bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of LBG addition to carrageenan on the mechanical stability of the gel and the fermentative activity of immobilized propionic acid bacteria
Authors: Czaczyk K. , Olejnik A. , Trojanowska K.
Published: December 2004

In the first part of the experiments, the mechanical properties of 1%, 2% and 3% carrageenan and 1%, 2% and 3% carrageenan/locust bean gum (LBG) gels stored in various concentrations of propionic and acetic acids and their mixtures were examined. The stability of these materials was measured by uniaxial compression between two parallel plates using the Instron Universal Testing Machine. A mathematical model explaining the dependence of the destroying force on the storage time was chosen for data analysis. Using this model, the average rate of gel deterioration was calculated. The structural properties of the examined gels were most influenced by the highest concentration of propionic and acetic acids and their mixtures (1% acetic acid and 2% propionic acid). The addition of LBG to carrageenan decreased the gel destroying force and increased its resistance to acids.

In the second part of the experiments, the Propionibacterium freudenreichii subsp. shermanii NCFB 1081 and NCFB 566 were immobilized in a living state in 1%, 2% and 3% carrageenan and 1%, 2% and 3% carrageenan/LBG gels. The ammonia consumption, glucose utilization, production of propionic and acetic acids and the biosynthesis of vitamin B12 were examined. An increase in the productivity of propionic acid and a significant decrease in the vitamin B12 produced in the biosynthesis were observed when immobilized cells were used. The immobilization of cells enhanced the productivity of propionic acid by up to 40% compared to free cells. The best results were obtained for the second and third applications of immobilized cells in all concentrations of carrageenan gels and 2% and 3% carrageenan/LBG gels The results showed that carrageenan/LBG is a better support material for the immobilization of propionic acid bacteria than the pure carrageenan.
Optimization of the production of bacterial cellulose using multivariable linear regression analysis
Authors: Galas E. , Krystynowicz A. , Tarabasz‐Szymanska L. , Pankiewicz T. , Rzyska M.
Published: December 2004

The biosynthesis of bacterial cellulose by Acetobacter xylinum was optimized by numerically finding the maximum of an arbitrarily chosen second order polynomial model function of several variables (describing the dependence of the cellulose production on the concentrations of the medium components), using multivariable linear regression analysis. The chosen function appeared to describe the analyzed correlation sufficiently well. Consequently, three to six stages of optimization made the determination of the optimum medium compositions possible for 16 days of fermentation at 30°C in a medium based on fructose (wt%: fructose, 3.68; yeast extract, 5.02; (NH4)2NO3, 0.001; KH2PO4, 0.3; MgSO4 × 7 H2O, 0.05; resulting in a cellulose production equal to 0.505 wt.% – namely 5.6 times higher than before the optimization) and for 7 days fermentations at 30°C in a medium based on sucrose and ethanol (wt.%: sucrose, 5.0; ethanol, 1.36; yeast extract, 1.27; (NH4)2SO4, 0.5; KH2PO4, 0.3; MgSO4 × 7 H2O, 0.05; resulting in a cellulose production equal to 0.251 wt.% – namely 1.5 times higher than before the optimization).
Flame‐burned stainless steel wire spheres as carriers of Zymomonas mobilis cells and extracellular levansucrase
Authors: Bekers M. , Laukevics J. , Upite D. , Kaminska E. , Linde R.
Published: December 2004

In the present work, the use of flame‐burned WS as carriers of Z. mobilis and extracellular levansucrase and the effect of the cell fixation method by dehydration on system productivity were investigated. Lyophilization and convective drying of Z. mobilis biomass at 30°C to a moisture content of 10–14% gave the best results for the repeated batch fermentations of a sucrose medium to obtain levan and ethanol. Significant correlation between the product formation and the concentration of free cells in the fermentation medium was established. Clearly, the cells were weakly bound to the newly generated WS and were washed out into the medium during fermentation. Here the hypothesis is presented that components excreted from damaged cells during dehydration can intensify the reactivation of damaged living cells and influence the interactions between the cells and the wire surface.

The passive immobilization of extracellular levansucrase in oxidized WS was also observed. The superiority of oxidized WS in comparison with non‐treated WS is related to an increase in the number of OH groups. The potential regeneration of WS by burning after the termination of fermentation cycles was also considered.
Production of L‐malate from fumarate by the yeast Dipodascus magnusii
Authors: Miková H. , Rosenberg M. , Krištofíková L. , Sulo P.
Published: December 2004

An alternative microbiological method for the production of malate from fumarate is presented. The yeast Dipodascus magnusii was used for this bioconversion.

The optimum cell growth temperature was 28°C and the working volume 120 ml. The highest level of fumarase activity during bioconversion was achieved at a pH of 7.5 and a temperature of 37°C. These conditions were determined as optimal. Using sodium fumarate (1M), the maximum specific productivity of malic acid obtained was 1.72 g/(gDCW × h) for intact cells. In the case of ammonium fumarate, it was 2.25 g/(gDCW × h).
Continuous preparative liquid chromatography in the downstrem processing of biotechnological products
Authors: Schulte M. , Britsch L. , Strube J.
Published: December 2004

Continuous counter‐current chromatographic processes have been successfully used in the petrochemical and sugar industry over the last 30 years. Only recently has simulated moving bed (SMB)‐technology attracted widespread interest in the pharmaceutical industry, mainly as a very efficient system for chromatographic enantioseparation. The application of this technique to the downstream processing of biotechnological products requires some specific changes to meet the special demands of bioproduct isolation. Production processes are set up on an multi‐ton scale, for example, for the purification of fructose with both yield and purity higher than 90%. Examples for other mono‐ and oligosaccharides are reported. In the purification of fatty acids or fat soluble vitamins, SMB technology under supercritical fluid conditions gives additional benefits and increases the productivity by a factor of four when a pressure gradient is applied. Another field of operation is the isolation of drug compounds from natural sources where different batch‐ and SMB‐chromatographic steps could be successfully combined. First examples are reported for cyclosporine A and paclitaxel isolation. Finally, step‐gradient elution modes can be used continuously, as demonstrated for the isolation of monoclonal antibodies.
Advanced primary treatment of waste water using a bio‐flocculation‐adsorption sedimentation process
Authors: Zhao W. , Ting Y. P. , Chen J. P. , Xing C. H. , Shi S. Q.
Published: December 2004

An advanced primary treatment process for a municipal waste water was systematically studied, using a bio‐flocculation‐adsorption, sedimentation and stabilzation process (BSS). It was shown that the organic removal efficiency was higher than that of the traditional primary treatment processes but lower than that of the traditional secondary treatment processes. Both adsorption and bio‐flocculation played an important role in the removal of pollutants. The activated sludge within the bio‐flocculation‐adsorption tank could be considered a bio‐flocculent which improved the quality of the effluent from the primary treatment process. As the effluent of the BSS process did not meet the requirements for a typical secondary effluent, the process may be regarded as an advanced (or enhanced) primary treatment process, suitable for waste water containing a high concentration of suspended solids and colloidal particles.
Scientific methodology for complex systems: Macroscopic patterns in eco‐ and anthropo‐sphere
Authors: Moser A.
Published: December 2004

A quite unconventional, innovative scientific methodology called “macroscopic pattern analysis” is presented in this paper. This approach is more adequate in the case of complex systems than the well‐known microscopic, mechanistic approach. Complex systems are not only attracting more engineering interest, but their scientific treatment is increasingly wanted by society due to the manifold problems in Earth's ecosphere. The macroscopic pattern approach will be explained in depth and illustrated in some case studies from the ecosphere (sustainability, hurricanes and avalanches), where nature serves as a teacher for the solution of the sustainability problem. Then, a series of case studies on macropatterns are described showing the problem‐solving capacity for anthropo‐ and technosphere: sustainability in society with an index of sustainability, the eco‐social market economy with eco‐tech as an instrument, biokinetics, bioreactor mixing and integrated bioprocessing with models, design of cars and houses and even quality of life as an attempt to quantify macropatterns.

The innovations are briefly compared in their problem‐solving capacity with known approaches such as the microscopic method in science, technology and society (free market economy), including the evaluation of other indices and cleaner production, industrial ecology and zero emission initiative. Finally, a deeper integration of sciences, ethics, arts and nature will be introduced based on the vision with macroscopic pattern analysis, where the different domains of human life are integratable to effect a reconciliation.
Materials for Biomedical Applications—Bone and Joint Replacements
Authors: Heimke Günther
Published: December 2004

Biomaterials replace body tissues which no longer fulfill their function. In the first article of a quarterly review series Günther Heimke traces the development of biomaterials research and highlights important areas such as ceramics, polymers and the interfaces between these materials and the organic host environment.

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Aerospace materials research opportunities
Authors: Salkind Michael
Published: December 2004

As we approach the second century of aerospace, increased emphasis is being placed on endurance, reliability, ease of manufacture, and lower cost, in addition to weight saving. This change in emphasis will have a major effect on not only the selection of materials, but on how materials are integrated into the total system design process. Subsonic aircraft will continue to play a major role in our future with emphasis on increased durability and lower cost. Non‐metals that do not corrode are attractive; however, the issues of reliable fracture resistance to ensure safety and durability as well as ease of manufacture and inspection will be key. Higher performance engines and hypersonic aircraft will require higher temperature materials (including a substantial amount of non‐metals) along with reliable toughness and ease of manufacture. In space, weight will continue to be a major driving force along with the need for long term vacuum and radiation stability. Ease of assembly and multifunctional use (e.g. electrically or thermally conducting structure) will be additional needs for spacecraft materials. We have reached a point in the evolution of structural materials where we are moving away from processing naturally occurring materials toward synthesizing designed microstructures to perform specific functions. The mathematical modeling of microstructure–property relationships and new chemical and biotechnical synthesis techniques appear to be critical technologies for the future. In addition, the future materials developer will need a broader understanding of the total structural life cycle so that the impact of utilization, maintenance, and training requirements in the design of new materials can be considered.
The materials research society
Authors: Chang Robert P. H.
Published: December 2004

In its seventeen years of existence the Materials Research Society (MRS) has witnessed tremendous advances in the research and development of, for example, ceramics, semiconductors and biomaterials. The basis and development of the Society as well as the newly founded International Materials Research Committee are described, and the MRS's interdisciplinary activities are presented.
Surface analysis II. Surface‐plasmon enhanced resolution in optical microscopy
Authors: Rabe Jürgen P.
Published: December 2004

Methods of improving the resolution of optical microscopes which involve, for example, forcing the light through an aperture which is smaller than the wavelength of the light (see Figure) or the coupling of the light to a plasmon to form a surface‐plasmon polariton are described. The latter method is particularly suitable for determining, for example, the optical thickness of an ultrathin transparent film with high precision on a micron scale.

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Materials science and engineering for the 1990's
Authors: Flemings Merton C.
Published: December 2004

Merton Flemings, head of materials science and engineering at the Massachusetts Institute of Technology recently co‐chaired a study of American performance in materials science and summarizes here the salient points of the report. Robert Cahn of Cambridge University, UK, gives his opinion in this issue's book review section.
Ultrasmall semiconductor particles sandwiched between surfactant headgroups in langmuir‐blodgett films
Authors: Xu Shuqian , Zhao Xiao Kang , Fendler Janos H.
Published: December 2004

The incorporation of performed CdS semiconductor particles between surfactants in LB‐films is reported. The sandwich structures are potentially of great technical importance and are characterized by absorption spectroscopy, electron diffraction and scanning tunneling microscopy.
Surface analysis III. Planar array of atomic scale tunneling diodes
Authors: Rabe Jürgen P.
Published: December 2004

Surface Analysis III: The recent demonstration of the tunneldiode effect on an atomic scale forms the basis of this article which also looks at the overall trends towards miniaturazation of devices down to the atomic scale. The latest achievement is based on the ability of the scanning tunneling microscope (STM) to image regions of negative differential conductivity on the surface of boron doped silicon.
Materials research in France
Authors: Garnier Francis
Published: December 2004

Francis Garnier of the CNRS in Thiais, France, introduces this special issue of ADVANCED MATERIALS which has a a theme “Materials Science in France”. Professor Garnier, who coordinated many of the articles for this edition starts the ball rolling with a general view of the particular strengths of French research. Individuals wishing to perform a similar role for a future issue, concentrating on another country or even topic, should contact the Editors as soon as possible to discuss their ideas.
Semiconductor wafer bonding
Authors: Lehmann V. , Ong I. W. K. , Gösele U. , Stengl R. , Mitani K.
Published: December 2004

High‐voltage pn‐diodes, and silicon on insulator (SOI) materials are two applications that could benefit from a new method of wafer bonding which can be carried out in a normal laboratory environment. The procedure, which involves spinning the wafers at high speed (see figure) thus creating a “micro‐cleanroom” between them, could also have applications in micro‐mechanical work and wafer protection.

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Biomaterials highlights VI Dental implants
Authors: Heinke Günther
Published: December 2004

The design of implants, the materials used, and the interactions of these materials with the surrounding living tissue are examined with respect to dental applications.
Intermag'90 in Brighton
Authors: Hartmann Uwe
Published: December 2004

Uwe Hartmann of the Jülich Research Center reports on his recent visit to meeting on magnetic materials which was held on the south coast of Britain.
III/V semiconductors: Substrate materials and epitaxy
Authors: Packeiser Gerhard
Published: December 2004

High‐speed‐, and optical devices are two applications of compound semiconductors. The methods used in the production of GaAs (and other III‐V semiconductors) including MBE and MOCVD, are discussed along with materials characterization and present and future applications.

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Polypyrrole‐dodecylsulfate: 2 × 104 cycles with an organic electrochromic material in a Basic Medium
Authors: De Paoli Marco‐A. , Panero Stefania , Paserini Stefano , Scrosati B.
Published: December 2004

The remarkable stability of the electrochromic title compound in aqueous base (KOH) has been demonstrated over 2 · 104 charge/dischage cycles. Conducting polymer films containing inorganic anions usually show high sensitivity to water, losing activity rapidly, but the dodecylsulfate surfactant anion improves the stability to the extent that efficient cycling is possible even in basis media.
Laser‐induced polymerization of siloxanes without photoinitiators
Authors: Roth Wolfgang , Henkel Hans‐J. , Hoffmann Klaus W. , Markert Helmut
Published: December 2004

High‐purity polymers even os the chemically inert dimethylsiloxane (see figure) can be produced by initiating the polymerization of the monomers using laser light rather than chemical initiators which are usually one of the main sources of impurities in the polymers. Polysiloxanes are used in electronics due to their excellent thermal and dielectric properties.

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Ceramic powder processing in san diego
Authors: Opitz Joachim
Published: December 2004

Joachim Optiz of Philips reports on a meeting on ceramic powders in the USA and Marcell Peuckert of Hoechst describes activities at a recent meeting on high‐Tc superconductors in southern Germany.
Hydrothermal modification of crystalline imperfections in a platinum sol
Authors: Duff Daniel G. , Edwards Peter P. , Kirkland Angus I. , Jefferson David A.
Published: December 2004

Small metallic particles in colloidal solutions can be used for the production of effective room‐temperature catalysts. Here, a method commonlyused in the structural modification of ceramic suspensions is applied to platinum particles and found to significantly improve the crystalline perfection of the colloid, as demonstrated by high‐resolution electron microscopy.
Polymer‐salt intercalation complexes in layer silicates
Authors: Ruiz‐Hitzky Eduardo , Aranda Pilar
Published: December 2004

Composite ionic conductors based on homoionic montmorillonites (2:1 charged layers silicates containing metal ions in their interlayer space) cinteracted with poly(ethylene oxide) exhibit enhanced condcutivity between silicate layers (see figure). The presence of tunnels in the intercalated polymer–salt complex is thought to facilitate intracrystalline ion mobility.

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Biomaterials highlights VII. Implants in ear nose and throat (ENT) surgery
Authors: Heimke Ganther
Published: December 2004

Implants are used in all three major fields of ENT surgery with, however, widely varying materials requirements. In contrast to most other fields of implantology, the transmission of functional loads is only of minor importance and, thus, neither the mechanical properties of the implant materials nor the interfacial stress and strain fields demand major consideration.
Materials from controlled exothermic reactions
Authors: Merzhanov Alexander G.
Published: December 2004

Technical ceramics, shape‐memory alloys and catalysts are among teh materials which can be produced using self‐propagating high‐temperature synthesis (SHS). The high‐temperatures and synthesis rates result in self‐purification, self annealing and self‐purfication phenomena which lead to materials which differ considerably in structure from those conventionally produced. The method and its applications are described by one of its discoverers.
Cluster formation during desorption of multilayers of fatty acid salts
Authors: Tippmann‐Krayer Petra , Meisel Werner , Mölnwald Helmut
Published: December 2004

The thermo desorption mechanism of Cd‐arachidate langmuir–Blodgett films has been shown to involve the lateral rupture of the film to give droplets (see Figure). On further heating, these droplets lose the aliphatic molecular part resulting in a uniform lateral distribution of three‐dimensional inorganic clusters on the substrate surface.

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Organic superconductors in South Lake Tahoe
Authors: Alberts Albert
Published: December 2004

Albert Alberts of Eindhoven University reports on a meeting on organic superconductors in the USA, and Wolfram Gronski (Freiburg, Germany) on the Networks '90 meeting in Israel.
Characterization and modification of conducting substrates for ultrathin organic films by scanning tunneling microscopy
Authors: Buchholz Stefan , Fuchs Harald , Rabe Jürgen P.
Published: December 2004

Communication: The structure of an organic film of molecular thickness depends strongly on the surface properties of the underlying substrate. STM is a method which enables a substrate surface to be characterized and controlled as demonstrated in the figure, where the letter “U” etched with an STM tip into a highly oriented pyrolytic graphite (HOPG) surface is shown. The holes, which are around 5 nm in diameter, could serve as nucleation sites for an organic adsorbate phase.

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Electrical and optical properties of polymers in canterbury
Authors: Pantelis Philip
Published: December 2004

Conference Reports Philip Pantelis, of British Telecom, describes a meeting on the electrical and optical properties of polymers held at the University of Kent, UK, and Palffy‐Muhoray (Ohio) reports on his visit to a liquid crystals conference in Canada.
Atomic‐resolution electron holography – a realization of gabor's dream?
Authors: Saldin Dilano K.
Published: December 2004

Research News: Three‐dimensional atomic‐resolution images of copper atoms have recently been produced by the computer reconstruction of superimposed far‐field (Fraunhofer) interference patterns generated by electron scattering by individual atoms in the sample. The use of photoelectron sources lends holography chemical specificity and enables the location of atoms around chemically identifiable species to be imaged separately. The historical development of electron holography is described and some examples of the latest achievements given.
The Synthesis of Polymer Supports
Authors: Arshady Reza
Published: December 2004

Conventional polymer supports (polymeric reagents, functional polymers) such as polyacrylamides and polystyrene are based on either strongly polar or nonpolar chemical structures. As a result, these polymers may show low reactivity and poor performance due to their relatively limited ranges of solvent and substrate compatibility. More‐recently introduced products are designed on the basis of copolymer structures, which incorporate both polar and nonpolar (hydrophilic and hydrophobic) residues and possess general solvent and substrate compatibility. Due to their ease of production, general solvent and substrate compatibility and improved performance, these new “amphiphilic” copolymers provide new impetus in the study and applications of polymer supports and functional polymers.
Solid‐state NMR of Heterogeneous Materials
Authors: Blümich Bernhard
Published: December 2004

Most solid matrials are hetorogeneous on a microscopic or a microscopic scale, or both. Examoles of hetrogeneties are the phase structure of incompatible polymers, pores in ceramics, distributions in mechanical stress, variations in molecular order and mobility of extruded polymers, and chemical composition in composite materials. Nuclear magnetic resonance (NMR) spectroscopy has unique capabilities for detailed characterization of such hetrogeneities: Microscopic structures between 1 nm and 200 nm can be investigated in spin‐diffusion studies, whereas macroscopic structures above 10 μm can be analyzed in imaging experiments.
Sol–gel processes
Authors: Reuter Hans
Published: December 2004

Research News: Ceramic materials for applications in electronics, solar‐energy conversion, optics, etc. can be synthesized using the sol–gel process. In the first part of a two‐part article the basic concepts of the process, its requirements, and potential, including ceramic precursors, reaction mechanisms and the historical development are described.
Metal injection molding: Shaping sintered metal parts
Authors: Michaeli Walter , Bielzer Raffael
Published: December 2004

Reserch News: Rapid production of high‐tolerance metal parts with complex shapes through combining the sintering process with injection molding, a technique usually used for plastics, is described. Injection of a mixture of metal powder and binder is followed by removal of the binder (right) and then sintering to the final density (left).

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Molecular materials IV. Buckminsterfullerene—a molecular material for the future?
Authors: Miller Joel S.
Published: December 2004

Research News/Molecular Materials IV: Superconducting C60 with the highest known Tc for molecular superconductors was reported recently by workers from AT&T. Recent work on the newest form of elemental carbon is discussed from a materials point of view.
The detection of halogenated hydrocarbons via host–guest chemistry—a mass‐sensitive sensor study with QMB‐ and SAW‐devices
Authors: Dickert Franz L. , Bauer Petra A.
Published: December 2004

Communication: Ring‐like structures composed of different numbers of glucose molecules, the cyclodextrins, in which the central cavity (see Figure) can be varied in diameter from 4.7–8.5 Å have been shown to act as specific host materials for a number of halogenated hydrocarbons. The effect, and potential applications as solvent sensors based on quartz‐microbalence‐ and surface‐accoustic‐wave oscillator devices are discussed.

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Electron/proton transfer reactions and superconductivity: The role of hydrogen in lanthanum copper oxide
Authors: Rudolf Peter , Paulus Werner , Schölhorn Robert
Published: December 2004

Communication: Is lanthanum copper oxide really lanthanum copper oxide? Evidence is presented showing that the conventionally prepared semiconductor La2CuO4, which has been the starting material in many studies of the high‐Tc superconducting copper oxides, is in fact a nonstoichiometric oxide hydroxide (La1.95CuO3.86(OH)0.14). It is also shown that the conversion of the semiconducting phase to the superconducting phase by anodic oxidation does not proceed via the insertion of oxygen into the La2CuO4 but rather over an electron/proton transfer process.
Of Mimesis and Men
Authors: Maddox John
Published: December 2004

Talking Point: Some of the criticisms levelled at the Journal Nature in the preceeding article of the issue are addressed by its Editor, and ethical reporting and portrayal of research advances discussed. Comments from readers, in the form of “Letters to the Editor” would be most welcome.
Crisis or change?
Authors: Paulus Kurt
Published: December 2004

„Publishing in Materials Science”︁, one of the main themes of this issue, which includes increased coverage of publishers' recent efforts in materials science, is introduced by Kurt Paulus, publishing director of the Institute of Physics. He discusses the effects of the information explosion both on publishing practice and on the ability of libraries to keep pace with new publications and the changing literature requirements of the research community.
Talking Point. Is it as simple as ABC?—a biocompatibility consensus
Authors: Braybrook Julian H.
Published: December 2004

Research News/Talking Point: The need for standardization in the analysis of the properties of materials intended for use in biomedical applications is the subject of this discussion type article. The various materials and characterization methods are summarized and the status of European and global efforts at coordinating activities examined.
Pillared randomly interstratified clay as a highly heat‐stable catalytic solid
Authors: Urabe Kazuo , Kouno Naoki , Sakurai Hiroaki , Izumi Yusuke
Published: December 2004

Communication: Catalytic interstratified clays with a thermal stability equal to that of zeolites have recently been produced based on the unfortunately rare rectorite clay. Here, a synthetic alternative to pillared rectorite is presented, which exhibits both a higher catalytic activity and thermal stability and is based on synthetic mica–montmorillonite.
Molecular materials V Part A. Molecular nonlinear optical materials—potential applications
Authors: Eaton David E. , Meredith Gerald R. , Miller Joel S.
Published: December 2004

Research News/Molecular Materials V Part A: The move from electronics through photronics to photonics in applications such as data transfer is discussed in terms of the need for new materials. The advantages gained through the use of photons instead of electrons in nonlinear‐optical applications include the absence of cross‐talk or interference due to the relatively weak interactions between photons.
Characterization and optimization of langmuir‐blodgett films containing polymer‐bound fluorophores
Authors: Siegmund Hans‐Ulrich , Becker Arno , Möbius Dietmar
Published: December 2004

Communication: The covalent and homogeneous incoporation of fluorophores (coumarin dyes) into Langmuir‐Blodgett films of amphiphilic polymethacrylates is reported. Method for optimizing the flourescence and quality of the films, which have potential applications in biosensing, are discussed and the properties of an amphiphilec, monomeric coumarin which forms mixed monolayers with other aphiphiles described.
High‐Performance Polymers
Authors: Herold Friedrich , Schneller Arnold
Published: December 2004

The various applications of high‐performance polymers, for example in hollow‐fiber membranes (see figure) or as gears in chemical pumps, require materials with widely differing properties. An overview of the different classes of high‐performance polymers available, including polyetherketones, polysulfones, and polyamides, is provided and the various combinations of mechanical strength, thermal stability, chemical resistance, and electrical properties are discussed.

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Covalent High‐Performance Ceramics
Authors: Böcker Wolfgang D. G. , Hamminger Rainer , Heinrich Jürgen , Huber Jürgen , Roosen Andreas
Published: December 2004

Non‐oxide ceramics, for example aluminum nitride, silicon carbide, and silicon nitride, are ideal materials for applications under high thermal and mechanical stress. The synthetic methods including liquid‐phase sintering processes, the microstructures of the resulting materials (figure shows Si3N4 from powder produced using the diimide route), and some aspects of the characteization and application of the materials are discussed.

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Ferroelectric liquid crystals in high information content displays
Authors: Escher Claus , Wingen Rainer
Published: December 2004

Rugged, light, high‐resolution flat panel displays are now being developed using liquid‐crystal (LC) technology with the aim of replacing cathode ray tubes in for example computer monitors and televisions. The basic concepts of the displays are described, the advantages and drawbacks of the most important technologies are compared, and some recent work on ferroelectric LC displays which promise high contrast and brightness (see figure) is reviewed.

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Miscible Polymer Blends: Local interaction energy theories and simulations
Authors: Jacobson Solomon H. , Gordon Douglas J. , Nelson Gregory V. , Balazs Anna
Published: December 2004

Polymer blends of two components, in general, are not miscible. However, according to Karasz‐MacKnight theory, intramolecular repulsion may outweigh intermolecular repulsion and cause two polymers to have a net interaction. Using a simple short chain molecular model incorporating both interand intramolecular interactions, estimates of net interaction energies for a series of polymeric imides, benzimidazoles and related high‐performance polymers can be calculated and used to predict miscibility in excellent agreement with experimental results, thus providing a useful confirmation of theory and a focus for the direction of further experimental work.
Synthesis, processing sand properties of thermotropic liquid‐crystal polymers
Authors: Yoon Hyun N. , Charbonneau Larry F. , Calundann Gordon W.
Published: December 2004

Thermotropic liquid‐crystal polymers for high‐performance applications are typically based on wholly aromatic polyester and polyamide architectures. The linear character of the aromtic monomers produces polymer chains with stiff, extended conformations. As a result, the chains organize themselves into a nematic melt and readily orient in response to processing flow fields. The close coupling between chain orientation and flow fields produces both a rich variety of materials and a high degree of controllability of their structure and properties (such as the tensile strength, elastic modulus and coefficient of thermal expansion). In this paper, we describe synthetic efforts to develop liquid‐crystal polymer structures and the relationships between chain molecular structure, processing, and properties of this class of polymers in two distinct processing situations: Injection molding and fiber formation. The special importance of the orientational flow field in developing high orientation and excellent mechanical properties will be highlighted.
Particle size control during production of ceramic nitride powders
Authors: Dorn Friedrich W. , Krquse Werner , Schröder Frank
Published: December 2004

Modern high‐performance ceramics, such as silicon nitride, silicon carbide, and aluminum nitride are manufactured from ceramic powders (see figure) which have to meet sstringent requirements regarding purity and grain size. Control of the grain size during the first steps of the chemical synthesis of the powders is importnat and has been achieved in the manufacture of silicon nitride via silicon diimide, and aluminum nitride via the carbothermal nitridation of aluminum hydroxide.

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Electrical contactswith low resistance for melt‐processed high‐Tc Superconductors
Authors: Elschner Steffen , Bock Joachim
Published: December 2004

Low electrical resistance and high thermal and mechanical stability are required of the materials used to connect ssuperconducting materials with normal conducting leads. The sputter deposition of silver or gold layers into melt‐processed BSCCO superconducting material results in contacts in the mω range which is too high for high‐current applications. An alternative method is presented which takes advantage of the BSCCO production method and requires no additional processing steps.
The dechema materials and the chemical industry
Authors: Kreysa Gerhard
Published: December 2004

The DECHEMA is a non‐profit making technical and scientific society dedicated to supporting the development of chemical apparatus and machinery, and of chemical engineering, biotechnology and their scientific fundamentals. The new Managing Director of the DECHEMA, which has over 2700 members, describes how the society meets the interdisciplinary challenge of supporting the study and use of materials in the chemical industry, for example by organizing the well‐known ACHEMA trade fair.
The quest for magnetic polymers – caveat emptor
Authors: Miller Joel S.
Published: December 2004

Molecular Materials VI A: Reports of ferromagnetic organic polymers have been published since 1986. The validity of these reports, and the research aimed at the synthesis and characterization of such materials are discussed and, since the reported saturation magnetization values are consistent with only a few percent of the bulk exhibiting cooperative magnetic behavior, the tissue of the source of the magnetic behavior is addressed.
Relatively isotropic superconductivity at 8.3 K in the Lamellar organometallic intercalate SnSe2{Co(η‐C5H5)2}0.3
Authors: O'Hare Dermot , Wong Heng‐Vee , Hazell Stephen , Hodby Jonathan W.
Published: December 2004

Superconductivity in SnSe2{Co(ν‐C5H5)2}0.3 is notable for its high transition temperature—teh highest of any known organometallic intercalate—and because it is more three‐dimensional and less anisotropic than in any other previously reported intercalate. While intercalation of organometallic guests into layered 5d transition metal dichalcogenides causes large increases in the anisotropy of the electronic properties, in SnSe2 the anisotropy is reduced. The critical properties of the superconducting state of this material, including their anisotropy, have been studied in order to investigate the origins of electron pairing in this system.
Two‐dimensional nucleation and layer‐by‐ layer deposition of conducting polymers
Authors: Li Feng‐Bin , Albery W. John
Published: December 2004

Highly conducting conjugated organic polymers have stimulated great interest and are now finding important applications. However, despite much recent research, the structure and conducting mechanism of these polymers as well as the way in which the polymers are build up are in general still poorly understood. This article describes a new line of attack: a detailed examination of the mechanism by which the solid polymer phase in built up from polymers dispersed in solution, revealing that the nucleation and growth may be two or three dimensional.
Electronic mail in Europe
Authors: Fassbender Frank
Published: December 2004

How can electronic mail improve access to, and the exchange of, scientific information? This is the question addressed. The structure of the various systems, their current status and development, and their importance with respect to participation in, for example, the BRITE‐EURAM projects, are discussed. A new European network, Y‐NET, which uses the X.400 system, is described and the Network's activities aimed at promoting the use of e‐mail services reviewed.
Spin Transition Molecular Materials for displays and data recording
Authors: Kahn Olivier , Kröber Jonas , Jay Charlotte
Published: December 2004

The development of recording media based on molecular spin‐transition (ST) materials is discussed and applications demonstrated for the first time. The figure shows a compound which exhibits an ST and which is based on FeII and 1,2,4‐triazole units. The central FeII ion undergoes an ST at around 210 K which is accompanied by a purple‐white color change. Requirements for future progress are reviewed.

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A new method for thermal polycondensation of volatile molecular precursors—synthesis of polymeric silicon methyldiimide si(NH)NCH3
Authors: Jonsen Martin , Löffelholz Josua
Published: December 2004

Inorganic polymers are attractive precursors for high‐performance ceramics. A new method of producing the polymers via thermal polycondensation of volatile molecular precursors is presented which does not involve the use of catalysts and therefore avoids contamination of the polymers with the catalysts or with byproducts of the catalytic reaction. The example presented is the polycondensation of tetrakis(methylamino)silane, which is a readily available precursor for Si3N4/SiC ceramics.
Electrochemical deposition and characterization of poly(2,5‐dimethoxyaniline): A new highly conducting polyaniline with enhanced solubility, stability and electrochromic properties
Authors: Zotti Gianni , Comisso Nicola , D'Aprano Giuseppe , Leclerc Mario
Published: December 2004

Substituted polyanilines are of interest due to their increased solubility over polyaniline. However, early experiments showed that the substituted materials, while exhibiting a higher solubility (and thus workability), were also less conducting. Here, it is shown that dialkoxy substitution of aniline increases solubility of the polymer while not reducing the conductivity. The lower steric hindrance caused by teh methoxy groups in comparison with methyl groups is thought to be responsible.
The Top‐CARL, process: A patterning technique for organic materials
Authors: Leuschner Rainer , Ahne Hellmut , Hammerschmidt Albert , Kolodziej Günter , Nordmann Jens , Schmidt Erwin , Sebald Michael , Sezi Recai
Published: December 2004

The patterning of organic layer materials is often hindered by the effects of the conditions used to “develop” the resist material, for example high temperatures for strong bases, which attack the substrate. The process described here allows the patterning even of delicate layers of oriented nonlinear optical polymers. The figure shown a patterned polyimide film 115 μm thick.

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Porous silicon preparation: Alchemy or electrochemistry?
Authors: Lehmann Volker
Published: December 2004

In microporous silicon (microPS) every tenth atom is a surface atom and surface processes in silicon are notoriously difficult to study, making the investigation of effects such as electroluminescence difficult. Add to this the profound effects of varying the production parameters and one has a complicated situation where results are often difficult to interpret correctly. Several preparation techniques are reviewed and recent progress made in understanding microPS discussed.
Progress toward biologically produced Biodegradable Thermoplastics
Authors: Poirier Yves , Dennis Douglas E. , Nawrath Christiane , Somerville Chris
Published: December 2004

Genetically‐engineered bacteria which produce biodegradable polymers and copolymers with structures which depend on the culture in which they are kept are receiving increasing attention. Up to 90% of the dry weight of the bacteria can be intracellular granules of the plastic (see Figure), and the properties of the polymers can be controlled by varying the carbon‐based nutrition of the bacteria. Recent advances are reviewed, including the use of plants instead of bacteria.

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Mesophase formation in α‐sexithienyl at high temperature—an X‐ray diffraction study
Authors: Destri Silvia , Mascherpa Marco , Porzio William
Published: December 2004

The formation of a mesophase in α‐sexithienyl is reported which cannot be identified as either a nematic or smectic phase. On heating, it is also shown that, through careful control of the reaction conditions, crystalline polythiophene comparable in quality with that prepared by electrosynthesis or other synthetic methods can be obtained. The materials are studied using high‐temperature X‐ray diffraction and differential scanning calorimetry.

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A novel metal‐containing polymer: Poly(germanium enolate)
Authors: Kobayashi Shiro , Shoda Shin‐ichiro
Published: December 2004

Germanium‐containing polymers based on metal enolates have in the past not been synthesized due to the difficulty in obtaining stable enolates and to the fact that traditional preparation routes were geared to the production of monomeric species. A method for preparing these technologically interesting organometallic polymers is presented and discussed.
The federation of european materials societies (f.e.m.s.)
Authors: Kostorz Gernot
Published: December 2004

The coordination of European materials research activities is one of the aims of the Federation of European Materials Societies (f.e.m.s.). The current President of the Federation describes the structure of the organization, which is made up of many national European materials societies, and discusses both planned activities, which include the extension of the successful “EUROMAT” conference series, and long‐term future aims.
Mechanical Alloying of Titanium‐Base Alloys
Authors: Suryanarayana Challipalli , Froes Francis H.
Published: December 2004

Application of mechanical alloying to titanium‐base alloys is a recent development. A wide range of terminal phases and those based on titanium aluminides (both Ti3Al and TiAl) have been examined and it has been shown that synthesis of metallic phases can be achieved by mechanical alloying. The phases so synthesized include solid solutions, intermediate crystalline phases, amorphous phases, and nanostructured materials. It has also been shown that the resistance to coarsening of both the grains and the dispersoids in mechanically alloyed Ti3Al based alloys is much higher than in rapidly solidified alloys. The review concludes with some thoughts on future developments in this exciting area.
Fluorescent sensors and color‐change indicators for molecules
Authors: Ueno Akihiko
Published: December 2004

Cyclodextrins substituted with a fluorescent group can be employed as molecular sensors. The Figure shows how the fluorophore usually occupies the hydrophobic interior of the cyclodextrin host. On addition of a guest, the fluorophore is displaced from the cavity, resulting in a change in its spectral response. Recent progress with this and related molecular sensors is discussed.

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Ferroelectric Liquid Crystals with an alkanoyl group
Authors: Kobayashi Shogo , Ishibashi Shigeki , Takahashi Kazue , Tsuru Shinji , Yamamoto Fumio
Published: December 2004

Recent studies on ferroelectric liquid crystals (FLCs) with an alkanoyl group are reviewed in this article. The FLCs exhibit large spontaneous polarization, especially when another chiral group is introduced at the opposite side of the core. The maximum value reaches 1130 nC/cm2, which is almost the same as the total transverse dipole in the molecule. Fastswitching FLC mixtures can be obtained by using these compounds. The synthesis and properties of FLC polymers having the same mesogen and chiral group are also described, and some applications of the FLC mixtures in devices for optical communication reported.
Overwrite repeatability of GeSbTe phase‐change‐type optical disk media
Authors: Yamazaki Hiroki , Sugiyama Yasuyuki , Chiba Reiichi , Yagi Shougo
Published: December 2004

Phase‐change‐type erasable optical recording media can be overwritten in a simple process, which should lead to a faster data transfer rate and cheaper optical storage devices. The properties of various protective layer materials for optical disks have been investigated, including their surface flatness (see Figure), reflectivity stability and error modes during repeated overwriting.

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High efficiency persistent spectral hole‐burning materials
Authors: Suzuki Hiroyuki
Published: December 2004

Persistent spectral hole‐burning (PSHB) materials based on donor–acceptor electron transfer have promising characteristics for future memory applications, i.e. high recording speed and high recording density, that cannot be matched by conventional PSHB materials. Novel PSHB materials are described in which spectral holes can be burnt on nanosecond or sub nanosecond time scales. A materials design guideline for optimizing donor‐acceptor combinations is presented and goals of future work are discussed.
Novel colorless composite materials for nonlinear optics
Authors: Aakeröy Christer B. , Azoz Nazar E. , Kadim Munteser , Seddon Kenneth R. , Trowbridge Lynne
Published: December 2004

Colorless SHG‐active composite materials could have great potential in nonlinear optics applications, for example in optoelectronic devices. The composite materials are produced using a novel solution‐based process, followed by poling through solvent evaporation along a thermal gradient, enabling the variation of the guests and hosts in order to tune the properties of the materials. The new method provides a versatile alternative to the thermal gradient zone melting technique.
Microwave absorbing materials based on conducting polymers
Authors: Olmedo Laurent , Hourquebie Patrick , Jousse Franck
Published: December 2004

Blends of conducting and insulating polymers (e.g. polypyrrole/PVC, see figure) offer distinct weight advantages over the materials, such as dispersions of carbon black or metallic powders in polymer matrices, traditionally used in microwave absorption applications. Polypyrrole, polyaniline, and polythiophene have been examined, their performance parameters compared, and requirements for further development of this technology dicussed.

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