bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microfibrillar reinforced composites—new materials from polymer blends
Authors: Fakirov Stoyko , Evstatiev Michail 
Published: December 2004

Microfibrillar‐reinforced composites (MFCs) are a fundamentally new type of polymer composites. MFCs are prepared by a novel technique comprising drawing a polymer blend, which leads to fibrillization (orientation of both components), followed by melting of one component while preserving the oriented structure of the higher melting point component (see Figure), This method is explained in detail by means of an example, and the mechanical parameters of an MFC are presented. magnified image
Rocking‐chair or lithium‐ion rechargeable lithium batteries
Authors: Guyomard Dominique , Tarascon Jean‐Marie 
Published: December 2004

AbstractOwing to the present exponential development of portable consumer electronics and to the increasing concern about the environment, new energy sources are required that provide more energy in the same volume and/or mass. Within a short period of time, less than three years, many changes in the area of rechargeable batteries for the consumer market have occurred, along with the emergence of several new technologies. The ubiquitous NiCd cells, which are environmentally unfriendly because of the toxicity of Cd, will be replaced by Ni‐metal hydride, rocking‐chair lithium (or Li‐ion), and lithium polymer electrolyte rechargeable cells. This paper reviews recent advances in the field of Li‐ion rechargeable batteries.
Chromophore–zeolite composites: The organizing role of molecular sieves
Authors: Caro JÜRgen , Marlow Frank , Wübbenhorst Michael 
Published: December 2004

Dyes incorporated in molecular sieve crystals can reveal information about the orientation of guests in these crystals through polarization microscopy (see Figure), Raman scattering, and second‐harmonic generation measurements. Pyroelectric studies of the dye molecule para‐nitro‐aniline inserted in the molecular sieve A1P04‐5 are described that show which of two rival models explaining the ordering of guests in molecular sieves actually holds. magnified image
Oligomeric Tetrathiafulvalenes: Extended donors for increasing the dimensionality of electrical conduction
Authors: Adam Martin , Müllen Klaus 
Published: December 2004

Novel monomeric, oligomeric, and polymeric charge‐transfer complexes with interesting electrical conductivity properties and even exhibiting superconductivity are expected to be obtainable by the systematic chemical modification of extended tetrathiafulvalenes (see Figure for one example). The synthesis and cyclic voltammetric characterization of such extended donors are reviewed in detail. magnified image
Nanostructures: New forms of luminescent silicon
Authors: Dag Ömer , Kuperman Alex , Ozin Geoffrey A. 
Published: December 2004

The cover picture represents a 60‐atom silicon nanocluster with a diamond‐like structure, within the supercage of zeolite Y. In this article, recent developments in the chemical synthesis of novel and well‐defined nanoscale forms of luminescent silicon are reviewed and the methods used to “trick” silicon (an indirect bandgap semiconductor with electric dipole forbidden luminescence) into emitting light discussed. magnified image
Nested interfacial growth of carbon nanotubes catalyzed by hafnium
Authors: Ata Masafumi , Yamaura Kiyoshi , Hudson Andrew J. 
Published: December 2004

Carbon nanotubes containing HfC crystals (see Figure) have been synthesized during the dc arc discharge of a Hf‐composite graphite electrode. Clear evidence is presented of the Hf‐catalyzed growth of the nanotubes based on transmission electron microscope images, and the growth mechanism, which is thought to be completely different to that active in the production of vapor‐grown carbon fibers or metal catalyzed nanotubes, is discussed. magnified image
Extended hybrid tetrathiafulvalene π‐donors with oligothienylenevinylene conjugated spacer groups
Authors: Elandaloussi El Hadj , Frère Pierre , Roncali Jean , Jubault Michel , Gorgues Alain , Richomme Pascal 
Published: December 2004

Hybrid tetrathiafulvalenes (HTTFs) where the TTF units are linked by thienylenevinylene spacers (see Figure) are reported. It is found that the π donor properties of the materials are improved over analogues with oligothiophene spacers, and that they exhibit a smaller band gap. The evolution of the properties as a function of spacer length and the materials syntheses are discussed. magnified image
Room‐temperature electrosynthesis of carbonaceous fibers
Authors: Herrick Robert D. , Kaplan Audrey S. , Chinh Beatrice K. , Shane Michael J. , Sailor Michael J. , Kavanagh Karen L. , McCreeey Richard L. , Zhao Jun 
Published: December 2004

Carbonaceous fibers are produced by the room‐temperature electrochemical reduction of CCl4. These fibers (see Figure) are structurally and morphologically similar to carbon fibers produced at high temperatures, and are formed sponaneously at an electrode without the need for a template, during cathodic decomposition of CCl4 in non‐aqueous electrolytes. magnified image
Novel metallic charge‐transfer complexes composed of a [3] radialene type acceptor: A 1,2‐Bis(p‐benzoquino)‐3‐12‐(dicyanomethylene)‐2,5‐selenoquinojcyclopropane Derivative**
Authors: Takahashi Kazuko , Tarutani Shinji 
Published: December 2004

Molecular metals based on the [3]radialene structure (see Fig.) as the acceptor are reported. They represent the first radialene and also the first non‐benzenoid aromatic compounds to afford molecular metals. Compressed pellets of these acceptrs complexed with TTF and TTT exhibit remarkable metallic behavior. The synthesis and the characterisation of the materials are presented magnified image.
Lithographic molding: A convenient route to structures with sub‐micrometer dimensions**
Authors: Wilbur James L. , Kim Enoch , Xia Younan , Whitesides George M. 
Published: December 2004

Elastomeric stamps with submicrometer features for use in the recently reported microcontact printing procedure are produced without the need for routine access to cleanrooms. The new technique is therefore an alternative to the use of photolithography for the fabrication of the stamps, simplifying the technology required to generate structures with sub‐micrometer dimensions (e.g. see Fig.) magnified image.
Molecular structure of sel‐organized layers of N‐Octyl‐D‐guconamide**
Authors: Crämer Konrad , Pfannemüller Beate , Magonov Sergei N. , Kreutz Werner , Tuzov Igor 
Published: December 2004

AFM images reveal deaths of self‐organized amphiphile structures of the title compound (see Fig.). Information on the morphology and the molecular order is obtained indicating that the structures are stabilized by relatively strong intermolecular interactions. The results are compared with those from studies of the same materials in gel and crystal statesmagnified image.
Transient photoconductivity in a discotic hexagonal plastic crystal
Authors: Simmerer Jürgen , Glüsen Birgit , Paulus Wolfgang , Kettner Andreas , Schuhmacher Peter , Adam Dieter , Etzbach Karl‐Heinz , Siemensmeyer Karl , Wendorff Joachim H. , Ringsdorf Helmut , Haarer Dietrich 
Published: December 2004

Charge‐carrier transport in organic materials is the fundamental physical process behind devices such as laser printers. Charge‐carrier mobility data are presented for hexabutyloxytriphenylene (H4T), which exhibits an unusually high charge‐carrier mobility, which can be traced to the formation of a plastic discotic phase. The Figure shows the normal discotic hexagonal texture with six‐fold symmetry observed for H4T at 144°C; this symmetry disappears at lower temperatures (see also the cover). magnified image
The first crystalline hexagonal Si3N4 microtubes
Authors: Huppertz Hubert , Stock Norbert , Schnick Wolfgang 
Published: December 2004

Hollow, regularly shaped hexagonal Si3N4 microtubes (see Figure) have been synthesized by reaction of cobalt metal with silicon diimide. Some are partially and some completely filled with metallic inclusions, which were identified as Co2Si. The formation of crystalline transparent filaments with non‐transparent spherical or polyhedral particles at the tip is also reported. magnified image
Bioactive polycrystalline silicon
Authors: Canham Leigh T. , Reeves Chris L. , King David O. , Branfield Paul J. , Crabb Jim G. , Ward Michael C. L. 
Published: December 2004

The bioactivity of a range of microstructured silicon materials should be assessed since it has been demonstrated that low porosity microporous silicon is “bioactive”. Work reported here shows that certain types of polycrystalline silicon are also bioactive, being corroded and exhibiting surface deposits of calcium phosphate (see Figure) when kept in simulated body fluids (SBF). magnified image
High order and submolecular imaging of end‐capped quinquethiophene on Ag(111)
Authors: Soukopp Andreas , Glöckler Kurt , Bäuerle Peter , Sokolowski Moritz , Umbach Eberhard 
Published: December 2004

Ultrathin films of functionalized oligomers with well‐defined chain and conjugation lengths are of interest for organic electronic devices. Using the example of end‐capped quinquethiophene vapor‐deposited onto a Ag(111) surface, it is demonstrated that highly ordered monolayers of chemisorbed oligomers can be obtained in very large defect‐free domains. LEED and STM (see Figure) studies provide information about the geometric parameters, molecular structure, and quality of the layers. magnified image
Deeply colored self‐assembled multilayers of anionic DPP bolaamphiphiles and cationic polyelectrolytes
Authors: Saremi Farnaz , Lange Gabriele , Tieke Bernd 
Published: December 2004

Self‐assembled ultrathin multilayer films containing DPP or DTPP chromophores are reported. The preparation of the multilayers built up out of a DPP derivative and a cationic polyelectrolyte on a silanized glass slide is described (see Figure), followed by the characterization of their optical properties. The stability of the deep red (DPP) or yellow (DTPP) films makes them particularly suitable for technical applications. magnified image
Self‐assembled wires and channels
Authors: van Nostrum Cornelus F. 
Published: December 2004

Supramolecular wires and channels are one‐dimensional molecular materials capable of transporting charge, etc. in a predefined direction. Examples are given of wires and channels that have been formed by self‐assembly in the liquid‐crystalline state or in solution, for example from alkoxy‐substituted triphenylenes (see Figure; R = aliphatic chain), using various approaches. The underlying principles are stressed. magnified image
Polyelectrolyte–Surfactant Complexes in the Solid State: Facile building blocks for self‐organizing materials
Authors: Ober Christopher K. , Wegner Gerhard 
Published: December 2004

AbstractEven though mixtures of polyelectrolytes and surfactants are used in a variety of technologies, little is known about the solid state properties of complexes formed by the two components. Recently reported methods for preparing polyelectrolytesurfactant complexes and their solid‐state structure will be described in the context of the self‐assembly behavior of the source surfactant molecules. This facile process offers the opportunity of producing a variety of new materials with applications that may range from switchable, permselective biological membranes to fluorinated materials with non‐wetting properties. In the form of a solid‐state complex, remarkably diverse mechanical properties ranging from elastomers to crystalline solids can easily be achieved. This review discusses the growing quantity of research in this new field, and in particular, the fabrication of such complexes in the form of processable self‐doped conducting polymers is described.
Electron field emitters based on carbon nanotube films
Authors: de Heer Walt A. , Bonard Jean‐Marc , Fauth Kai , Châtelain André , Ugarte Daniel , Forró László 
Published: December 2004

The excellent field emission characteristics of carbon nanotube films, i.e., the property that the tips of the nanotubes emit electrons when placed in an electric field, are discussed in some detail. The experimental configurations used (see Figure) and the results obtained are reviewed. It is suggested that carbon nanotube films should be considered as good candidates for display applications. magnified image
Template‐directed synthesis of aragonite under supramolecular hydrogen‐bonded langmuir monolayers
Authors: Litvin Arkadi L. , Valiyaveettil Suresh , Kaplan David L. , Mann Stephen 
Published: December 2004

The design of supramolecular templates to direct the synthesis of organized inorganic materials is illustrated for aragonite (CaCo3), which is metastable under ambient conditions but found in gallstones, fish otoliths, etc. Spreading of the template 5‐hexadecyloxyisophthalic acid at the air/water interface is shown to result in the specific nucleation of aragonitc (see Figure) from supersaturated calcium bicarbonate solution without additives. magnified image
Replica molding using polymeric materials: A practical step toward nanomanufacturing
Authors: Xia Younan , McClelland Jabez J. , Gupta Rajeev , Qin Dong , Zhao Xiao‐Mei , Sohn Lydia L. , Celotta Robert J. , Whitesides George M. 
Published: December 2004

The reliable fabrication of nanostructures is polymer materials, i.e. structures with feature sizes below 100 nm, is an important goal if progress in the application of such materials in electronic, magnetic, and optical devices is to be maintained. Replica molding has been used extensively to produce micrometer sized features. Here, the technique is extended to the nanometer regime such as that shown in the figure. fig.magnified image
Solid opalescent films originating from urethanes of cellulose
Authors: Zentel Rudolf , Müiller Manfred , Keller Harald 
Published: December 2004

Opalescent films of ca. 100 cm2 (see Figure and this month's cover picture) based on a renewable resource, cellulose, have been prepared. The films are based on cholesteric, semi‐interpenetrating networks which result from the crosslinking of lyotropic liquid crystalline phases of cellulose carbanilates in commercial acrylates. Photocrosslinking of the films at different temperatures allowing patterning. magnified image
Derivatized electrodes in the construction of organic light emitting diodes
Authors: Nüesch Frank , Si‐Ahmed Lynda , François Bernard , Zuppiroli Libero 
Published: December 2004

Overcoming the disadvantages of organic light‐emitting diodes (LEDs) is important if full advantage is to be taken of their benefits. It is shown that a significant increase in durability and decrease of the turn‐on operating field can be achieved by attaching the electroactive polymer to the metal‐oxide electrode chemically. The Figure shows a single‐layer LED device with an electrode derivatized with a functionalized oligophenylene layer. magnified image
3D Long‐range ordering in ein SiO2 submicrometer‐sphere sintered superstructure
Authors: Mayoral Raul , Requena Joaquin , Moya José S. , López Cefe , Cintas Adelaida , Miguez Hernán , Meseguer Francisco , Vázquez Luis , Holgado Miguel , Blanco Álvaro 
Published: December 2004

Three‐dimensional arrays of SiO2 nanometer particles lead to Bragg diffraction effects of visible light—as seen for natural opals, see also this issue's cover—and applications such as photonic bandgap materials. Teh fabrication of the opalline structures is described and details are given of how to obtain ordered compacts. The Figure shows a fracture surface of a sintered sample comprising 390 nm‐diameter silica spheres. magnified image
Polypeptide Materials: New synthetic methods and applications
Authors: Deming Timothy J. 
Published: December 2004

AbstractA review of recent developments in polypeptide synthesis is provided. This article is focused on development of new materials based on polypeptides rather than on reproduction or applications of natural protein‐based materials. Synthetic methods fall into two major categories: biological and chemical. The most successful biological approaches utilize cellular protein synthesis machinery to perform the task of assembling the polymeric molecules. Adaptation of this machinery for production of new, artificial polypeptide sequences and use of this machinery for incorporation of artificial amino acids into polypeptides have been the key recent contributions in this area. Advances in chemical polypeptide syntheses include new applications in solid and solution phase peptide coupling reactions as well as advances in the polymerization of a‐amino acid‐N‐carboxyan‐ hydride (NCA) monomers. The use of transition metal initiators in NCA polymerizations has allowed the preparation of very well defined homopolypeptides and may lead to facile routes into peptide block copolymer materials. The presence of stable, chiral structural elements in polypeptides results in self‐assembly into ordered films, composites, and liquid crystals. If their sequences are designed and constructed properly, artificial polypeptides have considerable potential for use in construction of artificial tissues and implants, ordered inorganic/organic composites, and in medical diagnostics and biosensors.
Poly(propyleneimine) dendromesogens with hexagonal columnar mesophase
Authors: Cameron James H. , Facher Andreas , Lattermann Günter , Diele Siegmar 
Published: December 2004

Dendritic mesogens—dendrimers that form mesophases—are the third group of liquid crystalline polymers (LCPs), following main‐chain and side‐chain LCPs. The synthesis of a series of different generations of dendromesogens (see Figure) is reported and their thermal behavior, molecular shape, and the textures observed by polarizing microscopy described. The role of hydrogen bonds in the formation of such mesophases is discussed. magnified image
Nanofibers
Authors: Liu Guojun 
Published: December 2004

The preparation of nanofibers—fibers with nanometer diameters—is briefly reviewed. Particular attention is paid to the synthesis based on locking‐in the mesophasic structures formed by diblock copolymers. Examples of the resulting nanofibers with a core‐shell structure (prepared for transmission electron microscopy by a freeze‐drying method) are shown in the Figure. magnified image
Dopant Electromigration in Semiconductors
Authors: Cahen David , Chernyak Leonid 
Published: December 2004

AbstractA doped semiconductor can be viewed as a mixed electronic‐ionic conductor, with the dopants as mobile ions. Normally the temperature range where this becomes true is not even close to that where the (opto)electronic properties of the material are of interest. However, notable exceptions exist and these are reviewed here, with special emphasis on those cases where semiconductivity is preserved when the (mobile) dopant concentration changes and ambipolar behavior can be obtained by dopant mobility. Dopant diffusion and drift are of interest not only in materials such as Si:Li, known from its use in radiation detectors, but also in other semiconductors, ranging from II‐VIs and related compounds, such as (Hg,Cd)Te and CuInSe2 to III‐Vs and potential high temperature semiconductors, such as diamond. Better understanding of the phenomena is important also because of the implications that it has for device miniaturization, as dopant diffusion and drift put chemical limits to device stability. Such understanding can also make dopant electromigration useful for low‐temperature doping. Some basic theory for electric‐field‐induced dopant migration is given and compared to experiments.
Design of strongly NLO‐active molecularly‐based ferromagnets
Authors: Bénard Sophie , Yu Pei , Coradin Thibaud , Rivière Eric , Nakatani Keitaro , Clément René 
Published: December 2004

Molecule‐based ferromagnets that exhibit strong second‐harmonic generation (SHG) are presented here for the first time. The strategy for producing such materials—replace the “innocent” bulky cations (C) in the C[M′M(ox)3] family of bimetallic magnets (M′ is e.g. Mn and M = CrIII or FeIII; the Figure shows the structure) by hyperpolarizable cationic chromophores—is described and X‐ray, magnetic, and SHG results are reported.magnified image
Self‐assembled PAMAM dendrimer films
Authors: Evenson Simon A. , Badyal Jas Pal S. 
Published: December 2004

Self‐assembly of starburst dendrimers into closely packed cells (see the optical micrograph in the Figure) is reported for generation 9.5 polyamidoamine (PAMAM) dendrimers solvent‐cast onto hydrophilic silicon substrates. It is shown that on the microscopic scale the cells are made up of a complex network of intertwined dendritic microfibrils. Potential applications of such novel surfaces are suggested.magnified image
Aligned aluminophosphate molecular sieves crystallized on floating anodized alutnina by hydrothermal microwave heating
Authors: Tsai Tzeng‐Guang , Chao Kuei‐Jung , Guo Xing‐Jian , Sung Shing‐Li , Wu Chih‐Ning , Wang Yuh‐Lin , Shih Han‐Chang 
Published: December 2004

Thin films of aligned zeolite crystals can significantly improve the quality of advanced materials prepared using zeolites as a nanostructured host. A membrane of vertically aligned aluminophosphate molecular sieves is prepared on floating anodized alumina using microwave heating. The Figure shows the first step in the proposed synthetic scheme—preformed nuclei penetrate the cylindrical nanochannels of the alumina substrate.magnified image
Wire formation on circuit boards using spatially coupled bipolar electrochemistry
Authors: Bradley Jean‐Claude , Crawford Jeffrey , Ernazarova Karima , McGee Michael , Stephens Samuel G. 
Published: December 2004

The creation of electrical contacts between selected copper rings on a commercial circuit board by a novel method is reported. The method relies on spatially coupled electrodissolution and electrodeposition mediated by an electric field, followed by electroless deposition. The Figure shows an example of a conductive wire formed between two circular rings after the electroless plating step—see also the cover of this issue.magnified image
Organoporous hosts with adjustable molecular environments
Authors: Swift Jennifer A. , Russell Victoria A. , Ward Michael D. 
Published: December 2004

Tailored organoporous materials—the organic counterparts to inorganic nanoporous materials–have been prepared by a design strategy based on the observation that guanidinium organosulfonates (C(NH2)3⊕RSO3⊖) crystallize predictably in layered structures. The extension to disulfonates is shown to produce, among others, the motif shown in the Figure (the ovals are organodisulfonate pillars and the rectangles, guests).magnified image
Glioma therapy and real‐time imaging of neural precursor cell migration and tumor regression
Authors: Shah Khalid , Bureau Emilie , Kim Dong‐Eog , Yang Katherine , Tang Yi , Weissleder Ralph , Breakefield Xandra O. 
Published: December 2004

AbstractDespite many refinements in current therapeutic strategies, the overall prognosis for a patient with glioblastoma is dismal. Neural precursor cells (NPCs) are capable of tracking glioma tumors and thus could be used to deliver therapeutic molecules. We have engineered mouse NPCs to deliver a secreted form of tumor necrosis factor–related apoptosis–inducing ligand (S‐TRAIL); S‐TRAIL is optimized to selectively kill neoplastic cells. Furthermore, we have developed means to simultaneously monitor both the migration of NSCs toward gliomas and the changes in glioma burden in real time. Using a highly malignant human glioma model expressing Renilla luciferase (Rluc), intracranially implanted NPC‐FL‐sTRAIL expressing both firefly luciferase (Fluc) and S‐TRAIL was shown to migrate into the tumors and have profound antitumor effects. These studies demonstrate the potential of NPCs as therapeutically effective delivery vehicles for the treatment of gliomas and also provide important tools to evaluate the migration of NPCs and changes in glioma burden in vivo. Ann Neurol 2005;57:34–41