bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular complexes of cyclodextrins: Application of ion‐spray mass spectrometry to the study of complexes with selected nitramines
Authors: Bakhtiar Ray , Bulusu Suryanarayana
Published: May 2005

Complex formation of the important nitramines, RDX, HMX and TNAZ with α‐, β‐, and γ‐cyclodextrins (CDs) was studied using ion‐spray mass spectrometry (IS‐MS). Complexations between β‐CD/TNAZ, β‐CD/RDX, γ‐CD/RDX, and γ‐CD/HMX were detected in the gas phase by this technique. Control experiments using α‐CD and TNAZ did not lead to a detectable molecular association, which is in accord with the previously reported NMR data. In addition, none of the nitramines showed any complex formation with the non‐cyclic sugar, maltohexose. The IS‐MS results are in agreement with the previously reported conclusions from proton nuclear magnetic resonance spin‐lattice relaxation time measurements.
Fully automated sample preparation and electrospray mass spectrometry analysis
Authors: Raso R. , Fehlhaber H.‐W.
Published: May 2005

A fully automated sample preparation–mass spectrometry system has been described which prepares samples prior to electrospray mass spectrometry analysis, injects the samples, and acquires and processes the data. Fifty samples can be analysed without operator intervention within 8 hours. This type of system ensures optimum use of both the mass spectrometer, which can be in operation 24 hours per day, and the mass spectroscopist, who can concentrate on more challenging samples and spectral interpretation. The laboratory robot system used can be easily adapted for different types of sample preparation and other methods of analysis. For example, in addition to a spectrum exhibiting mainly protonated or deprotonated molecular ions, data could be acquired concurrently with a higher cone voltage, or under tandem mass spectrometry conditions, to generate structurally informative fragment ions. This sample preparation method has been adapted to encompass a variety of samples such as proteins and nucleic acids.
The use of amine base to enhance the sensitivity of electrospray mass spectrometry towards complex polysulphonated azo dyes
Authors: Ballantine James A. , Slater Paul S. , Games David E.
Published: May 2005

Electrospray ionization mass spectrometry was employed in the detection of polysulphonated azo dye sodium salts, and other compounds containing the sulphonate‐sodium ion group [SO +Na]. Before amine addition, the polysulphonated azo dyes produced low intensity ions. Spectra were obtained in both positive‐ and negative‐ionization modes, the negative mode giving the best results. The typical spectrum of a dye depended on the number of cations associated to the compound. Each compound displayed a series of ion peaks which were the result of varied amount of cation–proton exchange during the ionization process. The number of protons observed to bind to a compound anion with (n) sodium cations simultaneously removed depended on the charge (z) carried by each ion within an ion series. We have found that the addition of an amine base sensitizes polysulphonated azo salts towards electrospray ionization mass spectrometry. We propose that the addition of the amine base assists the total removal of cations. This selectively enhances the intensity of the acid ion peaks of each ion series, by accumulating each peak present within z‐charged ion series into a single intense peak. The percentage increase in the intensity of the acid ion peaks was observed in most cases to follow the gas‐phase proton affinity of the applied amine base. Preliminary results have also indicated that a correlation exists between the percentage increase in the intensity of acid ion peaks and the number of cations originally associated to each compound.
Secondary ion mass spectrometric studies on the formation mechanism of IrO2/TiO2‐based coatings
Authors: Kristóf J. , Daolio S. , Piccirillo C. , Facchin B. , Pagura C.
Published: May 2005

The formation mechanism of an IrO2/TiO2 film electrode has been studied by secondary ion mass spectrometry (SIMS). A coating mixture with the composition 50% Ir+50% Ti prepared on a titanium support from an isopropanolic solution of hydrated iridium chloride and titanium bis‐2,4‐pentanedionate precursors was heated to specified temperatures and analysed by SIMS. Concentration depth profiles of some selected species (e.g. Cl−, O−, ClO−, TiO+, Ir+, IrO, TiO, CH, C2H, OH−) were used to follow the process of film evolution. Segregation phenomena resulting in the increased dispersity of the noble metal on the surface were identified. The results are in accordance with—and complementary to—those of former measurements by combined thermoanalytical, mass spectrometric and emission Fourier transform infrared (FTIR) techniques.
Characterization of acetals by means of capillary gas chromatography/mass spectrometry
Authors: De La Ruelle Hugo , Klok Jaap , Rinken Marian , Felix Mark
Published: May 2005

i‐Butylvinylether and diethyleneglycol‐n‐butyl ether (Dowanol‐DB

Trade name of The Dow Chemical Company.

) were reacted under mild acidic conditions to yield acetals. This report deals with the identification of the reaction products by means of gas chromatographic separation followed by mass spectrometric analysis in both electron impact and chemical ionization modes. Consultation of the standard NIST library (50k spectra) revealed that none of the spectra of the acetals in this study were present. A more elaborate study of fragmentation patterns was therefore initiated. The fragmentation patterns of the reaction products in electron impact ionization mode are discussed in detail. During ammonia chemical ionization, typical [M+NH4+26]+ ions are observed for 4,6‐dioxa‐2,5,8‐trimethylnonane. A hypothesis for this phenomenon is presented.
Detection of high molecular weight starburst dendrimers by electrospray ionization mass spectometry
Authors: Schwartz Brenda L. , Rockwood Alan L. , Smith Richard D. , Tomalia Donald A. , Spindler Ralph
Published: May 2005

An entire series of Starburst polyamidoamine (PAMAM) dendrimers consisting of generations 1 through 10 (G1–10) have been studied by positive‐ion electrospray ionization mass spectrometry (ESI‐MS) using an extended m/z range quadrupole mass spectrometer. Charge‐state distributions were detected as high as m/z 12 000 for the generation 10 dendrimer, having a theoretical molecular weight of 1 megadalton and containing approximately 93 maximum positive charges on the molecule. Accurate molecular weight determinations of the smaller generation dendrimers (G1–3, Mr ∼ 1.4kDa to 6.9kDa) were obtained using a commercial triple quadrupole instrument. The unit resolution ESI mass spectra provide information on the number of incomplete reactions which may occur during polymer synthesis. The extent of gas‐phase charging observed by ESI‐MS on the entire series of macromolecules was found to exhibit a linear relationship to M, consistent with theoretical models prediciting a spherical ion structure with maximum charging controlled by Coulombic effects.
The characterization of synthetic polymers by matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Cottrell J. S. , Koerner M. , Gerhards R.
Published: May 2005

Molecular weight parameters for synthetic polymers are defined and their determination by matrix‐assisted laser desorption/ionization (MALDI) is described. In particular, details of matrix materials that are suitable for this type of measurement are provided. The availability of increased instrumental resolution provides a simple means of endgroup identification for some synthetic polymers.
Analysis of linear oligogalacturonic acids by negative‐ion electrospray ionization mass spectrometry
Authors: Xie Mei , Giraud Denis , Arpino Patrick , Bertheau Yves , Casetta Bruno
Published: May 2005

Linear oligogalacturonic acids (1,4‐linked α‐D‐galacturonic acid oligomers), obtained by partial acid hydrolysis of orange polygalacturonides, were studied by negative‐ion electrospray ionization mass spectrometry, without prior sample derivatization. After preparative separation using high‐resolution anion‐exchange chromatography, some fractions enriched in uronic acids were desalted, transferred into a methanol+water solution adjusted to pH 10, and directly submitted to electrospray ionization mass spectrometry in the negative‐ion recording mode. Clear molecular mass assignments of the oligomers, covering a degree of polymerization between 4 and 7, were obtained.
Experimental study of the efficiency of storage in an RF ion trap
Authors: Vedel M. , Rocher J. , Knoop M. , Vedel F.
Published: May 2005

N+ ions were stored in a home‐made ion trap. The apparatus allows the systematic characterization of ion motion in the presence of anharmonicities due to geometric defects, or to a smaller degree, due to the space charge. Enrichment of the spectrum of the motion frequencies and drastic reduction of the storage capability occur due to radial‐axial couplings. The paper presents experimental observations of these effects.
Chemometric classification of some european wines using pyrolysis mass spectrometry
Authors: Montanarella Luca , Bassani Maria Rosa , Bréas Olivier
Published: May 2005

The application of Curie‐point pyrolysis mass spectrometry (Py/MS) to 33 certified wine samples from different regions of Spain, France and Italy is reported. The resulting mass spectra were submitted to principal component analysis, canonical variates analysis and cluster analysis producing a final dendrogram, using average linkage clustering. A good classification was achieved according to large geographical areas (country of origin), while no correlation was found to grape species or to local areas of cultivation. The same data were submitted to artificial neural networks analysis using the back‐propagation algorithm and dividing the data into a training and a test data set. More than 90% of the test wine samples were correctly identified according to their country of origin after training of the artificial neural network. Again no correlation was found between pyrolysis mass spectra and grape species or area of cultivation. Nevertheless, the technique could be applied to rapid screenings of wine samples for the tentative identification of country of origin. In combination with other techniques (IR‐MS, NMR) it can give complementary information about the samples and their regions of origin.
Autoradiographic localization of 3H‐paroxetine‐labeled serotonin uptake sites in rat brain
Authors: De Souza Errol B. , Kuyatt Brian L.
Published: May 2005

Paroxetine is a potent and selective inhibitor of serotonin uptake into neurons. Serotonin uptake sites have been identified, localized, and quantified in rat brain by autoradiography with 3H‐paroxetine; 3H‐paroxetine binding in slide‐mounted sections of rat forebrain was of high affinity (KD = 10 pM) and the inhibition affinity constant (Ki) values of various drugs in competing 3H‐paroxetine binding significantly correlated with their reported potencies in inhibiting synaptosomal serotonin uptake. Serotonin uptake sites labeled by 3H‐paroxetine were highly concentrated in the dorsal and median raphe nuclei, central gray, superficial layer of the superior colliculus, lateral septal nucleus, paraventricular nucleus of the thalamus, and the islands of Calleja. High concentrations of 3H‐paroxetine binding sites were found in brainstem areas containing dopamine (substantia nigra and ventral tegmental area) and norepinephrine (locus coeruleus) cell bodies. Moderate concentrations of 3H‐paroxetine binding sites were present in laminae I and IV of the frontal parietal cortex, primary olfactory cortex, olfactory tubercle, regions of the basal ganglia, septum, amygdala, thalamus, hypothalamus, hippocampus, and some brainstem areas including the interpeduncular, trigeminal, and parabrachial nuclei. Lower densities of 3H‐paroxetine binding sites were found in other regions of the neocortex and very low to nonsignificant levels of binding were present in white matter tracts and in the cerebellum. Lesioning of serotonin neurons with 3,4‐methylenedioxyamphetamine caused large decreases in 3H‐paroxetine binding. The autoradiographic distribution of 3H‐paroxetine binding sites in rat brain corresponds extremely well to the distribution of serotonin terminals and cell bodies as well as with the pharmacological sites of action of serotonin.
Defamliarizing Latin Literature, from Petrarch to Pulp Fiction
Authors: Hinds Stephen
Published: May 2005

In line with a growing trend to approach classics of Roman literature as much through their successors as through their antecedents, this essay offers a pair of case-studies in the post-antique reception of Cicero and Ovid. With an eye to the brief of the present volume, each case-study moves towards a crux locatable in the last decade, trying to show that our characteristic ways of interpreting a Latin author are implicated in changing ideas about the so-called "Classical Tradition" inside and outside the academy. The first part of the essay offers snapshots of the "Ciceronian man" from Petrarch to the present day; the second considers a new Ovidianism outside the academy, which has yielded a surprising range of re-readings of the Metamorphoses since the early 1990s.
The Aporia of AIDS and/as Holocaust
Authors: Goshert John Charles
Published: May 2005

The author considers the use of motifs and testimonial strategies of Holocaust narratives in AIDS narratives. Focusing on Sarah Schulman's 1996 novel, Rat Bohemia, the essay examines the formal and thematic connections Schulman draws between Jewish American characters' cultural/ethnic inheritance of a history of genocide, and their contemporary experiences as witnesses to the AIDS crisis. Through these resonances, Schulman suggests the singular position of people with AIDS: they have been abandoned not only by American cultural and political institutions, but also by their parents and families, precisely those who (especially among Jewish families) might be the best equipped to empathize with suffering. The essay also touches on Schulman's other creative and critical work and her challenge to celebratory Jewish lesbian writing and cathartic AIDS narratives.
Collective Portraits: The Anthological Imagination of Leo W. Schwarz
Authors: Shere Jeremy
Published: May 2005

In 1935 the literary intellectual Leo W. Schwarz published The Jewish Caravan, an anthology of stories spanning the entirety of Jewish historical experience. Two years later Schwarz published a follow-up volume, A Golden Treasury of Jewish Literature. Together, the anthologies formed a landmark testament to the richness of Jewish literary culture and attempted to buoy the flagging morale of American Jewry during the 1930s. Aimed primarily at an American audience, Schwarz's anthologies were among the first to include Jewish writing by American authors. Largely absent from leading American anthologies of the day, writers such as Waldo Frank, Thyra Samter Winslow, Albert Halper, Meyer Levin, and others were recognized by Schwarz as members of the centuries-long Jewish literary fraternity. Schwarz's anthological project thus helped give rise to the concept of an American Jewish literature—a body of work meant to help connect American Jewry to the Jewish experience in its most global aspect.
The mobility of anthropogenic129I in a shallow sand aquifer at Sturgeon Falls, Ontario, Canada
Authors: Renaud Robert , Clark I. D. , Kotzer T. G. , Milton G. M. , Bottomley D. J.
Published: May 2005

The transport and partitioning of129I has been examined for a shallow groundwater flow system at Sturgeon Falls in northeastern Ontario. Recharge into a sandy surficial postglacial deltaic aquifer occurs in the vicinity of a seasonally-wet boreal forest. Concentrations of stable iodine,129I, tritium, radiocarbon, stable isotopes and major ions were measured on samples of groundwater and precipitation. The present-day tritium profile delineates the position of the early 1960's above-ground nuclear weapons pulse at a depth of approximately 12 m.

The concentrations of stable iodine for groundwaters above, near and below the above-ground nuclear weapons pulse range from 0.07 to 1.7 ppb. Over that same interval129I concentrations decreased from 1.9 × 106atoms/L at 9 m, to approximately 1.9 × 105atoms/L in tritium-depleted waters at 35 m, below the present-day depth of the recharging above-ground nuclear weapons peak at approximately 12.7 m. No substantial increases in the levels of129I were evident in waters sampled near the location of the above-ground nuclear weapons peak.

The129I values in the lower aquifer are 1 to 2 orders of magnitude greater than published estimates of pre-bomb129I (103to 104atoms/L), and indicate contribution of129I from the fissiogenic decay of238U in the basal granite bedrock or from leaching of129I from the aquifer grains.

A precipitation sample collected at Sturgeon Falls had concentrations of stable iodine and129I of 0.2 ppb and 8.5 × 107atoms/L, respectively. Concentrations of129I in Sturgeon Falls groundwaters are lower than those reported in other studies in central Canada, suggesting that the levels of129I in these groundwaters may have been attenuated by complexation or ion exchange with organic materials in the near-surface soil horizons. Such processes have been documented during a previous study on the behavior of129I in a shallow aquifer near a low-level, radioactive waste management area.

Along a 30 cm soil profile at piezometer nest 28 at the Sturgeon Falls study site, the concentrations of129I ranged from approximately 4.3 × 108atoms/g in the uppermost soil litter layer to 5.6 × 107atoms/g in the siltier bottom soil horizons. Over that same profile, stable iodine varied from 4.7 ppm in the upper layers to 3.9 ppm in the lower layers.
GaAs/AlGaAs-Quantenkaskaden-Laser (GaAs/AlGaAs Quantum Cascade Lasers)
Authors: Höfling Sven , Reithmaier Johann P. , Forchel Alfred
Published: May 2005

Es wurden Quantenkaskaden-Laser für den 10-μm-Spektralbereich hergestellt. Zur Miniaturisierung, Verbesserung der Bauelementeigenschaften und Erzielung monomodiger Emission wurden Laser mit eindimensionalen photonischen Kristallstrukturen in Form von tiefgeätzten Bragg-Spiegeln entwickelt. Es wurde erstmals erfolgreich nahezu gitterangepasstes GaInNAs auf GaAs-Substraten bei 590 °C aufgewachsen, womit eine wesentliche Erhöhung des Ladungsträgereinschlusses ermöglicht wird.
Monomodige DFB-Quantenkaskadenlaser mit Metall-Bragg-Rückkopplungsgittern (Single Mode Quantum Cascade DFB-Lasers with Metal Bragg gratings)
Authors: Seufert Jochen , Koeth Johannes , Fischer Marc , Höfling Sven , Reithmaier Johann P. , Forchel Alfred
Published: May 2005

Auf der Basis von GaAs/AlGaAs-Heterostrukturen wurden monomodige Quantenkaskadenlaser im Wellenlängenbereich von 9–11 μm entwickelt. Die Rotations-Schwingungs-Grundzustände vieler industriell wichtiger Gase fallen in diesen Spektralbereich im mittleren Infrarot. Daher eignen sich diese Laser in besonderem Maße für den sensitiven Nachweis von beispielsweise CO2 (9,5 μm Wellenlänge), O3 (9,7 μm) und NH3 (10,7 μm). Die Laser werden auf standardisierte c-mounts montiert, die sehr einfach in komplexere Optikmodule eingebaut werden können. Im gepulsten Betrieb liefern die hergestellten Bauteile bei Peltiertemperaturen Ausgangsleistungen von einigen mW und erweisen sich aufgrund ihres kontinuierlichen Durchstimmbarkeitsverhaltens der Emissionswellenlänge insbesondere für spektroskopische Anwendungen als geeignet.
Untersuchungen des Intensitätsrauschens von Quantenkaskadenlasern (Investigations of the Intensity Noise of Quantum Cascade Lasers)
Authors: Gensty Tobias , von Staden Jens , Elsäßer Wolfgang
Published: May 2005

Quantenkaskadenlaser (QCLs) repräsentieren die jüngste Generation von Halbleiterlasern, die viel versprechende Lichtquellen für die Gasanalytik darstellen. Wir untersuchen ihr Intensitätsrauschen und finden ein neues Skalierungsverhalten als Funktion der emittierten optischen Leistung. Im Hinblick auf Anwendungen in Laserspektroskopie-Systemen charakterisieren wir das Verhalten eines QCL in Externer-Resonator-Konfiguration. Schließlich zeigen wir, dass moderne Hohlleiter-Fasern geeignete Lichtwellenleiter für die Laserspektroskopie im mittleren infraroten Spektralbereich darstellen.
External-Cavity-QCL-Systeme (External Cavity QCL Systems)
Authors: Hildebrandt Lars , Knispel Richard , Stry Sandra , Sacher Joachim
Published: May 2005

Für zahlreiche Anwendungen in der industriellen Messtechnik werden durchstimmbare Laser im mittleren infraroten Spektralbereich benötigt. Aufgrund charakteristischer Spektren vieler umwelt- und medizinisch relevanter Moleküle ist dieser Bereich von besonderem Interesse. Um einen Laser mit einem großen monomodig spektral durchstimmbaren Wellenlängenbereich zu realisieren, sind Quantenkaskadenlaser entspiegelt und in einem externen Resonator betrieben worden.
Superfine oxide powders— flame hydrolysis and hydrothermal synthesis
Authors: Kriechbaum Gangolf W. , Kleinschmit Peter
Published: May 2005

Nanocrystalline materials which can be plastically deformed at low temperatures have revolutionized the applications for ceramics. Two methods for the production of high‐tech ceramics with grain sizes of less than 1 pm are described and the quality of the materials, for example ZrO2 powder (see figure), assessed.

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Spatially selective conducting patterns in transparent films derived from ladder type polymers
Authors: Belaish Igal , Davidov Dan , Selig Heny , McLean Malcolm R. , Dalton Larry
Published: May 2005

Conducting patterns embedded in a completely transparent polymer film can be produced using selective heating by laser annealing of cross‐linked, stable, ladder‐like polymers followed by fluorination. The figure shows a transparent film treated in this way containing the permanent, conducting pattern.

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The function of polymers in the tape casting of alumina
Authors: Böhnlein‐Mauß Jutta , Sigmund Wolfgang , Wegner Gerhard , Meyer Wolfgang H. , Heßel Friedrich , Seitz Katharina , Roosen Andreas
Published: May 2005

Polymeric additivesshave a great influence on the processing parameters in the produciton of high‐performance ceramics. The various types of additives are described and the interactions between the organic additives and the inorganic ceramic powders, some examples of which are shown in the figure, are examined with emphasis on one of the most important ceramic forming processes.

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Electronic properties of quasicrystals
Authors: Klein Thierry , Berger Claire , Mayou Didier , Cyrot‐Lackmann Françoise
Published: May 2005

Quasicrystalline structures exhibit long‐range orientational order without translational periodicity and as a result have been found to exhibit a number of unusual properties. The AlCuFe alloys highlighted here, for example, have very high resistivities which are in the rangre of what would be expected for heavily ddoped semiconductors on the metallic side of a metal–insulator transition. The materials and their properties are discussed.
Reaction pathways in organometallic chemical vapor deposition(OMCVD)
Authors: Zinn Alfred , Niemer Burkhard , Kaesz Herbert D.
Published: May 2005

The incorporation of heteroatom impurities derived from the ligands in organometallic chemical vapor deposition can now be avoided due to an understanding of the raection pathways involved. The development of the technique is traced, the various mechanisms discussed, and the important questions which still have to be answered presented.
3,4‐Dimethoxypyrrole: Monomer synthesis and conducting polymer formation
Authors: Merz Andreas , Scnwarz Roland , Schropp Roland
Published: May 2005

Processible conducting polymers based on 3, 4‐substituted polythiophenes have been known for some time. Here, the synthesis and polymerization of an analogue to the thiophenes, the dialkoxypyrrole monomer shown in the figure, are reported. The polymer formed exhibits a relatively high conductivity pointing to a regular, possibly coiled structure.

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Magnetic ordering in a molecular material containing dysprosium(III) and a nitronyl nitroxide
Authors: Benelli Cristiano , Caneschi Andrea , Gatteschi Dante , Sessoli Roberta
Published: May 2005

Molecular‐based magnetic materials have been shown to order both as bulk ferro‐ and ferrimagnets. Here, the effect of anisotropy of the magnetic interaction between interacting centers on the transition temperature to magnetic order is investigated and it is shown that molecular materials containing rare‐earth elements can have magnetic transition temperatures comparable to those containing transition‐metal ions.
The High‐Tc superconducting solid solution Bi2+x(Sr,Ca)3Cu2O8+d (2212 Phase)—chemical composition and superconducting properties
Authors: Majewski Peter , Su Huang‐Lung , Hettich Bernhard
Published: May 2005

Superconducting bulk ceramics in the form of rods, tubes, rings or blocks are best produced from the 2212 phase of the title system. Until now, however, the 2212 single‐phase region, which also involves regions of varying Sr/Ca ratio and varying Bi contents, has not been unambiguously characterized. In this work, the 2212 single‐phase region is defined and the critical temperature (Tc) correlated with the chemical composition.
A theoretical way of aiding the design of solid‐state syntheses
Authors: Dronskowski Richard , Hoffmann Roald
Published: May 2005

While aids to synthesis design are available to the organic chemist, for example the Woodward‐Hoffmann rules, the situation for the chemist involved in solid‐state synthesis is somewhat different. Here, the researcher is forced into planning synthetic steps in a much more rudimentary way. In this, somewhat extended article, a new concept for the design of solid‐state syntheses, based on improved descriptions for acidity, basicity, electrophilicity, and nucleophilicity in the solid, is presented.
Crystal growth in space
Authors: Benz Klaus‐W.
Published: May 2005

Magterials science in space, including the crystal growth of organic and inorganic materials, is an interesting discipline that dates back to the growth of the first single crystals in space during the Apollo and Soyuz missions. Progress made since then is reviewed and the current goals of today's crystal growth experiments in space are considered. Crystals growth in spae may not be larger or more beautiful than those grown under terrestial conditions, but such experiments can provide answers to basic scientific questions.
Molecular engineering of side‐chain liquid‐crystalline polymers by living cationic polymerization
Authors: Percec Virgil , Tomazos Dimitris
Published: May 2005

Molecularly designed polymers with narrow polydispersities and well‐defined molecular weights, tailor‐made mesophases, and reactive systems that can be used for further functionalization or cross‐linking reactions are required for applications in areas as diverse as optical data storage, nonlinear optical systems and electro‐optic displays. Recent progress is discussed in the molecular engineering of side‐chain liquid‐crystalline polymers by living coationic polymerization, statistical and sequential copolymerization, and chain and functionalization reactions.
A construction principle of the κ‐phase based on the efficient (OH)donor…Oanion structural functionality: The examples of κ‐(EDT–TTF(CH2OH))2X (X = ClO and ReO)
Authors: Blanchard Philippe , Boubekeur Kamal , Sallé Marc , Duguay Guy , Jubault Michel , Gorgues Alain , Martin James D. , Canadeli Enric , Auban‐Senzier Pascale , Jérome Denis , Batail Patrick
Published: May 2005

The search for κ‐phases of conducting and superconducting organic cation radical salts is difficult because it is not yet known which characteristics of the donor molecule are required for this structure to be generated. The figure shown the hydroxy‐methyl‐functionalized non‐centroxymmetrical donor EDT‐TTF(CH2OH), which has been purposely associated with the discrete tetrahedral perchlorate and perrhenate anions to form two new examples of a κ‐phase.

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Fast electroclinic switching in a ferroelectric LC‐polysiloxane
Authors: Poths Holger , Andersson Gunnar , Skarp Kew , Zentel Rudolf
Published: May 2005

A ferroelectric liquid‐crystal (LC) polymer with extremely rapid electroclinic switching is reported: The LC‐polysiloxane can optically follow an electric field of more than 100 kHz. This high switching speed should make it possible to transform spoken language into optical signals for transmission through optical fibers. The polymer exhibits strictly linear behavior in the high‐temperature region of the smectic A* phase, in which the high‐speed switching occurs, while pronounced nonlinearity is found as the smectic C* phase is approached. For applications in which a nonlinear response is acceptable, the greater contrast in this region is a bonus.
Well‐defined pyrrole oligomers: Electrochemical and UV/vis studies
Authors: Zotti Gianni , Martina Stefano , Wegner Gerhard , Schlüter Arnulf‐Dieter
Published: May 2005

The properties of oligo(pyrrole)s can give vital clues to the intrinsic properties and behavior of poly(pyrrole), which is important in the field of polyconjugated conducting polymers but difficult to obtain defect‐free. However, up to now little work has been done on oligo(pyrrole)s, perhaps because of their sensitivity to oxygen, which makes their handling and preparation difficult. The reported electrochemical analysis of well‐defined pyrrole oligomers has allowed both the determination of the limiting value for the potential of reversible charging of poly(pyrrole) and the production by electrochemical coupling of a virtually defect‐free poly(pyrrole).
Crystals of an antiferromagnetic 1,3‐butadiyne compared with a ferromagnetic 1,3,5‐hexatriyne carrying a 4‐Chloro‐3‐(N‐tent‐butyl‐N‐oxyamino)phenyl Group as a Persistent Free Radical Substituent
Authors: Inoue Katsuya , Iwamura Hüzu
Published: May 2005

Persistent organic radicals with a ferromagnetic interaction in the crystalline state are few and far between. One example is crystalline 1,3,5‐hexatriyne carrying a [4‐chloro‐3‐(N‐tert‐butyl‐N‐oxyamino)‐phenyl] substituent at position 1. This has been studied and compared with crystalline 1,3‐butadiyne (see Figure) carrying the same substituent, which, in contrast, exhibits antiferromagnetic interactions at cryogenic temperatures.

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A general approach to NR‐stabilized metal colloids in organic phases
Authors: Bönnemann Helmut , Brinkmann Rainer , Köppler Rainer , Neiteler Peter , Richter Joachim
Published: May 2005

The stabilization of metal particles in a recent synthesis of colloidal transition metals was achieved by combining the stabilizing agent (NR) with the reducing agent (NR4BEt3H). The disadvantages inherent to this method (the cost of the reducing agent synthesis and the need for stoichiometric amounts of stabilizing agent) have been overcome in the development reported here: NR‐stabilized (isolatable) metals of groups 6‒11 are produced by coupling the stabilizing agent to the metal salt that is to be reduced and reducing with simple inorganic and organic reducing agents. These isolatable colloid powders are precursors to highly active homogeneous and heterogeneous metal colloid catalysts.
Optoelectronic device technology for coherent optical communication systems
Authors: Debney Brian , Park Chris , Hankey Judith
Published: May 2005

Optical heterodyning, the principle incorporated in coherent optical communication systems, is of great interest in present‐day fiber‐optic research because it offers the ability to construct very sensitive optical receivers and to transmit and demultiplex large numbers of closely spaced optical channels carried on a fiber, thus leading to efficient use of the fiber bandwidth. The requirements on materials for heterodyne receivers and semiconductor lasers—indispensable components of coherent optical communication systems—and recent progress made toward satisfying these requirements are discussed, together with device technologies in this field.
Electronic publishing—a question of quality
Authors: Hastings Philip
Published: May 2005

Radical changes in publishing are expected in the next decade due to the acceptance and accessibility of electronic media. With the advent of powerful networks such as SuperJANET, a vast quantity of data becomes available to the scientist. Perhaps the most difficult challenges presenting themselves to the scientific community are the maintenance of quality for the benefit of users, copyright for the benefit of authors and publishers, and security of information for everyone.
Sensors for organic solvent detection in the ppm range based on dioxo[6.1.6.1]paracyclophanes—from molecular modeling to analyte recognition
Authors: Dickert Franz L. , Haunschild Alexander , Reif Martin , Bulst Wolf‐E.
Published: May 2005

Hydrophobic coatings for mass‐sensitive sensor devices, which yield a negligible water cross sensitivity, are the aim of the reported research. Molecular modeling was used to gain an understanding of the binding mechanism of some solvent molecules with a tetraazaparacyclophane containing alkyl substituents at the amino bridgeheads (CPO44VAL)— the figure shows the calculated geometry of the benzene complex of CPO44VAL. The theoretical results were then compared with the actual performance of CPO44VAL in devices.

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Geometry‐induced charge localization in doped phenylene chains
Authors: Gregorius Heike , Heitz Walter , Müllen Klaus
Published: May 2005

The mechanism of charge delocalization in mono‐ and dianions of differently substituted oligo(p‐phenylenes) has been studied by absorption spectroscopy. (Polyp‐phenylene) is of great interest in this respect, but is experimentally inaccessible because of its complete insolubility and infusibility, so data on more soluble oligomeric systems that are structurally related to the polymer have to be used to extrapolate towards the behavior of the polymer. Results from UV/vis/NIR spectra and cyclic voltammetry are reported that allow the influence of substituents on the conjugation length to be reliably predicted.
Novel cable shielding materials based on the impregnation of microporous membranes with inherently conducting polymers
Authors: Kathirgamanathan Poopathy
Published: May 2005

Cables are shielded from electromagnetic interference by wrapping them in conductive tapes such as aluminum polyester laminates, μ‐metals, or metal‐coated non‐wovens. Inherently conducting polymer (ICP) based tapes would be a lightweight option, but these are difficult to produce continuously in large quantities. This problem can be overcome by impregnating commercially available microporous membranes with an ICP. The production and electrical characterization of such impregnated membranes, including shielding efficiency measurements, are reported.
Capped nanometer silicon electronic materials
Authors: Brus Louis
Published: May 2005

New properties, structures, and concepts in solid silicon materials have been glimpsed in several experiments. In addition to the recent systematic effort to use organometallic chemical methods to make and characterize free‐standing “capped” crystallites or quantum dots—the figure shows one structure of a capped polysilyne oligomer–new chemical approaches to capped nanometer silicon micelles, puckered sheets, clusters and crystallites are presented.

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Applications of the 1,3‐dithiole unit in a post‐TTF era
Authors: Hansen Thomas K. , Becher Jan
Published: May 2005

The versatile 1,3‐dithiole (DT) ring systemprobably holds the record among heterocyclic systems for the most widespread use in modern materials science. Interest in derivatives of DT and the 1,3‐dithiolium cation DT⊕ was boosted in the past by the discovery of metal‐like conductivity in the charge‐transfer complex TTF–TCNQ and superconductivity in cation radical salts of TMTSF and BEDT–TTF. The authors examine some of the new functionalized π‐donor systems based on the TTF framework and comment on possible applications as sensors, molecular shuttles, organic ferromagnets and electroactive Langmuir–Blodgett films.
Dissipative structure formation in colloidal systems
Authors: Wessling Bernhard
Published: May 2005

Self‐organization phenomena are observed in most real systems. Is this true also for colloidal or microemulsion systems? It is argued that the current general practice of assuming that polymeric and non‐polymeric colloidal systems are in equilibrium is not valid and that non‐equilibrium thermodynamics should be applied. Photon correlation spectroscopy experiments on polyaniline dispersions are considered to indicate the presence of elongated structures (Figure).

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Novel tellurium‐containing p‐terphenoquinone analogues: Preparation and unique redox properties of paramagnetic tellurium‐centered radical cation complexes
Authors: Tamura Rui , Nagata Yuya , Matsumoto Akira , Shimizu Hiroshi , Ono Noboru , Kamimura Akio , Hori Kenzi
Published: May 2005

Amphoteric tellurium‐containing π‐donors'acceptors are reported. The electrical and magnetic properties of the charge‐transfer complexes and radical cation salts prepared from 1 (see Figure; X  Te, R1  Me) are presented. 1 exhibits a remarkably low oxidation potential compared with S analogues and a one‐step two‐electron reduction potential, indicating that its derivatives could also be of use as the first Te‐containing organic electron acceptors.

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Tuning of the photo‐ and electroluminescence in multi‐block copolymers of poly[ (silanylene)thiophene]s via exciton confinement
Authors: Malliaras George G. , Hadziioannou Georges , Herrema Jan K. , Wildeman Jurjen , Wieringa Rienier H. , Gill Richard E. , Lampoura Stephania S.
Published: May 2005

The combination of wide‐ and narrow‐band‐gap polymers in a block copolymer can provide a means of increasing the luminescence efficiency of the materials. This occurs because the excitons that are formed are trapped within specific units in the polymer chains and therefore cannot migrate to quenching sites caused by the presence of dopants. Color‐tunability is also possible through adjusting the band gaps of the components. Devices based on silanylene'thiophene lock copolymers are reproted.
Poly(arylene cobaltacyclopentadienylene)s: A new class of organometallic π‐conjugated polymers
Authors: Nishihara Hiroshi , Shimura Tadashi , Ohkubo Akira , Matsuda Nao , Aramaki Kunitsugu
Published: May 2005

A new class of π‐conjugated organometallic conducting polymers has recently been prepared making use of a novel polymerization method, metallocycling polymerization (MCP). The polymers has been found to have small band gaps and exhibit low ionization potentials. MCP is generally utilizable for complex polymers irrespective of whether they are π‐conjugated systems. The method and the new materials are presented.
Advanced materials: An emerging industrial sector
Authors: Bangemann Martin
Published: May 2005

European Community support for research on advanced materials is provided within the four‐year Framework programs for research and technological development. In particular, the current program “Industrial and Materials Technologies–BRITE/Euram II” is aimed at establishing the necessary technological base for the development of new products and processes. The Vice President of the Commission of the European Communities describes his view of the present market and future prospects for advanced materials, taking restraints imposed by a need to protect the environment into consideration.
Mass sensitive detection of solvent vapors with calix[n]arenes—conformational adaptation to the analyte
Authors: Dickert Franz L. , Schuster Oliver
Published: May 2005

Calixarenes have a hig molecular flexibility, facilitating an optimized adaptation to the shape of a large variety of guest molecules. Large substituents result in conformationally rigid compounds (Figure) but other calixarenes are ideal for coatings exhibiting high chemical sensitivity.

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Alloyed deuterated copper‐DCNQI salts: Phase transitions and reentry of conductivity, giant hysteresis effects, and coexistence of metallic and semiconducting modes
Authors: Bauer Dagmar , von Schütz Jost Ulrich , Wolf Hans Christoph , Hünig Siegfried , Sinzger Klaus , Kremer Reinhard K.
Published: May 2005

The copper salts of DCNQI (N, N'‐dicyanoquinonediimine), quasi‐three‐dimensional systems, show three possible modes of behavior at low temperatures: they remain metallic, they undergo a phase transition, or they have a suppressed phase transition, as is the case for alloyed copper salts. Deuteration of these salts can change their behavior. Alloyed deuterated copper‐DCNQI salts have been investigated using electron spin resonance, susceptibility, and conductivity measurements, revealing a reduction of the phase transition temperaturewith hystersisand reentry effects in the conductivity.
Recording of transient gratings using the short lived bacteriorhodopsin photocycle intermediates
Authors: Wu Shuguang , Bräuchle Christoph , El‐Sayed Mostafa A.
Published: May 2005

Bacteriorhodopsin, a light‐transducing protein in the purple membrane of Halobacterium halobium, has unique properties that make it a potentially attractive material for use in optical imaging and processing. A transient diffraction grating based on the K intermediate of the bacteriorhodopsin photocycle has been produced on the nanosecond time scale. The diffraction efficiency, which would be sufficient for pattern recognition for example, was measured and the intensity dependence assessed.
The Diels–Alder adduct of C60 and 4,5‐dimethoxy‐o‐quinodimethane—synthesis, crystal structure, and donor–acceptor behavior
Authors: Belik Pavel , Gügel Andreas , Kraus Alexander , Spickermann Jochen , Enkelmann Volker , Frank Georg , Müllen Klaus
Published: May 2005

Covalent linking of C60 to electron donors is expected to create attractive substrates for the study of electron or energy transfer. The successful synthesis of a 4,5‐dimethoxy‐o‐quinodimethane‐C60 adduct is described. The unique crystal structure has been determined and the bandgap measured by ESCA. One of the most interesting features of the crystal structure of the mono‐adduct is the close contact of one of the methoxy groups to a neighboring C60, leading to the formation of a chain of interacting fullerene cages.
Intrinsically conducting polymers—quo vadis?
Authors: Bäuerle Peter
Published: May 2005

Of the various types of synthetic metals, intrinsically conducting polymers (once discovered) quickly became te materials most frequently studied, owing to their properties, structural variability, and great potential for commercial applications. This month's essay traces the progress made in their investigation during the last 15 years as reflected in the contributions presented at the series of biennial international conference on synthetic metals (ICSM). Possible directions for their future development are also outlined.
Development of novel biosensor enzyme electrodes: Glucose oxidase multilayer arrays immobilized onto self‐assembled monolayers on electrodes
Authors: Willner Itamar , Riklin Azalia , Shoham Benjamin , Rivenzon Dalia , Katz Eugenii
Published: May 2005

Amperometric biosensors under development are based on electron transfer communication between enzyme redox sites and electrodes. These require well‐organized networks of enzymes exhibiting long‐range electron transfer properties. An enzyme electrode is described that consists of glucose oxidase networks organized on a self‐assembled monolayer of functionalized thiols on gold electrodes. The protein array supports electrical communication with the electrode, and the resulting assembly can be used as a glucose biosensor.
Highly oriented poly(di‐n‐alkylsilylene) films on oriented PTFE substrates
Authors: Frey Holger , Sheiko Sergej , Möller Martin , Wittmann Jean Claude , Lot Bernard
Published: May 2005

Highly oriented polysilylene layers have potential applications in electrophotography, nonlinear optics, display fabrication, and microlithography. The preparation of such layers by crystallization on a highly oriented PTFE substrate is reported, and their assessment by optical birefringence, electron diffraction and dichroic infrared experiments described. Why this orientation technique works is not yet clear, especially as it can be applied to poly(di‐n‐alkylsilylen)s with different crystal structures. Several possible underlying mechanisms are discussed.
Functionalized viologens for novel electron relay systems
Authors: Kameyama Atsushi , Nambu Yoko , Endo Takeshi
Published: May 2005

Molecular electron relay systems based on viologens substituted with, for example, crown ethers offer the opportunity to combine molecular recognition/complexation with electron transfer. Recent progress in the synthesis of such materials is reported, together with examples of their application as electron‐transfer mediators in biomimetic electron transfer systems, and the controlled reduction of organic compounds such as aromatic aldehydes and α‐ketoesters in organic solvents in which the reducing agent (e.g. Na2S2O4) is usually insoluble.
Crystal structure of α,ω‐bis(triisopropylsilyl)‐sexithiophene: Unusual conjugated chain distortion induced by interchain steric effects
Authors: Yassar Abderrahim , Garnier Francis , Deloffre Françoise , Horowitz Gilles , Ricard Louis
Published: May 2005

The structure of a sexithiophene derivative end‐substituted by two bulky triisopropylsilyl groups has been determined in an attempt to better understand the relationship between structure and the electronic and optical properties of polythiopenes. The synthesis and structural characterizaation of derivative are descried in detail and the unusual crystal system that involves staggered parallel arrays of molecules and a strong deviation from coplanarity of the π‐ conjugated backbone is discussed.
EPR study of a chiral metallomesogen: Bis{N‐[4″‐((2S)‐2‐chloropropoxy)phenyl], 4‐(4′‐n‐ decyloxybenzoyloxy)salicylaldimine}copper(II)
Authors: Alonso Pablo J. , Marcos Mercedes , Murtinez Jesús I. , Serrano José Luis , Sierra Teresa
Published: May 2005

A paramagnetic chiral smectic C material has been studied by electron paramagnetic resonance (EPR) for the first time. EPR, in conjunction with differential scanning calorimetry and optical microscopy, provides information about the molecular arrangements in the different phases. The spectra of a chiral smectic C liquid crystal copper(II) complex derived from a chiral Schiff base are discussed, which reveal polymorphic transformations that may be related to the asymmetry of the chiral molecules.
One‐step preparation of double‐walled microspheres
Authors: Pekarek Kathleen J. , Jacob Jules S. , Mathiowitz Edith
Published: May 2005

Multilayered microspheres for drug delivery can be produced by several methods, but most techniques involve several stages and often lead to layers of non‐uniform thickness. The solcent evaporation method of producing double‐layered microspheres described here svoids these difficulties, a single step yielding micrespheres consisting of an inner core of polymer surrounded by a second polymer. The theory is presented and the characterization of the microspheres discussed.
Conductiong polymer connections for molecular devices
Authors: Sailor Michael J. , Curtis Corrine L.
Published: May 2005

Ways of connecting molecular devices will be needed if the ideas of molecular electronics are ever to be realized. The potential of conducting polymer nanowires for this purpose is discussed and illustrated with the case of poly(3‐alkylthiophene), which can be made to connect two Pt wires by forming dendrites between them (see Figure).

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CVD of Covalent Compounds and high‐Tcsuperconductors
Authors: Gómez‐Aleixandre Cristina , Sanchez Olga , Albella José M. , Santiso José , Figueras Albert
Published: May 2005

Chemical vapor deposition at high temperaturesprovided the deposited atoms with the necessary surface mobility to ensure crystallinity and epitaxial growth. The use of high‐temperaure CVD in the deposition of high‐Tcsuperconducting ceramics and covalent materials such as diamond (see Figure) and boron nitride is reviewed, and, for example, the methods used to maintain the terahedral arrangement of neighboring atoms during deposition discussed.

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