bluuebunny/crossref_metadata_2025 huggingface dataset:
Local round robin test for determination of aromatics in diesel fuels by HPLC
Authors: Šegudović Nikola , Tomić Tatjana , Škrobonja Liviana , Kontić Ljubica
Published: January 2004

Determination of aromatics in diesel fuels by HPLC is covered by European Standard EN 12916 (April 2000). The Standard is based on former standards IP 391/90 and IP 391/95. The method used for measurements is NP HPLC and separation is performed on silica or modified silica columns with RI detection. The precision of the method was checked by determining the repeatability and reproducibility. The content of aromatics was measured in a number of commercial samples. The measurements have been performed in three different laboratories and under different working and instrumental conditions. Satisfactory agreement was established for repeatability and was slightly poorer for reproducibility. The content of polyaromatics is within the tolerance range (IP 590/99) and the content of tricyclic and higher aromatics (tri+) is close to the limit of quantitition in some samples. Clear differences in the content of polycyclic aromatics in domestic diesel and eurodiesel fuels were observed. The results have confirmed the ruggedness and robustness of the measuring method.
Pressurized hot water extraction of insecticides from process dust – Comparison with supercritical fluid extraction
Authors: Eskilsson Cecilia Sparr , Hartonen Kari , Mathiasson Lennart , Riekkola Marja‐Liisa
Published: January 2004

Pressurized hot liquid water and steam were used to investigate the possibilities of extracting insecticides (carbofuran, carbosulfan, and imidacloprid) from contaminated process dust remaining from seed‐pellet production. Extraction temperature was the most important parameter in influencing the extraction efficiency and rate of extraction, while varying the pressure had no profound effect. A clean‐up procedure of the water extracts using solid phase extraction (SPE) was found to be necessary prior to final analysis by high‐performance liquid chromatography (HPLC). Quantitative extraction (compared to a validated organic solvent extraction method) of imidacloprid was obtained at temperatures of 100–150°C within 30 min extraction time. Temperatures above 150°C were required to extract carbofuran efficiently. The most non‐polar analyte of the investigated compounds, carbosulfan, gave no detectable concentrations with pressurized hot water extraction (PHWE). One reason might be its low solubility in water, and when attempts are made to increase its solubility by increasing the temperature it may degrade to carbofuran. This can explain recovery values above 100% for carbofuran at higher temperatures. A comparison of the PHWE results and those obtained with supercritical fluid extraction (SFE) revealed that PHWE is advantageous for polar compounds, where the solubility of the analyte in water is high enough that lower temperatures can be used. For non‐polar compounds carbon dioxide based extraction is preferred unless the target analyte is highly thermostable.
Development of a solid phase extraction method for simultaneous determination of corticoids and tranquilizers in serum samples
Authors: Quintana M. Carmen , Ramos Lourdes , González M. Jose , Blanco Manuel H. , Hernández Lucas
Published: January 2004

A simple and fast solid phase extraction (SPE) method allowing the preconcentration, clean‐up, and subsequent separate elution of phenothiazines (chlorpromazine hydrochloride, acetopromazine, and propionylpromazine hydrochloride) and glucocorticoids (dexamethasone, betamethasone acetate, and phenylbutazone) from serum samples has been developed. Both fractions were separately collected and analyzed without any additional treatment by high performance liquid chromatography with UV‐Vis. The performance of the complete procedure was satisfactory irrespective of the spiking level with recoveries in the range 64–85% for all analytes investigated but for phenylbutazone (20%). Repeatability, evaluated as the relative standard deviation, was globally better than 12%. LC‐MS was used for final confirmation of the results.
Using analytical multidimensional isocratic HPLC methods of separation to isolate active constituents in natural products
Authors: Wong Victor , Sweeney Alan P. , Shalliker R. Andrew
Published: January 2004

Multidimensional reversed‐phase HPLC was employed to isolate the active constituents from a crude extract of Clerodendrum floribundum R. Br. These active constituents were known to have bioactivity against the enzyme xanthine oxidase and potentially could be employed in the treatment of gout. Using a multidimensional separation approach, rapid isolation of the active constituents was achieved from a complex sample matrix. As each separation dimension was isocratic, no equilibration time was required and consequently the technique shows promise in the scale up to preparative levels where high throughput is important.
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

With 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

Fused‐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

A 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

A 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

Among 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

The 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

Resolution 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

A 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

Cigarette 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

This 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

Getting 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.
Answering the call: Job assignments that grow leaders
Authors: Ohlott Patricia J.
Published: January 2004

Challenging job assignments are perhaps the most potent form of leader development. But what makes a job
assignment challenging, and what specific types of assignments fit the bill? Here's a look at the five
main sources of challenge in job assignments that help people become better leaders.
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

The 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

A 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

A 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

The 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

The 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

Nitrite 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

We 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

A 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

Derndinger [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

There 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

We 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)
Level by level equivalence and strong compactness
Authors: Apter Arthur W.
Published: January 2004

We force and construct models in which there are non‐supercompact strongly compact cardinals which aren't measurable limits of strongly compact cardinals and in which level by level equivalence between strong compactness and supercompactness holds non‐trivially except at strongly compact cardinals. In these models, every measurable cardinal κ which isn't either strongly compact or a witness to a certain phenomenon first discovered by Menas is such that for every regular cardinal λ > κ, κ is λ strongly compact iff κ is λ supercompact. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the linear Lindenbaum algebra of Basic Propositional Logic
Authors: Alizadeh Majid , Ardeshir Mohammad
Published: January 2004

We study the linear Lindenbaum algebra of Basic Propositional Calculus, called linear basic algebra. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Automorphism group actions on trees
Authors: Ivanov Alexandre , Kossak Roman
Published: January 2004

We study the situation when the automorphism group of a recursively saturated structure acts on an ℝ‐tree. The cases of (ℚ, <) and models of Peano Arithmetic are central in the paper. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Finitely generated submodels of an uncountably categorical homogeneous structure
Authors: Hyttinen Tapani
Published: January 2004

We generalize the result of non‐finite axiomatizability of totally categorical first‐order theories from elementary model theory to homogeneous model theory. In particular, we lift the theory of envelopes to homogeneous model theory and develope theory of imaginaries in the case of ω‐stable homogeneous classes of finite U‐rank. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transport and recombination dynamics studies of polymer/fullerene based solar cells
Authors: Choulis S.A. , Nelson J. , Tuladhar S.M. , Cook S. , Kim Y. , Durrant J.R. , Bradley D.D.C.
Published: January 2004

We have studied the electron/hole transport and recombination dynamics in blends of poly[2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐1,4‐phenylene vinylene], (MDMO‐PPV) and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) at room temperature, as a function of laser excitation density and PCBM concentration. The experimental results of these studies indicate the important role played by hole‐trap states in MDMO‐PPV. Electron and hole transport are not balanced within the blend. PCBM is a less disordered material than MDMO‐PPV and electron transport dominates the response of the solar cell device.
Voltage‐induced infrared spectra from polymer field‐effect transistors
Authors: Furukawa Yukio , Yamamoto Jun , Cho Don‐Chan , Mori Tatsuo
Published: January 2004

Charge‐induced infrared absorption spectra from the metal‐insulator‐semiconductor diodes fabricated with aluminum oxide, poly(p‐xylylene), and SiO2 as gate dielectric and regioregular poly(3‐octylthiophene) as organic semiconductor have been measured in situ with reflection or transmission configurations by the FT‐IR difference‐spectrum method. The observed bands have been attributed to the carriers injected into the polymer layers under the application of minus gate bias. The wavenumber of the band around 1300 cm−1 depends on the gate voltage, indicating that the structure of the carriers depends on the carrier concentration. There exist upper limits in the concentrations of the injected carriers. In situ infrared absorption measurements provide the information about the injected carriers, which affect the properties and the functions of polymer field‐effect devices.
Synthesis and characterization of conjugated polymers and their blends for optoelectronic applications
Authors: Economopoulos S.P. , Govaris G.K. , Chochos C.L. , Tzanetos N.P. , Andreopoulou A.K. , Kallitsis J.K. , Yianoulis P. , Gregoriou V.G.
Published: January 2004

Various polymeric blends of hole transporting materials, (such as MEH‐PPV and P3HT) and electron transporting materials (such as poly(phenyl‐vinyl‐quinoline) and poly[2‐(4‐methacryloxyphenyl)‐5‐phenyl)‐1,3,4‐oxadiazole]) have been prepared and investigated. Moreover a soluble, main chain oxadiazole bearing polyether has been synthesized, aiming towards an efficient electron transporting polymeric material which was also used for blend preparation together with P3HT. A deeper investigation into their spectroscopic characteristics using, primarily, FT‐IR spectroscopy, but also UV‐Vis spectroscopy has been conducted. The surface morphology of these blends was investigated using Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) in an attempt to gather information for their solid state properties and morphologies. Finally, DSC measurements provided additional insight into the thermal behaviour of these materials.
Infrared spectroscopy studies of structure and orientation in clay‐reinforced polyamide‐6 nanocomposites
Authors: Cole Kenneth C. , Denault Johanne , Bureau Martin N.
Published: January 2004

Infrared (IR) spectroscopy was used to study the surface (by means of external reflection) and the bulk (by means of transmission measurements on microtomed slices) of specimens obtained by injection moulding of a commercial polyamide‐6 clay‐based nanocomposite material (NCH = nylon clay hybrid) at different mould temperatures and with different part geometries. Comparisons were made with equivalent non‐reinforced polymer (PA‐6). For the PA‐6, the mould temperature influences the crystalline structure, with the γ phase predominating at 50°C and the α phase at 80°C. However, in the NCH material the ( phase is favoured, even at 80°C. In all cases the crystallinity increases on going from the surface to the core. The polymer chains are oriented in the flow direction, and the orientation is higher for parts with more elongated shapes. It does not vary greatly across the part thickness, except for a thin surface layer, where it is significantly higher. Both at the surface and in the bulk, the crystalline phase orientation is higher for the NCH than for the PA‐6.
Application of vibrational spectroscopy for the analysis of polymer composites
Authors: Bokobza Liliane
Published: January 2004

Various examples of filled elastomeric networks will illustrate the potential of Fourier‐transform infrared spectroscopy for a better understanding of the properties of elastomeric composite materials which are two‐phase materials. The addition of an inorganic component to polymers leads to improvements in various physical and mechanical properties. These improvements are the result of a complex interplay between the properties of the individual constituent phases : the polymer, the filler and the interfacial region. Infrared spectroscopy has been used to characterize the interface in the isotropic state and also under uniaxial extension.
Polarized FT‐IR photoacoustic spectroscopy on polymer fibers
Authors: Eichhorn Klaus‐Jochen , Adam Gudrun
Published: January 2004

The orientation of macromolecular chains in two melt‐spun polymer fibers (segmented polyurethane elastomer and melt‐modified polyolefine fibers) was studied by photoacoustic spectroscopy (PAS) with polarized light in the mid‐infrared range. The PAS orientation functions calculated from the photoacoustic signal intensities of orientation sensitive bands describe the orientation of the different chain segments with respect to the fiber axis. Thus, the orientation of hard and soft segments in the unstressed polyurethane fiber is different and both are similiar to that of the corresponding injection molded bars. With increased spinning velocity an improved orientation of the polyolefine chains along the fiber axis, but only in the amorphous regions of the polymer, were detected.

Only a slight reduction of orientation was measured as a result of the subsequent chemical crosslinking in the polyolefines.
Diblock copolymer adsorption from the aqueous micellar phase to solid surfaces: real time monitoring by ATR spectroscopy in the mid‐infrared
Authors: Keskini I. , Gionis V. , Chryssikos G.D. , Hiotelis I. , Toprakcioglu C. , Stavrouli N. , Tsitsilianis C.
Published: January 2004

Attenuated Total Reflectance (ATR) in the mid‐infrared is employed to monitor the adsorption of poly(tert‐butyl styrene ‐ b ‐ styrene sulfonate), PtBS‐PSS, copolymers with a small hydrophobic head as well as of an analogous poly(styrene sulfonate), PSS, homopolymer on germanium and Au‐plated germanium surfaces from aqueous NaCl solutions. The surface density of the adsorbed polyelectrolyte is monitored via the growth of characteristic infrared absorptions of the sulfonated ring at 1036‐ and 1008 cm−1 in the 2nd derivative mode. These probe bands do not exhibit shifts or changes in bandshape over very prolongued adsorption experiments. Pronounced differences in the kinetics of adsorption are observed between the PSS homopolymer and the PtBS‐PSS copolymers in agreement to previous investigations by phase‐modulated ellipsometry on similar systems. Adsorption of the diblocks above the critical micelle concentration is found to involve a sequence of diffusion, micellar relaxation and brush‐limited processes.
NMR study of water bound to soft segments in thermoplastic elastomers
Authors: Horstmann Martin , Urbani Marcus , Veeman Wiebren S.
Published: January 2004

The interaction between water absorbed in four hard‐soft segment block‐copolymers and the polymer chains is investigated by pulsed field gradient echo NMR spectroscopy and Nuclear Overhauser NMR spectroscopy. The results show, depending on the structure and mass fraction of the soft segments, a strong interaction between water and the soft segments. Most likely this is due to a hydrogen bond between water and the ether groups. The self‐diffusion of water has been determined and is described as a jumping process between the ether sites with a residence time t and a time between sites t. It is found that the residence time is of the order of a few ns and also that the ratio t/τ decreases with increasing soft segment rigidity.
Role of hydration in the phase transition of polypeptides investigated by NMR and Raman spectroscopy
Authors: Dybal Jiří , Schmidt Pavel , Kříž Jaroslav , Kurková Dana , Rodríguez‐Cabello José Carlos , Alonso Matilde
Published: January 2004

NMR, Raman spectroscopy and ab initio quantum‐chemical calculations have been employed to investigate the role of the hydration water in the inverse temperature transition of elastin‐derived biopolymers represented by poly(Gly‐Val‐Gly‐Val‐Pro) and poly(Ala‐Val‐Gly‐Val‐Pro). Temperature and concentration dependences of the Raman spectra measured for water solutions of polymers and of a low‐molecular‐weight model have been correlated with the vibrational frequencies calculated at the DFT (B3LYP) and MP2 levels for the peptide segment surrounded by a growing number of water molecules. The results indicate strong hydration before the transition that, in addition to water hydrogen‐bonded to amide groups, includes hydrophobic hydration of non‐polar groups by a dynamic cluster of several water molecules. According to 1H longitudinal and transverse relaxation of HOD signals in D2O solutions, the number of water molecules motionally correlated with the polymer is about 4 per one amino acid residue.
On‐line monitoring of the acrylate conversion in UV photopolymerization by near‐infrared reflection spectroscopy
Authors: Scherzer Tom , Mehnert Reiner , Lucht Hartmut
Published: January 2004

Near‐infrared (NIR) reflection spectroscopy was used to determine the conversion in acrylate coatings after UV photopolymerization in order to test it as a method for process control in UV curing. A probe head was developed which is adapted to the specific requirements of UV curing and which is linked to a photodiode array spectrometer by an optical fiber. Reflection spectra from thin acrylate layers which were taken in intervals down to the millisecond range have shown an excellent signal‐to noise ratio. Quantitative conversion data show good correlation with results from independent reference methods (FTIR, HPLC). Following thesebasic investigations, it was demonstrated that NIR reflection spectroscopy can be used for on‐line monitoring of the acrylate conversion in thin coatings. Some examples of such investigations in pilot scale are presented.
Spectroscopic imaging techniques for characterization of polymer morphologies: a combination of infrared and electron microscopy
Authors: Gupper Andreas , Wilhelm Peter , Kothleitner G. , Eichhorn K.‐J. , Pompe G.
Published: January 2004

The morphological characterization of polymer blends consisting of polyamide and poly(tetrafluoroethylene) using FT‐IR spectroscopy and electron microscopy is described. To enhance the lateral resolution ‐ one of the main limits in infrared spectroscopy ‐ a combination with scanning electron microscopy and analytical electron microscopic methods of a transmission electron microscope was made. The possibilities of electron energy loss spectroscopy and energy filtered transmission electron microscopy (EFTEM) in the area of polymer characterization are outlined.
PM‐IRRAS spectroscopy for the characterization of polymer nanofilms: chains conformation, anisotropy and crystallinity
Authors: Elzein T. , Bistac S. , Brogly M. , Schultz J.
Published: January 2004

This paper is focused on the use of the Polarization‐Modulation Infrared Reflection‐Absorption Spectroscopy (PM‐IRRAS) for studying thin polymer films at interfaces. When forming a polymer film on a metallic substrate, for instance by spin‐coating, the characterization of the polymeric layer becomes very difficult given the small amount of matter deposited and also because of the contact with the metal. Among the techniques well adapted to surface and interface analyses, the PM‐IRRAS spectroscopy represents an excellent tool to probe ultra‐thin films.

Different systems have been selected in this study such as polyamides (PA) and ethylene‐co‐vinyl acetate (EVA) nanofilms spin‐coated onto chemically controlled surfaces (i.e. thiol self‐assembled monloayers grafted onto gold coated glass slides). PM‐IRRAS spectroscopy allowed us to characterize the polymer anisotropy (chains orientation and conformation), to suggest a model for chain organization at the polymer/substrate interface, and to calculate the orientation angles. Moreover, we were able to determine, by using PM‐IRRAS, the degree of crystallinity of PA and EVA films of nanometric dimensions without any calibration procedure needed by other techniques.
On the use of vibrational spectroscopy to characterize the structure and aroma barrier of food packaging polymers
Authors: Lagarón J.M. , Cava D. , Giménez E. , Hernandez‐Muñoz P. , Catala R. , Gavara R.
Published: January 2004

High barrier polymers are of increasing interest and use in nowadays food packaging applications. The reason for that is packaging being more often regarded as a very efficient and convenient means of preserving foodstuffs from deterioration during products handling, transport and shelf‐life. This study reports on some novel morphological characterization aspects by means of vibrational spectroscopy of one of the most widely used families of high gas and aroma barrier materials in commercial food packaging, i.e. the ethylene‐vinyl alcohol copolymers (EVOH). Nevertheless, and as a result of the highly hydrophobic character of the EVOH resins, it is usually low density polyethylene (LDPE) the high water barrier material that is put in direct contact with foods. A description of a simple methodology, yet effective, based on FT‐IR to determine diffusion coefficients of aroma components in LDPE is also presented.
Nanomechanical and optical studies on polymeric membranes
Authors: Charitidis C. , Gioti M. , Logothetidis S.
Published: January 2004

The nanomechanical properties of poly(ethylene terephthalate) (PET) membranes, were examined in light of nanoindentation experiments under conditions of maximum contact load in the range of 0.5‐12 m?. Spectroscopic Ellipsometry (SE) from 1.5 to 6.5 ev (Vis‐FUV range) was also applied to probe the dielectric function (ϵ(ω) of the industrially supplied membranes, as well as their geometrical structure. Mechanical stretching (uniaxial or biaxial) procedures are usually applied for the elongation of the polymeric membranes, their thickness reduction and enhancement of their mechanical and optical performance, causing a preferable orientation of the macromolecules close to the surface. Nanoindentation and se testing have revealed the existence of a two‐layer geometrical structure of the pet membranes, consisting of a thick amorphous pet layer and a thin crystalline‐like pet overlayer, with increased hardness (elastic modulus). The analyses of the experimental dataprovides quantitative information on the formed overlayer, which is ascribed to the processing history of the membrane.
Characterization of the epoxy‐metal interphase: FTIR‐ERAS and spectra calculation for ultra‐thin films
Authors: Wehlack Carsten , Possart Wulff
Published: January 2004

The interphase between polymers and metal substrates can be elucidated by studying ultra‐thin films. In this paper, spin coating films (20 nm ‐ 2 μm) are prepared from a two‐part epoxy adhesive on Au, Al and Cu. After room temperature cure, the chemical structure of the epoxy films is studied by FTIR external reflection absorption spectroscopy (FTIR‐ERAS) and the results are compared with the state in the polymer bulk as measured by attenuated total reflection (FTIR‐ATR). Inevitably, this evaluation of the thin film spectra has to account for the optical situation which is significantly different from bulk measurements. Spectra calculation provides the essential tool for a reasonable comparison between bulk and thin film spectra, thus allowing for a detailed quantitative analysis. Thickness and substrate effects on the interphase can then be separated from the optical situation of the measurement.

The results reveal very specific features caused by adhesive interactions and different cure behaviour in the interphase on different metal surfaces.
Dielectric properties and molecular mobility of organic/inorganic polymer composites
Authors: Zois Haralampos , Kanapitsas Athanasios , Pissis Polycarpos , Apekis Lazaros , Lebedev Eugene , Mamunya Yevgen P.
Published: January 2004

Microstructure‐dielectric properties relationship and molecular mobility of organic/inorganic polymer composites (OIPCs), consisting of polyurethane (PU) and sodium silicate (NaSi), were investigated in this work. Broadband dielectric relaxation spectroscopy (DRS) and thermally stimulated depolarization current (TSDC) techniques were employed. Our interest was focused on the study of the glass transition mechanism and conductivity relaxation. The influence of the molecular weight of PU and inorganic phase content on the dielectric properties of the composites was of particular interest. Glass transition temperature shifts to higher temperatures with the addition of NaSi. The overall molecular mobility was found to increase in the composites, compared to the pure PU matrix. The results are more intense for the composites based on the PU with low molecular weight.