the pumping ratio of the secondary mass flow to the primary mass flow for a mixer bend angle equal to 40° is the same as that for the same lobed nozzle with the same diameter cylindrical mixer that was used in the author's previous papers. There is a great decrease of the pumping ratio for a mixer bend angle larger than 40°. The higher the bend angles, the lower the pumping ratios. The pumping ratios initially increase and then decrease with the increasing of the cross‐area ratio of mixer to lobe. The optimal cross‐area ratio that corresponds to the maximum pumping ratio is strangely nearly equal to the optimal cross‐area ratio of a cylindrical mixer, although the maximum pumping ratio is less than that for a cylindrical mixer. The pumping ratios increase approximately linearly with the cross‐area ratio of the secondary inlet to the lobed nozzle. To investigate the flow characteristics and the pumping ratio changing mechanism, the flow field inside the ejector is numerically simulated. The numerical results show that the main reason for the great decrease of the pumping ratio when the mixer bend angle is larger than 40° is due to the great static pressure around the bend part, which is caused by the primary flow jet. The great static pressure around the bend section chokes back the exhausted secondary fluid flow. There is a good agreement between the calculated and the measured wall static pressure coefficients in the mixer wall along the lobe crest symmetry plane of the lobed ejector. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(7): 387–397, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20175
Effect of growing watershed imperviousness on hydrograph parameters and peak discharge
Authors: Huang Huang‐jia , Cheng Shin‐jen , Wen Jet‐chau , Lee Ju‐huang 
Published: October 2007

AbstractAn increasing impervious area is quickly extending over the Wu‐Tu watershed due to the endless demands of the people. Generally, impervious paving is a major result of urbanization and more recently has had the potential to produce more enormous flood disasters than those of the past. In this study, 40 available rainfall–runoff events were chosen to calibrate the applicable parameters of the models and to determine the relationships between the impervious surfaces and the calibrated parameters. Model inputs came from the outcomes of the block kriging method and the non‐linear programming method. In the optimal process, the shuffled complex evolution method and three criteria were applied to compare the observed and simulated hydrographs. The tendencies of the variations of the parameters with their corresponding imperviousness were established through regression analysis. Ten cases were used to examine the established equations of the parameters and impervious covers. Finally, the design flood routines of various return periods were furnished through use of approaches containing a design storm, block kriging, the SCS model, and a rainfall‐runoff model with established functional relationships. These simulated flood hydrographs were used to compare and understand the past, present, and future hydrological conditions of the watershed studied. In the research results, the time to peak of flood hydrographs for various storms was diminished approximately from 11 h to 6 h in different decrements, whereas peak flow increased respectively from 127 m3 s−1 to 629 m3 s−1 for different storm intensities. In addition, this study provides a design diagram for the peak flow ratio to help engineers and designers to construct hydraulic structures efficiently and prevent possible damage to human life and property. Copyright © 2007 John Wiley & Sons, Ltd.