bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parallel separations of oligonucleotides with optically gated sample introduction on multi‐channel microchips
Authors: Xu Hongwei , Roddy Elizabeth S. , Roddy Thomas P. , Lapos Julie A. , Ewing Andrew G. 
Published: January 2004

AbstractWith the release of the human genome sequence, there has been increasing attention given to other genetic analyses, including the detection of genetic variations and fast sequencing of multiple samples for pharmacogenomics studies. Rapid injections of samples in multiplexed separation channels by optically gated sample introduction are shown here for DNA separation. Serial separations of four amino acids are shown in less than four seconds on a microchip with four multiplexed channels. Five short oligonucleotides have also been rapidly separated in 2% LPA with four channels using this technique. In addition, multiple unique samples have been simultaneously separated and five‐base resolution has been demonstrated.
Capillary isoelectric focusing of proteins utilizing poly(vinylpyrrolidone)‐ and plexiglas‐coated columns
Authors: Palm Anders , Zaragoza‐Sundqvist Maximiliano , Marko‐Varga György 
Published: January 2004

AbstractFused‐silica capillaries chemically derivatized with silane/poly(vinylpyrrolidone) (PVP) or dynamically modified with plexiglas [poly(methyl methacrylate)] were prepared and evaluated with regard to column stability and separation performance for capillary isoelectric focusing of standard proteins. The PVP coating showed the better stability and was good for at least 100 runs while the plexiglas coating started to deteriorate after about 30 runs. The time spent for the plexiglas coating is about 40 minutes while the PVP coating requires two days. The migration time reproducibility was better with the PVP capillary (RSD 0.7–1.6%, n = 5) compared to the plexiglas‐coated column (RSD 1.2–2.9%, n = 5) while peak area and height varied over a similar interval (RSD 2–28.1% area; 0.9–22.7% height, n = 5). The two most consistent proteins in this evaluation, viz. myoglobin A and carbonic anhydrase II, showed linear dynamic ranges between 5–150 and 5–50 μg/mL, and limits of detections at 2 and 1 μg/mL, respectively, employing UV detection at 280 nm.
Determination of betulin in Grewia tiliaefolia by HPTLC
Authors: Badami Shrishailappa , Gupta Mahesh Kumar , Ramaswamy Saravanan , Rai Sujay R. , Nanjaian Mahadevan , Bendell David J. , Subban Ravi , Bhojaraj Suresh 
Published: January 2004

AbstractA sensitive, rapid, simple, and accurate high performance thin layer chromatographic method has been developed to standardize the bark of Grewia tiliaefolia Vahl. (Family: Tiliaceae) using betulin as an analytical marker. Chloroform extracts of bark from five different sources were used for HPTLC on silica gel with toluene‐ethyl acetate, 90 + 10 v/v, as mobile phase. Under these conditions, the Rf of betulin was 0.22. The calibration plot was linear in the range of 1000 ng to 1800 ng of betulin and the correlation coefficient, 0.999, was indicative of good linear dependence of peak area on concentration. The mean assay of betulin was 2.596 ± 0.594 mg g–1 of bark. The method permits reliable quantification of betulin and good resolution and separation of betulin from other constituents of Grewia tiliaefolia. Recovery values from 96.09 to 98.87% showed that the reliability and reproducibility of the method were excellent. The proposed HPTLC method for quantitative monitoring of betulin in Grewia tiliaefolia can be used for routine quality testing.
GC‐FID/MS method for the impurity profiling of synthetic d‐allethrin
Authors: Bragieri Matteo , Liverani Alessandra , Zanotti Maria Cristina , Borzatta Valerio , Fiori Jessica , Cavrini Vanni , Andrisano Vincenza 
Published: January 2004

AbstractA GC/FID/MS method was developed for the identification and quantification of d‐alle thrin (DA) and its major impurities in commercial samples. Optimisation of the experimental conditions was carried out considering such important requirements as resolution, reproducibility, detection limits of 0.1% (m/m) for the impurities, and short analysis time. Under the optimised final conditions the method was validated for specificity, precision (CV% = 0.133 at 2.10 mg/mL and CV% = 0.035 at 3.00 mg/mL), linearity (0–3.00 μg injected), limits of detection (0.09 ng injected) and quantitation (0.28 ng injected), and robustness. The DA related impurities were identified by using a GC/MS method with ion trap mass detection and also by comparison with synthesised standards. The most abundant impurities were crysolactone, allethrolone, chrysanthemic acid, and chloro‐derivatives of DA.
Approaches to identifying and quantifying polycyclic aromatic hydrocarbons of molecular weight 302 in diesel particulates
Authors: Sauvain Jean‐Jacques , Vu Duc Trinh 
Published: January 2004

AbstractAmong the PAH class of compounds, high molecular weight PAH are now considered as relevant cancer inducers, but not all of them have the same biological activity. However, their analysis is difficult, mainly due to the presence of numerous isomers and due to their low volatility. Retention indices (Ri) for 13 dibenzopyrenes and homologues were determined by high‐resolution capillary gas chromatography (GC) with four different stationary phases: a 5% phenyl‐substituted methylpolysiloxane column (DB‐5 ms), a 35% phenyl‐substituted methylpolysiloxane column (BPX‐35), a 50% phenyl‐substituted methylpolysiloxane column (BPX‐50), and a 35% trifluoropropylmethyl polysiloxane stationary phase (Rtx‐200). Correlations for retention on each phase were investigated by using 8 independent molecular descriptors. Ri has been shown to be linearly correlated to PAH volume, polarisability α, Hückel‐π energy on the four examined columns. Ionisation potential Ip is a fourth variable which improves the regression model for DB‐5ms, BPX‐35, and BPX‐50 column. Correlation coefficients ranging from r 2 = 0.935 to r 2 = 0.952 are then observed. Application of these indices to the identification and quantification of PAH with MW 302 in certified diesel particulate matter SRM 1650a is presented and discussed.
Retention behaviour of unsaturated fatty acid methyl esters on porous graphitic carbon
Authors: Gaudin Karen , Chaminade Pierre , Baillet Arlette 
Published: January 2004

AbstractThe eluotropic strength of binary mobile phases was calculated for three homologous series of cis, trans, and cis‐cis unsaturated fatty acid methyl esters (FAMEs). Binary mobile phases with chloroform, dichloromethane, or tetrahydrofuran as strong solvent and methanol or acetonitrile as weak solvent were tested. The volume fraction of strong solvent in the binary phases was between 0.3 and 0.8. Curves of eluotropic strength versus volume fraction of strong solvents showed similar trends to previously published results for saturated homologues. Correlation coefficients of the plots of eluotropic strength values for saturated versus unsaturated FAMEs were close to 1.0. Therefore these similarities validate the model of eluotropic strength previously established with saturated FAMEs as relevant for unsaturated FAMEs. The separation factors between cis and trans homologues always showed elution of the cis before the trans homologue. The difference in retention is due primarily to the geometry of the molecule. The retention is lowered more by the addition of a first carbon double bond than by the addition of a second one, independently of the mobile phase composition.
Improving resolution for channel‐format chip‐based electrophoresis with electrochemical array detection
Authors: Suljak Steven W. , Thompson Lynn A. , Ewing Andrew G. 
Published: January 2004

AbstractResolution in channel electrophoresis has been improved by means of the addition of a surfactant to the running buffer and minimization of the channel internal height and sampling capillary internal diameter. Micellar electrokinetic channel chromatography with electrochemical detection has been applied to the separation of several cationic catecholamines and has been used to continuously monitor a dynamic system of dopamine, norepinephrine, and epinephrine. Resolution was also enhanced by coupling small internal‐diameter (5 μm) sampling capillaries with sub‐micrometer internal‐height separation channels. The improvements in resolution offered by these methods will extend the applicability of channel electrophoresis with electrochemical detection to more complex samples while permitting sample volumes in the nL range to be probed.
Quantification and stability of Salbutamol in human urine
Authors: Forsdahl Guro , Gmeiner Günter 
Published: January 2004

AbstractA sensitive method for the quantification of free salbutamol in human urine is described. Sample clean up is performed using SPE on a mixed phase extraction column. Derivatisation is performed with N‐methyl‐N‐trimethylsilyltrifluoroacetamide (MSTFA) and the extract is analysed by GC‐MS. The method was found to be suitable for use in the doping field, where a cut‐off limit of 1 μg salbutamol/mL urine is set by the International Olympic Committee (IOC) and approved by the World Anti‐Doping Agency (WADA). Above that value a doping violation occurs. In addition, the stability of salbutamol in human urine has been evaluated.
Characterization of cigarette smoke condensates by comprehensive two‐dimensional gas chromatography/time‐of‐flight mass spectrometry (GC×GC/TOFMS) Part 2: Basic fraction
Authors: Lu Xin , Zhao Mingyue , Kong Hongwei , Cai Junlan , Wu Jianfang , Wu Ming , Hua Ruixiang , Liu Jianfu , Xu Guowang 
Published: January 2004

AbstractCigarette smoke condensate is a complex chemical matrix. Analysis of nitrogen‐containing compounds present therein is very difficult because of the limitation of the peak capacity of conventional one‐dimensional chromatography. Extensive and laborious sample preparation is frequently required or selective detectors are frequently used. In this study, the basic fraction of mainstream cigarette smoke condensate has been investigated by using comprehensive two‐dimensional gas chromatography/time‐of‐flight mass spectrometry (GC×GC/TOFMS). Auto data processing by TOFMS software combined with manual identification was used to assign the components. 377 nitrogen‐containing compounds, including 155 pyridine derivatives, 104 quinoline/isoquinoine derivatives, and 56 pyrazine derivatives were tentatively identified. By selecting appropriate unique masses and in the light of the component positions in the structured chromatogram, alkyl‐substituted pyridines, pyrazines, and quinolines/isoquinolines were separately shown and further validated. The peaks of eight individual positional isomers of two‐carbon‐substituted pyridines and thirteen positional isomers of methyl‐substituted quinolines/isoquinolines were further confirmed, based on linear incremental retention behavior in combination with TOFMS and the structured chromatogram of GC×GC.
Analysis of low molecular weight aldehydes in air samples by capillary electrophoresis after derivatization with 4‐hydrazinobenzoic acid
Authors: Pereira Elisabete A. , Rezende Maria Olímpia O. , Tavares Marina F.M. 
Published: January 2004

AbstractThis work reports the analysis of selected aldehydes in air samples using capillary electrophoresis (CE). The method is based on the reaction of aldehydes with 4‐hydrazinobenzoic acid (HBA) to give the corresponding hydrazones with maximum absorbance at 290 nm. Under optimized CE conditions, the HBA derivatives of four carbonyls (formaldehyde, acetaldehyde, propionaldehyde, and acrolein) were completely separated from one another, in less than 6 min, using a pH 9.3 tetraborate buffer at 0.040 mol L–1 concentration as background electrolyte. A few method validation parameters were determined revealing good migration time repeatability (< 1.5% CV) and area repeatability (< 2% CV), excellent linearity (50–300 μg/L, r > 0.996) and adequate sensitivity for environmental applications. The limits of detection with respect to each single aldehyde were in the range of 2.7–8.8 ng L–1. The methodology was applied to the determination of aldehydes indoors. Samples were collected in HBA impregnated octadecylsilica cartridges, at different times during the day. The most abundant carbonyls in the samples were acetaldehyde followed by formaldehyde, with estimated peak concentrations of 4.3 and 2.9 ppbv, respectively.
Going the distance: The challenges of leading a dispersed team
Authors: Kossler Michael E. , Prestridge Sonya 
Published: January 2004

AbstractGetting a group of people to work successfully as a team–communicating effectively, establishing trust,
sharing the load, and completing tasks on time–is difficult even when the team members are all in the same
location. When team members are spread out in various locations, it presents new obstacles for the team leader.
Here are some of the potential pitfalls that leaders of dispersed teams need to look out for and how they can
keep them from hindering team performance.
Influence of biofilms growth on corrosion potential of metals immersed in seawater
Authors: Wang W. , Li X. , Wang J. , Xu H. , Wu J. 
Published: January 2004

AbstractThe changes of corrosion potential (Ecorr) of metals immersed in seawater were investigated with electrochemical technology and epifluoresence microscopy. In natural seawater, changes of Ecorr were determined by the surface corrosion state of the metal. Ecorr of passive metals exposed to natural seawater shifted to noble direction for about 150 mV in one day and it didn't change in sterile seawater. The in‐situ observation showed that biofilms settled on the surfaces of passive metals when Ecorr moved in noble direction. The bacteria number increased on the metal surface according to exponential law and it was in the same way with the ennoblement of Ecorr. The attachment of bacteria during the initial period played an important role in the ennoblement of Ecorr and it is believed that the carbohydrate and protein in the biofilm are reasons for this phenomenon. The double layer capacitance (Cdl) of passive metals decreased with time when immersed in natural seawater, while remained almost unchanged in sterile seawater. The increased thickness and reduced dielectric constant of Cdl may be reasons.
Exfoliation corrosion of aluminum alloy AA7075 examined by electrochemical impedance spectroscopy
Authors: Cao F.‐H. , Zhang Z. , Li J.‐F. , Cheng Y.‐L. , Zhang J.‐Q. , Cao C.‐N. 
Published: January 2004

AbstractA typical aluminum alloy, AA7075, was immersed in the EXCO solution, and its corrosion properties during different immersion time were measured repetitively using electrochemical impedance spectroscopy technique (EIS). The EIS data a were simulated using equivalent circuit with ZView program. The results show that once the exfoliation occurs, the low frequency inductive loop in the Nyquist plot associated with the relaxation phenomenon of reaction intermediates disappears, and the Nyquist plane is mainly composed of two capacitive arcs in the high frequency range and low frequency range respectively. The former originates from the original corroded surface, while the latter from the newly formed interface by exfoliation corrosion (EXCO). With the increased immersion time, the high frequency capacitance arc decreases gradually, while the low frequency capacitance arc increases gradually. From the beginning of immersion up to 9 hours, charge transfer resistance gradually decreases, illustrating the acceleration of the corrosion rate, whereas the proton concentration decreases steeply, indicating the cathodic process is pre‐dominant. Then the corrosion rate decreases gradually corresponding to the exhausting of proton ions. The results also show that the exfoliation corrosion is developed from pitting corrosion through intergranular corrosion to general corrosion at the end.
Electrochemical response of Fe65.5Cr4Mo4Ga4P12 C5B5.5 bulk amorphous alloy in different aqueous media
Authors: Chattoraj I. , Baunack S. , Stoica M. , Gebert A. 
Published: January 2004

AbstractA bulk amorphous Fe65.5Cr4Mo4Ga4P12C5B5.5 alloy was investigated for its electrochemical behaviour in different electrolytes. The investigations showed substantial differences in response between the rapidly quenched and cast samples of the same composition. Annealing of the cast samples improved their corrosion resistance, which was possibly due to structural relaxation processes. The alloy was found to have very good resistance to neutral and slightly acidic chloride solutions in the rapidly quenched form. The passivation observed could not be attributed to any metal/metalloid oxide and was most probably due to an adsorbed oxygen layer. No chromium or molybdenum enrichment was observed at the surface. However, a sub‐surface phosphorus enrichment was observed in rapidly quenched samples, in the as‐received state as well as after electrochemical treatments, which may be responsible for their improved corrosion resistance.
Effects of anaerobe in sea bottom sediment on the corrosion of carbon steel
Authors: Huang Y. , Duan J. , Ma S. 
Published: January 2004

AbstractThe in‐situ study of steel corrosion in sea bottom sediment (SBS) was carried out by Transplanting Burying Plate method (TBP method). It was found that the corrosion rate of steel in the sea bottom sediment with sulfate reducing bacteria (SRB) could be as high as ten times of that in sea bottom sediment without SRB. The experiments in simulated sea bottom sediments with different SRB contents by artificial culturing showed that the electrochemical behavior of steel in the sea bottom sediment with SRB was different from that without SRB. SRB altered the polarization behavior of steel significantly. The environment was acidified due to the activity of SRB and the corrosion of steel was accelerated. The corrosion of carbon steel in sea bottom sediment is anaerobic corrosion, and the main factor is anaerobe. There are SRB commonly in SBS, and the amount of SRB decreases along with the depth of sediment. Because of the asymmetry and variation of sea bottom sediment, the most dangerous corrosion breakage of steel in SBS is local corrosion caused by SRB. So the main countermeasure of corrosion protection of sea bottom steel facilities should be controlling of the corrosion caused by anaerobe.
An investigation of the effect of thermal cycling on plasma‐sprayed zirconia/NiCoCrAlY thermal barrier coating
Authors: El‐Turki A. , Allen G. C. , Younes C. M. , Day J. C. C. 
Published: January 2004

AbstractThe microstructural change, crack initiation and spallation of a vacuum plasma sprayed (VPS) thermal barrier coating on an INCONEL‐738 superalloy substrate were investigated after successive 300 h thermal cycles at 1050°C. The coating was characterised using Raman spectroscopy, scanning electron microscopy (SEM) energy dispersive X‐ray analysis (EDX) and Auger electron spectroscopy (AES). Localised micro‐cracks at the yttrium (III) oxide stabilised zirconium (IV) oxide (YSZ) ceramic coating/thermally grown oxide (TGO) interface were observed after 8 cycles. Spallation of the YSZ coating occurred after approximately 21 cycles. Significant amounts of the elements titanium, tantalum and chromium were found within the TGO together with the formation of nickel, cobalt and chromium‐rich oxides at this TGO/YSZ interface.
Reduction of nitrite in aged heat transfer media at elevated temperatures
Authors: Madera M. , Fischer M. , Höflinger W. , Kadnar R. , Österreicher E. 
Published: January 2004

AbstractNitrite is part of many commercially available inhibitor formulations used for corrosion protection in water or water/glycol based heat transfer media in contact with carbon steel. In a heat transfer system of the OMV‐AG used to heat crude oil to lower its viscosity, the nitrite concentration was found to decrease in about three months from 300 ppm to 10 ppm. The system is operated at a maximum temperature of 110°C and 6 bar and an ethylene glycol/water mixture is used as the heat transfer media. An oxidation to nitrate was assumed, but the nitrate concentration was found to be constant. An analysis of the vapor phase present in the system showed next to significant amounts of hydrogen dinitrogen oxide. A possible microbiological infection of the system was investigated, but no bacteria were found. To find the reason for the reduction of nitrite, a laboratory investigation was performed. Stability of nitrite at elevated temperatures and pressure was tested in water and water/glycol mixtures. It was found that nitrite is instable in glycol solutions at temperatures above 120°C. The degradation reaction in aged and unused MEG/water mixtures was compared. An accelerated reduction reaction was found in aged heat transfer media.
Collapsing functions
Authors: Schimmerling Ernest , Velickovic Boban 
Published: January 2004

AbstractWe define what it means for a function on ω1 to be a collapsing function for λ and show that if there exists a collapsing function for (2)+, then there is no precipitous ideal on ω1. We show that a collapsing function for ω2 can be added by forcing. We define what it means to be a weakly ω1‐Erdös cardinal and show that in L[E], there is a collapsing function for λ iff λ is less than the least weakly ω1‐Erdös cardinal. As a corollary to our results and a theorem of Neeman, the existence of a Woodin limit of Woodin cardinals does not imply the existence of precipitous ideals on ω1. We also show that the following statements hold in L[E]. The least cardinal λ with the Chang property (λ, ω1) ↠ (ω1, ω) is equal to the least ω1‐Erdös cardinal. In particular, if j is a generic elementary embedding that arises from non‐stationary tower forcing up to a Woodin cardinal, then the minimum possible value of j(ω1) is the least ω1‐Erdös cardinal. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
CharacterizingNCwith tier 0 pointers
Authors: Oitavem Isabel 
Published: January 2004

AbstractA two‐sorted term system characterizingNCimplicitly is described. The term system is defined over the tree algebra 𝕋, the free algebra generated by0,1and ∗︁, and the recursion scheme uses pointers over tier 0. This differs from previous characterizations ofNC, where tier 1 pointers were used or full parameter substitution over tier 0 was allowed. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
F‐products and nonstandard hulls for semigroups
Authors: Kellner Jakob , Ploss Hans 
Published: January 2004

AbstractDerndinger [2] and Krupa [5] defined the F‐product of a (strongly continuous one‐parameter) semigroup (of linear operators) and presented some applications (e. g. to spectral theory of positive operators, cf. [3]). Wolff (in [7] and [8]) investigated some kind of nonstandard analogon and applied it to spectral theory of group representations. The question arises in which way these constructions are related. In this paper we show that the classical and the nonstandard F‐product are isomorphic (Theorem 2.6). We also prove a little “classical” corollary (2.7.). (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A short proof of the preservation of the ωω‐bounding property
Authors: Schlindwein Chaz 
Published: January 2004

AbstractThere are two versions of the Proper Iteration Lemma. The stronger (but less well‐known) version can be used to give simpler proofs of iteration theorems (e.g., [7, Lemma 24] versus [9, Theorem IX.4.7]). In this paper we give another demonstration of the fecundity of the stronger version by giving a short proof of Shelah's theorem on the preservation of the ωω‐bounding property. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The strong partition relation on ω1 revisited
Authors: Jackson Steve , May Russell 
Published: January 2004

AbstractWe give a new proof of the strong partition relation on ω1, assuming the axiom of determinacy, which uses only a general argument not involving the complete analysis of a measure on ω1. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)