bluuebunny/crossref_metadata_2025_split huggingface dataset:
The radical cation iodide of the new electron donor tetraiodotetrathiafulvalene: Magnetic properties and crystal structure
Authors: Gompper Rudolf , Hock Joachim , Polborn Kurt , Dormann Elmar , Winter Hubert 
Published: December 2004

Tetrathiafulvalene and its derivatives can be chemically or electrochemically oxidized to yield stable radical cation salts which display unusual electrical properties. In order to increase the dimensionality of the system by extending the π‐conjugation and thus stabilizing the metallic state, while at the same time keeping the system small, the tetraiodo‐derivative (see Fig.) has been synthesized and characterized. magnified image
Imaging the surfaces of nanoporous semiconductors by atomic force microscopy
Authors: Enzel Patricia , Henderson Grant S. , Ozin Geoffrey A. , Bedard Robert L. 
Published: December 2004

Open framework semiconductors tin(IV) sulfides and tin(IV) selenides) exhibiting bulk crystalline nanoporosity have been studied using atomic force microscopy (AFM). The bulk porosity is reflected in the surface structures of these materials (see Fig.), and little reconstruction can be detected, important points in the assessment of the electrical transport characteristics of this new class of nanoporous materials. magnified image
Excited‐state complexes of conjugated polymers
Authors: Jenekhe Samson A. 
Published: December 2004

Excited‐state charge‐transfer complexes (exciplexes) of conducting polymers can be formed by the absorption of light by the polymers (e.g. see Figure), and their generation is not restricted by the free‐energy requirements of their ground‐sate analos. This makes them of particular interest for applications ranging from xerographic photoconductors to nonlinear optics and LEDs. magnified image
Synthesis and compositional tuning of the band properties of isostructural TMA–SnSxSe1–x−1 Nanoporous Materials
Authors: Ahari Homayoun , Ozin Geoffrey A. , Bedard Robert L. , Petrov Srebri , Young David 
Published: December 2004

Crystalline, nanoporous tin chalcogenide semiconducting materials (see Figure) in which the band gap can be fine tuned chemically are reported. Variation of the proportions of slfur and selenium in the title materials results in the absorpton maxima red shifting with increasing selenium content over a range of 100 nm (350–450 nm). magnified image
New angular molecular donor containing two tetrathiafulvalene (ttf) units fused to selenophene: synthesis, x‐ray structure, cyclic voltammetry and conducting charge transfer complex with TCNQ**
Authors: Wang Changsheng , Ellern Arkady , Becker James Y. , Bernstein Joel 
Published: December 2004

Extended TTF‐based donor systems based for the first time on selenophene (see Fig.) are reported. Selenophene is an isologue of thiophene but has a stronger electron‐donating ability, a larger size, and a higher polarizability. These factors should lead to materials with increased bandwidth, improved dimensionality, increased electrical conductivity, and reduced on‐site Coulombic repulsion. The one‐pot synthesis of these materials and their complexation with TCNQ are presented magnified image.
Noncovalent synthesis of organic fibers**
Authors: Menger Fredric M. , Lee Stephen S. , Tao Xueliang 
Published: December 2004

The self‐assembly of organic molecules into fibers (e.g. see Fig.) is reversible. In the dreams of chemists the exploitation of this phenomenon could lead, for example, to the use of bio‐compatible fibrous organics to simulate blood clots. Dissolution of the clot could be affected thermally or chemically. Recently developed technology which could make this sort of ting possible in the future is reviewed magnified image.
Fabrication of three‐dimensional micro‐structures: Microtransfer molding
Authors: Zhao Xiao‐Mei , Xia Younan , Whitesides George M. 
Published: December 2004

Microtransfer molding is a new technique for rapidly fabricating micrometer‐scale structures over large areas (3.5 cm × 0.8 cm). This new technique, which involves the solidification of a liquid precursor in an elastomeric mold, can generate microstructures of organic polymers and ceramics such as that shown in the Figure on both planar and contoured surfaces and is able to make three‐dimensional structures layer by layer. magnified image
Tools and strategies for Developing New Materials
Authors: Gür Turgut M. 
Published: December 2004

AbstractThe synergistic dependence of materials properties and performance upon structure and processing provides effective strategies for developing new materials for advanced technologies. This intimate interplay provides the central theme of this article. Advanced synthesis techniques, controlled microstructure, compositional tuning and theoretical predictions are powerful tools for searching for new materials or improved properties. These are discussed by selected examples including fullerenes, giant magnetoresistance multilayers, diamond and nitride films. The article also provides a brief overview of these materials and discusses their technological significance.
Aligned ZrO2(c)‐CaZrO3 eutectics grown by the laser floating zone method: Electrical and optical properties
Authors: Peña José I. , Merino Rosa I. , de la Fuente Germán F. , Orera Victor M. 
Published: December 2004

Ceramic eutectics grown from the melt have great structural advantages compared to conventional ceramics and also properties that make them suitable for applications as electronic and optical materials. The preparation of ordered lamellar eutectics of ZrO2(c)CaZrO3 is described and the macroscopic and engineering characteristics of the material reported. The Figure shows an optical micrograph of a transverse section obtained in the transmission illumination mode. magnified image
Molecularly imprinted polymers for optochemical sensors
Authors: Dickert Franz L. , Thierer Sylvia 
Published: December 2004

Molecular imprinting can be used to generate selective cavities—which are required for sensors—more easily than traditional synthesis. Polyurethanes with exactly adapted cavities, created by the evaporation of solvent vapors, are used to demonstrate the principle and also how the embedding of a dye enables optical detection to be employed. The Figure shows a polyurethane host with ethanol guest molecules. magnified image
Alteration of the electrochemistry of fullerene C60 in the presence of dioxygen: Formation of a redox‐active polymeric film
Authors: Winkler Krzysztof , Costa David A. , Fawcett W. Ronald , Balch Alan L. 
Published: December 2004

A new route to the formation of an electrochemically active film that contains fullerene units is reported. The method involves the reduction of C60 to its dianion in the presence of dioxygen and produces a film (see Figure) that is similar, but not identical to films prepared by the electrochemical reduction of C60O. This new method of fullerence polymerization therefore avoids the need for the tedious preparation and purification of C60O. fig.magnified image
Controlling the surface properties of high temperature superconductors
Authors: Mirkin Chad A. , Xu Feng , Zhu Jin 
Published: December 2004

Molecular monolayer‐based surface modification has been used extensively for three of the four important classes of electronic materials, namely metals, semiconductors, and insulators. In this article recent progress in the application of t. is technique, which is commonly called “self‐assembly”, to the modification of the surfaces of high‐Tc superconductors (e.g. see Figure) is reviewed. magnified image
The phthalocyanine approach to second harmonic generation
Authors: de la Torre Germa , Torres Tomás , Agulló‐López Fernando 
Published: December 2004

Phthalocyanine‐based nonlinear optical (NLO) materials are reviewed, with particular emphasis on second‐order effects. The requirements on materials and molecules for NLO activity are outlined before three recently studied families are briefly considered: asymmetrically substituted phthalocyanines (Pcs), subphthalocyanines. magnified image
Soluble alkyl‐ and alkoxy‐substituted titaniumoxo phthalocyanines: Synthesis and photoconductivity
Authors: Haisch Peter , Winter Götz , Hanack Michael , Lüer Larry , Egelhaai Hans‐Joachim , Oelkrug Dieter 
Published: December 2004

The high photosensitivity of titaniumoxo phthalocyanines makes them suitable for application as charge generation materials, e.g., in photocopiers. The synthesis, photophysical, and photochemical properties of soluble titaniumoxo phthalocyanines containing alkyl and alkoxy substitutents (see Figure) in the periphery of the phthalocyanine ring are reported, the photoconductivity and photooxidation behavior being stressed. magnified image
Elastomeric light valves
Authors: Qin Dong , Xia Younan , Whitesides G. M. 
Published: December 2004

Two types of elastomeric light valves, their fabrication, performance, and application, are described. Both are thin blocks of poly(dimethylsiloxane), PDMS, with relief structures on their surfaces, either an array of square pyramids or an array of retroreflective corner cubes (see Figure). Use of the valves in a display device is demonstrated, in which the transparency can be controlled by mechanical compression. magnified image
Orientation of liquid‐crystalline suspensions of vanadium pentoxide ribbons by a magnetic field
Authors: Commeinhes Xavier , Davidson Patrick , Bourgaux Claudie , Livage Jacques 
Published: December 2004

Non‐invasive alignment and rotation of liquid‐crystalline suspensions of vanadium pentoxide ribbons by a magnetic field is reported. The ribbons align as shown in the Figure if the magnetic field, initially applied along the capillary main axis, is perpendicular to the main axis but still in the plane of the figure. It is believed that this simple idea could be applied to any nematic suspension of mineral compounds.magnified image
Magnetically modulated microwave absorption (MMMA) measurements at low magnetic fields on the ferromagnetic state of [TDAE]C60
Authors: Bele Petra , Brunner Hermann , Schilder Andreas , Gmeiner Jürgen , Scheoerer Markus 
Published: December 2004

The ferromagnetic state and reported superconductivity of [TDAE]C60 (where TDAE is titrakis(dimethylamino)ethylene, see Figure) are investigated by magnetically modulated microwave absorption (MMMA). The results are compared with those‐reported using alternative physical measurement techniques, and a hypothesis proposed to explain the observed behavior. No evidence for superconductivity is found.magnified image
Self‐Organized Quantum Wires and Dots in III – V semiconductors
Authors: Asahi Hajime 
Published: December 2004

The fabrication of quantum wires and quantum dots in III–V semiconductors using self‐organization phenomena is reviewed. The Stranski–Krastanov (S‐K) mode growth, step‐bunching, and strain‐induced lateral composition modulation techniques are covered. The Figure shows the vertical stacking of islands that are formed by the alternate S‐K mode growth of five cycles of an In(Ga) quantum dot layer and a GaAs spacer layer.magnified image
Measurement of CdxHgi‐xTe composition depth profiles using auger electron spectrometry on bevelled sections
Authors: Gale I. G. , Clegg J. B. , Capper P. , Maxey C. D. , Mackett P. , O'Keefe E. 
Published: December 2004

AbstractThe width of the band gap in the ternary system CdxHgI‐xTe (CMT) is a function of the value of x and the assessment of device structures requires reliable techniques for the measurement of x both laterally and with depth. This work describes the development of an Auger electron spectrometry (AES) method for the measurement of CMT composition depth profiles, based on measurement of the Cd/Te ratio along shallow‐angle bevelled sections through epitaxial layers. Results are accurate to within 3% relative and the depth resolution (Δz = 2σ) is about 0.04 μm even through layer structures with a total thickness of about 20 μm. Techniques for making the bevel sections are described together with the AES measurement and calibration techniques. A composition depth profile is given for a heterostructure grown by metal organic vapour phase epitaxy (MOVPE), showing the interface width (Δz = 2σ) at the composition change to be 0.3 μm. The CdTe/CMT interface widths in material grown by liquid phase epitaxy (LPE), MOVPE and molecular beam epitaxy (MBE) are shown to be highly dependent on growth temperature, with widths of 1.5, 0.2 and ⩽ 0.04 μm respectively.
Macro‐ and microsegregation of Zn in bridgman‐grown CdZnTe
Authors: Capper P. , Harris J. E. , O'Keefe E. S. , Jones C. L. , Gale I. 
Published: December 2004

AbstractOne of the remaining problems in the use of CdZnTe material as substrates in liquid phase epitaxy (LPE) of CdxHg1‐xTe (CMT) layers is that of variation in lattice matching, i.e. Zn content, across substrates. This wil become increasingly important in the future as larger focal plane arrays of infrared detectors are required. The basic Bridgman growth process for CdTe/Cd0.96Zn0.04Te has been extended by applying the accelerated crucible rotation technique (ACRT). A marked reduction in axial Zn segregtion is seen in 50 mm diameter ACRT material, but this effect is smaller in the case of 75 mm diameter crystals. Radial variations in Zn content are small in both sizes of crystal, demonstrating the benefits obtained from ACRT stirring. Both macro‐ and microsegregation effects have been studied in these crystals in an attempt to understand the growth mechanism. Zinc distributions have been assessed by near‐infrared transmission, X‐ray lattice parameter measurements, atomic absorption spectrometry (AAS) and Auger electron spectrometry (AES). The last technique was used for the microsegregation studies, while AAS provides the absolute calibration for Zn content. Comparisons with segregation behaviour found in the literature will be given. It will be shown that the low temperature gradient and low growth rate lead to a degree of supercooling in the first‐to‐freeze region and this leads to significant Zn segregation in both radial and axial directions. As the crystals reach full diameter, the radial variation is decreased, presumably by the action of the ACRT, and axial segregation is also reduced.
Controllable transmission of information in excitable media: The 2+ medium
Authors: Adamatzky Andrew I. 
Published: December 2004

AbstractIn this paper we address the problem of how to implement directed dispatching of information in homogeneous excitable media. To do this, we surveyed cellular automaton models which reveal spatial oscillating patterns of excitation. Thus we discovered a medium where any element at rest was excited if just two of its nearest neighbours were excited. A medium of this kind, the 2+ medium, does not support the spreading of ordinary autowaves, but in its evolution one can find compact movable groups of excited states. Here we demonstrate that such solitary waves with particle‐like behaviour will change their velocity vectors as a result of external singular stimulation. Thus they can be used as objects with controllable movement which transmit information in disordered surroundings. The results of this work can be utilised in the design of molecular computers.
Diffusion of iodine into CdTe at room temperature
Authors: Malzbender J. , Jones E. D. , Shaw N. , Mullin J. B. 
Published: December 2004

AbstractStudies on the diffusion of iodine into CdTe at a temperature of 20°C using four widely differing types of diffusion sources are compared and discussed. The concentration profiles were measured using either a radiotracer sectioning (RTS) technique or secondary ion mass spectrometry (SIMS).The profiles were composed of four parts to which a computer package consisting of the sum of four complementary error functions (erfc) gave accurate fits, providing four empirical values of the diffusivity. The diffusivities for the fastest component in all four cases were in agreement (∼2 × 10−14 cm2 s−1) and were consistent with previously published data. These results indicate that when iodine is diffused from the vapour it is not a suitable long‐termstable dopant in devices where sharp junctions are required.
New cubane MOCVD precursors for gallium sulphide and gallium selenide: Synthesis of [(Et2MeC)GaS]4 and [(Me2EtC)GaS]4: Structural determinations of [(Et2MeC)GaS]4 by X‐ray diffraction and [(tBu)GaSe]4 by electron diffraction
Authors: Power Michael B. , Barron Andrew R. , Hnyk Dráhomír , Robertson Heather E. , Rankin David W. H. 
Published: December 2004

AbstractThe gallium sulphide cubane compounds [(Me2EtC)GaS]4 and [(Et2MeC)GaS]4, have been synthesised, and their potential as MOCVD precursors for GaS is discussed. The molecular structure of [(Et2MeC)GaS]4 has been determined by X‐ray diffraction. In addition, the vapour phase structure of the GaSe precursor, [(tBu)GaSe]4 has been determined by gas phase electron diffraction and is compared with that previously determined in the solid state by X‐ray diffraction.
Fuel utilization in subjects with carnitine palmitoyltransferase 2 gene mutations
Authors: Ørngreen Mette C. , Dunø Morten , Ejstrup Rasmus , Christensen Ernst , Schwartz Marianne , Sacchetti Massimo , Vissing John 
Published: December 2004

AbstractPatients with the myopathic form of carnitine palmitoyltransferase II (CPT II) deficiency typically experience muscle pain, cramps, and myoglobinuria during prolonged exercise. It has been suggested that carriers of CPT2 gene mutations also may have milder clinical symptoms, but fatty acid oxidation (FAO) has never been investigated in vivo in this group. We studied fuel utilization by indirect calorimetry and stable isotope methodology in four patients with CPT II deficiency, three subjects who carried one CPT2 gene mutation, and five healthy control subjects. Cycle exercise at a constant workload of 50% of maximal oxygen uptake capacity was used to facilitate FAO. We found that in vivo oxidation of long‐chain fatty acids was normal at rest but severely impaired during prolonged, low‐intensity exercise in patients with CPT II deficiency, and that two of the single CPT2 gene mutation carriers, who displayed symptoms of CPT II deficiency, had an FAO comparable with the patients. These results indicate that residual CPT II activity is sufficient to maintain long‐chain FAO at rest in CPT II deficiency but not to increase FAO during exercise. The findings also suggest that single CPT2 gene mutations may exert a dominant‐negative effect on the tetrameric CPT II protein. Ann Neurol 2005;57:60–66
Natural history of neurofibromatosis 1–associated optic nerve glioma in mice
Authors: Bajenaru M. Livia , Garbow Joel R. , Perry Arie , Hernandez M. Rosario , Gutmann David H. 
Published: December 2004

AbstractChildren affected with the inherited tumor predisposition syndrome, neurofibromatosis 1 (NF1), are prone to the development of low‐grade astrocytic optic pathway tumors (optic pathway glioma [OPG]). Previously, we developed a model of NF1‐associated astrocytoma (GFAPCre; Nf1flox/mut mice) in which mice develop optic nerve and chiasm glioma. To define the molecular pathogenesis of OPG, we used this mouse model to study the natural history of OPG formation using immunohistological and radiographic approaches. We observed that whereas astrocyte hyperplasia is present in the optic nerves associated with gross optic nerve thickening at 3 weeks of age, overt neoplastic changes were not seen until 2 months of age. Astrocyte proliferation was maximal between 3 weeks and 2 months of age, suggesting that the most rapid period of growth occurs early. Mouse OPG tumors were detected by magnetic resonance imaging at 2 months of age and exhibited contrast enhancement, as seen in human OPG. In addition, the mouse OPG tumors exhibited expression of proteins associated with astroglial progenitors, including nestin and brain lipid binding protein. Last, we observed neovascularization and microglial cell infiltration by 3 weeks of age before overt neoplastic transformation, suggesting that these cellular changes participate in the early stages of tumor formation. Ann Neurol 2005;57:119–127
p.S143F mutation in lamin A/C: A new phenotype combining myopathy and progeria
Authors: Kirschner Janbernd , Brune Thomas , Wehnert Manfred , Denecke Jonas , Wasner Christina , Feuer Anja , Marquardt Thorsten , Ketelsen Uwe‐Peter , Wieacker Peter , Bönnemann Carsten G. , Korinthenberg Rudolf 
Published: December 2004

AbstractWe report a young girl with a phenotype combining early‐onset myopathy and a progeria. She had myopathy and marked axial weakness during the first year of life; progeroid features, including growth failure, sclerodermatous skin changes, and osteolytic lesions, developed later. We identified the underlying cause to be a hitherto unreported de novo missense mutation in the LMNA gene (S143F) encoding the nuclear envelope proteins lamins A and C. Although LMNA mutations have been known to cause Hutchinson–Gilford progeria syndrome and Emery–Dreifuss muscular dystrophy, this is the first report of a patient combining features of these two phenotypes because of a single mutation in LMNA. Ann Neurol 2005;57:148–151
Fragile X–associated tremor/ataxia syndrome in sisters related to X‐inactivation
Authors: Berry‐Kravis Elizabeth , Potanos Kristina , Weinberg Dahlia , Zhou Lili , Goetz Christopher G. 
Published: December 2004

AbstractFragile X tremor/ataxia syndrome (FXTAS) is a recently described condition consisting of tremor, ataxia, parkinsonism, and executive dysfunction, presenting predominantly in male carriers of a fragile X mental retardation 1 premutation. In this report, we present premutation carrier sisters in whom severity of clinical signs correlated with a molecular pattern of X‐inactivation favoring higher expression of the premutation allele. In these women with a common genetic background, we suggest that symptom severity may be dictated by X‐inactivation, and thus a higher percentage of cells producing the premutation‐containing mRNA result in increased toxicity and disease. Ann Neurol 2005;57:144–147
Band centrifugation of macromolecules in self‐generating density gradients. III. Conditions for convection‐free band sedimentation
Authors: Vinograd Jerome , Bruner Robert 
Published: December 2004

AbstractThe conditions for convection‐free hand sedimentation are analyzed in terms of the negative density gradients associated with the leading edge of a band and the positive density gradients generated during the experiment. The amount of material necessary to perform a band‐centrifugation experiment depends on the diffusion coefficient of the macromolecules, which determines the rate at which the concentration at band maximum decreases, and on the extinction coefficient at the wavelength of observation. The maximum negative gradients in bands of macromolecules with diffusion and extinction coefficients typical of proteins, nucleic acids, and viruses are calculated. Positive density gradients generated by diffusion of small molecules between the thin lamella and the bulk solution are calculated for bulk solutions such us 1M NaCl or 95% D2O. These “diffusion gradients” are generally adequate to stabilize bands of the above macromolecules. Positive density gradients generated by sedimentation of salts within the bulk solution may be significant in providing stability near the bottom of the cell. The effects of inadequate stabilizing gradients are discussed, and are found to cause forward spreading of the band.