bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of thermal‐ and photo‐polymerization of lauryl methacrylate monolithic columns for CEC
Authors: Bernabé‐Zafón Virginia , Cantó‐Mirapeix Amparo , Simó‐Alfonso Ernesto F. , Ramis‐Ramos Guillermo , Herrero‐Martínez José Manuel 
Published: June 2009

AbstractLauryl methacrylate‐based (LMA) monolithic columns for CEC, prepared using either thermal initiation or by UV‐irradiation in the presence of AIBN have been compared. Thermal polymerization was carried out at 70°C for 20 h. For UV initiation, the effects of the time exposure to UV light and irradiation energy were investigated. For each initiation process, the influence of composition of porogenic solvent (1,4‐butanediol/1‐propanol ratio) on the physical and electrochromatographic properties of the resulting monoliths was also evaluated. Photochemically lauryl methacrylate stationary phases initiated showed higher permeabilities and better efficiencies than those prepared by thermal initiation. After optimization of polymerization mixture, photopolymerized columns provided a permeability of 4.25×10−13 m2 and a minimum plate height of 13.4 μm for a mixture of polycyclic aromatic hydrocarbons. Similar column‐to‐column and batch‐to‐batch reproducibilities, with RSD values below 11.6 and 11.0 % for the thermal‐ and UV‐initiated columns, respectively, were obtained.
Improved dynamic range of protein quantification in silver‐stained gels by modelling gel images over time
Authors: Grove Harald , Færgestad Ellen M. , Hollung Kristin , Martens Harald 
Published: June 2009

AbstractSilver staining is a commonly used protein stain to visualise proteins separated by 2‐DE. Despite this, the technique suffers from a limited dynamic range, making the simultaneous quantification of high‐ and low‐abundant proteins difficult. In this paper we take advantage of the fact that silver staining is not an end‐point stain by photographing the gels during development. This procedure provides information about the change in measured absorbance for each pixel in the protein spots on the gel. The maximum rate of change was found to be correlated with the amount of applied protein, providing a new way of estimating protein amount in 2‐DE gels. We observed an improvement in the dynamic range of silver staining by up to two orders of magnitude.
Online preconcentration and two‐dimensional separation of cationic compounds via hyphenation of capillary zone electrophoresis with cyclodextrin‐modified micellar electrokinetic capillary chromatography
Authors: Zhang Zhao‐Xiang , Zhang Ming‐Zhe , Zhang Shu‐Sheng 
Published: June 2009

AbstractA novel preconcentration/separation approach, which online combined CZE with CD‐modified MEKC, was developed for simultaneous enhancing resolving power and detection sensitivity. CZE with cation‐selective exhaustive injection and transient ITP preconcentration was used as the first dimension, from which the effluent fractions were further analyzed by CD‐modified MEKC acting as the second dimension. As the key to successful integration of CZE with MEKC, a new interface was designed and electroaccumulation focusing strategy was employed to avoid analyte band diffusion at the interface. The comprehensive 2‐D system was successfully established with only one high voltage and four electrodes. The grouping of two orthogonal separation techniques, together with analytes preconcentration techniques, significantly enhanced resolution and sensitivity for 2‐D separation of cationic compounds. The resulting electrophoregram was quite different from that of either single CZE or MEKC. Up to 14 000‐ to 35 000‐fold improvement in sensitivity was obtained relative to conventional electrokinetic injection method. The limits of detection (S/N=3) were in the range of 0.03–0.1 μg/L. The number of theoretical plates was in the range of 103 000–184 000. This method was successfully applied to the analysis of trace cationic cardiovascular drugs in wastewater.
A simple preparative free‐flow electrophoresis joined with gratis gravity: I. Gas cushion injector and self‐balance collector instead of multiple channel pump
Authors: Chen Su , Palmer James F. , Zhang Wei , Shao Jing , Li Si , Fan Liu‐Yin , Sun Ren , Dong Yu‐Chao , Cao Cheng‐Xi 
Published: June 2009

AbstractThis paper describes a novel free‐flow electrophoresis (FFE), which is joined with gratis gravity, gas cushion injector (GCI) and self‐balance collector instead of multiple channel pump, for the purpose of preparative purification. The FFE was evaluated by systemic experiments. The results manifest that (i) even though one‐channel peristaltic pump is used for the driving of background buffer, there is still stable flow in the FFE chamber; (ii) the stable flow is induced by the gravity‐induced pressure due to the difference of buffer surfaces in the GCI and self‐balance collector; (iii) the pulse flow of background buffer induced by the peristaltic pump is greatly reduced by the GCI with good compressibility of included air; (iv) the FFE can be well used for zone electrophoretic separation of amino acids; (v) up to 20 inlets simultaneous sample injection and up to five to tenfold condensation of amino acid can be achieved by combining the FFE device with the method of moving reaction boundary. To the best of authors' knowledge, FFE has not been used for such separation and condensation of amino acids. The relevant results achieved in the paper have evident significance for the development of preparative FFE.
A new route for simple and rapid determination of hydrogen peroxide in RAW264.7 macrophages by microchip electrophoresis
Authors: Gong Xiaocong , Li Qingling , Xu Kehua , Liu Xin , Li Hongmin , Chen Zhenzhen , Tong Lili , Tang Bo , Zhong Hongbo 
Published: June 2009

AbstractA new method using MCE with LIF detection was developed for the determination of hydrogen peroxide (H2O2). Bis(p‐methylbenzenesulfonyl)dichlorofluorescein, a new fluorogenic reagent synthesized by our laboratory was employed as a labeling reagent, the derivatization reaction was performed in 0.10 M HEPES buffer (pH 7.4) for 30 min at 37°C. The detection of H2O2 was accomplished in 55 s, using a 40 mM HEPES buffer, 20% mannitol, pH 7.4, on a glass microchip. The RSDs of migration time and peak area were 1.8 and 3.7%, respectively. Method validation showed the linear response ranging from 0.50 to 50 μM with an LOD (S/N=3) of 0.20 μM (19.1 amol). The proposed method was applied to determine H2O2 in phorbol myristate acetate‐stimulated RAW264.7 macrophages, the concentration of H2O2 was found to be 1.86±0.05 μM; recoveries for macrophage samples were from 96.7 to 97.8%, within‐days and between‐days accuracies were 4.5% (n=5) and 6.8% (n=5), respectively.
Characterisation of mixed lithium dodecyl sulphate/lithium perfluorooctanesulphonate pseudo‐stationary phases in MEKC
Authors: Varga András , Huszár Mónika , Dobos Zsófia , Kiss Éva , Horváth Anikó , Idei Miklós 
Published: June 2009

AbstractLipophilicity and methylene selectivity of mixed pseudo‐stationary phases (PSPs) (containing lithium dodecyl sulphate (LDS) and lithium perfluorooctanesulphonate (LiPFOS) in different molar ratios) applied in MEKC have been investigated. Micellar proportion (tprop,mic, a quantity expressing that how much time is spent by the analyte in the micellar phase related to its whole migration time), CLOGP50 value (showing the value of hydrophobicity of a molecule spending exactly 50% of its migration time in the PSP) and methylene selectivity have been determined for different LDS/LiPFOS mixed phases. Values of the above‐mentioned parameters have been determined for analytes with different chemical structures (alkylbenzene and alkylphenone homologous series, alcohols). Good linear correlation was obtained between either the micellar proportion, CLOGP50, or methylene selectivity and the phase composition for the mixed phases. Lipophilicity and methylene selectivity of the mixed LDS/LiPFOS PSPs can be calculated and can continuously be changed by mixing the two single phases (LDS and LiPFOS) in the appropriate (and calculable) portion.
Influence of polyelectrolyte capillary coating conditions on protein analysis in CE
Authors: Nehmé Reine , Perrin Catherine , Cottet Hervé , Blanchin Marie‐Dominique , Fabre Huguette 
Published: June 2009

AbstractCE of biomolecules is limited by analyte adsorption on the capillary wall. To prevent this, monolayer or successive multiple ionic‐polymer layers (SMILs) of highly charged polyelectrolytes can be physically adsorbed on the inner capillary surface. Although these coatings have become commonly used in CE, no systematic investigation of their performance under different coating conditions has been carried out so far. In a previous study (Nehmé, R., Perrin, C., Cottet, H., Blanchin, M. D., Fabre, H., Electrophoresis 2008, 29, 3013–3023), we investigated the influence of different experimental parameters on coating stability, repeatability and peptide peak efficiency. Optimal coating conditions for monolayer and multilayer (SMILs) poly(diallyldimethylammonium) chloride/ poly(sodium 4‐styrenesulfonate) coated capillaries were determined. In this study, the influence of polyelectrolyte concentration and ionic strength of the coating solutions, and the number of coating layers on coating stability and performance in limiting protein adsorption was carried out. EOF magnitude and repeatability were used to monitor coating stability. Coating ability to limit protein adsorption was investigated by monitoring variations of migration times, time‐corrected peak areas and separation efficiency of test proteins. The separation performance of polyelectrolyte coatings were compared with those obtained with bare silica capillaries.
In‐capillary microextraction using monolithic polymers: Application to preconcentration of carbamate pesticides prior to their separation by MEKC
Authors: Rodríguez‐Gonzalo Encarnación , Ruano‐Miguel Luis , Carabias‐Martínez Rita 
Published: June 2009

AbstractIn the present work we report a novel procedure for in‐capillary microextraction using a monolithic polymeric sorbent. In the proposed methodology, sample treatment takes place in the CE instrument but in a different capillary from that used for the electrophoretic separation. Polymers based on butyl methacrylate and divinylbenzene formed in situ inside a capillary column were assayed. The best results were found with the divinylbenzene‐based polymers. The usefulness of the proposed procedure was checked for the determination of carbamate pesticides (Methomyl, Asulam, Carbendazim, Aldicarb, Carbetamide, Propoxur, Pirimicarb, Carbaryl, Carbofuran and Methiocarb) and three of their degradation compounds (Aldicarb sulphoxide, 2‐isopropoxyphenol and α‐naphthol) using MEKC. The optimization of the MEKC is reported, a good separation of the 13 analytes being obtained in less than 6 min. The analytical method using in‐capillary microextraction was validated in terms of linearity, repeatability, precision (RSD≤18% for 50 μg/L), and LODs (1–16 μg/L), and it revealed the usefulness of this in‐capillary preconcentration procedure for the determination of analytes of intermediate polarity.
Assessment of the finite volume method applied to the v2 − f model
Authors: Mortensen Mikael , Reif Bjørn Anders Pettersson , Wasberg Carl Erik 
Published: June 2009

AbstractThe objective of this paper is to assess the accuracy of low‐order finite volume (FV) methods applied to the v2 − f turbulence model of Durbin (Theoret. Comput. Fluid Dyn. 1991; 3:1–13) in the near vicinity of solid walls. We are not (like many others) concerned with the stability of solvers ‐ the topic at hand is simply whether the mathematical properties of the v2 − f model can be captured by the given, widespread, numerical method. The v2 − f model is integrated all the way up to solid walls, where steep gradients in turbulence parameters are observed. The full resolution of wall gradients imposes quite high demands on the numerical schemes and it is not evident that common (second order) FV codes can fully cope with such demands. The v2 − f model is studied in a statistically one‐dimensional, fully developed channel flow where we compare FV schemes with a highly accurate spectral element reference implementation. For the FV method a higher‐order face interpolation scheme, using Lagrange interpolation polynomials up to arbitrary order, is described. It is concluded that a regular second‐order FV scheme cannot give an accurate representation of all model parameters, independent of mesh density. To match the spectral element solution an extended source treatment (we use three‐point Gauss–Lobatto quadrature), as well as a higher‐order discretization of diffusion is required. Furthermore, it is found that the location of the first internal node need to be well within y+=1. Copyright © 2009 John Wiley & Sons, Ltd.
Relationship between white matter changes and cognition in healthy elders
Authors: Ota Miho , Nemoto Kiyotaka , Sato Noriko , Yamashita Fumio , Asada Takashi 
Published: June 2009

AbstractObjectivesCerebral WMHs on T2‐weighted magnetic resonance imaging (MRI) are common incidental findings in cognitively healthy elderly subjects. The relationship between such changes and cognitive function remains unclear.MethodsThe present study evaluated the relationship between the degree of white matter changes and cognitive function using data from 172 cognitively healthy subjects who underwent MRI and a battery of neuropsychological tests. The degree of WMHs was rated using a four‐point scale for images on a computer screen.ResultsRegarding the frontal and parieto‐occipital regions and basal ganglia region, compared with the group with no WMHs, the group with the most severe WMHs showed significantly lower performances for attention and disorientation to time, respectively.ConclusionsOur results suggest that even in cognitively healthy elderly individuals, presence of large WMHs affects performance on certain cognitive domains according to their localization. Copyright © 2009 John Wiley & Sons, Ltd.
Circadian patterns of ad libitum smoking by menstrual phase
Authors: Allen Alicia M. , Mooney Marc , Chakraborty Rima , Allen Sharon S. 
Published: June 2009

AbstractObjectiveRecent research suggests nicotine metabolism may be influenced by sex hormones. Thus, we hypothesized that circadian smoking patterns would vary by menstrual phase.MethodsHealthy female smokers (n = 31) between the ages of 18 and 40 with regular menstrual cycles, and not using hormones or psychotropic medications, were recruited for a randomized clinical study. Subjects recorded the time of each cigarette smoked and their menstrual phase with daily diaries prospectively for one complete menstrual cycle of ad libitum smoking. Analyses included Poisson regression to assess variations in the rate of smoking during waking hours (i.e., 6:00 a.m. and 12:00 midnight) and circadian smoking patterns by menstrual phase.ResultsParticipants were 29.61 ± 5.44 years of age and smoked 16.93 ± 5.37 cigarettes per day. Participants had a lower rate of smoking during waking hours in the follicular phase as compared to the menses phase. There were no significant menstrual phase differences in the circadian smoking patterns.ConclusionsThese results offer further support for the influence of sex hormones on smoking behavior, but not on circadian patterns of smoking. Additional research is needed to study the direct relationship between nicotine metabolism, sex hormones, menstrual phase, and smoking behavior. Copyright © 2009 John Wiley & Sons, Ltd.
Enhancement of monoclonal antibody productivity by promoting active hypothermic growth in hybridoma cells
Authors: Chong Sun Li , Mou Duen Gang , Lim Saw Hoon , Ali Abdul Manaf , Tey Beng Ti 
Published: June 2009

AbstractBACKGROUND: Many reports have suggested that mild hypothermic culture conditions improve the specific monoclonal antibody (mAb) productivity of mammalian cells. The effect of active hypothermic growth on the mAb productivity of the hybridoma C2E7 was investigated. Hybridoma growth under hypothermic conditions (32 °C) was stimulated by supplementation of the culture medium with high serum concentrations (up to 30%).RESULTS: Specific and volumetric mAb productivity of a stimulated, active growth, mildly hypothermic hybridoma culture (30% FBS supplemented, 32 °C) were 1.38‐ and 1.34‐fold greater than the control culture (10% FBS supplemented, 37 °C). The enhanced specific mAb productivity under hypothermic conditions was associated with an increase in IgM mRNA levels during both the lag and early exponential phases of hypothermic growth.CONCLUSION: Stimulation of hybridoma growth under mildly hypothermic conditions increased both the specific and volumetric mAb productivity of hybridoma cells. Copyright © 2009 Society of Chemical Industry
An evaluation of high resolution precipitation products at low resolution
Authors: Sapiano Mathew Raymond Paul 
Published: June 2009

AbstractThe large‐scale homogeneity of several high‐resolution satellite‐based estimates of precipitation is assessed against the Global Precipitation Climatology Project (GPCP) between January 2003 and December 2006. The high‐resolution estimates are aggregated to match the resolution of GPCP (monthly, 2.5°) and an Empirical Orthogonal Functions (EOF) analysis is conducted on each product along with an analysis of the slope from a linear regression with time. The results show that some of the datasets have significant artefacts and that none of the high‐resolution products give a good depiction of precipitation above 50°N. The two datasets which are most consistent with GPCP are the Tropical Rainfall Monitoring Mission (TRMM) Multi‐satellite Precipitation Analysis (TMPA) and the Global Satellite Mapping Project (GSMaP) both of which have undergone recent re‐processing which is an important quality for dataset homogeneity. Copyright © 2009 Royal Meteorological Society
Novel pH‐ and Temperature‐Responsive Methacrylamide Microgels
Authors: Pérez‐Álvarez Leyre , Sáez‐Martínez Virginia , Hernáez Estíbaliz , Katime Issa 
Published: June 2009

AbstractA novel transition temperature in MeAM copolymer microgels is reported. Despite the fact that MeAM homopolymers do not show thermosensitive properties, a specific synthetic strategy leads to a thermo‐responsive swelling behavior that could be potentially useful in medical and/or industrial applications. The pH and temperature‐dependent swelling response of microgels of MeAM copolymerized with 2‐aminomethylpyridine and ethylenediamine is reported. The changes in particle sizes, which depend on the nature of the surrounding environment, are recorded by QELS. The relation between copolymer structure and its novel behavior is analyzed by several techniques (1H NMR, TGA).magnified image
Taking the distortion of component parts along a manufacturing chain into consideration during planning
Authors: Klein D. , Seifert M. , Thoben K.‐D. 
Published: June 2009

AbstractDistortion of a component part can already be minimized if it is considered in the planning of the manufacturing process. Thus, costs of the removal of distortion, e. g. by grinding, can be reduced. Beginning with steel production the state of a workpiece changes every process step continuously. Thereby, a distortion potential arises that will be visible at the component part after hardening as distortion. To consider distortion in planning the state has to be determined at every time of manufacturing. So far, no tools exist to describe the workpiece state along an entire process chain. In this article an alternative will be presented which is able to describe changes of states along an entire manufacturing chain. Finally, with this description an estimation of the expected distortion can be carried out.
Characterization of segregations and microstructure and their influence on distortion of low alloy SAE 5120 steel
Authors: Prinz C. , Hunkel M. , Clausen B. , Hoffmann F. , Zoch H.‐W. 
Published: June 2009

AbstractInvestigations within the SFB 570 “Distortion Engineering” showed that shafts produced of the low alloy steel SAE 5120 (EN 20MnCr5) changed curvature into a preferred direction after blank hardening. The changes of curvature could be correlated with a macroscopic structure, which was visible in the metallographic cross section of the hardened shafts. Due to a quantitative description of the orientation of the square structure within the metallographic cross section it could be shown that the changes of the orientation of the structure were similar to the changes of the preferred direction of the curvature of the blank hardened shafts. Metallographic structures in different sections became visible because of differences of the local corrosion behavior. Such differences cause in varieties of the local chemical composition or grain size. Therefore the local chemical analysis was characterized by means of EPMA measurements with highest resolution. Further the grain size was described by quantitative image analysis of the former austenite grain boundaries. Additionally, characteristic areas of the metallographic cross section were investigated by FEM measurements due to the fact that the grain size could be affected by elemental precipitations. The laminar EPMA‐measurements (mapping) at blank hardened shafts of the element distributions concerning the substantial alloying elements C, Mn and Cr showed a square structure in the element distribution. Best reproduction of the square structure within the metallographic cross section could be reached by moving averages of the highly resoluted mappings and their standard deviations.Different distributions of the former austenite grain boundary were found within characteristic areas of the metallographic cross section. FEM measurements seem to point on the fact that differences of the former austenite grain size distributions could cause in varieties of the character and distribution of elemental precipitations.
Material flow analysis for hot‐forming of 20MnCr5 gear wheel blanks
Authors: Rentsch R. 
Published: June 2009

AbstractDuring the manufacture of disk‐like gearwheel blanks made of 20MnCr6 (SAE 5120) a characteristic distortion behavior was observed which has been related to the forging process. The steel showed a typical banded structure and a distribution of chemical elements (segregations) perpendicular to rolling direction. When analyzing the micrographs of the forged gearwheel blanks, a significant variation in the material flow was found. In order to clarify the cause of the observed material flow variations and to determine its impact on the distortion potential of the disks, a twofold approach has been applied: a) to determine and to describe the material flow characteristics on basis of micrographs of forged disks and b) to carry out FE‐analyses on the theoretical material flow and its parameters. In this contribution results of the material flow analysis are presented and compared with FE‐analyses of the forming process.
Modeling and simulation of ring deformation due to clamping
Authors: Sölter J. 
Published: June 2009

AbstractThe paper gives an overview of analytical models for calculating the out‐of‐roundness for rings clamped in a 3‐jaw‐chuck and addresses their limitations regarding their applicability in machining practice. Results from analytical models and Finite Element Analyses (FEA) of clamping rings with two different clamping sequences are compared and discussed. Analytical models are applied to predict elastic deformations and stresses for a ring clamped on the outer and inner surface with a 3‐jaw‐chuck. A combined approach of analytical models and FEA is used to calculate the out‐of‐roundness and the stress distribution of a ring clamped with a 3‐jaw‐chuck on the outside and with segment jaws on the inside. Especially the influence of the angular position between outer and inner clamping (0 °, 60 °) will be addressed. Additionally the expected shape changes will be qualitatively predicted from simulated elastic stresses. Finally, the simulation results are compared with measured out‐of‐roundness and residual stresses of machined rings.