bluuebunny/crossref_metadata_2025 huggingface dataset:
Mass spectra ofSceletiumalkaloids
Authors: Martin Ned H. , Rosenthal David , Jeffs P. W.
Published: May 2005

The mass spectra of several naturally occuringSceletiumalkaloids, as well as several synthetic variants, have been investigated. Techniques used include high resolution mass measurements, analysis of metastable transitions by the technique of ion defocusing and specific deuterium labeling in conjunction with low resolution mass spectrometry. Characteristic major fragmentation pathways have been determined for four basic structure types studied: thecis‐3a‐aryl‐octahydroindole ring system, exemplified by mesembrine; its 2,3‐pyrido analog,SceletiumA4; thesecoseries of pyridine bases, represented by tortuosamine; and thesecoanalog of the mesembrine‐type represented by tortuosamine; and thesecoanalog of the mesembrine‐type represented by dehydrojoubertiamine.
Mass spectra of acyl and α‐hydroxyalkyl derivatives of biferrocene
Authors: Hisatome Masao , Ichida Shigeto , Yamakawa Koji
Published: May 2005

The mass spectral fragmentation pathways of acyl and α‐hydroxyalkyl derivatives of biferrocene and related compounds are presented. A substituent effect for the cleavage of the cyclopentadienyl ring‐metal bonds has been found in the spectra of acyl derivatives. It has been shown that the fragmentation of α‐hydroxyalkyl derivatives proceeded via the ions corresponding to the [M]+⋅ ions of oxidation or hydrogenolysis products of the hydroxyl derivatives.
Metastable ion studies. IX—Thermochemistry and ion structures among fragmentating ions, an electron impact and field ionization investigation
Authors: Holmes John L. , Weese Gwynneth M. , Blair Alan S. , Terlouw John K.
Published: May 2005

Metastable peak shapes, dimensions and relative abundances have been measured for the fragmentations ions were generated from but 1‐ene, cis‐and trans‐ but‐2‐ene, 2‐methylpropene, methylcyclopropane and cyclobutane. Forward and reverse activation energies for the above reactions have been estimated and daughter ion structures proposed. The pathway for the consecutive reaction which generates the metastable peak (m/e 56 → m/e 53) is proposed to be
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Observations on metastable peaks for fourteen assorted daughter ion fragmentations are also presented and the thermochemistry and daughter ion structures for some of the reactions are discussed. Metastable peaks for the fragmentation of ions generated by field ionization are also described.
A method for estimation of the heats of formation of some gaseous cations
Authors: Bowen Richard D. , Williams Dudley H.
Published: May 2005

A method for estimating the heats of formation of gaseous, open chain cations via a suitable isodesmic substitution is reported.
Notiz zur protonenkatalysierten Gasphasencyclisierung von N‐Benzoyl‐α‐aminosäremethylestern
Authors: Höfle Gerhard , Höhne Gerhard , Respondek Johannes , Schwarz Helmut
Published: May 2005

Art und Anzahl der Alkylsubstituenten am α‐C‐Atom der Titelverbindungen beeinflußen in entscheidender Weise die durch chemische Ionisation induzierte Methanol‐Eliminierung aus den [M + H]+‐Ionen. Die Cyclisierungstendenz entspricht sehr stark der von aktivierten Estern in kondensierter Phase.
The mass spectrum of 2,4‐dihydroxybenzophenone oxime
Authors: Kallury R. Krishna Mohan Rao , Rao E. V. Suguna Bhushana
Published: May 2005

2,4‐Dihydroxybenzophenone Oxime is found to undergo loss of OH·, H2O, NHOH·; and PhCNO when subjected to electron impact, revealing novel hydrogen and skeletal migrations. The fragmentation mechanisms are found to differ considerably from those of benzophenone oxime and we confirmed these cleavages by exact mass measurements and deuterium labelling.
Mass spectra of heterocyclic compounds. IV–2,4,5‐Trioxoimidazolidines
Authors: Corral Renée A. , Orazi Orfeo O. , Zinczuk Juan
Published: May 2005

General fragmentations induced by electron impact of twenty‐one examples of 2,4,5‐trioxoimidazolidines are rationalized with the aid of metastable transitions, high resolution measurements and deuterium and 18O labelling. The results can be used for the recognition of different types of derivatives.
Analogies Photochimiques. III—Diméthyl‐4,4 allyl‐2 Cyclohexanone. Elimination Inattendue de C2H4O et Perte de 15 Unités de Masse
Authors: Morizur Jean‐Pierre , Mercier Jacquelline , Niazi Riad
Published: May 2005

Le spectre de masse de la diméthyl‐4,4 allyl‐2 cyclohexanone, présente un ion m/z 122 correspondant à l'élimination D'une molécule D'acétaldéhyde à partir de l'ion moléculaire. Le marquage isotopique montre que quatre atomes D'hydrogène sont tranférés lors de cette élimination. L'ion moléculaire de la diméthyl‐4,4 allyl‐2 cyclohexanone perd également 15 unités de masse à partir du substituant allyle. Les mécanismes sont discutés en analogie avec le comportment photochimique.
Mass spectral identification of isomeric fluoronitroanilines
Authors: Fu Emil W. , Rosenberg Ira E.
Published: May 2005

The electron impact and methane chemical ionization mass spectra of 2‐fluoro‐5‐nitroaniline and 4‐fluoro‐3‐nitroaniline have been investigated. Similar fragment ions were observed for both compounds under electron impact conditions, but the difference in the relative ion intensities of two key fragment ions allowed the positive identification of these two isomers. The difference can be attributed to an ortho effect involving fluorine and the amino substituent. A fragmentation pathway consistent with this observation is suggested.
Electron impact fragmentations of 1‐ and 3‐aryl‐3‐buten‐1‐ols
Authors: Smith Grant Gill , Voorhees Kent J.
Published: May 2005

The electron impact fragmentation of 1‐ and 3‐aryl‐3‐buten‐1‐ols show several distinguishing fragmentations. α‐Cleavage predominates in the fragmentation of the 1‐aryl‐3‐buten‐1‐ols to such an extent that molecular ions of only low intensity are observed. The ion resulting from α‐cleavage fragments readily with the loss of the ring substituent to the phenyl ion. An intense molecular ion is observed in the 3‐aryl series and a loss of 70 u is a major fragmentation in this series. Based on deuterium labeling studies, this unique fragmentation was explained by a hydroxylic hydrogen migration to the ring accompanied by the loss of allene and formaldehyde. Other major fragmentations observed in the 3‐aryl series are: a McLafferty‐type rearrangement (loss of formaldehyde), loss of 33 u (water + methyl radical), and the loss of 43 u (C2H3O and C3H7). The proposed mechanisms have been substantiated by deuterium labeling and high resolution mass spectrometry. Substituent effects play a major role in the 3‐aryl series, but are insignificant in the 1‐aryl series.
Mass spectroscopy of natural products. IX—comparative positive–negative ion mass spectroscopic investigation of plumieride
Authors: Voigt D. , Adam G. , Schade W.
Published: May 2005

The positive and negative ion mass spectra of plumieride and its pentaacetyl derivative are reported and compared. Using high resolution measurements and low voltage ionization techniques the main fragmentation processes are discussed.
Atmospheric pressure ionization mass spectrometry
Authors: Proctor Christopher J. , Todd John F. J.
Published: May 2005

Atmospheric pressure ionization has been used to great effect by mass spectrometrists in widely diverse fields. The aim of this brief review is to set down the advantages of API/MS to fundamental and analytical chemists alike through discussion of the basic processes of ionisation and through its application.
Structure and fragmentation of [C3H7O]+ ions formed by chemical ionization
Authors: Harrison Alex. G. , Gäumann Tino , Stahl Daniel
Published: May 2005

The unimolecular metastable and collision‐induced fragmentation reactions of [C3H7O]+ ions produced by gas‐phase protonation of acetone, propanal, propylene oxide, oxetan and allyl alcohol have been studied. The CID studies show that protonation of acetone and allyl alcohol yield different stable ions with distinct structures while protonation of propanal or propylene oxide yield [C3H7O]+ ions of the same structure. Protonated oxetan rearranges less readily to give the same structure(s) as protonated propanal and propylene oxide. The [C3H7O]+ ions fragmenting as metastable ions after formation by CI have a higher internal energy than the same ions fragmenting after formation by EI. Deuteronation of the C3H6O isomers using CD4 reagent gas shows that loss of C2H3D proceeds by a different mechanism than loss of C2H4. The results are discussed in terms of potential energy profile for the [C3H7O]+˙ system proposed earlier.
Metastable and collision induced fragmentation of some small cluster ions: Ar2+ Ar3+, ArN2+ and N4+
Authors: Illies Andreas J. , Bowers Michael T.
Published: May 2005

The results of a study on collision induced dissociation and a search for metastable reactions of four gas phase ion‐molecule clusters, Ar2+, Ar3+, ArN2+ and N4+, are presented. The ionic clusters were formed in a high pressure mass spectrometer ion source which was cooled to enhance the association products. Subsequent fragmentations were studied using mass analyzed ion kinetic energy spectrometry. Decomposition pathways consistent with experimental collision induced dissociation peak shapes and ab initio potential diagrams are presented for the fragmentation of Ar2+ and N4+. Mechanisms for the collision induced dissociation of Ar3+ and ArN2+ are suggested. No metastable reactions for any of the cluster ions were observed. This result is in conflict with the results of Märk et al. using electron impact ionization of neutral van der Waals' clusters formed in a supersonic nozzle beam.
Scanning a triple quadrupole mass spectrometer for doubly charged ions
Authors: Kenttämaa H. I. , Wood K. V. , Busch K. L. , Cooks R. G.
Published: May 2005

Charge exchange reactions within a triple quadrupole mass spectrometer characterize doubly charged ions formed in the ion source. Two methods have been developed for identifying the singly charged ions formed from doubly charged ions by charge exchange in the collision quadrupole. The first is based on the characteristically high kinetic energy‐to‐charge ratios of the products of charge exchange; this property can be used to separate these ions from all other singly charged ions. This retarding potential method is analogous to procedures for recording doubly charged ion mass spectra using sector instruments. The second method is based on the fact that, although mass remains constant in the charge exchange reaction, the change in mass‐to‐charge ratio can be followed. A charge exchange linked scan, predicated on changes in charge rather than mass, but otherwise analogous to neutral loss/gain scans, is described. Information on the structure of doubly charged ions can be obtained by recording the fragmentation products of dissociative charge exchange. The utility of the charge exchange linked scan for the selective identification of polynuclear aromatic compounds in a complex mixture is described. The methods given can be generalized to cover other charge permutation reactions.
Peptide sequencing by metastable mapping
Authors: Farncombe Martin J. , Jennings Keith R. , Mason Rod S. , Schlunegger Urs P.
Published: May 2005

The amino acid sequence of three simple peptides has been determined by the technique of metastable mapping. The products of decompositions in the first field free region of a forward geometry double focussing mass spectrometer are studied by decreasing the electric sector field between scans of the magnetic field.
Studies in chemical ionization mass spectrometry 10—CI(CH3NH2) spectra of olefins
Authors: Budzikiewicz H. , Laufenberg G. , Brauner A.
Published: May 2005

Both alkenes and cyloalkenes react with [CH3NH2]+˙. The possibilities and limitations of CI(CH3NH2) for the identification of structural isomers and for the determination of double bond positions are discussed. The quasi‐molecular ions [M+CH3NH2]+˙ are shown to fragment in a manner observed for amines under MIKE conditions rather than at 70 eVelectron impact, which suggests that one is dealing with long‐lived low‐energy species.
Characterization of and energy deposition in [C2H4O2]+˙ ions using energy‐resolved mass spectrometry
Authors: Jiang Y.‐X. , Wood K. V. , Cooks R. G.
Published: May 2005

Energy‐resolved mass spectrometry (ERMS) has been used to distinguish [C2H4O2]+˙ ions generated from seven precursor molecules. The low collision energy ERMS data confirm conclusions reached from previous high‐energy experiments; all seven ions have different structures or mixtures of structures. Structural distinctions are at least as easy to make using the two‐dimensional ERMS data as through collisional activation at high energy. The average internal energy deposited in low‐energy collisions (30 eV) is shown to be similar to the internal energy deposited at 8 keV in these systems.
Interference peaks in collisional activation mass spectra: The loss of CH3˙ from [C13H9] ions
Authors: Holzmann Gerhard , Terlouw Johan K. , Hop Cornelis E. C. A. , Burgers Peter C.
Published: May 2005

It was concluded from earlier metastable ion and collisional activation experiments that [C13H9]+ ions generated by dissociative ionization of stilbenes and diphenylmethane consist of a mixture of isomeric structures. It is shown in this paper that the methyl loss upon which this conclusion rests originates to a large extent from metastable molecular ions decomposing in the magnetic sector field (interference signal). Our results do not show, nor do they require, that more than one isomeric [C13H9]+ species is present. The importance of recognizing such interference signals is stressed.
Chemical ionization mass spectrometry with amines as reactant gases. I—amine chemical ionization mass spectrometry of flavonoid aglycones
Authors: Bankova V. S. , Mollova N. N. , Popov S. S.
Published: May 2005

Chemical ionization mass spectrometry of 34 flavones, isoflavones, flavanones, chalcones and aurones with aliphatic amines and ammonia as reactant gases have been investigated. Some unusual ions have been obtained and are discussed. This method can be used to determine the type of flavonoid and the location of some functional groups in the molecule.
Translational energy release and stereochemistry of steroids. VII—the loss of angular methyl groups after the dehydration of molecular ions of cholesterol and related C(5)‐unsaturated 3β‐hydroxy steroids
Authors: Zaretskii Z. V. I. , Kustanovich Z. , Kingston E. E. , Beynon J. H. , Djerassi Carl , Tökes L.
Published: May 2005

The translational energy, T, released during the loss of the angular 18‐ and 19‐methyl groups both from metastable molecular ions and metastable [M  H2O]+ and [M  2H2O]+ ions, in C(5)‐unsaturated mono‐and di‐hydroxy steroids, as well as in their 19‐nor and deuterated analogues bearing the label in the 19‐methyl group, has been measured. It was found that, while the T values for the 19‐CH3 loss, following the dehydration of the molecular ions, are increased substantially when compared to those for the same loss from the molecular ions, the T values for the 18‐CH3 loss are increased much more moderately. Nevertheless, the amounts of translational energy released in the [M  H2O]+˙  18‐CH3˙ and [M  2 H2O]+˙  18‐CH3˙ transitions are still higher than those found for the respective 19‐methyl loss, in accordance with the general rule established recently.
Sensitivity of charge transfer reactions to hydrocarbon ion structures
Authors: Shields G. C. , Wennberg L. , Wilcox J. B. , Moran T. F.
Published: May 2005

Charge transfer reactivities of hydrocarbon ions have been measured with time‐of‐flight techniques, and results correlated with theoretical structures computed by self‐consistent field molecular orbital methods. Recombination energies, ion structures, heats of formation, reaction energetics and relative charge transfer cross‐sections are presented for molecular and fragment ions produced by electron bombardment ionization of CH4, C2H4, C2H6, C3H8 and C4H10 molecules. Even‐electron bridged cations have low ion recombination energies and relatively low charge transfer cross‐sections as compared with odd‐electron hydrocarbon cations.
Ion‐molecule reactions observed for nitroaromatic compounds in negative ion fast atom bombardment mass spectrometry
Authors: Balasanmugam Kesagapillai , Miller Jack M. , Smith Richard W.
Published: May 2005

Analyses of a series of nitroaromatic compounds using fast atom bombardment (FAB) mass spectrometry are discussed. An interesting ion‐molecule reaction leading to [M + O − H]− ions is observed in the negative ion FAB spectra. Evidence from linked‐scan and collision‐induced dissociation spectra proved that [M + O − H]− ions are produced by the following reaction: M + NO2− → [M + NO2]− → [M + O − H]−. These experiments also showed that M−˙ ions are produced in part by the exchange of an electron between M and NO2− species. All samples showed M−˙, [M − H]− or both ions in their negative ion FAB spectra. Not all analytes studied showed either [M + H]+ and/or M+˙ in the positive ion FAB spectra. No M+˙ ions were observed for ions having ionization energies above ∼9 eV.
Mass spectrometry of bis‐quinolizidine alkaloids: 13‐keto and hydroxy substituted derivatives of sparteine and lupanine
Authors: Wyrzykiewicz E. , Wysocka W. , Wiewiórowski M.
Published: May 2005

The mass spectral fragmeutations of 13‐ketosparteine, 13‐hydroxysparteine, 13‐epihydroxysparteine, 13‐ketolupanine, 13‐keto‐α‐isolupanine, 13‐hydroxylupanine, 13‐hydroxy‐α‐isolupanine, 13‐epihydroxylupanine and 13‐epihydroxy‐α‐isolupanine are reinvestigated and discussed. Fragmentation pathways, elucidation of which was assisted by accurate mass measuiements and metastable transitions, are proposed. The fragmentation assignments are not consistent with those previously reported in the literature. Many fragment species of the same m/z (low‐resolution spectra) are composed of two fragment ions of different elemental compositions (high‐resolution spectra). The obtained data create a safe basis for distinguishing structural and stereoisomers.
Mass spectrometry of labile onium ions and carbocation salts. Study by desorption‐ionization mass spectrometry: Fast atom bombardment, field desorption and 252Cf plasma desorption time‐of‐flight mass spectrometry
Authors: Laali Khosrow , Fishel Derry L. , Lattimer Robert P. , Hunt Jerry E.
Published: May 2005

In contrast to the accepted notion that mass spectrometry is impractical as an analytical tool in condensed‐phase preparative carbocation chemistry, it has been shown that desorption ionization techniques (fast atom bombard‐ment, field desorption and252Cf plasma desorption time‐of‐flight mass spectrometry) provide rapid and reliable methods for relative molecular mass determination for a wide variety of highly unstable, fragile carbocation salts and onium ions. In addition, interesting fragment ions and cluster ions (two cations and one anion) are observed. Application of these methods to study several dication ether salts has also been demonstrated.
Mass spectra of halogenated esters. 7. Methyl esters of 2‐chloro C2C20n‐alkanoic acids
Authors: Korhonen Ilpo O. O.
Published: May 2005

The mass spectral fragmentation of a homologous series of methyl esters of 2‐chloro n‐alkanoic acids ranging from acetic (C2) to eicosanoic (C20) acid on electron impact has been investigated. The fragmentation pathways were elucidated with the aid of the first field‐free region metastable ions, the results being presented with one compound, i.e. with ionized methyl 2‐chloro‐octauoate. Owing to the Cl/H exchanges and to the formation of the non‐chlorinated parent esters prior to the fragmentations the spectra show the peak pairs with and without the chlorine atom. The effects become more evident with increasing chain length; shown most visually by the abundance ratios of the McLafferty rearrangement ions atm/z108/110 and 74, and fragments at m/z121/123 and 87.
Characterization of sphingosine long‐chain bases by fast atom bombardment and high‐energy collision‐induced decomposition tandem mass spectrometry
Authors: Rubino Federico Maria , Zecca Luigi , Sonnino Sandro
Published: May 2005

The fragmentation of protonated and cationized sphingosine and sphinganine under metastable and high‐energy collision‐induced decomposition is reported. The protonated compounds undergo abundant charge‐remote fragmen tation of the long alkyl chain, while the cationized molecules yield much less abundant fragmentation and little or no electrocyclic fission of the hydrocarbon portion.
Stereochemical effects in mass spectrometry XV— chemical ionization of some substituted alkenes using dichlorocarbene as the reagent gas
Authors: Yang Hou‐Jun , Li XiȧO‐Ling , Pan Yuan‐Jiang , Chen Yao‐Zu
Published: May 2005

Chemical ionization (CI) of trans‐ and cis‐stilbene and of fumaric and maleic acid, using dichlorocarbene as reagent, was studied. In the CI ion source (CH4), dichlorocarbene added stereospecifically to the double bond of the sample molecule to form the corresponding ion of the 1,1‐dichloropropane derivative. From the different relative abundances of the characteristic fragment ions of these cyclopropanes, the geometric configuration of the original substituted olefins may be predicted.
Dynamic mechanical analysis of fiber reinforced composites
Authors: Reed Katherine E.
Published: May 2005

Dynamic mechanical and thermal properties were determined for unidirectional epoxy/glass composites at various fiber orientation angles. Resonant frequency and relative logarithmic decrement were measured as functions of temperature. In low angle and longitudinal specimens, a transition was observed above the resin glass transition temperature which was manifested mechanically as anadditional damping peak and thermally as a change in the coefficient of thermal expansion. The new transition was attributed to a heterogeneous resin matrix induced by the fiber. The temperature span of the glass‐rubber relaxation was found to broaden with decreasing orientation angle, reflecting the growth of fiber contribution and exhibiting behavior similar to that of Young's modulus. The change in resonant frequency through the glass transition was greatest for samples of intermediate fiber angle, demonstrating behavior similar to that of the longitudinal shear modulus.
Optimization of phenolic resins for friction materials
Authors: Lambla M. , Vo V. C.
Published: May 2005

The physicomechanical properties of phenolic composites containing a large amount of mineral fillers were enhanced through a chemical modification of the basic resin. Various phenolic compounds were first introduced in the condensation mixture leading to modified novolaks, but the final properties of the resulting composites were only slightly improved. Better results were obtained using an optimum content of epoxy‐novolak or melamine in the last stage of processing as confirmed by static and dynamic mechanical analysis. The new procedure introduced recently by Halpin and Sendeckyj for fitting fatigue models was applied to our particle‐filled material. The results confirm the reinforcement of the composite through the co‐reactivity of phenolic resins with the introduced species in the final curing stage.
Characterization of the rheological behavior of fiber‐filled polypropylene melts under steady and oscillatory shear using cone‐and‐plate and rotational parallel plate rheometry
Authors: Mutel A. T. , Kamal M. R.
Published: May 2005

Utilization of cone‐and‐plate and rotational parallel plate rheometry to characterize the rheological behavior of fiber‐filled polymer melts at low shear rates was evaluated. The effect of flow geometry and dimensions on the viscoelastic and viscometric functions was considered. Stress growth functions were found to be dependent on the dimensions of the flow channel. However, viscometric functions were not affected by the dimensions or the geometry of the flow channel. The initial state of orientation was found to be an important factor in determining the flow found to be an important factor in determining the flow behavior. Oscillatory shear tests yielded highly strain‐dependent loss and storage moduli even at very small strain amplitudes. However, the stress response was found to be sinusoidal in most cases, although the properties were strain dependent.
Characteristics of thermoplastics containing electrically conducting asymmetric particles: Anisotropic electrical conductivity of injection molded parts and extrusion behavior
Authors: Martinsson Jan , White James L.
Published: May 2005

The characteristics of compounds of acrylonitrile‐buta‐diene‐styrene and high impact polystyrene resins, filled with carbon fibers, steel fibers, carbon black, and aluminum flakes have been investigated with special emphasis on electrical conductivity and flow behavior in a capillary rheometer. Compression and injection molded compounds were found to be highly electrically anisotropic. The components of the electrical conductivity tensor, K11, K22 and K33, were measured, Generally K11, the flow direction conductivity, has the highest value and the thickness direction, and K33 has the lowest. The injection molded parts were usually electrically heterogeneous with the conduetivities highest at the greatest distances from the gate. The results were interpreted in terms of particle orientation and distribution. Shear viscosities were measurable for all but the aluminum flake compounds which exhibited fluctuating pressure drops. The flow of these compounds through dies was investigated. Examination of material from the die entrance indicated streamline flow without entrance vortices. Sometimes high entrance concentration of particulates were observed especially for the aluminum flakes. Extrudates were found to contain oriented particles.
Reaction injection molding of mica reinforced polyurethane
Authors: Rémillard B. , Vu‐Khanh T. , Fisa B. , Naik S.
Published: May 2005

Reaction injection molded polyurethanes are reinforced with inorganic materials to improve stiffness and structural integrity at elevated temperatures and to reduce the coefficient of thermal expansion. This work describes the reinforcement obtained with an experimental grade of mica designed to achieve low viscosity of mica suspensions in polyol. The effect of mica on properties is essentially identical to that of glass flake (i.e., improved stiffness at the cost of reduced impact strength). Compared to hammer milled glass fiber, mica and glass flakes yield more isotropic, albeit weaker, materials. The study of unreinforced polyurethane shows that mechanical properties (tensile and impact strength, flexural modulus) are approximately proportional to the square of foam density.
The influence of fibers on the crystallization of poly(ethylene terephthalate) as related to processing of composites
Authors: Reinsch Veronika E. , Rebenfeld Ludwig
Published: May 2005

The effect of fiber reinforcement on the isothermal crystallization of poly(ethylene terephthalate) (PET) was investigated using differential scanning calorimetry (DSC). Unidirectional fiber composites were prepared using glass and aramid fibers in PET. The rate of crystallization, as reflected by crystallization half‐time, and the degree of crystallinity of PET are seen to depend on the type of reinforcing fiber as well as on crystallization temperature. Crystallization kinetics are also analyzed using an Avrami model for the volume of polymer crystallized as a function of time. The crystalline morphology of PET in fiber‐reinforced systems was studied using polarized light microscopy. Results concerning nucleation densities and growth morphologies are used in explaining differences seen in crystallization kinetics in fiber‐reinforced systems.
Morphological aspects of the interface in the PEEK‐carbon fiber system
Authors: Lustiger A.
Published: May 2005

Although high modulus PAN based carbon fibers (HMS) induce transcrystallinity in PEEK and a wide variety of other semi‐crystalline polymers, the interfacial strength is lower than PEEK in contact with low modulus carbon fibers (AS4) where transcrystallinity is not induced. In the PEEK/HMS system, crystalline lamellae were found to be oriented edge‐on to the fibers, while in AS4 they were oriented flat‐on, reflecting the difference in surface energies between the two fibers. The intrinsic effect of transcrystallinity on the fiber matrix interaction is therefore obscured when the chemistry of the interaction varies.
Analysis of deformation processes in glassy polycarbonate using internal friction measurements during a tensile test
Authors: Parisot J. , Rafi O. , Choi W. J.
Published: May 2005

Internal friction has been measured by torsion at 1 Hz during tensile tests performed on glassy polycarbonate at room‐temperature. Steady‐state flow and transient effects have been studied during continuous tensile tests and strain‐rate changes. During steady‐state, internal friction and flow‐stress vary in a similar way with strain‐rate. But during transients, internal friction varies continuously while flow‐stress passes through a maximum (or a minimum). These results are interpreted assuming that non‐elastic deformation of glassy polymers requires some microscopic discontinuous processes such as motion of defects. Two parameters are considered: the velocity v and the density ρ of mobile defects. Assuming that the former is directly related to the flow stress, it has been shown that internal friction is related to the density of mobile defects ρ. This feature is used to interpret the different stages of a tensile test curve. Activation volumes for both velocity and density of mobile defects are calculated from experimental data.
A thermoviscoelastic model for residual stress in injection molded thermoplastics
Authors: Rezayat Mohsen , Stafford Roger O.
Published: May 2005

The main sources for residual stress build‐up and warpage in injection‐molded thermoplastic parts are the holding pressures at the gate and the asymmetry in temperature at the mold walls. Accurate computation of these stresses requires a viscoelastic model since creep and stress relaxation behavior of polymers is magnified at the temperature range for filling, packing, and cooling stages of the injection molding process. Furthermore, injection molded parts can rarely be treated as isotropic; orientation, crystallinity, and presence of fibers require a more general material‐model presentation. In this paper, we present a transversely isotropic thermoviscoelastic model for injection‐molded thermoplastic parts, provide a description of the material properties, and briefly discuss measurement techniques and their limitations.
New polythiourethane hardeners for epoxy resins
Authors: Strzelec Krzysztof , Leśniak Elżbieta , Janowska Grażyna
Published: May 2005

New mercaptan‐terminated polythiourethanes were synthesized from low‐molecular‐weight dimercaptan oligomers and diisocyanates. The characteristic bands in the FT‐IR spectra, and the specific peaks in the 1H‐NMR spectra correlate rather well with the proposed structures of these polymers. Chemical analysis of the epoxy group conversion and swelling measurements were conducted in order to determine the crosslink densities of the cured epoxy resins. The curing characteristics and thermal behaviour of the formulated curing mixtures indicate that the epoxy/polythiourethane stoichiometry and thermal history during cure may greatly affect the curing mechanism and final properties of the epoxy networks. Mechanical studies indicated that the application of polythiourethane hardeners improves the flexibility with increasing tensile strength and impact toughness. The prepared polythiourethane hardeners have an acceptable odour and give a perfectly homogeneous system with the epoxy resins and have good storage stability with other coreactants such as diamines. Copyright © 2005 Society of Chemical Industry
Proteomic expression analysis of colorectal cancer by two‐dimensional differential gel electrophoresis
Authors: Alfonso Patricia , Núñez Antonio , Madoz‐Gurpide Juan , Lombardia Luis , Sánchez Lydia , Casal J. Ignacio
Published: May 2005

The identification of specific protein markers for colorectal cancer would provide the basis for early diagnosis and detection, as well as clues for understanding the molecular mechanisms governing cancer progression. In this report, we describe the proteomic analysis of the samples of colorectal cancer corresponding to seven patients. We have used the highly sensitive two‐dimensional differential gel electrophoresis (2‐D DIGE) coupled with mass spectrometry (MS) for the identification of proteins differentially expressed in tumoral and neighboring normal mucosa. We have detected differences in abundance of 52 proteins with statistical variance of the tumor versus normal spot volume ratio within the 95th confidence level (Student's t‐test; p < 0.05). Forty‐one out of 52 analyzed proteins were unambiguously identified by matrix‐assisted laser desorption/ionization‐time of flight MS coupled with database interrogation as being differentially expressed in colorectal cancer. An ontology analysis of these proteins revealed that they were mainly involved in regulation of transcription (synovial sarcoma X5 protein, metastasis‐associated protein 1), cellular reorganization and cytoskeleton (cytokeratins, vimentin, β actin), cell communication and signal transduction (annexins IV and V, relaxin, APC), and protein synthesis and folding (heat shock protein 60, calreticulin, cathepsin D, RSP4) among others. Preliminary studies demonstrated that the differentially expressed proteins found by 2‐D DIGE could be confirmed and validated by immunoblotting and immunohistochemistry analyses in those few cases where antibodies were available. We believe that the incorporation of more samples and new datasets will permit the definition of a collection of proteins with a potential interest as biomarkers for colorectal cancer.
Carbonylated proteins in bronchoalveolar lavage of patients with sarcoidosis, pulmonary fibrosis associated with systemic sclerosis and idiopathic pulmonary fibrosis
Authors: Rottoli Paola , Magi Barbara , Cianti Riccardo , Bargagli Elena , Vagaggini Cecilia , Nikiforakis Nikolaos , Pallini Vitaliano , Bini Luca
Published: May 2005

Oxygen‐derived free radicals produced by phagocytes have been postulated to contribute to lung tissue damage occurring during diffuse lung diseases (DLD). The two‐dimensional electrophoretic (2‐DE) analysis of bronchoalveolar lavage (BAL) protein composition revealed different protein profiles in sarcoidosis (S), idiopathic pulmonary fibrosis (IPF) and systemic sclerosis (SSc) with a significant increase of low molecular weight proteins in IPF. Some of these proteins are involved in antioxidant processes. The aims of this report were to analyse the oxidative stress occurring in patients with DLD through determination of BAL protein carbonyl content and to identify target proteins of oxidation by a proteomic approach (2‐DE combined with immunoblotting with specific antibodies for carbonyl groups). Carbonylated proteins detected by enzyme‐linked immunosorbent assay (ELISA) were increased in BAL of patients with S, IPF and SSc compared to healthy controls with a significant difference for S and IPF. The proteomic approach to the analysis of BAL revealed that protein carbonylation was a process involving specific carbonylation‐sensitive proteins and that in IPF a greater number of proteins target of oxidation were present. In conclusion, to our knowledge, this is the first report providing a database of proteins target of oxidation in BAL of patients with sarcoidosis, idiopathic pulmonary fibrosis and systemic sclerosis.
Application of fluorescence difference gel electrophoresis saturation labelling for the analysis of microdissected precursor lesions of pancreatic ductal adenocarcinoma
Authors: Sitek Barabara , Lüttges Jutta , Marcus Katrin , Klöppel Günter , Schmiegel Wolff , Meyer Helmut E. , Hahn Stephan A. , Stühler Kai
Published: May 2005

In order to identify new molecular markers for pancreatic intra‐epithelial neoplasias (PanINs), the precursor lesions of pancreatic ductal adenocarcinoma, we established a proteomics approach analysing microdissected PanIN cells. Due to the limited amount of proteins available from microdissection, we developed a procedure including fluorescence dye saturation labelling in combination with high resolution two‐dimensional gel electrophoresis. With this procedure we were able to analyse proteins extracted from 1000 microdissected cells with a high resolution of up to 2500 protein spots. Using protein lysates from the pancreatic carcinoma tissue as a reference proteome, we were able to successfully identify the proteins. Thus, we could match approximately 2200 protein spots (92%) of the microdissected sample proteome to the reference proteome for protein identification using matrix‐assisted laser desorption/ionisation‐time of flight mass spectrometry and nanoliquid chromatography‐electrospray ionisation tandem mass spectrometry after in‐gel digestion. The first proteome analysis of microdissected PanIN‐2 grades revealed eight differentially expressed proteins. The differential expression of the three actin filament‐associated proteins – transgelin, vimentin and MRCL3 as well as actin itself – indicates a relevant role of the actin cytoskeleton during pancreatic tumour progression. Additionally, two members of the annexin family (annexin A2 and A4) implicate a functional contribution of exocytotic and endocytotic pathways at that stage.
Open Air Deposition of SiO2 Films by an Atmospheric Pressure Line‐Shaped Plasma
Authors: Zhu Xiaodong , Arefi‐Khonsari Farzaneh , Petit‐Etienne Camille , Tatoulian Michael
Published: May 2005

Summary: A line‐shaped atmospheric pressure filamentary plasma is developed to carry out the open air deposition of silicon oxide films from N2/hexamethyldisoxane (HMDSO) mixtures with/without adding oxygen. FT‐IR, XPS, SEM, and ellipsometry were used to analyse the samples. It is found that the deposited films present mainly inorganic characteristics even without an oxygen admixture in the open air system. Smooth, continuous, and uniform films can be formed at relatively low monomer content. By increasing the monomer content for a fixed power density or oxygen in the input gases, the deposition rates increase and then show a plateau, suggesting that there exists saturation values for the deposition rates corresponding to the monomer and oxygen content. By the comparison of films deposited in the open air device and in a controlled nitrogen atmosphere in the same device, the important role of the oxygen in the open air reactor has been shown. This study exhibits a potential of open air deposition at atmospheric pressure to form SiO2 films for large‐scale deposition.

An FT‐IR spectrum of an SiOx film deposited in open air without adding any oxygen to the discharge.

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An FT‐IR spectrum of an SiOx film deposited in open air without adding any oxygen to the discharge.
Computer Simulation of Randomly Packed Spheres ‐ a Tool for Investigating Polydisperse Materials
Authors: Schlüßler Karl Heinz , Walter Lutz
Published: May 2005

In the field of material science, especially for polydisperse materials, many questions arise which cannot be answered sufficiently and precisely without information which represents the random character of the structure in space. Computer simulation is here an effective tool used to create random arrangements of particles which may be regarded as a realistic representation of the underlying material. Of course, the presumption that the shape of each particle is a sphere is an idealization which is a certain handicap in modeling all the possible system properties. Nevertheless, it can be demonstrated that, by having an adequate subroutine, many phenomena which are influenced by the local topology of the particles and their interaction forces can be studied in more detail.
On the Detonation Characteristics of CHNO‐Type Condensed Explosives. A parameter study
Authors: Swaminathan V. , Rajagopalan S.
Published: May 2005

The object of the present paper is to carry out a parametric study which takes into consideration the variations of the detonation characteristics such as CJ pressure, CJ temperature, velocity of detonation (VOD), and gas volume of CHNO‐based condensed explosive systems in connection with the changes in input parameters like loading density and heat of formation of the explosive in question. Meaningful equations which describe adequately the interrelationships between the parameters were derived for a typical CHNO‐type explosive. The study is likely to be of considerable help in determining the variations in the magnitudes of the detonation parameters corresponding to a given change in the relevant input characteristics. The results of such studies should also be important in estimating the uncertainty of a parameter, like VOD, arising from the uncertainty in the heat of formation of the explosive which is often determined experimentally and whose values is often of questionable validity. The principal features that emerge from the investigations in this paper are: (1) while CJ pressure and VOD tend to increase sizably with the loading density of the explosive, CJ temperature and CJ volume decrease with an increase in the loading density; and (2) all the four parameters, viz., CJ pressure, CJ temperature, VOD, and CJ volume increase, however, being of a marginal nature, barring the CJ temperature whose variations with the heat of formation are not insignificant.
Thermal Decomposition of RDX Composite Propellants
Authors: Maruizumi H. , Fukuma D. , Shirota K. , Kubota N.
Published: May 2005

The thermal decomposition characteristics of RDX, binders, and RDX composite propellants were studied using thermal analytical techniques. Three kinds of binders were tested to elucidate the role of binder on the burning rate of the propellants. There were no apparent correlations between the thermal decomposition rates of binders and the burning rates of propellants, whereas there was a correlation between the decomposition temperature and the burning rate of the propellants.

It is found that the major factor which controls the burning rate is the initial thermal‐decomposition stage of the binders. Thus, the burning rate of nitramine composite propellants appeared to be largely dependent on the physical and chemical properties of binder.
Application of the Robbins‐Monro Method to the Sensitivity Testing of Explosives. I. A computer simulation study
Authors: Schilperoord A. A. , Bijlsma M. , Verweij H. D. , Bruckman H. W. L.
Published: May 2005

A computer simulation study of the Robbins‐Monro method is presented. This method can be used to determine percentage points of a distribution function describing the probability of explosion as a function of some stimulus level. Calculations were performed to establish the influence of several parameters involved in the process. It is concluded that the method is suitable for determining 50, 10 and 1 percent points for several distribution functions. The efficiency for a restricted number of experiments and for a reasonable choice of the parameters is similar to that of a situation where experiments are performed at a fixed level, however with the advantage that the desired percentage point is obtained by convergence.
Rapid Methods for Quality Control of Gun Propellants
Authors: Volk F. , Wunsch G. , Müller D.
Published: May 2005

Several single‐base, double‐base, and triple‐base gun propellants were analyzed by three different methods:

Conventional analytical methods (TL 1376–600)

High‐pressure liquid chromatography (HPLC)

Derivative spectroscopy.

The results obtained by these methods agree well and show a good reproducibility. However, compared with each other, the chromatographic methods are not only more rapid and more flexible than the conventional wet chemical analysis, they enable a quantitative determination of blasting oil mixtures like nitroglycerin or diglycoldinitrate. The same holds for many other explosives, stabilizers and stabilizer reaction products.
On the adhesion between Hydroxyl‐Terminated Polybutadiene Fuel‐Binder and Ammonium Perchlorate. Performance of bonding agents
Authors: Hori K. , Iwama A. , Fukuda T.
Published: May 2005

A simple method to evaluate the adhesive force between solid oxidizer and polymeric fuel‐binder is presented. As an illustration, hydroxyl‐terminated polybutadiene (HTPB) sticks including several different bonding agents are bonded on ammonium perchlorate (AP) single crystals, and stress‐strain history until rupture occurs is obtained by applying uniaxial tensile stress perpendicularly to the adhesion surface. Further, whether each bonding agent reacts with AP or not was analysed with pursuing infrared absorption spectra. The hypothesis that the interfacial adhesive force arises from hydrogen bonding force is proposed.
Mechanistic Studies on Self Deflagrating Solids from temperature profile analysis
Authors: Kishore K. , Patil K. C. , Gajapathi D.
Published: May 2005

A preliminary investigation has been made to study the mechanism of decomposition of self deflagrating solid (iron oxalate dihydrazinate) using temperature profile technique. A three step decomposition mechanism of two hydrazine losses and subsequent oxidation of anhydrous salt has been proposed. The enthalpy changes for these steps, obtained from the temperature profile measurements agree well with the values calculated using heat of formation data obtained from combustion calorimetry and differential scanning calorimetry.
Combustion of HMX‐CMDB Propellants (I)
Authors: Yano Y. , Kubota N.
Published: May 2005

The combustion wave structure of HMX‐CMDB (composite modified double‐base) propellants was studied in order to elucidate the gas phase reaction mechanism and to understand the burning rate characteristics. Experiments were conducted to determine the thickness of the reaction zone, gaseous products in the dark zone, and the temperature profile in the combustion waves. The reaction rate in the dark zone is increased by the addition of HMX. This is caused by the equivalence ratio of the oxidizer/fuel in the dark zone shifting towards a stoichiometric ratio when HMX is added. However, the reaction rate in the fizz zone and the heat feedback from the gas phase to the burning surface is decreased by the addition of HMX. Thus, the burning rate of HMX‐CMDB propellants decreases when HMX is mixed within double‐base propellants.
A Study of Solid Propellant Containing Titanium Hydride
Authors: Nakahara M. , Yano Y.
Published: May 2005

The burning rate characteristics of the propellant containing TiH2 have been examined in order to understand the effect of TiH2 addition on the combustion wave structure. The burning rate increases and the pressure exponent of burning rate decreases as the addition of TiH2 increases. Using very fine thermocouples which were embedded within the propellant samples, the heat transfer process in the combustion wave was determined. The results indicate that the heat flux feedback from the gas phase to the burning surface increases when TiH2 is mixed within the propellants.